Bosch Appliances Water Heater 125B LP User Manual

INSTALLATION AND OPERATING INSTRUCTIONS FOR AUTOMATIC  
INSTANTANEOUS TYPE WATER HEATERS FOR USE WITH NATURAL AND  
LIQUEFIED PETROLEUM GAS  
MODEL 125B LP and 125B NG (Flow Modulated)  
Suitable for heating potable water only  
Not approved for space heating purposes  
Intended for variable flow applications with steady cold water inlet temperatures only  
WARNING  
If the information in this manual is not followed exactly, a  
fire or explosion may result causing property damage,  
personal injury or death.  
FOR YOUR SAFETY  
Do not store or use gasoline or other flammable,  
combustible or corrosive vapors and liquids in the vicinity  
of this or any other appliance.  
WHAT TO DO IF YOU SMELL GAS  
- Do not try to light any appliance.  
- Do not touch any electrical switch; do not use any  
phone in your building.  
- Immediately call your gas supplier from a neighbor’s  
phone. Follow the gas supplier’s instructions.  
- If you cannot reach your gas supplier, call the fire  
department.  
- Installation and service must be performed by a  
qualified installer, service agency or the gas supplier.  
TABLE OF CONTENTS  
Specifications....................................... Page 2  
Rules for safe operation..................... Page 4  
WARNING: Improper installation, adjustment,  
alteration, service or maintenance can cause injury or  
property damage. Refer to this manual. For assistance  
or additional information consult a qualified installer,  
service agency or the gas supplier.  
Upon completion of the installation, these instructions  
should be handed to the user of the appliance for future  
reference.  
Locating the Heater ............................ Page 4  
Combustion Air Requirements .......... Page 5  
Mounting the Heater ........................... Page 6  
Venting the Heater .............................. Page 7  
Gas Connections ..............................Page 10  
Water Connections ...........................Page 12  
Safety before lighting the pilot .......Page 12  
Lighting instructions ..........................Page 13  
Setting water temperature ...............Page 13  
Maintenance & Service....................Page 13  
Trouble Shooting................................Page 14  
Diagram of AquaStar ........................Page 19  
Components and Parts List ............ Page 20  
In the Commonwealth of Massachusetts this product  
must be installed by a licensed plumber or gas fitter.  
 
FRONT VIEW  
SIDE VIEW  
MINIMUM INSTALLATION CLEARANCES FROM COMBUSTIBLE AND NON  
COMBUSTIBLE MATERIALS FOR ALCOVE OR CLOSET INSTALLATIONS  
MODEL 125B  
TOP (A)  
12 "  
4 "  
FRONT (B)  
BACK  
0 "  
SIDES  
4 "  
FLOOR (C)  
VENT DIAMETER  
12 "  
5 "  
AQUASTAR MODEL 125B  
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GENERAL RULES TO FOLLOW  
FOR SAFE OPERATION  
PROPER LOCATION FOR INSTALLING YOUR  
HEATER  
Carefully select the location of your new heater. For your  
safety and for proper heater operation, you must provide an  
abundant supply of combustion air and a proper venting  
installation.  
The heater may still operate even when improperly vented.  
It will, however, be less efficient and could eventually damage  
the heater. It could even result in human sickness or death  
due to oxygen deprivation and carbon monoxide poisoning.  
Follow the guidelines below:  
1. You should follow these instructions when you install your  
heater. In the United States: The installation must conform  
with local codes or, in the absence of local codes, the  
National Fuel Gas Code ANSI Z223.1/NFPA 54.  
In Canada: The Installation should conform with CGA  
B149.(1,2) INSTALLATION CODES and /or local installation  
codes.  
2. Carefully plan where you install the heater. Correct  
combustion air supply and flue pipe installation are very  
important. If not installed correctly, fatal accidents can be  
caused by lack of air, carbon monoxide poisoning or fire.  
1. Place your heater as close to a vent or chimney as  
possible.  
2. National building codes require that you do not install  
this appliance in bathrooms, bedrooms, unvented closet or  
any occupied rooms normally kept closed.  
3. The place where you install the heater must have enough  
ventilation. The National Fire Codes do not allow gas fired  
water heater installation in bathrooms, bedrooms or any  
occupied rooms normally kept closed. See the section below  
on locating the heater.  
3. Simultaneous operation of other appliances such as  
exhaust fans, ventilation systems clothes dryers, fireplaces  
or wood stoves could create a vacuum effect in your home  
which could cause dangerous combustion by-products to  
spill back into your home rather than venting to the outside  
through the flue. Confirm that your Aquastar is venting  
properly when all these other appliances are running. See  
section on venting.  
4. You must vent your heater. See section on Venting, Page  
6.  
5. The appliance must be disconnected from the gas supply  
piping system during any pressure testing at pressures in  
excess of 1/2 Psig (3.5 kPa).  
The appliance must be isolated from the gas supply piping  
system by closing its individual manual shutoff valve during  
any pressure testing of the gas supply piping system at test  
pressures equal to or more than 1/2 Psig (3.5Kpa). The  
appliance and its gas connection must be leak tested before  
placing the appliance in operation.  
Do not obstruct the flow of combustion and ventilation  
air to the appliance. If installed near a clothes dryer it is  
very important that the dryer be properly vented. Failure to  
properly vent a dryer could result in a gradual accumulation  
of lint on the water heater fin coils and burners, leading to a  
dangerous condition of vent blockage and poor unsafe  
combustion.  
6. Keep water heater area clear and free from combustibles  
and flammable liquids. Do not locate the heater over any  
material which might burn.  
4. Your hot water lines should be kept short to save energy.  
It is always best to have hot water lines insulated.  
7. Correct gas pressure is critical for the optimum  
operation of this heater (see specifications on page 2). Gas  
piping must be sized to provide the required pressure at the  
maximum output of the heater, while all the other gas  
appliances are in operation. Check with your local gas  
supplier, and see the section on connecting the gas supply.  
5. This product is neither designed nor approved for outside  
installations. This product is not approved for manufactured  
homes (mobile home), recreational vehicles (RV) or boats.  
Reference ANSI Z21.10.3.  
WARNING: The water in this water heater is cold and  
always remains cold except for the times that hot water is  
being used DO NOT INSTALL IN AN AREA WHERE IT  
COULD FREEZE.  
8. Should overheating occur or the gas supply fail to shut  
off, turn off the gas supply at the manual gas shut off valve  
on the gas line.  
9. Do not use this appliance if any part has been underwater.  
Immediately call a qualified service technician to inspect  
the appliance and to replace any part of the control system  
and any gas control which has been underwater.  
Drain the heater entirely if freezing temperatures are  
anticipated in area where heater is installed by disconnecting  
both the inlet and outlet water connections from the heater  
(disconnect the outlet flex line from where it connects to  
the copper heat exchanger). Additionally, remove the drain  
plug under the water valve. See Fig 1.  
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Air Vents  
(10 ¾ X 10 ¾ in. each)  
125B  
Fig. 1 - Water heater drain plug  
WARNING: Flammable materials, gasoline,  
pressurized containers, or any other items or articles  
that are potentially fire hazards must NOT be placed on  
or adjacent to the heater. The appliance area must be  
kept free of all combustible materials, gasoline and other  
flammable vapors and liquids.  
Air Vents  
125B  
(5 ½ X 5 ½ in. each)  
Appliances located in confined spaces:  
The confined space must be provided with two permanent  
openings, one commencing within 12 inches of the top and  
one commencing within 12 inches of the bottom of the  
enclosure. Each opening must have a minimum free area of  
one square inch per:  
- 1000 Btu/hr if all air is taken from inside the building.  
- 2000 Btu/hr if all air is taken from the outside by horizontal  
ducts.  
- 4000 Btu/hr if all air is taken from the outside by direct  
openings or vertical ducts.  
Or the confined space must be provided with one permanent  
opening or duct that is within 12 inches of the ceiling of the  
enclosure. This opening must have a minimum free area of  
one square inch per:  
COMBUSTION AIR REQUIREMENTS  
The AquaStar water heater holds cold water in its copper  
heat exchanger and brass water valve when not in use.  
Because of this, any cold air that comes down through the  
unit’s vent pipe is capable of freezing these components.  
This Installation Manual specifies the minimum vertical vent  
pipe and the amount of combustion air required for this unit.  
When all requirements are followed, the unit will operate  
properly and safely. However, there may still be a risk of  
freezing due to negative draft if all the combustion appliances  
in the area are not being supplied with a sufficient amount  
of make-up air. A wood stove or furnace can rob the make-  
up air in the AquaStar’s vent pipe, leaving the cold infiltrating  
air capable of freezing the cold water in the AquaStar heat  
exchanger. More make up air is the solution. Follow the  
instructions on venting and checking adequacy of make up  
air. A HVAC specialist should be used to design solutions  
for providing more make-up air if necessary.  
- 3000 Btu/hr if all air is taken from the outside by a direct  
opening or vertical duct.  
Louvers, grills and screens have a blocking effect. If the  
effective free area is not known, increase the sizes of your  
openings by 75% if your louvers are wood and by 30% if  
your louvers are metal. Refer to the National Fuel Gas Code  
for complete information. In buildings of tight construction  
all air should be taken from outside.  
Observe the following instructions concerning combustion  
air.  
CLEARANCES  
Appliances located in unconfined spaces:  
a) An unconfined space is one whose volume is greater  
than 50 cubic feet per 1000 Btu per hour of the combined  
rating of all appliances installed in the space. That would  
be 5850 cubic feet for the AquaStar 125B alone.  
The Aquastar 125 B is design certified for installation on a  
combustible wall and for installation in an alcove or closet  
with the minimum clearances to combustible and non -  
combustible construction listed below  
A. Top 12 inches (306 mm)  
b) In unconfined spaces in buildings of conventional frame,  
masonry, or metal construction, infiltration is normally  
adequate to provide air for combustion, ventilation, and  
dilution of flue gasses.  
B. Front 4 inches (102 mm)  
C. Back 0 inches  
D. Sides 4 inches (102mm)  
E. Bottom 12 inches (306 mm)  
Clearance from vent is dependent upon the clearance rating  
of the venting material used. For example: type B-1 vent is  
approved for 1 inch clearance.  
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Note: Typically, the minimum clearence to combustible The incandescent particle tray (shipped loose in the carton  
with the water heater) must be attached at the bottom of  
the water heater front cover at the time of installation. Use  
the screws provided. See figure 3  
materials should not be less than 6for single wall flue  
pipe. Note that this clearance can be reduced if combustible  
materials are protected as per table VI of the National Fuel  
Gas Code or if Type B gas vent is used.  
MOUNTING INSTALLATION  
The Aquastar 125 B is design certified for mounting on a  
wall.  
Secure the two L shaped hooks, which are provided with  
heater, to a wall surface. Place them 13 ¼” apart as shown  
in Fig. 2.  
SCREWS  
INCANDESCENT PARTICLE TRAY  
Do not install this appliance on a carpeted wall or over floor  
covering which is combustible, such as carpet. The heater  
must be mounted on a wall using appropriate anchoring  
materials. If wall is a stud wall sheathed with plasterboard, it  
is recommended that support board(s), either 1x4’s or  
1/2" (minimum) plywood first be attached across a pair  
of studs and then the heater should be attached to the  
support boards. See Fig. 2.  
Fig. 3 - Incandescent Particle Tray Illustration  
Expansion and contraction of piping due to changing water  
temperature in the pipes imparts movement to the heater  
which, if mounted directly to a brittle, friable board, such as  
plasterboard, can cause failure of mounting.  
In earthquake-prone zones, CEC recommends that installers  
use a large washer and lag screw through the existing holes  
used to hang the heater to affix the upper third of the heater  
to the mounting board. To affix the lower third of the heater,  
CEC recommends that two new holes be drilled in the  
heater’s frame, each one 16 inches below the top two holes,  
and that washers and lag screws be used to secure the  
lower portion of the heater to a spacing board.  
Before installing the unit, be certain you have the correct  
heater for your type of Gas – Propane or Natural Gas.  
Identification labels are found on the shipping box, and on  
the rating plate which is located on the right side panel of  
the cover. Also, each burner orifice is stamped with a number  
(79 for LPG and 120 for Natural Gas).  
WALL STUDS  
13 ¼”  
SUPPORT  
BOARD  
1” X 4”  
SPACE BOARD  
Fig. 2 - Mounting the Heater  
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VENTING  
Vent pipe connection. WARNING: Do not reduce the vent pipe size. See Fig. 4 for high altitude installations  
The heater must be vented to the outside following all local ordinances and specifications for installing a gas appliance  
vent or chimney. The heater must be located as close as practicable to a vertically rising chimney or vent that has a listed  
vent cap at its termination point. The venting system must be designed and constructed so as to develop a positive flow  
adequate to remove flue gasses to the outdoors.  
Consult the National Fuel Gas Code if the vent will have elbows or share venting with another natural draft appliance.  
The heater should never be common vented with a mechanically vented appliance. Single wall vent pipe is not  
recommended, if used consult the National Fuel Gas Code.  
Horizontally venting to a sidewall vent terminator or a vertically constructed vent stack along an outside wall of a building  
is not permissible. A Powervent (Model AQ-1), with a proof-of-draft safety interlock device, is required and is available in  
order to sidewall vent. Contact your dealer. In the Commonwealth of Massachusetts: Powervented applications must  
utilize proof-of-draft safety interlock device.  
VERTICAL GAS VENT: A 5 inch diameter gas vent constructed of double wall Type B gas vent is recommended. 6 inch is  
required in elevations greater than 2000 feet, see Fig. 4. Any gas vent section that is greater than 45 degrees from the  
vertical is considered horizontal. Horizontal sections must slope upwards at least ¼ inch for every foot of its horizontal  
length and be properly supported. Keep the horizontal section short and avoid too many elbows. The minimum vertical gas  
vent height allowed is 6 feet; horizontal vent connectors and elbows are not to be considered in the total gas vent height.  
All gas vent sections must be secured to each other with sheet metal screws and be properly supported.  
The gas vent constructed of double wall Type B gas vent must terminate above the roof surface with a listed vent cap at  
a height that’s in accordance with Figure A or B and their table, provided they are at least 8 feet (2.4 m) from a vertical wall  
or similar obstruction. All other gas vents that are not able to terminate within the minimum specified height allowed must  
terminate not less than 2 feet (0.6 m) above the highest point where it’s passed through the roof and at least 2 feet (0.6  
m) higher than any vertical wall or similar obstruction within 10 feet (3.1 m).  
LISTED VENT CAP  
LISTED VENT CAP  
LOWEST DISCHARGE OPENING  
H (minimum) height  
from roof to lowest  
X
discharge opening  
12  
ROOF PITCH  
IS X/12  
MINIMUM 6  
FEET (1.8M)  
MINIMUM 6  
FEET (1.8M)  
LISTED GAS VENT  
ESTABLISH A ONE  
FOOT RISE BEFORE  
ANY ELBOWS  
GAS VENT TERMINATIONS FOR LISTED VENT CAPS  
Roof pitch  
Flat to 6/12  
H (minimum) feet  
meters  
0.30  
0.38  
0.46  
0.61  
0.76  
0.99  
1.22  
1.52  
1.83  
2.13  
2.27  
2.44  
1.0  
1.25  
1.5  
2.0  
2.5  
3.25  
4.0  
5.0  
6.0  
7.0  
7.5  
8.0  
6/12 to 7/12  
Over 7/12 to 8/12  
Over 8/12 to 9/12  
Over 9/12 to 10/12  
Over 10/12 to 11/12  
Over 11/12 to 12/12  
Over 12/12 to 14/12  
Over 14/12 to 16/12  
Over 16/12 to 18/12  
Over 18/12 to 20/12  
Over 20/12 to 21/12  
Figure B  
Figure A  
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MASONRY CHIMNEY: Masonry chimneys shall be built and installed in accordance with NFPS 211 or local codes. A minimum  
5” diameter gas vent pipe (metal double wall Type B), or an approved clay flue liner or a listed chimney lining system must  
be used when venting into a naturally drafting, internal masonry chimney. 6 inch is required in elevations greater than 2000  
feet, see Fig. 4. Local codes may require the use of both gas vent and an approved lining system when venting into a  
masonry chimney. The Commonwealth of Massachusetts requires the use of a listed liner. Lining systems include approved  
clay flue lining, a listed chimney lining system or other approved material that will resist corrosion, erosion, softening, or  
cracking from exhaust flue gases at temperatures up to 1800 degrees F. The lining system must be listed for use with  
naturally drafting, draft hood equipped gas appliances. Follow local codes and refer to NFGC 54 and NFPA 58.  
When connecting the water heater to a masonry chimney the following connector guidelines must be followed for  
safe and proper operation: An approved gas vent connector must be attached to the top of the water heater and rise  
vertically at least 12” before entering into an approved gas vent connector elbow. Any gas vent section that is greater than  
45 degrees from the vertical is considered horizontal. If a horizontal vent connector is to be used to connect the vertical  
gas vent connector on the top of the water heater to the masonry chimney, that approved horizontal gas vent connector  
must be kept as short as possible and must be sloped upwards at least ¼” per foot of its length. This connector must be  
supported throughout its horizontal length. This horizontal gas vent connection may be no greater than 75% of the total  
vertical gas flue vent within the chimney. Also, an approved thimble or collar must be used when penetrating a masonry  
chimney.  
A) Existing INTERIOR Masonry Chimney  
The metal gas vent pipe should be permanently mounted inside the masonry chimney. Double wall Type B gas vent is  
recommended. The masonry chimney may have to be tile or metal lined before the insertion of the gas vent pipe; check  
local codes for clarification. The lining material must be listed for use only with naturally drafting, draft hood equipped gas  
appliances. Follow manufactures instructions for installation of listed lining material. You may not vent any other fuel  
burning appliances into any free space remaining in the chimney. The minimum vertical gas vent length within the masonry  
chimney should be no less than 5 ft (1.5 m); the vent terminator should extend at least 3 feet (0.9 m) above where the  
chimney meets the roofline and at least 2 feet (0.6 m) higher than any vertical wall or similar obstruction within 10 feet (3.1  
m). The top of the gas vent should have an approved vent terminator. See Figure C.  
B) Tile Lined INTERIOR Masonry Chimney  
The masonry chimney must have an approved liner, ceramic tile, clay or metal. The masonry chimney must be able to  
accommodate the spent fuel gasses; consult a venting HVAC contractor for chimney capacity. A common venting like-fuel  
appliance into this lined masonry chimney is permissible. The chimney’s diameter must be large enough to adequately draft  
the spent fuel gasses. A venting HVAC contractor will be required to spec a chimney system. The minimum vertical  
chimney length should be no less than 5 ft (1.5 m); the termination point should extend at least 3 feet (0.9 m) above where  
the chimney meets the roofline and at least 2 feet (0.6 m) higher than any vertical wall or similar obstruction within 10 feet  
(3.1 m). See Figure C.  
C) EXTERIOR masonry Chimney  
Refer to the National Fuel Gas Code and consult a local venting HVAC contractor.  
MASONRY CHIMNEYS  
LISTED VENT CAP  
GAS  
VENT  
VENT CONNECTOR  
ESTABLISH A ONE  
FOOT RISE BEFORE  
ANY ELBOWS  
Figure C  
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To check the draft:  
Close all doors and windows to the outside.  
Turn on all appliances that force air out of the building.  
These include all exhaust/ventilation fans, furnaces, clothes  
dryers, wood burning stoves, etc.  
5” X 6” ADAPTOR  
USED ON HIGH ALTITUDE  
Open all doors between the AquaStar and these other  
appliances.  
With the control knob set fully clockwise and strong hot  
water flow rate, run the unit for at least 10 minutes. The  
125B is equipped with a Flue Gas Sensor; it’s mounted on  
the right side of the draft diverter (Flue Gas Sensor #20 on  
page 17). If the main burners and the pilot flame shut off  
during this test it is because the Flue Gas Sensor has  
detected inadequate venting. This is a serious health hazard  
and must be corrected. Poor venting can result in soot  
building up inside the heater, overheating of the heater and  
freezing of the heat exchanger in a non-freezing environment  
when not in use, which is all a result of negative air flow.  
Additional combustion air and/or improved venting is  
necessary to correct this.  
Fig. 4 - Vent Adaptor for High Altitude Installations  
WARNING: Failure TO INCREASE THE VENT SIZE  
TO SIX INCHES AND/or assure that the manifold pressure  
is set to proper value listed for applications at high altitudes  
will cause unsafe venting, asphyxiation, and will void CSA  
Certification.  
WARNING  
Note: The burners of an instantaneous “on demand” water  
heater such as the AquaStar are only on at the time that  
hot water is actually being used, the vent pipe is therefore  
cold except for the short durations when hot water is being  
used, it is therefore very important that the venting and air  
supply be adequate to provide a good positive draft as soon  
as the burners turn on.  
The AquaStar 125B instantaneous water heaters have built-  
in draft diverters and are designed for indoor installation  
only. The draft diverter outlet must be connected to an,  
unobstructed vent of the same size, or larger.  
In Canada, CAN/CGA-B149 Installation Code for detailed  
requirements  
In U.S.A., ANSI Z223.1 - NFPA 54, National Fuel Gas  
Code for detailed requirements.  
The vent connection for the Aquastar 125B is 5 inches.  
However, for installations at high altitude (over 2000 feet  
above sea level) a six inch vent is required. A 5” by 6” vent  
adaptor must be affixed to the flue collar of the Aquastar  
with at least two screws. See Fig. 4.  
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GAS LINE SIZING  
GAS CONNECTIONS  
-It is strongly recommended that the Natural Gas pipe  
be Black Iron pipe the entire distance from the outside  
meter to the inlet of the Aquastar regulator. 1/2” Black  
Iron pipe up to 10 feet, 3/4” Black Iron pipe up to 40 feet  
and 1” Black Iron pipe up to 150 feet distances. Flex line  
tubing is NOT recommended, but if used then oversize  
it.  
-It is strongly recommended that the LP Gas pipe be  
semi-rigid copper or Black Iron pipe from the outside  
regulator to the inlet of the Aquastar regulator. For semi-  
rigid copper piping: 5/8” up to 20 feet and 3/4” up to 60  
feet distances. For Black Iron piping: 1/2 “ up to 45 feet  
and 3/4” up to 160 feet distances. Flex line tubing is NOT  
recommended, but if used then oversize it.  
NOTE: The Aquastar 125 B is supplied with a gas pressure  
regulator that must be installed on the heater before  
attaching the gas supply line. See fig. 5. Failure to install  
the gas regulator as shown in figure 5 will be a violation  
of CSA certification of the unit. The regulator supplied  
with the heater is preset for the gas shown on the rating  
plate to the correct pressure. It is an appliance level  
regulator designed for (low inlet) pressure (less than 1/  
2 Psig or 15” W.C.)  
DO NOT connect to an unregulated or high pressure  
propane line or to a high pressure commercial natural  
gas line.  
THESE FIGURES ARE FORAQUASTAR SUPPLY ONLY, ALL  
OTHER APPLIANCES IN THE BUILDING WILL NEED TO  
BE INCLUDED IN THE PIPE SIZING.  
National Fuel Gas Code requires that a sediment trap (drip  
leg) be installed on gas appliances not so equipped. The  
drip leg must be accessible and not subject to freezing  
conditions. Install in accordance with the recommendations  
of the serving gas supplier.  
GAS INLET PIPE  
PRESSURE TAP  
PLASTIC VENT CAP  
WARNING: The heater must be disconnected from  
the gas supply piping system during any pressure testing of  
that system at test pressures in excess of 0.5 psig.  
The water heater must be isolated from the gas supply piping  
system by closing the manual shutoff valve during any  
pressure testing of the gas supply piping system at test  
pressures equal to or more than 0.5 psig.  
The water heater, including the pressure regulator provided  
with it, must not be operated at gas supply pressures in  
excess of 0.5 psig. If overpressure has occurred, such as  
through improper testing of the gas lines or malfunction of  
the supply system, the gas valve and regulator must be  
checked for safe operation. Make sure that the regulator  
vent is protected against blockage.  
When your connections are made, check for gas leaks at  
all joints (not just the ones you made). Apply some soapy  
water to all gas fittings and gas valve. Soap bubbles are a  
sign of a leak.  
NOTE: Do not apply soap solution to pilot filter screen or  
pilot orifice area. If you have a leak, shut off the gas. After  
verifying that required gaskets are in place, tighten  
appropriate fittings to stop leak. Turn the gas on and check  
again with a soapy solution. Never test for gas leaks using  
a match or flame.  
PRESSURE REGULATOR  
(with directional arrow on  
reverse side pointing  
upward)  
Fig. 5 - Installation of Gas Pressure Regulator  
The pressure regulator provided with the heater is adjusted  
to deliver the proper gas pressure (as indicated on the rating  
plate and in the manual for altitude up to 2000 feet (660  
meters) above sea level. On appliances being installed above  
2000 ft (660 meters) elevation, the inlet gas pressure should  
be set at installation to the value shown below.  
NOTE: The gas pressures specified below refer to  
pressures taken at the pressure tap on the gas inlet pipe  
just above the regulator (See Fig. 5).  
These readings should be taken while the heater is  
operating at full input — i.e. maximum water flow with  
the temperature dial selector turned all the way clockwise.  
MAXIMUM INLET GAS FLOW PRESSURE SETTING  
Altitude  
Natural Gas  
inches W.C:  
5.7"  
Liquid Propane  
inches W.C:  
10.5"  
0' - 2.000 ft  
2.000 ft - 4.500 ft  
4.6"  
8.4"  
Above 4.500 ft consult your local gas supplier.  
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GAS PIPING, CONNECTIONS and Gas Regulator  
Before connecting the gas supply, check the rating plate on the right side of the front cover to be sure that the heater is  
rated for the same gas to which it will be connected.  
In the United States: The installation must conform with local codes or, in the absence of local codes, the National Fuel  
Gas Code ANSI Z223.1/NFPA 54.  
In Canada: The Installation should conform with CGA B149 INSTALLATION CODES and /or local installation codes.  
GAS LINE SIZING  
FOR NATURAL GAS  
Maximum Capacity of pipe in Cubic Feet of Gas per Hour  
for Gas Pressure of 0.5 Psig or less and a Pressure drop of  
0.3 in Water Column.  
Follow boxed numbers for piping just one Aquastar 125B  
(example: 3/4” B.I. Natural Gas pipe for 30 ft. will handle  
152,000 btu’s). For multiple appliances combine the total  
btu input load and then refer to applicable chart below.  
(Based on a 0.60 Specific Gravity Gas) Btu numbers given  
in thousands.  
Nominal  
Length of Black Iron Pipe, Feet  
Iron  
Pipe  
Internal  
Size, Diameter  
inches inches  
10  
20  
30  
40  
50  
60  
70  
80  
90  
100  
125  
150  
175  
200  
1/4  
3/8  
1/2  
0.364  
0.493  
0.622  
32  
72  
22  
49  
92  
18  
40  
73  
15  
34  
63  
14  
30  
56  
12  
27  
50  
11  
25  
46  
11  
23  
43  
10  
22  
40  
9
8
8
7
6
21  
38  
18  
34  
17  
31  
15  
28  
14  
26  
132  
3/4  
1
0.824  
1.049  
278  
520  
190  
350  
152  
285  
130  
245  
115 105  
215 195  
96  
90  
84  
79  
72  
64  
59  
55  
180  
170  
160  
150  
130  
120  
110  
100  
1 1/4  
1 1/2  
2
1.380  
1.610  
2.067  
2.469  
3.068  
4.026  
1050  
1600  
3050  
4800  
8500  
730  
590  
890  
500  
760  
440 400  
670 610  
370  
560  
350  
530  
320  
490  
930  
305  
460  
870  
275  
410  
780  
250  
380  
710  
225  
350  
650  
210  
320  
610  
1100  
2100 1650 1450  
3300 2700 2300  
5900 4700 4100  
1270 1150 1050 990  
2 1/2  
3
2000 1850 1700 1600 1500 1400 1250  
3600 3250 3000 2800 2600 2500 2200  
1130 1050 980  
2000 1850 1700  
4
17,500 12,000 9,700 8,300 7,400 6,80 6,200 5,800 5,400 5,100 4,500 4,100 3,800 3500  
Nominal  
FOR LP GAS  
Iron Pipe  
Size,  
Black Iron Pipe  
Length of Pipe, Feet  
Maximum Capacity of Pipe in Thousands of  
BTU per Hour of Undiluted Petroleum Gases  
(at 11 inches Water Column Inlet Pressure)  
(Based on a Pressure Drop of 0.5 Inch Water  
Column).  
10 20 30  
40 50 60 70 80 90 100 125 150  
Inches  
1/2  
275 189 152 129 114 103 96 89 83  
78  
69  
63  
3/4  
1
567 693 315 267 237 217 196 185 173 162 146 132  
107 732 590 504 448 409 378 346 322 307 275 252  
1 1/4 220 149 121 103 913 834 771 724 677 630 567 511  
1 1/2 330 229 185 155 141 127 118 108 102 976 866 787  
2
622 433 346 299 264 239 220 204 192 1811 1606 1496  
Copper  
Outside  
Diameter,  
Inch  
Length of Tubing, Feet  
Maximum Capacity of Semi-Rigid  
10 20  
39 26  
92 62  
30  
21  
50  
40  
19  
41  
50  
_
60 70 80 90 100  
Tubing in Thousands of BTU per Hour of  
Undiluted Liquified Petroleum Gases (at 11  
inches Water Column Inlet Pressure)  
_
_
_
_
_
3/8  
1/2  
37  
79  
35 31 29 27 26  
72 67 62 59 55  
121 112 104 95 90  
187 164 155 146 138  
(Based on a Pressure Drop of 0.5 Inch Water  
Column)  
5/8 199 131 107 90  
3/4 329 216 181 145 131  
7/8 501 346 277 233 198  
* Source National Fuel Gas Code NFPA 54, ANSI Z223.1 - No  
Additional Allowance is necessary for an ordinary number of fittings  
6 720 607 030  
11  
 
WATER CONNECTIONS  
Install the heater centrally in the building if possible and  
make hot water piping runs as short as possible When facing  
the heater, the cold water inlet will be on the right and the  
hot water outlet on the left..  
Although water piping throughout the building may be other  
than copper, copper or galvanized piping should be used  
when connecting to the heaters ½” male NPT flex connectors  
(follow local codes if more stringent). Plastics or other PEX  
type plumbing line materials are not suitable for connecting  
directly to the water heater. Keep water inlet pipe to no less  
than ½” (19.05mm) diameter to allow the full flow capacity.  
If the cold and hot connections to the heater are reversed,  
the heater will not function.  
PIPE PRV TO  
APPROPRIATE  
DISCHARGE  
Fig. 7 - Pressure Relief Valve  
The Aquastar 125B is provided with one flexible type  
connector that must be connected to the cold inlet fitting of  
the water valve as shown in Fig. 6. The union end of the  
flexible connector should be attached to the rear inlet port  
of the water valve with the supplied washer gasket. No pipe  
dope or thread tape is to be used at this joint. The ½” flexible  
hot water outlet line is supplied attached to the heater.  
Be certain there are no loose particles or dirt in the piping.  
Blow out or flush the lines before connecting to the water  
heater. Full port valves should be installed on both the cold  
water supply and hot water outlet lines to facilitate servicing  
the heater (see Fig. 7). For installation on a private well  
system with the use of a pressure tank, the lowest pressure  
range setting recommended is 30-50 psi (2.07-3.45 bar).  
OPERATINGINSTRUCTIONS  
Before proceeding with the operation of the heater make  
sure that the system is filled with water.  
Open the cold water inlet supply to the heater fully.  
Open a hot water faucet to permit the water to fill the heater  
and the piping and to eliminate the air trapped in the system  
Close the hot water faucet after the water flows freely and  
all the air has escaped from the system. The water heater is  
now ready to operate.  
FOR YOUR SAFETY READ BEFORE LIGHTING  
THE PILOT  
Warning: If you do not follow these instructions  
exactly, a fire or explosion may result causing property  
damage, personal injury or loss of life.  
A. This appliance has a piezo-igniter for lighting the pilot  
burner. When lighting the pilot, follow these instructions  
exactly.  
B. BEFORE LIGHTING smell all around the appliance area  
for gas. Be sure to smell next to the floor because some gas  
is heavier than air and will settle on the floor.  
WHAT TO DO IF YOU SMELL GAS  
- Do not try to light any appliance.  
- Do not touch any electric switch; do not use any phone  
in your building  
Fig. 6 - Water valve and water connector, top view  
- Immediately call your gas supplier from a neighbor’s  
phone. Follow the gas supplier’s instructions.  
- If you cannot reach your gas supplier, call the fire  
department.  
Connecting the pressure relief valve (PRV)  
A listed pressure relief valve supplied with the heater must  
be installed at the time of installation. No valve is to be  
placed between the PRV and the heater. No reducing  
coupling or other restriction may be installed in the discharge  
line. The discharge line must be installed such that it allows  
complete drainage of both the PRV and the line. The location  
of the PRV must be readily accessible for servicing or  
replacement, and be mounted as close to the water heater  
as possible. See Fig 7.  
C. Use only your hand to push in or turn the gas control  
buttons. Never use tools. If a button will not push in, check  
to make sure the buttons are being pushed in the proper  
sequence. Follow these instructions exactly. If control  
button(s) are jammed, close the gas supply and call a  
qualified service technician. Attempted forceful repair may  
result in a fire or explosion.  
D. Do not use this appliance if any part has been under  
water. Immediately call a qualified service technician to  
inspect the appliance and to replace any part of the control  
system and any gas control which has been under water.  
To install the PRV, a suitable fitting connected to an extension  
on a “T” fitting can be sweated to the hot water line.  
12  
6 720 607 030  
 
LIGHTING INSTRUCTIONS (as seen on front cover  
of heater)  
GAS CONTROL SLIDE  
1. STOP! Read the safety information above on this plate.  
2. The Gas valve must be turned off by sliding the gas valve  
button to the far left under the OFF ( ) mark.  
3. Wait five (5) minutes to clear out any gas. If you smell  
gas, STOP! Follow “B” in the safety information above  
on this plate. If you don’t smell gas, go to next step.  
4. The pilot burner is located behind the peephole in the  
front center of the jacket directly below this instruction  
plate.  
TEMPERATURE  
ADJUSTMENT KNOB  
Fig. 9 - Water Flow Control Knob  
(counterclockwise) will produce a temperature rise of  
approximately 45F for flow rates between 1.1 and 3.7 gallons  
per minute. When setting the gas control slide to the single  
5. Slide the gas valve button to the right, under mark (  
).  
flame (  
) setting and positioning the knob fully clockwise,  
6. Fully depress gas valve button and light pilot by pushing  
“PILOT IGNITER” button ( ). This step may have to be  
repeated.  
7. Observe the pilot flame through the peephole. The gas  
valve button should be held down at least 15 seconds  
with pilot burning. When the gas valve button is released,  
the pilot should continue to burn.  
the heater will produce a temperature rise of approximately  
55F at flow rates between 0.5 and 2.0 gallons per minute.  
Turning the dial all the way the counterclockwise will produce  
a temperature rise of approximately 33F for flow rates  
between 1.1 and 3.7 gallons per minute. It is safest to select  
a comfortable temperature and not have to mix in a  
considerable amount of cold water. The positions you select  
will depend on the temperature of the incoming water (50F  
is average in the U.S.). In warm weather regions where the  
incoming ground water is generally warmer, or during hot  
weather months in other areas, a single flame ( ) setting  
may be best. During the colder months, or in cold climate  
- If the gas valve button does not pop up when released,  
stop and immediately call your service technician or gas  
supplier.  
- If pilot does not stay lit, repeat steps 1 through 7.  
- If pilot will not stay lit after several tries, slide the gas  
valve button to the left, under the OFF ( ) mark and call  
service technician or gas supplier.  
areas, a three flame (  
) setting may be best. NOTE: The  
knob setting will affect the activation point of the heater;  
fully clockwise will allow the heater to activate at 0.5 gal/  
minute. Fully counterclockwise will allow the heater to  
activate at 1.1 gal/minute.  
Do not supply the 125B with preheated water. For this type  
of application, use the solar back-up model 125B LPS or  
125B NGS.  
8. Once pilot remains lit, then release gas valve button. The  
heater will now fire when water is drawn at a rate greater  
than the threshold flow rate.  
NOTE: If main burner should fail to ignite, make sure pilot is  
burning. If not, repeat lighting steps 1 through 7.  
NOTE: The 125B operates in two modes. See SETTING  
THEWATERTEMPERATURE.  
If the inlet water temperature to the water heater is very  
warm the heater can produce temperatures that may be  
found to be too hot. A temperature balance shower valve  
can automatically mix in cold water to reduce such hot water  
temperature, in the event of any temperature instability with  
the use of a temperature balance shower valve, refer to  
shower valve manufactures instructions for internal  
adjustment setting. Adjustments should be made to the  
hottest setting in the shower valve. Additionally the  
temperature control of the heater can be adjusted to produce  
a more comfortable hot water temperature.  
TO TURN OFF GAS TO APPLIANCE  
Slide the gas valve button to the far left, under the off (  
mark and close the gas supply to the heater.  
)
SETTING THE WATER TEMPERATURE  
The Aquastar 125B has a gas control that modulates burner  
input in response to hot water flow. Its purpose is to ensure  
that the hot water temperature will remain steady, although  
the water flow demand may vary (down to ½ gal/minute).  
Also, depending on the unit’s adjustable gas control slide  
MAINTENANCE AND SERVICE  
being set in the single flame (  
) or three flame (  
)
REVIEW MAINTENANCE TABLE ON THE  
BACK OF THIS MANUAL  
setting, the 125B can produce and control comfortable hot  
water temperatures as seasonal ground water temperatures  
vary.  
To adjust the temperature on the heater, turn on a hot water  
tap. At the water heater, turn the temperature adjustment  
knob (see Fig. 9) all the way to the right (clockwise) and set  
Approximately once a year, the AquaStar should be checked  
and cleaned. To remove the front cover, first remove the  
incandescent particle tray, then pull off the temperature  
adjustment knob and unscrew and remove the plastic collar.  
Pull main cover out toward you and lift up and out. THE  
FOLLOWING OPERATIONS SHOULD BE PERFORMED  
BY A QUALIFIED SERVICE PERSON:  
the gas control slide to the three flame (  
) setting. This  
will produce a temperature rise of approximately 90F at flow  
rates between 0.5 and 2.0 gallons per minute. Given that  
average incoming water temperatures are 50F in winter  
months; this heater will produce approximately 140F water  
at these flow rates. Turning the dial all the way to the left  
Vent System: Should be checked annually. Clean and repair  
as needed.  
6 720 607 030  
13  
 
Water Valve (Part # 8707002649): The water valve on  
this heater should be serviced periodically. Lubricate  
component #23 on page 19 with a small amount of silicon,  
faucet or lithium grease every two years to keep its o rings  
fresh and pushrod sliding smoothly. Every 3-5 years replace  
component #23 on page 19. The frequency will depend on  
the mineral content of the water and conditions of use or  
whenever signs of corrosion appear at the gas and water  
valve joint. Periodically check that the water inlet filter (#25  
on page 19) is clean as well.  
AIR SCREEN  
NOTE: If water valve is removed, be sure to also inspect the  
o ring seal on the end of the right hand side water pipe  
before re-installing. Lubricating the o ring with lithium or  
faucet and valve grease is recommended.  
PILOT ORIFICE  
Fig. 11 - Pilot burner with air screen/ pilot orifice  
Pilot Flame: The pilot flame should burn with a clean sharp  
blue flame and should resemble the diagram in Fig 10. If the Main Burner Flames: The main burner flames should be  
flame is yellow, or if the pilot knob has to remain depressed blue, with a more intense blue cone in the center core. Yellow  
for a long time in order to keep the pilot lighted, the pilot flames could be a sign of wrong size gas orifices or dirty  
burner and or the pilot burner orifice may need to be cleaned, burners, or a blockage on the heat exchangers fins. If some  
the orifice may need to be replaced, and or the air screen burners have yellow flames while others have good flames,  
may need cleaning. The pilot flame should envelop it is likely that dust, lint or spider webs have partially clogged  
approximately 10 mm (3/8") of the tip of the thermocouple. the burner venturis. To clean the burners, contact a gas  
If it is too small, the pilot burner must be cleaned. To obtain service person.  
a spark, the position of the Piezo igniter electrode should be  
approximately 3 mm (1/8") from the pilot burner tip.  
Mineral Scale Build-up: The AquaStar heater, when operated  
at lower temperatures settings, does not accumulate mineral  
build-up. If however, the heater is used at the higher  
temperature settings and the water has a high mineral  
content, periodic descaling may be necessary. The heating  
coils should be flushed with a descaling solution. Consult  
your dealer or Controlled Energy for instructions.  
3mm  
Correct gap between pilot  
burner tip and electrode tip  
Consult your service person.  
Piezo Electrode  
Air screen filter  
TROUBLE SHOOTING (see maintenance table)  
Introduction  
The AquaStar 125B burners are activated by a water flow  
valve. Numerous water related problems can cause this water  
valve to malfunction such as: Insufficient water flow volume  
to activate the burners at its minimum flow requirement;  
Dirt in the water flow valve causing it to malfunction;  
Sediment build-up in faucet aerators, or shower heads;  
Uneven pressures between cold and hot. (with single lever  
faucets) Plumbing cross overs. These water flow related  
problems can cause the heater to deliver less than its full  
output, or to fail to ignite or to shut down completely.  
Thermocouple  
Piezo  
Electrode  
Fig. 10 - Characteristic Pilot Flame  
Problems are stated in upper case, bold face. Most common  
causes for the problems follow in order of likelihood. The  
suggested solutions require that the cover be taken off. To  
do this, remove incandescent particle tray, pull off the  
temperature adjustment knob and unscrew and remove the  
plastic collar. Pull main cover out toward you and lift up and  
out.  
To clean the pilot burner and/ or the pilot orifice : Turn  
off the gas at the unit. Remove the cover of the heater. To  
do so, pull off the temperature adjustment knob and unscrew  
and remove the plastic collar and unscrew the central screw  
located at the bottom of the front cover. Pull main cover out  
toward you and lift up and out . Pull the air screen off, wash  
it and blow any lint off (See Fig 11). The pilot orifices should  
also be cleaned or replaced. Do not enlarge the orifice. Do  
not use any wire or sharp object to clean orifices. Natural  
gas orifices are large enough that you can usually clean  
them by blowing through them. LP orifices, on the other  
hand, are too small to clean and should be replaced. See  
#3 in Trouble Shooting Section.  
To access the pilot orifice, remove 2 screws holding pilot  
assembly in place. Then loosen compression fittings to expose  
pilot orifice.  
14  
6 720 607 030  
 
PILOT LIGHT WILL NOT LIGHT  
3. Poor thermocouple connection at the electromagnet  
Note: Electromagnet is part #8707201012 located on the  
right side of the gas valve behind the piezo push-button  
assembly. Check the tightness of the thermocouple  
1. No gas to the AquaStar  
A. Gas cock on gas line may not be open.  
B. Gas valve button has not been moved to single flame connection nut at the electromagnet: The Electro-magnet  
position (  
). Slide button to right to PILOT.  
connection is a large aluminum 17mm hex head nut. The  
thermocouple end is a 5 mm brass nut which screws into  
the 17 mm nut. Tighten the thermocouple nut snugly but not  
too tight.  
C. Gas regulator may be shut or damaged.  
2. In-line AquaStar gas regulator jammed (usually on  
LP gas)  
Replace or unlock the regulator. Note: The regulator 4. Poor circuit connections at the ECO (overheat sensor)  
furnished with the heater is designed for low gas pressure. or the flue gas safety device  
Excessive pressure will lock it up (propane only). Locking Oxidation or looseness of the terminal connections can result  
usually happens if the gas pressure between the gas tank in millivolt current loss through the thermocouple safety  
(propane) and the water heater’s gas regulator has not been circuit. Clean terminals with very fine sand paper or an eraser  
reduced. See page 2 for recommended correct gas pressure. and reconnect leads.  
To unlock a regulator, consult your gas supplier.  
5. Faulty ECO (part #8707206074)  
If cleaning the terminals attached to the ECO did not fix the  
problem, connect a jumper wire between the two wires and  
3. Pilot orifice clogged and/or air screen dirty, or pilot  
gas filter is dirty.  
Clogging of the pilot burner can be caused by dust and any try to relight the pilot. If the pilot flame now remains on,  
suspended matter contained in the ambient air. replace the ECO. If the flame still goes out when the button  
As a result, the pilot flame is weakened and thus can no is released, the ECO is not defective. Go to next step.  
longer heat the thermocouple sufficiently. For cleaning  
purposes, the air filter screen is pulled off, washed and blown 6. Faulty thermocouple (part #8707206074) or  
out. The pilot orifice has likewise to be cleaned or exchanged.  
electromagnet ) Unless these 2 parts are at least 8 to  
10 years old, it is very unlikely that they are faulty.  
Before testing, reconfirm that #2 is absolutely correct,  
and that all connections are clean and tight.  
4. Air in the Gas Line  
Note: Normally this is a problem only at the time of initial  
installation, after the pipes have been worked on, or after a To test the thermocouple, disconnect the thermocouple lead  
propane tank has been allowed to empty, or after the heater at the ECO. Insert a multi-meter probe into the thermocouple  
has been shut down for a long time.  
lead and attach or hold the other lead at the metal gas  
Bleed all the air trapped in the gas line. Because of the very valve (DC common). Light the pilot flame and hold button,  
small pilot orifice (especially on LP gas models), bleeding meter reading should be 24 mVDC or more. If the reading is  
out all the air could take several minutes. Slide the gas 24 mVDC or more the thermocouple is good. To test the  
valve button to single flame position (  
) and depress this electromagnet, re-connect the thermocouple lead to the  
button until all the air has escaped, and the gas has arrived. ECO, light pilot and hold button while taking a reading  
During this process, press repeatedly on the piezo ignition between the ECO and flue gas sensor leads and the metal  
button until the pilot flame has ignited.  
gas valve (DC common). The reading should drop to 19  
mVDC or less. If it does not, replace the electromagnet.  
PILOT LIGHTS BUT FLAME GOES OUT WHEN BUTTON  
IS RELEASED  
BURNERSDO NOTIGNITE WHEN HOTWATERIS TURNED  
ON  
1. Pilot push button was not pushed in far enough or  
was not held in long enough  
Once pilot flame has been lighted. Hold button pushed in  
for at least 15 seconds to give time for the pilot flame to  
properly heat the tip of the thermocouple.  
1. Pilot is not on.  
Light the pilot. See lighting instructions.  
2. Cold incoming water connection made to wrong side  
of heater  
Make sure cold water inlet connection is on the right side of  
heater when you are facing heater.  
2. Pilot flame improperly aimed or is too weak so it is  
not properly heating the tip of the thermocouple.  
The Pilot flame should be a sharp blue flame and aimed at  
the tip of the thermocouple so that it envelops 10 mm(3/8")  
of the thermocouple tip. Pilot flame has to be properly aimed  
at the thermocouple. See Fig 10.  
3. Water flow rate at hot water tap is too low.  
Note: When the flow control knob is turned all the way  
clockwise, the AquaStar models 125B require 1/2 gallon  
per minute flow to activate the burners. This is a flow which  
would fill a quart jar in 30 seconds. If the flow control knob  
is turned fully counterclockwise, a flow rate of 1.1 gpm is  
required to activate the burners.  
4. Cold water inlet filter on heater is dirty.  
Remove filter and clean. This screen filter is located at the  
inlet side of the water valve (fig. 13, #25). Check and clean  
faucet aerators too.  
6 720 607 030  
15  
 
5. Crossover in household plumbing  
WATER IS TOO HOT  
The AquaStar burner activates when there is sufficient water  
pressure drop in the AquaStar water valve assembly — i.e.  
when a hot water faucet is opened. If there is a crossover in  
the plumbing, the necessary pressure drop in the AquaStar  
will be insufficient, or totally eliminated. A plumbing crossover  
can be caused by a bad washer at a single lever faucet or  
incorrect plumbing or a mixing valve in the line, etc. which  
permits hot and cold water to mix in the plumbing. The  
crossover will create a back pressure in the system preventing  
the pressure drop in the Aquastar — i.e. cold water is entering  
the water heater from both sides and the burners will not  
come on. To confirm there is no crossover in the plumbing,  
shut off the cold water supply to the AquaStar. Open your  
hot water taps. There should not be any water flowing. If  
there is water flowing, there is a crossover in the plumbing.  
This is a plumbing problem, not an Aquastar problem. Please  
contact your plumber.  
1. Temperature Selection too high  
Position the gas control slide to the single flame (  
setting to reduce the burner output and/or turn the  
temperature adjustment knob counterclockwise to lower the  
maximum water temperature. Note: turning the knob  
counterclockwise will increase the activation flow rate.  
)
2. Inlet water temperature is very warm  
Increased seasonal ground water temperatures will affect  
the hot water output temperature. Reduce the burner output  
if the inlet water is very warm (60-75F) by positioning the  
gas control slide to the single flame (  
) setting. The  
temperature adjustment knob setting may also be lowered if  
necessary, reference SETTING THE WATER  
TEMPERATURE section.  
WATER IS NOT HOTENOUGH  
6. Water valve parts may be dirty or components  
damaged.  
1. Temperature selection too low.  
Change the setting. Turn the temperature adjustment knob  
clockwise and/or slide the gas control to the winter mode  
setting for increased burner output.  
Water valve and component parts must be totally free of  
dirt. First check that the venturi is free of dirt particles. In  
hard water areas, mineral deposits can eventually (3 to 5  
years in hard water areas) corrode the water valve parts to  
a point where they will need replacing. Any sign of moisture  
or corrosion at the joint of the water valve and the gas valve  
is a sign that the water valve assembly components need to  
be serviced immediately. Note: Water valve for model 125B  
is part# 8707002649 for both LP and NG models. (Contact  
service person to clean water valve or replace if corrosion  
is present).  
Note: This will decrease the activation flow rate.  
2. Btu input is too low due to insufficient gas pressure  
It is extremely important for a tankless instantaneous  
water heater to have the right size gas line to obtain  
the correct gas pressure  
See specifications on page 2. Unlike storage tank water  
heaters, the burners of a tankless water heater must be very  
powerful to heat water instantaneously since they do this  
only at the time hot water is actually being used. It is therefore  
imperative that the gas pressure requirement be met exactly.  
Insufficient gas pressure will directly affect the water  
temperature at the time of usage. See page 2 for correct  
PILOT LIGHT GOES OUT DURING OR IMMEDIATELY  
AFTER HOT WATER HAS BEEN USED  
1. Gas pressure too low  
Very low gas pressure may be caused by low delivered gas gas pressure settings and page 10 for locations where gas  
pressure, a jammed gas regulator or undersized gas lines. If pressures are taken.  
the gas lines are undersized, there may still be the specified  
3. Btu input is too low due to insufficient gas supply  
Make sure your main gas line is fully opened. If using LP  
gas, be sure that the size of the propane tank is adequate to  
supply the required gas pressure.  
static gas line pressure. However when the water valve opens,  
and gas enters the burners, the pressure could drop sharply,  
causing the pilot flame to go out. Have a gas technician  
confirm the gas pressure both static and at maximum Btu  
output. Specifications for your heater are on page 2.  
4. Cold water is mixing with the hot water between the  
AquaStar and the outlet  
Compare water temperature at outlet of the AquaStar (hold  
the AquaStar’s outlet pipe with your hand) and at the tap. If  
2. Pilot may be dirty or weak  
See Page 14 for instructions on pilot maintenance.  
3. Burners are not shutting down immediately when hot these two are very different, check for mixing valve or  
water is turned off plumbing crossover (see “MAIN BURNERS WILL NOT  
Note: If burners don’t shut down immediately when the hot IGNITE...” paragraph #6). Where automatic “anti-scald”  
water is turned off, the heater will overheat and the ECO valves are required by code, lower the temperature setting  
will shut-off the gas. Rebuild the water valve assembly. on the AquaStar as much as possible and balance the  
Contact service person to clean or rebuild water valve.  
pressure between cold and hot water after the AquaStar.  
4. ECO (overheat sensor) tripped due to overheating  
Re-ignite the appliance 10 minutes later. If it happens again,  
contact your service person.  
5. Parts in water valve are dirty or damaged, which will  
prevent the gas valve from being fully opened.  
Water valve maintenance needs to be performed, see #7  
under BURNERS DO NOT IGNITE WHEN HOT WATER  
IS TURNED ON.  
5. Flue gas safety device tripped  
Ventilate the room and re-ignite the appliance 10 minutes  
later. If it happens again, contact your service person.  
16  
6 720 607 030  
 
HOT WATER TEMPERATURE FLUCTUATES / UNIT  
DEACTIVATED  
1. Unbalanced pressure in waterlines  
The added restriction caused by the Aquastar in the hot  
water system can result in uneven pressures between the  
cold and the hot. In such cases when mixing cold water at  
the tap, the lower hot water pressure may be overpowered  
by the higher cold water pressure in the building, which may  
cause the Aquastar burners to shut down (deactivate).  
Do not add any flow restrictor to the shower head.  
Position the gas control slide to the single flame (  
)
setting to reduce the burner output and/or turn the  
temperature adjustment knob counterclockwise to lower the  
maximum water temperature.  
Note: turning the knob counterclockwise will increase  
the activation flow rate.  
2. Temperature balance valves  
If the inlet water temperature to the water heater is very  
warm the heater can produce temperatures that may be  
found to be too hot. A temperature balance shower valve  
can automatically mix in cold water to reduce such hot water  
temperature, in the event of any temperature instability with  
the use of a temperature balance shower valve, refer to  
shower valve manufactures instructions for internal  
adjustment setting. Adjustments should be made to the  
hottest setting in the shower valve. Additionally the  
temperature control of the heater can be adjusted to produce  
a more comfortable hot water temperature. See SETTING  
THE WATER TEMPERATURE section.  
3. Cold water is mixing with the hot water between the  
AquaStar and the outlet  
See #6 under “Burners do Not Ignite When Hot Water Is  
Turned On”.  
4. Inlet water pressure is erratic due to inadequate supply  
water pressure or saturated pressure tank on well  
system  
For installation on a private well system with the use of a  
pressure tank, the lowest pressure range setting  
recommended is 30-50 psi (2.07-3.45 bar).  
5. Gas pressure is too low  
See page 2 and 10 for correct specifications.  
6 720 607 030  
17  
 
18  
6 720 607 030  
 
Fig. 12 - Diagram of AquaStar 125 B  
1
4
3
2
5
6
7
8
9
10  
11  
13  
12  
6720606800-07.1AL  
1. Heat exchanger  
2. Pilot assembly  
3. Burner manifold gas  
pressure test nipple  
4. Main gas burner  
5. Pilot gas tubing  
6. Gas valve  
8. Gas control slide  
9. Piezo igniter  
10. Water valve  
11.  
Temperature adjustment  
selector  
12. Gas inlet gas pressure test  
nipple  
7.  
Pressure tap screw  
location  
13. Flexible hot outlet  
6 720 607 030  
19  
 
Fig. 13 - INTERIOR COMPONENTS DIAGRAM AND PARTS LIST  
20  
6 720 607 030  
 
Fig. 13  
INTERIOR COMPONENTS DIAGRAM  
AND PARTS LIST 125B  
1
2
3
4
5
6
7
8
9
Cover  
8 705 421 025  
Temperature adjustment knob  
Temperature adjustment collar  
Draft diverter  
Heat exchanger  
Outlet flex hose  
Washer  
Cold water pipe  
Main burner  
Main burner  
Pilot burner  
Pilot air screen  
Piezo electrode  
Pilot injector  
Pilot injector  
Pilot tube  
Burner assembly washer  
Throttle disc  
Gas valve  
Gas valve  
Gas supply pipe  
Electromagnet  
Thermocouple / Flue Gas Sensor  
Water valve  
Water valve cover  
Pushrod  
Diaphragm  
8 702 000 111  
8 700 403 008  
8 705 505 354  
8 705 406 235  
8 700 703 130  
8 700 103 658  
8 700 705 627  
8 708 120 298 NG  
8 708 120 296 LP  
8 718 105 051  
8 700 507 055  
8 708 107 002  
8 708 200 005 NG  
8 748 200 173 LP  
8 700 707 320  
8 710 103 060  
8 700 100 174 LP  
8 707 021 090 NG  
8 707 021 091 LP  
8 700 705 552  
8 707 201 012  
8 707 206 074  
8 707 002 649  
8 705 500 101  
8 700 306 114  
8 700 503 053  
8 700 507 001  
8 710 103 043  
8 708 500 289  
8 705 705 009  
8 708 205 279  
8 700 703 114  
8 707 206 040  
8 700 715 178  
8 710 103 045  
8 703 401 051  
9
10  
11  
12  
13  
13  
14  
15  
16  
17  
17  
18  
19  
20  
21  
22  
23  
24  
25  
26  
27  
28  
29  
30  
31  
32  
34  
35  
Water inlet filter  
Water connection gasket  
Water valve selector screw  
Volumetric water governor  
Venturi  
Water elbow fitting  
Overheat sensor (ECO)  
Connecting pipe hot  
Washer  
Water valve set screw  
6 720 607 030  
21  
 
LIMITED WARRANTY  
Aquastar  
General  
Service labor costs  
Aquastar water heaters are warranted by the Manufacturer This warranty does not cover any labor costs associated  
(BOSCH) through Controlled Energy Corp. Controlled with service, removal or re-installation of part(s). All such  
Energy Corp. (CEC) will furnish a replacement heat costs must be borne by the Purchaser. Additionally, this  
exchanger and will furnish a replacement of any other part warranty does not cover any labor costs associated with  
which fails in normal use and service within the applicable service, removal or re-installation of the original water heater  
periods specified below, in accordance with the terms of or a replaced water heater.  
this warranty. The CEC replacement will be warranted for  
the unexpired portion of the original warranty. This warranty How to Make a Claim  
will be valid only for water heaters in possession of the original Any claim for warranty parts should be made to your local  
purchaser as recorded on the warranty card.  
dealer, distributor or to CEC. If CEC, please contact the  
Technical Support Department:  
The heat exchanger  
When the unit is professionally installed: If the heat  
exchanger fails within fifteen (15) years after the original  
installation and operation CEC will furnish a replacement  
heat exchanger. However, if the water heater is installed in  
other than a single family dwelling this heat exchanger  
warranty is limited to two (2) years from date of original  
installation and operation.  
Controlled Energy Corp.  
340 Mad River Park  
Waitsfield, VT 05673  
Phone: 800-642-3111  
In most cases, the dealer or distributor will be able to promptly  
* The 15 year warranty period on the heat exchanger is honor your claim and subsequently notify CEC. However,  
reduced to ten (10) years if the unit is not installed by a all replacements are made subject to validation by CEC of  
plumber or licensed gas fitter.  
in-warranty coverage. The damaged or defective item must  
be made available in exchange for the replacement.  
Exceptions  
This warranty will not apply:  
Miscellaneous  
1. to defects or malfunctions resulting from failure to properly No one is authorized to make any other warranties on behalf  
install, operate or maintain the unit in accordance with of CEC. It is expressly understood that the replacement  
the printed instructions provided;  
2. to damage or abuse, accident, neglect or freezing and warranties, express or implied, including warranties of  
other acts of nature; merchantability or fitness for a particular use or purpose,  
3. to damage resulting from operation with either the flame and further that CEC shall not be liable for any loss or  
sensor rod or overheat sensor removed; damage directly or indirectly arising from the use of the hot  
warranty of CEC shall be in lieu of any and all other  
4. to failure of the heat exchanger resulting from the water heater, or for any consequential damages arising from  
operation of the water heater in a corrosive atmosphere such use (including damages from water leakage). CEC’s  
or at water temperatures exceeding the maximum rating, sole liability with respect to any defect shall be for the  
or if the water heater is not supplied with potable water; replacement of the defective part(s). Some states do not  
5. to defects or damage cause by any attachment allow such limitations and exclusions, so the above may not  
or modification, including any energy-saving device.  
apply to you.  
This warranty gives specific legal rights. You may also have  
other rights which vary from state to state.  
All other parts  
If any other part fails within two (2) years after original  
installation and operation, CEC will furnish a replacement  
part free of charge.  
Shipping costs  
In addition to supplying the replacement part(s), CEC will  
provide ground service delivery for these parts. Expedited or  
upgraded shipping will be charged to the customer.  
06.03  
22  
6 720 607 030  
 
Fig. 14 - Flow chart of Aquastar 125 B  
6 720 607 030  
23  
 
MAINTENANCE TABLE see pages 13 & 14  
EVERY YEAR  
EVERY 2 YEARS EVERY 3-5 YEARS  
LUBRICATE WATER VALVE  
REBUILD WATER VALVE  
INSPECT WATER FILTER SCREEN  
INSPECT PILOT ASSEMBLY  
INSPECT VENT ASSEMBLY  
INSPECT MAIN BURNER  
Replacement Parts available from North American  
Distributor  
CONTROLLED ENERGY CORP.  
340 Mad River Park  
VULCANO Termodomésticos S.A.  
Estrada de Cacia  
3801 - 856 Aveiro - PORTUGAL  
Waitsfield, Vermont 05673  
Phone 800-642-3111  
Fax (802) 496-6924  
© 2003 Controlled Energy Corporation, Waitsfield,  
VT all rights reserved  
Recycled paper  
 

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