AquaStar 125B LP User manual

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.
Uponcompletionoftheinstallation,theseinstructions
should be handed to the user of the appliance for
future reference.
FEATURING: Automatic Variable Power Modulating Gas
Valve
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 water (potable) heating and space heating
Intended for variable flow applications with steady cold water inlet temperatures. For preheated domestic
hot water, install the 125 BS model. For recirculating applications, install the 125 BL model.
WARNING
Iftheinformationinthismanualisnot 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.
-Immediatelycallyourgassupplier 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
qualifiedinstaller, service agency or thegassupplier.
Specifications .................................................... Page 2
Rules for safe operation .................................... Page 4
Locating the Heater ........................................... Page 5
Combustion Air Requirements........................... Page 5
Mounting the Heater .......................................... Page 6
Venting the Heater............................................. Page 6
Gas Connections ............................................... Page 7
Water Connections ............................................ Page 8
Safety before lighting the pilot............................ Page 8
Lightinginstructions ........................................... Page 9
Setting water temperature ................................. Page 9
Maintenance & Service...................................... Page 9
Trouble Shooting ............................................. Page 10
Diagram of AquaStar ....................................... Page 13
Components and Parts List ............................. Page 14
TABLE OF CONTENTS
6 720 605 297 PT 862 (12.98)

2
This well engineered, gas water heater has all the fea-
tures a water heater should have:
Itoperates ontheprincipleofheating waterinstantaneously
“on demand”. When a hot water faucet is opened, cold
waterflows through the coilsof the heatexchanger in the
Aquastar. This same flow opens the gas valve, and the
burnersareignitedby the pilot flame. The heatexchanger
coils absorbtheheat generated bytheburners and trans-
fer heat to the water. When the hot water faucet is shut
off, the gas valve automatically closes and the burners
turn off. Your hot water faucet is an ignition key to turn on
the water heater, giving you control over your hot water
energyuse. Each timeyou turn off yourhot water faucet,
you also shut off the water heater.
FEATURES
- High Quality Materials for Long Working Life.
- Copper heating coils for endless supply of hot water.
- Burner output proportional to hot water flow demand
for maximum energy efficiency.
- Safety thermocouple at pilot burner.
- Automatic overheating protection shut-off sensor.
- Stainless steel burners with stabilized blue flame.
- Built-in corrosion resistant draft inducer.
- Compactspacesaver:mountsonawallwithtwohooks.
- Easily removable one-piece cover.
- Easy one person installation.
- Adjustablewaterflowrestrictortoensurethatwaterflow
demand will not exceed the heating capacity of the
heater.
- Easypilotflame lighting withpushbutton piezo ignition.
AquaStar 125B LP and 125B NG Specifications
Gas Input max.: 117,000 Btu/hr
min.: 28,000 Btu/hr
Water Connection 1/2” Thread fitting
H x W x D 29 3/4” x 18 1/4” x 8 3/4"
Vent 5”
Gas Connection 1/2” NPT thread
Min. Water Pressure 18 Psi at 4 GPM
Max. Water Pressure 150 Psi
Shipping Weight 42 LB
Net Weight 39 LB
1.8 GPM at 90°rise
3.7 GPM at 45°rise
Min. Water Flow 1/2 gal/min
LP GAS Supply Pressure inlet. min. 11” W.C.
max. 14” W.C.*
LP GAS Manifold pressure 9.0” W.C.**
Natural Gas Pressure inlet min.: 7” W.C.
max.: 14” W.C.*
Natural Gas Manifold Pressure 4.2 W.C.**
* Inlet gas pressure must not exceed this value
** For purposes of input adjustment
UNPACKING THE AQUASTAR HEATER
Thisheaterispackedsecurely.Theboxincludestwowaterconnectionfittings,agaspressureregulator,anincandescent
particle tray, two hooks for hanging the heater, this manual, a personal letter, a warranty statement and a warranty
registration card. Do not lose this manual, as there is a charge for replacement. Please complete and return the
enclosed warranty registration card.

3
D861_059
MINIMUM INSTALLATION CLEARANCES FROM COMBUSTIBLE AND
NON COMBUSTIBLE MATERIALS FOR ALCOVE INSTALLATIONS
FRONT VIEW SIDE VIEW
AQUASTAR MODELS 125B / 125BL / 125BS / 125X
MODEL 125B / 125B LOW
PRESSURE / 125B SOLAR / 125X
TOP (A) 12"
FRONT (B) OPEN
BACK 0"
SIDES 4"
FLOOR (C) 12"
FLUE DIAMETER 5"

4
If you are using the AquaStar for combined space heating and potable water heating (see
schematic diagram below) , all piping and other components connected to the system must
be suitable for potable water, (b) toxic chemicals such as those commonly used for boiler
treatment to prevent corrosion and freezing must not be introduced into the system, and
(c) if the space heating requires water temperatures higher than those required for do-
mestic, potable water, a mixing valve or other similar device must be provided to reduce
scald hazard potential, (d) maximum system water temperature must not exceed 140°F
(60°C). DO NOT CONVERT AN EXISTING, CLOSED HOT WATER HEATING SYSTEM TO A
COMBINATION SPACE AND POTABLE WATER HEATING SYSTEM USING THE AQUASTAR
OR ANY OTHER HEAT SOURCE.
GENERAL RULES TO FOLLOW
FOR SAFE OPERATION
1. You should follow these instructions when you install
your heater. In the United States: The installation must
conformwithlocal codes or, intheabsence 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.
3. The place where you install the heater must have
enough ventilation. The National Fire Codes do not allow
water heater installation in bathrooms, bedrooms or any
occupied rooms normally kept closed. See the section
below on locating the heater.
Open loop potable water and combination space heating system*
* To be used with a tank, check local codes. May not be permitted in some jurisdictions.
1. Maximum operating temperature of 125B: 140°F
2. Maximum heating capacity: 40°F rise 20°F rise
AquaStar 125B - 80,000 BTU/hr 40,000 BTU/hr
3. Systemshowniselectric storage tank with recirculatingsupplydrawnfromthe tapping for the lowerheatingelement.
4. Schematic is for illustration and example only and must not be used for actual installation without appropriate
engineeringand technical advicefroma professional properlylicensed in the localitywhere the installationismade.

5
4. You must vent your heater. See section on Vent Pipe
Connections, Page 5.
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).
Theappliancemust be isolated from thegassupplypiping
systembyclosing its individual manual shutoffvalveduring
any pressure testing of the gas supply piping system at
test pressures equal to or less than 1/2 Psig (3.5Kpa).
Theappliance and itsgas connection mustbe leak tested
before placing the appliance in operation.
6. Keep water heater area clear and free from
combustibles and flammable liquids. Do not locate the
heater over any material which might burn.
7. Correct gas pressure is critical for the optimum
operation of this heater (see specifications on page 2).
Gaspipingmust be sizedtoprovide the required pressure
at the maximum output of the heater, while all the other
gasappliancesare in operation. Check withyourlocalgas
supplier,andseethesectiononconnectingthegassupply.
8. Shouldoverheating occur orthe gas supplyfailto shut
off,turnoffthe gassupplyat the manual gasshutoffvalve
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.
PROPERLOCATION FOR INSTALLING YOUR
HEATER
Carefully select the location of your new heater. For your
safety and for proper heater operation, you must provide
anabundantsupplyofcombustionairandaproperventing
installation.
Theheatermaystilloperate even when improperly vented.
It will, however, be less efficient and could eventually
damagetheheater. Itcouldevenresult in human sickness
or death due to oxygen deprivation and carbon monoxide
poisoning. Follow the guidelines below:
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. Simultaneous operation of other appliances such as
exhaustfans,ventilation systems clothes dryers, fireplaces
orwoodstoves couldcreateavacuumeffectin your home
which could cause dangerous combustion by-products to
spillbackintoyour home rather than ventingtotheoutside
through the flue. Confirm that your Aquastar is venting
properlywhenall these otherappliancesare running. See
section on venting.
Donotobstructtheflow 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 venting
blockage and poor unsafe combustion.
4. Yourhot waterlinesshouldbekeptshorttosaveenergy.
It is always best to have hot water lines insulated. Having
a floor drain or sink nearby is handy in case you need to
drain water from your heater.
WARNING: The water in this water heater is cold and
alwaysremains cold except forthe times thathotwater is
being used DO NOT INSTALL IN AN AREA WHERE IT
COULD FREEZE.
This heater is neither designed for nor approved for
outside installation.
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.
COMBUSTION AIR REQUIREMENTS
Observethefollowing instructions concerning combustion
air.
Appliances located in unconfined spaces:
a) An unconfined space is one whose volume is greater
than50 cubic feetper1000Btuper hour ofthecombined
ratingofallappliancesinstalled in the space. That would
be 5850 cubic feet for the AquaStar 125B alone.
b) Inunconfinedspacesinbuildings of conventional frame,
masonry, or metal construction, infiltration is normally
adequateto provide air forcombustion, ventilation, and
dilution of flue gasses.
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 openingmust have a minimum freearea
of one square inch per:
- 1000 Btu/hr if all air is taken from inside the building.
- 2000Btu/hr ifallairistaken fromtheoutsidebyhorizontal
ducts.
- 4000 Btu/hr if all air is taken from the outside by direct
openings or vertical ducts.
Louvers, grills and screens have a blocking effect. If the
effectivefreearea is not known,increase the sizes ofyour
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.

6
CLEARANCES
TheAquastar 125 Bis design certifiedforinstallation on a
combustible wall and for installation in an alcove with the
minimumclearancestocombustibleandnon-combustible
construction listed below
A. Top 12 inches ( 305 mm)
B. Front Open
C. Back 0 inches
D. Sides 4 inch (102mm)
E. Bottom 12 inches (306 mm)
Clearance from vent is dependent upon the clearance
ratingof the ventingmaterial used. Forexample: type B-1
vent is approved for 1 inch clearance, B-2 vent for 2 inch,
etc.
Note:Minimum clearance to combustible materialsshould
not be less than 6" for single wall flue pipe. Note that this
clearance can be reduced if combustible material 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.
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 1.
Expansionandcontractionofpipingduetochangingwater
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.
Before installing the unit, be certain you have the correct
heater for your type of Gas – Propane or Natural Gas.
Identificationlabels arefound onthe 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).
Fig. 1 - Mounting the Heater
Fig. 2 - Incandescent Particle Tray Illustration
VENTING
Vent pipe connection.WARNING: Do not reduce the
vent pipe size.
This appliance must be vented to the outside following all
local ordinances and specifications for installing a gas
appliance vent or chimney. The venting system must be
designedand constructed soasto develop apositive flow
adequatetoremove flue gasses totheoutdoors.Minimum
vent size must be 5". Minimum height must be 6 feet,
provided there are no elbows. Termination of vent
must be 2 feet above any obstruction within a 10 foot
radius. Consult your gas utility or National Fuel Gas
Code if vent will have elbows or share venting with
another appliance. The vent connector should have
asmuch vertical rise as possible(minimum12”) before
any horizontal run. The appliance must be located as
close as practicable to a chimney or vent. The vent pipe
sections must be secured to each other with sheet metal
screws. Keep in mind the minimum clearance from the
top of your heater. Remember also that single wall vent
pipe connectors require a 6 inch clearance from
combustibles. National Fuel Gas Code specifies double
wall — Type “B” — vent pipe be used in cold climates and
for gas vents running through attics. We consider double
wall vent pipe preferable in all circumstances. Any vent
sectiongreaterthan45degreesfromverticalisconsidered
horizontal. Horizontal sections of vent connectors must
slope upwards at least 1/4 inch for every foot of its
horizontal length. Keep the horizontal section short and
avoid too many elbows.
WARNING
Note: Theburnersofaninstantaneous“ondemand”water
heater such as the AquaStar are only on at the time that
hot water is actually being used, the venting stack is
thereforecold except fortheshortdurationswhen hot water
isbeingused,itisthereforeveryimportantthat theventing
and air supply be adequate to provide a good positive
draft as soon as the burners turn on. See venting guide
on back page.
The AquaStar 125B instantaneous water heaters have
built-in draft diverters and are designed for indoor
installationonly.Thedraftdiverteroutlet mustbeconnected
to a clear, 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 incandescent particle tray (shipped loose in the car-
tonwith the waterheater) must beattachedat the bottom
of the water heater front cover at the time of installation.
Use the screws provided. See figure 2
SCREWS
INCANDESCENT PARTICLE TRAY
WALL STUDS
1” X 4”
SPACE BOARD
SUPPORT BOARD
13 ¼”

7
The flue connection for the AquaStar 125B is 5 inches.
However,in Canada, for installationsathighaltitude(2000-
4500feet above sealevel) a sixinch flue isrequired. A 5"
by 6" flue adaptor must be affixed to the flue collar of the
AquaStar with at least two screws. See figure 3
Fig. 3 - Flue Adaptor for High Altitude Installations
WARNING: Failure TO INCREASE THE VENT SIZE TO
SIXINCHES AND/orassure that the manifold pressureis
set to proper value listed for applications at high altitudes
will cause unsafe venting, asphyxiation, and will void IAS
Certification.
GAS CONNECTIONS and Gas Regulator
Before connecting the gas supply, check the rating plate
ontherightsideofthefrontcovertobesurethattheheater
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.
InCanada: The InstallationshouldconformwithCGAB149
INSTALLATION CODES and /or local installation codes.
NOTE: The Aquastar 125 B is supplied with a gas
pressureregulatorthatmustbeinstalledontheheater
before attaching the gas supply line. See figure 4.
Failure to install the gas regulator as shown in figure
4 will be a violation of IAS 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.
GAS LINE SIZE
It is strongly recommended that the natural gas pipe line
be 3/4" for the entire distance. If the maximum length is
above 40 feet, use 1" line. Flexible tubing is NOT
recommended, but if it is to be used, oversize it. With LP
gas installation, the recommended sizes are 5/8" up to a
maximum of 20 feet distance, 3/4" up to 50 ft distance
and 7/8" up to 100 feet.
NationalFuelGasCoderequiresthatasediment 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 accordancewiththerecommendations
of the serving gas supplier.
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 less than 0.5 psig.
Thewater heater,includingthepressure 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 emergency
malfunction of the supply system, the gas valve and
regulator must be checked for safe operation. Make sure
thattheregulator vent is protected againstblockage. Vent
blockage could occur during ice storms.
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
appropriatefittingstostopleak. Turnthegason and check
again with a soapy solution. Never test for gas leaks
using a match or flame.
Fig. 4 - Installation of Gas Pressure Regulator
(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 test pressure nipple on the gas
inlet pipe just above the regulator (See Fig 4). These
readings should be taken while the heater is operating
at full input — i.e. maximum water flow with the
temperature dialselector turned all the way clockwise.
MAXIMUM INLET GAS FLOW PRESSURE SETTING
5” X 6” ADAPTOR
USED ON HIGH ALTITUDE
Altitude Natural Gas Liquid Propane
inches W.C: inches W.C:
0' - 2.000 ft 5.7" 10.5"
2.000 ft - 4.500 ft 4.6" 8.4"
GAS INLET PIPE
PRESSURE TAP
PRESSURE REGULATOR
Thepressureregulator provided with the heater isadjusted
to deliver the proper gas pressure (as indicated on the
rating plate and in the manual for altitude up to 2000 feet
Above 4.500 ft consult your local gas supplier.

8
OPERATING INSTRUCTIONS
Before proceeding with the operation of the heater make
sure that the system is filled with water.
Makesure the waterheaterdrainplugis closed. SeeFigure
7 below.
Fig. 7 - Water heater drain plug
Open the cold water inlet supply to the heater fully.
Openahotwaterfaucet to permit the water to fill the heater
andthe piping andtoeliminatetheair trapped inthesystem
Closethe hot waterfaucet after thewater flows freelyand
alltheair has escapedfromthe system. The water heater
is now ready to work
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. Thisappliance has a piezo-igniter forlighting 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
- 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.
C. Use only your hand to push in or turn the gas control
buttons.Neveruse tools. Ifabutton will not pushin,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
qualifiedservicetechnician.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
inspecttheapplianceandto replace any part of thecontrol
system and any gas control which has been under water.
WATER CONNECTIONS
Although water piping throughout your structure may be
other than copper, we recommend that copper piping be
used for at least three feet before and after the heater
(followlocalcodesif more stringent). Keep waterinletpipe
to no less than 1/2 inch diameter to allow the full flow
capacity.Rememberthatwater pressure mustbe sufficient
to activate the heater when drawing hot water from the
top floor. If the hot and cold connections to the heater are
reversed,the heater willnot function. TheAquaStar125B
is provided with two elbow type connectors that must be
connected to the inlet and outlet fittings of the water valve
asshown in Fig 5.These fittings seal tothewater valve by
meansof a union connectionwith a washer typegasketat
the joint. No pipe dope or thread tape is to be used at
these joints. Be certain there are no loose particles or dirt
inthe piping. Blowout or flushthelines before connecting
to the AquaStar. A ball valve should be installed on the
cold water feed line to facilitate servicing the heater.
For installation on a private well system, be sure that the
water pressure is set between 30 and 50 psi.
Fig. 5 - Water valve and Elbows water
connectors, top view
Connecting the pressure relief valve (PRV)
Alistedpressure relief valve supplied withtheheatermust
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
forservicing or replacement.,and be mountedas close to
thewaterheater as possible. See Fig6.Toinstall the PRV,
a suitable fitting connected to an extension on a “T” fitting
can be sweated to the hot water line.
Fig. 6 - Pressure Relief Valve

9
LIGHTING INSTRUCTIONS
1. STOP!Read the safetyinformationabove 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.
5. Slide the gas valve button to the right, under the pilot
mark ( ).
6. Fullydepressgasvalvebuttonandlightpilot 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 10 seconds
withpilot burning.Whenthegasvalve buttonisreleased,
the pilot should continue to burn.
- If the gas valve button does not pop up when released,
stopandimmediately call yourservicetechnician 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
valvebutton to theleft,under the OFF( ) mark and call
service technician or gas supplier.
8. Slide the gas valve button to the right, under the ON
mark ( ). 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.
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
TheAquaStar125B LP and 125 BNGwaterheatershave
a gas control that modulates burner input in response to
flow. Itspurposeisto ensurethatthehotwater temperature
will remain steady, although the water flow demand might
vary (down to 1/2 gal/minute). To adjust the temperature
on your AquaStar, turn on a hot water faucet to its
maximum flow. At the water heater, turn the large knob
located beneath the main gas controls on the front of the
heaterall the way to theright (clockwise). See Fig 8. This
will produce a temperature rise of approximately 90oF at
flow rates between 0.5 and 2.0 gallons per minute. Given
that average incoming water temperatures are 50oF, this
heater will produce approximately 140oF water at these
flow rates. Turning the dial all the way to the left
(counterclockwise) will produce a temperature rise of
approximately 45oF 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 cold water.
What is the best temperature setting? Because AquaStar
waterheatersdeliverendlesshot water at the temperature
you have selected, there is no need to produce very hot
water and then mix in cold. It just does not make sense to
overheatwater andthenmixincold tocoolitoff.Youcannot
run out of hot water with an AquaStar, so set the dial for
the temperature you prefer . Note: 105°F is the maximum
recommended for a hot bath. The position you select on
the temperature adjustment knob will depend on the
temperatureof the incomingwater (50°Fis average inthe
U.S.). In warm weather regions where the incoming cold
water is generally warmer, or during the hot weather
months in some other areas a midway setting on the
temperature adjustment knob would produce a
temperature rise of about 70°F, giving an output of
approximately120°F. Atthis setting, if itisstillnecessary,
one could mix a small amount of cold water in a shower
andhavea comfortable shower at about3gallons/minute.
Duringthecolder months, or in coldclimateareas,it might
be necessary to set the control to the maximum position,
all the way clockwise to the right.
If you supply the AquaStar 125B, with preheated water
(i.e.) in a solar installation the unit could overheat. It will
thenshut offon safety whentheoutlettemperaturereaches
194°F.Forthis type ofapplication,purchasea solar model
125 B LPS or 125 B NGS.
MAINTENANCE AND SERVICE
Approximately once a year, the AquaStar should be
checked, cleaned and serviced as necessary. To remove
thefront cover, first removethe incandescent particle tray,
thenpulloffthetemperatureadjustmentknobandunscrew
and remove the plastic collar. Unscrew the central screw
located at the bottom of the front cover. Pull main cover
out toward you and lift up and out. THE FOLLOWING
OPERATIONS SHOULD BE PERFORMED BY A
QUALIFIED SERVICE PERSON:
Vent System: Should be checked annually. Clean and
repair as needed.
Water Valve (Part # 8707002499): The water valve on
this heater should be serviced periodically The frequency
will depend on the mineral content of the water and
conditions of use or whenever signs of corrosion appear
atthe gas andwater valve joint.Checkthat the waterinlet
filter (#28 on Figure 12, page 14) is clean.
Pilot Flame: Thepilotflameshouldburnwith a cleansharp
blue flame and should resemble the diagram in Fig 9. If
the flame is yellow, or if the pilot knob has to remain
depressedfora long timeinorder to keep thepilotlighted,
Fig. 8 - Water Flow Control Knob

10
TROUBLE SHOOTING
Introduction
The AquaStar 125 burners are activated by a water flow
valve. Numerous water related problems can cause this
watervalve tomalfunction such as: Insufficient waterflow
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
waterflowrelatedproblemscancausetheheaterto deliver
less than its full output, or to fail to ignite or to shut down
completely.
Problems are stated in upper case, bold face. Most
common causes for the problems follow in order of
likelihood.The suggested solutions require thatthe cover
betakenoff.Todo this, remove incandescentparticletray,
pulloffthe temperature adjustmentknobandunscrewand
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.
PILOT LIGHT WILL NOT LIGHT
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 “PILOT”
position ( ). Slide button to right to PILOT.
C. Gas regulator may be shut or damaged.
2. In-line AquaStar gas regulator jammed (usually on
LP gas)
Replace or unjam the regulator. Note: The regulator
furnishedwiththeheater is designed for lowgaspressure.
Excessivepressurewilllockitup(propaneonly). Jamming
usuallyhappens if thegas pressure betweenthegas tank
(propane) and the water heater’s gas regulator has not
been reduced. See page 2 for recommended correct gas
pressure.To unjama regulator,consult yourgas supplier.
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 suspended matter contained in the ambient air.
To clean the pilot burner and/ or the pilot orifice : Turn
off the gas atthe unit. Removethe cover ofthe 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 itand blow any lint off (SeeFig10). 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
thatyou can usuallyclean them byblowing 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.
Fig. 10 - Pilot burner with air screen/ pilot orifice
Fig. 9 - Characteristic Pilot Flame
the pilot burner and or the pilot burner orifice may need to
be cleaned, the orifice may need to be replaced, and or
the air screen may need cleaning. The pilot flame should
envelop approximately 10 mm (3/8") of the tip of the
thermocouple. If it is too small, the pilot burner must be
cleaned.Toobtaina spark, the position ofthePiezoigniter
electrode should be approximately 3 mm (1/8") from the
pilot burner tip.
Main Burner Flames: The main burner flames should be
blue, with a more intense blue cone in the center core.
Yellowflames could be asignof wrong sizegasorifices or
dirty burners, or a blockage on the heat exchangers fins.
Ifsomeburners have yellow flameswhileothershavegood
flames,itis likely that dust, lint orspiderwebshavepartially
cloggedthe burner venturis. To clean the burners,contact
a gas service person.
Mineral Scale Build-up: AquaStars, when operated at
lowertemperaturesettings, tend not to accumulate mineral
buildup. If however, the heater is used at the higher
temperature settings and the water has a high mineral
content,periodic descaling may benecessary.The heating
coilsshould be flushed witha descaling solution.Consult
your dealer or Controlled Energy for instructions.
3mm
Correct gap between pilot
burner tip and electrode tip
Piezo Electrode
Air screen filter
10mm
3/8”
PILOT ORIFICE
AIR SCREEN
Piezo
Electrode
Thermocouple

11
6. Faulty thermocouple (part #8747202083) or
electromagnet ) Unless these 2 parts are at least 8
to10 years old, it is very unlikelythatthey are faulty.
Before testing, reconfirm that #2 is absolutely
correct,and that all connections arecleanand tight.
To test the thermocouple, disconnect the thermocouple
lead to the ECO. Insert a multi-meter probe on the
thermocoupleECOconnection and attach the othermeter
lead on the spade connector of the ECO. Light the pilot
flame, and take a reading on the meter. If it reads less
than 24mV, replace the thermocouple. If the reading is
24mVorover the thermocouple isgood.Totesttheelectro-
magnet,takeanotherreadingacrosstheECOspadewhile
thepilot flame ison. Thereading should dropto about 15
mV. If it does not and remains unchanged, replace the
electromagnet.
Although the filters can lengthen the cleaning intervals,
they can never completely prevent such clogging. In
consequence the gas jet issuing from the pilot orifice is
reduced and or the air mixture is reduced. The pilot flame
is weak and thus can no longer heat the thermocouple
sufficiently. For cleaning purposes, the air filter screen is
pulled off, washed and blown out. The pilot orifice has
likewise to be cleaned or exchanged. Consult Controlled
Energy or a gas service person.
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 propane tank has been allowed to empty, or after the
heater has been shut down for a long time.
Bleed all the air trapped in the gas line. Because of the
very small pilot orifice (especially on LP gas models),
bleeding out all the air could take several minutes. Slide
thegas valve buttonto pilot position( ) and depressthis
buttonuntil all theairhasescaped,andthegas has arrived.
Duringthisprocess, press repeatedly onthepiezo ignition
button until the pilot flame has ignited.
PILOT LIGHTS BUT FLAME GOES OUT WHEN
BUTTON IS RELEASED
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.
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“) ofthethermocoupletip.Pilot flamehastobeproperly
aimed at the thermocouple. See Fig 9.
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
connectionnut at theelectromagnet: The Electro-magnet
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.
4. Poor circuit connections at the ECO. (Energy Cut-
Off overheat protection)
Oxidation or looseness of the ECO terminal connections
canresultinmillivoltcurrent loss through the thermocouple
safetycircuit. Clean terminals withvery fine sand paperor
an eraser and reconnect ECO leads.
5. Faulty ECO (part #8707206040)
If cleaning the terminals attached to the ECO did not fix
the problem,connectajumperwirebetweenthetwowires
and try to relight the pilot. If the pilot flame now remains
on, replace the ECO. If the flame still goes out when the
button is released, the ECO is not defective. Go to next
step.
BURNERS DO NOT IGNITE WHEN HOT WATER IS
TURNED ON
1. Pilot is not on.
Light the pilot. See lighting instructions.
2. Gas valve buttonnotpositionedonBurner Position
Be sure pilot flame is on. Slide gas valve control to burner
position ( ).
3. 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.
4. Water flow rate at hot water tap is too low.
Note:Whenthe flow controlisturnedallthewayclockwise,
the AquaStar models 125B require 1/2 gallon per minute
flow to activate the burners. This is a flow which would fill
aquart jar in 30seconds. If the flow controlknobis turned
fully counterclockwise, a flow rate of 1.1 gpm is required
to activate the burners.
5. Cold water inlet filter on heater is dirty.
Remove filter and clean. This screen filter is located at
theinlet side of thebrass water valve (fig.12,#28). Check
and clean faucet aerators too.
6. Crossover in household plumbing
The AquaStar burner activates when there is sufficient
waterpressuredropintheAquaStarwatervalveassembly
— 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
singlelever faucet orincorrect plumbing ora mixing valve
in the line, etc. which permits hot and cold water to mix in
the plumbing. The crossover will create a back pressure
inthesystempreventingthepressuredropin 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.

12
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 pressure, a jammed gas regulator or undersized gas
lines.If the gas linesare undersized, there maystillbe the
specifiedstaticgaslinepressure.Howeverwhenthewater
valve opens, and gas enters the burners, the pressure
coulddrop sharply, causingthe pilot flametogo out. Have
a gas technician confirm the gas pressure both static and
atmaximum Btu output. Specificationsfor your heater are
on page 2.
2. Pilot may be dirty or weak
See Page 9 for instructions on pilot maintenance.
3. Burners are not shutting down immediately when
hot water is turned off
Note: If burners don’t shut down immediately when the
hot water is turned off, the heater will overheat and the
ECOwill shut-offthegas.Rebuildthe watervalveassembly
using the repair kit from CEC (part #8 703 406 178).
WATER IS TOO HOT
1.Temperature Selection too high
Turn the temperatureadjustment knob counter-clockwise
(to the left) to lower the maximum water temperature.
Note: This will increase the activation flow rate.
2. Inlet water temperature is too high (as with solar
preheated water)
Note: Only the Model “S” AquaStar should be used if the
inlet water is preheated.
3. Reduce inlet gas pressure
WATER IS NOT HOT ENOUGH
1. Temperature selection too low.
Changethesetting.Turnthetemperatureadjustmentknob
clockwise (to the right).
Note: This will decrease the activation flow rate.
2. Water flow through the heater is higher than the
capacity of the AquaStar to heat it
Reduce the flow demand at the faucet. See flow rates at
specific temperature rises on page 2.
7. Water valve parts may be dirty or components
damaged.
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
componentsneedto be replaced immediately .Note: Water
valve for model 125B is part# 8707002499 for both LP
and NG models. (Contact service person to clean water
valve or replace if corrosion is present).
3. Btu input istoolowdueto 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
verypowerful to heatwater instantaneously sincetheydo
this only at the time hot water is actually being used. It is
therefore imperative that the gas pressure requirement
bemetexactly. Insufficientgas pressure willdirectlyaffect
the water temperature at the time of usage. See page 2
forcorrectgas pressure settings and page13forlocations
where gas pressures are taken.
4. 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.
5. Cold water is mixing with the hot water between
the AquaStar and the outlet
Comparewatertemperature at outlet of the AquaStar(hold
the AquaStar’s outlet pipe with your hand) and at the tap.
If these two are very different, check for mixing valve or
plumbing crossover (see “MAIN BURNERS WILL NOT
IGNITE...” paragraph #6). Where automatic “anti-scald”
valvesarerequiredby code, lower the temperaturesetting
on the AquaStar as much as possible and balance the
pressure between cold and hot water after the AquaStar.
6. Parts in water flow valve are corroded so that the
gas passage is not fully opening.
Contact your service person or Controlled Energy.
HOT WATER TEMPERATURE FLUCTUATES
1. Unbalanced pressure in waterlines
The added restriction caused by the Aquastar in the hot
watersystem can result inuneven pressures between the
coldand the hot.In such caseswhen mixing coldwater at
thetap,thelower hot water pressure maybeoverpowered
by a much higher cold water pressure, which may cause
the Aquastar burners to shut down. Make sure faucet
aerators or shower heads are free of minerals. Do not
add any flow restrictor to the shower head.
2. Cold water is mixing with the hot water between
the AquaStar and the outlet
See #6 under “Burners do Not Ignite When Hot Water
Turned On”.
3. Inlet water pressure is erratic due to inadequate
supply water pressure or saturated pressure tank
on well system
Check the inlet water pressure. On a private well, raise
minimum pressure setting to 30 psi. Confirm that the
pressure tank is not water logged.
4. Gas pressure is too low
See page 2 for correct specifications.

13
Fig. 11 - Diagram of AquaStar 125 B
5
11
1
4
9
10
1. Heat exchanger
2. Pilot assembly
3. Burner manifold gas
pressure test nipple
4. Main gas burner
5. Pilot gas tubing
6. Gas valve
7. Pressure tap screw
location
8. Gas control slide
9. Piezoigniter
10. Water valve
11. Temperature adjustment
selector
12. Gas inlet gas pressure
test nipple
3
12
2
6
7
8

14
Fig. 12 - INTERIOR COMPONENTS DIAGRAM AND PARTS LIST

15
Fig. 12
INTERIOR COMPONENTS DIAGRAM
AND PARTS LIST 125B
1Cover ¤ 8 705 421 025
2Plastic collar ¤ 8 700 403 008
3Temperature adjustment knob ¤ 8 702 000 111
4Panel back ¤ 8 705 402 164
5Draft divertor ¤ 8 705 505 354
6Heat exchanger ¤ 8 705 406 235
7Hot water pipe ¤ 8 700 705 556
8Cold water pipe ¤ 8 700 705 294
9Heat exchanger washer ¤ 8 710 103 045
10 Overheat sensor (ECO) ¤ 8 707 206 040
11 Main burner assembly LPG 8 708 120 296
Main burner assembly NG 8 708 120 298
12 Pilot burner assembly ¤ 8 718 105 048
12a Pilot air screen ¤ 8 700 507 055
13 Piezo electrode ¤ 8 708 107 002
14 Pilot orifice NG 8 708 200 005
“ LPG 8 748 200 173
15 Pilot Tube ¤ 8 700 707 320
16 Thermocouple ¤ 8 747 202 083
17 Burner assembly washer ¤ 8 710 103 060
18 Throttle disc LPG 8 700 100 174
19 Gas valve LPG 8 707 011 463
Gas valve NG 8 707 011 459
20 Gas supply pipe ¤ 8 700 705 552
21 Electromagnet ¤ 8 707 201 012
22 Thermocable ¤ 8 747 202 209
23 Water valve assembly ¤ 8 707 002 499
24 Water valve repair kit ¤ 8 703 406 178
25 Slow ignition valve ¤ 8 708 503 063
26 Water valve diaphragm ¤ 8 700 503 053
27 Water valve selector screw assembly ¤ 8 708 500 251
28 Water inlet filter ¤ 8 700 507 045
29 Water valve venturi ¤ 8 708 205 249
30 Water valve water governor ¤ 8 707 402 013

Replacement Parts available from North American Distributor
CONTROLLED ENERGY CORP.
340 Mad River Park
Vermont 05673 (U.S.A.)
Phone [phone]
Fax [phone]
WWW.CECHOT.COM
VULCANO Termodomésticos S.A.
Estrada de Cacia
3800 Cacia - PORTUGAL
Recycled paper
[email protected]
GAS LINE SIZE
Natural Gas
Nominal Iron Pipe Size* 1/2" 3/4" 1"
MAXIMUM LENGTH 10' 40' 150'
Liquid Propane
Semi-rigid Tubing 1/2" 5/8" 3/4" 7/8"
MAXIMUM LENGTH NOT
RECOMMENDED 20' 60' 150'
* Flex tubing greatly reduces capacity and, therefore, is not recommended.
Minimum Vent Size* and Height
Minimum Diameter Minimum Height**
5 inches 6 feet**
* NOTE: Vent size must not be restricted. Installation must comply with national fuel
g
as code ventin
g
requirements
for a 117,000 Btu Cate
g
ory I appliance and any applicable local codes.
Water Pressure
For installation on well systems, insure that your water pressure is between 30 - 50 psi.
** NOTE: Minimum vent hei
g
ht must be 6 feet, provided there are no elbows. Termination of the vent must be 2
feet above any obstruction within a 10 foot radius of vent pipe. Consult your
g
as utility or National Fuel Gas Code
if vent will have elbows or share ventin
g
with another appliance. The vent connector should have as much vertical
rise as possible (minimum 12") before any horizontal run.
INSTALLATION CHECKLIST