Bosch AquaStar 125X LP User manual

WARNING: Improper installation,
adjustment, alteration, service or maintenance can
causeinjuryorpropertydamage.Refertothismanual.
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 and Electronic Ignition
INSTALLATION AND OPERATING INSTRUCTIONS FOR AUTOMATIC
INSTANTANEOUS TYPE WATER HEATERS FOR USE WITH NATURAL AND
LIQUEFIED PETROLEUM GAS
MODEL 125X LP and 125X NG (Flow Modulated with Electronic Ignition)
Suitable for heating potable water only
Not approved for space heating purposes
Intended for variable flow applications with steady cold water inlet temperatures
WARNING
If the information in this manual is not followed
exactly, a fire or explosion may resultcausingproperty
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.
-Immediatelycallyourgassupplierfromaneighbor’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,serviceagencyorthegassupplier.
Specifications .................................................... Page 2
Rules for safe operation .................................... Page 4
Locating theHeater ............................................ Page 4
CombustionAirRequirements ............................ Page5
MountingtheHeater........................................... Page5
Ventingthe Heater ............................................. Page6
GasConnections ............................................... Page7
WaterConnections ............................................ Page8
Safetybeforeturning on the heater..................... Page 8
Operatinginstructions ........................................ Page9
Settingwatertemperature .................................. Page9
Maintenance&Service..................................... Page10
TroubleShooting .............................................. Page 10
MicroswitchAdjustment ....................................Page11
ElectricalDiagram............................................ Page 12
DiagramofAquaStar......................................... Page13
Interiorcomponentsdiagram ............................ Page14
Parts List ......................................................... Page15
TABLE OF CONTENTS
6 720 606 520 (01.10) AL

2
Principle of Operation:
Whenahotwater faucet is opened,thewater flow through
the heater causes the gas valve to open. At the same
timea microswitch isactivated which sends aspark to the
pilot.The flame sensor confirmsthe pilot hasbeen lighted
and allows the first two burners to come on. The flame
sensor confirms correct activation and all burners come
on. The pilot goes off. The heat exchanger coils absorb
theheat generated by theburners and transfer heatto the
water. When the hot water faucetis shut off,the gas valve
automatically closes and the burners turn off. Your hot
waterfaucet is an ignitionkey to activatethewater heater,
giving you control over your hot water energy use. Every
time you turn off your hot water faucet, the energy
consumption of your hot water returns to zero.
FEATURES
- Electronic Pilot Ignition
- 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 flame sensor 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.
- Electronic Pilot Ignition
- SafetyFlameSensor at pilot burner(not thermocouple)
- On/Off Switch to activate system
- LEDindicator flashes before battery needs replacement
AquaStar 125X LP and 125X NG Specifications
GasInput max.: 117,000 Btu/hr
min.: 28,000 Btu/hr
WaterConnection1/2” Thread fitting
H x W x D 29 3/4” x 18 1/4” x 8 3/4"
Vent 5”
GasConnection1/2”NPT thread
Min. Water Pressure 18 Psi at 4 GPM
Max. Water Pressure 150 Psi
Shipping Weight 43 LB
Net Weight 40 LB
1.8 GPM at 90°rise
3.7 GPM at 45°rise
Min. Water Flow 1/2 gal/min
LP GAS Supply Pressure
(beforeAquastarregulator) min. 11” W.C.
max. 14”W.C.*
Required LP GAS Pressure at inlet
tapwhileAquastaris operating: 10.5” W.C.
LPGAS Burner Manifold pressure whileAquastaris
operating atmaximum input: 9.0” W.C.
NaturalGas Supply Pressure
(beforeAquastarregulator) min.: 7” W.C.
max.: 14” W.C.*
RequiredNatural Gas Pressure atinlet
tap whileAquastaris operating: 5.7” W.C.
NaturalGas Burner Manifold PressurewhileAquastaris
operating atmaximum input: 4.2” W.C.
* Inlet gas pressure before Aquastar regulator must not
exceed this value. Pressure may need to be adjusted for
high altitudes, see page 7.
UNPACKING THE AQUASTAR HEATER
Thisheateris packedsecurely. The box includestwo water connection fittings,acontrol knob, agaspressure regulator,
apressurereliefvalve,anincandescentparticletray, two hooks for hanging the heater,thismanual,awarrantystatement
and a warranty registration card. Do not lose this manual, as there is a charge for replacement. Please complete
andreturnthe enclosed warrantyregistration card.

3
MINIMUM INSTALLATION CLEARANCES FROM COMBUSTIBLEAND NON
COMBUSTIBLE MATERIALS FOR ALCOVE OR CLOSET INSTALLATIONS
FRONT VIEW SIDE VIEW
AQUASTAR MODEL 125X
D870_072
MODEL 125 X
TOP (A) 12"
FRONT (B) 4"
BACK 0"
SIDES 4"
FLOOR (C) 12" *
FLUE DIAMETER 5"
* Some local codes require 18” in garage installations

4
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,in the absence oflocalcodes,
theNational Fuel Gas CodeANSIZ223.1/NFPA54.
In Canada: The Installation should conform with CGA
B149.(1,2)INSTALLATIONCODESand/orlocalinstallation
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. Theplacewhereyouinstalltheheatermusthaveenough
ventilation.The National Fire Codesdo not allow gasfired
water heater installation in bathrooms, bedrooms or any
occupiedroomsnormallykeptclosed.Seethesectionbelow
onlocating the heater.
4. You must vent your heater. See section on VENTING,
Page6.
5. Theappliancemustbedisconnectedfromthegassupply
piping system during any pressure testing at pressures in
excess of 1/2 Psig (3.5 kPa).
Theappliancemustbe isolated from thegassupplypiping
systemby closing 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 must be leaktested
beforeplacingthe appliance in operation.
6. Keepwaterheaterareaclearandfreefromcombustibles
and flammable liquids. Do not locate the heater over any
materialwhich might burn.
7. Correct gas pressure is critical for the optimum
operationof this heater (see specifications on page2).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,andseethesectiononconnectingthegassupply.
8. Shouldoverheating occur orthe gas supplyfail to shut
off,turnoff the gassupplyat the manual gasshut off valve
on the gas line.
9. Do not use this appliance if any part has been
underwater. Immediately callaqualifiedservicetechnician
to inspect the appliance and to replace any part of the
control system and any gas control which has been
underwater.
PROPER LOCATION FOR INSTALLING
YOUR HEATER
Carefully select the location of your new heater. For your
safetyand forproperheateroperation,you must providean
abundant supply of combustion air and a proper venting
installation.
Fig. 0 - Water heater drain plug
Theheater may still operate even when improperly vented.
Itwill,however,belessefficientandcouldeventuallydamage
theheater. It could evenresultin human sickness ordeath
dueto oxygendeprivationandcarbonmonoxide poisoning.
Followtheguidelines 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 or any occupied
rooms normally kept closed.
3. Simultaneous operation of other appliances such as
exhaustfans, ventilation systems clothes dryers,fireplaces
orwoodstoves couldcreateavacuumeffectinyourhome
which could cause dangerous combustion by-products to
spillbackintoyour home rather than ventingtotheoutside
through the flue. Confirm that your Aquastar is venting
properlywhenall these otherappliances are running. See
sectiononventing.
Donot obstruct the flow of combustion and ventilation
air to the appliance. If installed near a clothes dryer it is
veryimportantthatthe dryer be properlyvented. Failure to
properlyvent a dryer couldresultinagradualaccumulation
oflintonthewaterheaterfincoilsandburners, leading to a
dangerous condition of vent blockage and poor unsafe
combustion.
4. Yourhotwaterlinesshouldbekept shorttosaveenergy.
It is always best to have hot water lines insulated.
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
WHEREIT COULDFREEZE.
This heater is neither designed for nor approved for
outside installation.
Drain the heater entirely if freezing temperatures are
anticipated in area where heater is installed by
disconnecting both the inlet and outlet elbow
connections at the rear of heater. Additionally remove
the drain plug under the water valve. See Fig. 0.
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.

5
Louvers, grills and screens have a blocking effect. If the
effectivefreearea is notknown,increase the sizesofyour
openings by 75% if your louvers are wood and by 30% if
yourlouversaremetal.RefertotheNationalFuelGasCode
forcomplete information. In buildings of tight construction
all air should be taken from outside.
CLEARANCES
TheAquastar125 X 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 -
combustibleconstruction listed below
A. Top 12inches (306 mm)
B. Front 4 inches (102 mm)
C. Back 0 inches
D. Sides 4 inch (102mm)
E. Bottom 12 inches (306 mm)
Clearancefromventisdependentupontheclearancerating
oftheventing material used. For example:typeB-1 vent is
approvedfor1inchclearance.
Note: Minimumclearancetocombustiblematerialsshould
not be less than 6" for single wall flue pipe. Note that this
clearance can be reduced if combustible material are
protectedaspertableVIoftheNationalfuelGasCodeorif
Type B gas vent is used.
MOUNTING INSTALLATION
The Aquastar 125 X is design certified for mounting on a
wall.
SecurethetwoLshapedhooksprovidedwiththeheaterto
a wall surface. Place them 13 ¼ inches apart as shown in
Fig1.
Donotinstallthisapplianceonacarpetedwalloroverfloor
coveringwhichis combustible, such ascarpet.Theheater
must be mounted on a wall using appropriate anchoring
materials.Ifwall is a studwallsheathed 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
asplasterboard, can cause failureof 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
thirdofthe heater to themountingboard.Toaffixthe lower
third of the heater, CEC recommends that two new holes
bedrilled in theheater’s frame, eachone 16 inchesbelow
the top two holes, and that washers and lag screws be
usedtosecure the lowerportionof the heatertoa spacing
board.
Before installing the unit, be certain you have the correct
heater for your type of Gas – Propane or Natural Gas.
Identification labels arefound onthe shipping box,andon
the rating plate which is located on the right side panel of
thecover.Also,eachburnerorificeisstampedwithanumber
(79for LPG and 120for Natural Gas).
Thisproduct is not approved for manufactured homes
(mobile home), recreational vehicles (RV) or boats.
Reference ANSI Z21.10.3.
This product is neither designed or approved for
outside installations.
COMBUSTION AIR REQUIREMENTS
TheAquaStar 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 in through the
unit’s vent pipe is capable of freezing these components.
ThisInstallation Manualspecifiestheminimum verticalvent
pipe and the amount of combustion air required for this
unit. The vent pipe must not be restricted and its 6 foot
minimum height (provided there are no elbows) must
terminate 2 feet above any obstruction within a 10 foot
radius.
When all requirements are followed, the unit will operate
properly and safely. However, there may still be a risk of
freezingduetonegativedraftifallthecombustionappliances
inthe area arenot being suppliedwith a sufficientamount
ofmake-upair.Awood stove orfurnacecanrob the make-
upairintheAquaStar’sventpipe,leavingthecold infiltrating
aircapable of freezingthe cold waterin theAquaStarheat
exchanger. More make up air is the solution. Follow the
instructionsonventingandcheckingadequacyofmakeup
air. AHVAC specialist should be used to design solutions
forprovidingmoremake-up air if necessary.
Observethefollowinginstructions concerning combustion
air.
Applianceslocated in unconfinedspaces:
a) An unconfined space is one whose volume is greater
than50 cubicfeetper1000Btu per hourofthecombined
ratingofallappliancesinstalledinthe space.That would
be5850cubic feet fortheAquaStar125Xalone.
b) Inunconfined spaces in buildings of conventional frame,
masonry, or metal construction, infiltration is normally
adequateto provide air forcombustion, ventilation, and
dilutionof flue gasses.
Applianceslocatedinconfinedspaces:)Theconfinedspace
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 free area
ofone square inchper:
- 1000 Btu/hr if all air is taken from inside the building.
- 2000Btu/hr ifallairis takenfromtheoutsideby horizontal
ducts.
- 4000 Btu/hr if all air is taken from the outside by direct
openingsor vertical ducts.
Ortheconfinedspacemustbeprovidedwithonepermanent
openingorduct that iswithin12 inches of theceiling of the
enclosure.This opening must have a minimum free area of
onesquare inch per:
- 3000 Btu/hr if all air is taken from the outside by a direct
openingorvertical duct.

6
Fig. 2 - Incandescent Particle Tray Illustration
atleast1/4inch for every foot ofitshorizontallength.Keep
thehorizontal section short and avoid too manyelbows.
To check the draft:
Close all doors and windows to the outside.
Turn on all appliances that force air out of the building.
Theseincludeallexhaust/ventilationfans, furnaces,clothes
dryers,wood burning stoves,etc.
Open all doors between the AquaStar and these other
appliances.
Runtheunitfor at least 10 minutes. Thenholdanordinary
mirror at the side above the front shell. Any flue gases
backdrafting will cause the mirror to fog. This is a serious
health hazard and must be corrected. Poor venting can
result in soot building up inside the heater, overheating of
theheaterandfreezingof the heat exchanger in afreezing
environment.
Themirrorwillremainclearwith aproperlyfunctioningdraft.
WARNING
Note: Theburnersofaninstantaneous“ondemand”water
heater such as the AquaStar are only on at the time that
hotwater is actuallybeing used, the vent pipeis therefore
coldexceptfor the short durations whenhotwater is being
used,itis therefore very importantthat the venting and air
supply be adequate to provide a good positive draft as
soon as the burners turn on. See venting guide on back
page.
TheAquaStar125Xinstantaneouswaterheatershavebuilt-
in draft diverters and are designed for indoor installation
only.The draftdiverteroutletmust be connected to a clear,
unobstructedvent of thesame size, orlarger.
InCanada,CAN/CGA-B149InstallationCodefordetailed
requirements
In U.S.A., ANSI Z223.1 - NFPA 54, national Fuel Gas
Codefordetailedrequirements.
The flue connection for the AquaStar 125X is 5 inches.
However,inCANADA,forinstallationsathighaltitude(2000-
4500 feet above sea level) a six inch flue is required.A5"
by 6" flue adaptor must be affixed to the flue collar of the
AquaStar with at least two screws. See figure 3.
WARNING:FailureTOINCREASETHEVENTSIZE
TOSIX INCHESAND/orassurethatthemanifoldpressure
issettopropervaluelistedforapplicationsathighaltitudes
willcause unsafe venting, asphyxiation,and will void CSA
Certification.
Fig. 3 - Flue Adaptor for High Altitude Canadian
Installations
5” X 6” ADAPTOR
USED ON HIGH ALTITUDE
Theincandescentparticletray(shippedlooseinthecarton
with the water heater) must be attached at the bottom of
thewater heater frontcover at the timeof installation. Use
thescrewsprovided.Seefigure2
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 so asto develop apositive flow
adequateto remove flue gassestotheoutdoors.Minimum
vent size must be 5". Minimum vent height 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 the vent pipe. Consult your gas
utility or National Gas Fuel Code if vent will have
elbows or share venting with another appliance. The
vent connector should have as much vertical rise as
possible (minimum 12”) before any horizontal run.
Optional powervent available in order to sidewall vent.
Contact your local dealer. The appliance must be located
ascloseaspracticableto a chimney or vent.Theventpipe
sections must be secured to each other with sheet metal
screws.Keepin mind the minimumclearancefrom the top
of your heater. Remember also that single wall vent pipe
connectorsrequire a 6inch clearance fromcombustibles.
NationalFuel Gas Code specifies double wall —Type “B”
— vent pipe be used in cold climates and for gas vents
runningthrough attics.We considerdouble wallvent pipe
preferable in all circumstances.Any vent section greater
than45degrees from verticalis considered horizontal.
Horizontalsections of vent connectorsmustslopeupwards
SCREWS
INCANDESCENT PARTICLE TRAY
Fig. 1 - Mounting the Heater
WALL STUDS
1” X 4”
SPACE BOARD
13 ¼”
SUPPORTBOARD

7
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 X 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 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.
GAS LINE SIZING
-It is strongly recommended that the Natural Gas pipe
be Black Iron pipe the entire distance from the outside
meter to the inlet of theAquastar 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
tubingis NOT recommended, but if used then oversize
it.
THESEFIGURESARE FORAQUASTARSUPPLYONLY,
ALLOTHERAPPLIANCESINTHEBUILDINGWILLNEED
TO BE INCLUDED IN THE PIPE SIZING.
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 inaccordancewiththerecommendations
oftheserving gas supplier.
WARNING:The heater must bedisconnected 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,includingthepressureregulatorprovided
with it, must not be operated at gas supply pressures in
excess of 0.5 psig. If overpressure has occurred, such as
throughimproper testing ofthe gas linesor 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. 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.Turnthegasonand check
again with a soapy solution. Never test for gas leaks
using a match or flame.
Fig. 4 - Installation of Gas Pressure Regulator
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
PRESSUREREGULATOR
(with directional arrow on
reverse side pointing
upward)
Thepressure regulator provided with theheaterisadjusted
to deliver the proper gas pressure (as indicated on the
rating plate and in the manual for altitude up to 2000 feet
(660meters)abovesealevel.Onappliancesbeinginstalled
above2000 ft(660meters)elevation,the inletgaspressure
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 dial selector turned all the way
clockwise.
Above 4.500 ft consult your local gas provider.
PLASTIC VENT CAP
MAXIMUM INLET GAS FLOW PRESSURE SETTING

8
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.
Opena hot water faucet to permit the water to fill the heater
andthe pipingandtoeliminatethe air trappedinthesystem
Closethe hot waterfaucet after the water flowsfreely and
allthe air hasescaped from the system. Thewater heater
is now ready to operate.
FOR YOUR SAFETY READ BEFORE
OPERATING YOUR HOT WATER HEATER
Warning:Ifyoudonot followthese instructions exactly,
a fire or explosion may result causing property
damage, personal injury or loss of life.
A. This appliance is equipped with electronic ignition for
lightingthe pilot andmainburners.Whenturningthe heater
on, follow these instructions exactly.
B. Before operating the unit, set the On/Off switch to the
On (I) position. The On/Off switch is located behind the
flip-downcoverplateonthefrontpanelstrip.Smellallaround
the appliance area for gas. Be sure to smell next to the
floor because some gas is heavier than air and will settle
onthefloor.
WHAT TO DO IF YOU SMELLGAS
- Do not try to light any appliance.
- Do not touch any electric switch; do not use any phone
inyourbuilding
- 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. Useonlyyour hand topushin the on/offcontrolbutton.
Neveruse tools. Follow these instructions exactly.Ifcontrol
buttonisjammed, close the gassupplyand call a qualified
servicetechnician.Attemptedforceful repair may resultin
afire 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 ofthecontrol
system and any gas control which has been under water.
Connecting the pressure relief valve (PRV)
Alistedpressure relief valve supplied withtheheater 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.
THREADEDASSEMBLY SWEATEDASSEMBLY
The location of the PRV must be readily accessible for
servicingorreplacement., and bemountedas close to the
water heater as possible. See Fig 7. To install the PRV, a
suitable fitting connected to an extension on a “T”fitting
can be sweated to the hot water line.
HWSHWS CWSCWS
Pressure
Relief
Valve
Pressure
Relief
Valve
Fig. 7 - Pressure Relief Valve
1/2”FLEX
PIPEPRVTO
APPROPRIATE
DISCHARGE
Fig. 6 - Plumbing connections for the Aquastar 125X
S FITTING
PIPEPRVTO
APPROPRIATE
DISCHARGE
1/2”FLEX
Fig. 5 - Water valve and water
connectors, top view
WATER CONNECTIONS
Whenfacingtheheater,the cold water inlet isonyourright
and the hot water outlet is on your left.
Although water piping throughout your structure may be
other than copper, we recommend that copper piping be
usedforatleastthreefeetbeforeandafter theheater(follow
local codes if more stringent). Keep water inlet pipe to no
less than 1/2 inch diameter to allow the full flow capacity.
Rememberthatwaterpressuremustbe sufficienttoactivate
theheaterwhen drawing hot waterfromthe top floor. If the
hot and cold connections to the heater are reversed, the
heaterwillnotfunction.TheAquaStar 125Xisprovidedwith
twoflexibletype connectors that mustbeconnected to the
inlet and outlet fittings of the water valve as shown in Figs
5 and 6. ½” Galvanized or brass fittings work best when
connectedto the connectors. See Fig6.These connectors
seal to the water valve by means of a union connection
with a washer type gasket at the joint. No pipe dope or
thread tape is to be used at these joints. Be certain there
arenoloose particles or dirtinthe piping. Blow outorflush
thelines before connecting totheAquaStar. Full port valves
shouldbeinstalledonboththe cold water feed line andthe
hot water outlet 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.
WASHER
WATER FILTER
WATER VALVE
WASHER
INLET
OUTLET
FLEX
CONNECTORS

9
Thepositionyouselectonthetemperatureadjustmentknob
willdepend on thetemperatureoftheincomingwater(50°F
isaverageintheU.S.).Inwarmweatherregionswherethe
incomingcold water isgenerally warmer, orduring 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. At this setting, ifitis still necessary,
one could mix a small amount of cold water in a shower
andhavea comfortable shower atabout3gallons/minute.
Duringthecolder months, or incoldclimate areas, itmight
be necessary to set the control to the maximum position,
all the way clockwise to the right.
Do not supply the AquaStar 125X with preheated water.
For this type of application, purchase a solar model 125B
LPS or 125B NGS.
Fig. 8 - Temperature Adjustment Knob
LIGHTINGAND OPERATING INSTRUCTIONS
1. STOP!Read the safetyinformation above on thislabel.
2. The gas valve must be shut off by putting the ON/OFF
switch to position “0”. Wait five (5) minutes to clear out
anygas.Ifyousmellgas,STOP!Follow “B”inthesafety
information above. If you do not smell gas, go to the
next step.
3. This water heater is equipped with a safety pilot burner
and an automatic ignition control system.
4. Setthe ON/OFF switch (flipdown cover plateonfrontal
panelstrip) marked I/0 to theIposition. In thisposition,
the water heater is ready to use.
5. If the red LED indicator light (visible through the
peephole in the front panel strip) is flashing, this is a
warning that the batteries are less than 1.2 Volts and
willneedtobereplacedwithinthenextcoupleofweeks.
Plan to have two D type 1.5 volt long-life (Alkaline)
batteries available for replacement.
6. Turn the hot water faucet on the minimum flow rate
required to activate the heater. The automatic ignition
system first ignites the safety pilot burner which then
ignites the main burner in about 4 seconds.
7. The pilot flame will extinguish 10-30 seconds after the
burners come on. The burners will remain on until the
hot water tap is turned off.
NOTE: On a first time initial installation, existence of air in
the gas supply line and in the water line may cause some
ignitiondelay.In that case, repeatedly openand close the
hot water tap in order to restart the ignition process until
all the air has been purged.
TO TURN OFF GAS TO APPLIANCE
Turn off the manual lever on the gas supply line to the
heaterandsettheON/OFFswitchtotheOFF(0)position.
See Fig 9.
SETTING THE WATER TEMPERATURE
TheAquaStar125XLPand125 XNGwaterheaters havea
gascontrol that modulates burner input in response toflow.
Itspurposeis to ensurethatthe hot watertemperaturewill
remainsteady,althoughthewaterflow demand might vary
(downto 1/2 gal/minute).Toadjustthetemperatureon 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 control on the front of the heater all the way
to the right (clockwise). See Fig 8. This will produce a
temperatureriseofapproximately90°Fatflowratesbetween
0.5and2.0gallonsperminute.Giventhataverageincoming
water temperatures are 50°F, this heater will produce
approximately140°Fwater at theseflowrates.Turningthe
dialalltheway to the left(counterclockwise)willproduce a
temperature rise of approximately 45°F for flow rates
between1.1 and3.7gallonsperminute. Itissafesttoselect
acomfortabletemperatureandnothavetomixincoldwater.
TEMPERATURE
ADJUSTMENT KNOB
Align batteries as
shown
To operate the heater, set the ON/OFF switch to position I.
The switch is located behind the flip down cover plate on
the front panel strip.
To shut down the gas to the heater, set the ON/OFF switch
to position 0
TemperatureAdjustment Knob
If the LED light is flashing, prepare to
replace the batteries. Use two D cell
(1.5 volt) long life alkaline batteries.
G667_092
G667_090
G667_091
G661_004
Decrease temperature
and increase flow Increases temperature and decreases flow
Fig. 9 - Principles of Operation

10
MAINTENANCE AND SERVICE
REVIEW MAINTENANCE TABLE ON THE BACK
OF THIS MANUAL
Approximatelyonceayear,theAquaStarshouldbechecked
and cleaned. To remove the front cover, first remove the
incandescent particle tray, then pull off the temperature
adjustmentknobandunscrew andremovethe plasticcollar.
Pull main cover out toward you and lift up and out. THE
FOLLOWINGOPERATIONS SHOULD BE PERFORMED
BYAQUALIFIEDSERVICE PERSON:
Vent System: Should be checked annually. Clean and
repairasneeded.
Water Valve (Part#8707002534):Thewatervalveonthis
heatershouldbeservicedperiodically.Lubricatecomponent
#25 on page 14 with a small amount of silicon, faucet or
lithiumgreaseeverytwoyearstokeepits o rings freshand
pushrod sliding smoothly. Every 3-5 years replace
components #25 and #26 on page 14. The frequency will
dependonthe mineral content ofthewater and conditions
of use or whenever signs of corrosion appear at the gas
andwater valve joint. Periodically check that the water inlet
filter (#28 on page 14) is clean as well.
Pilot Flame: The pilot flame should burn with a clean,
sharp, blue flame and should resemble the diagram in
Fig.10.Iftheflameissoftandyellow, the pilot burner orifice
mayneed to be cleanedorreplaced.Thepilotflameshould
be approximately 2 inches long, extending past the flame
sensor. If the flame is too small, it will not reach the flame
sensor and the burners will not come on.
Do not use any wire or sharp object to clean orifices.
Naturalgas orifices arelarge enough thatyou can usually
clean them by blowing through them. LP orifices, on the
otherhand,are too small tocleanand should be replaced.
To access the pilot orifice, remove 2 screws holding pilot
assembly in place. Then loosen compression fittings to
expose pilot orifice.
Fig. 11 - Pilot burner with pilot orifice
Fig. 10 - Characteristic Pilot Flame
PILOT ORIFICE
Main Burner Flames: The main burner flames should be
blue, with a more intense blue cone in the center core.
Yellowflames could bea sign of wrongsize gas orificesor
dirty burners, or a blockage on the heat exchangers fins.
Ifsome burners haveyellowflameswhileothershavegood
flames,it is likely that dust, lint orspiderwebshavepartially
cloggedthe burner venturis.Toclean the burners,contact
a gas service person.
Mineral Scale Build-up: The AquaStars heater, when
operatedatlowertemperaturesettings,donotaccumulate
mineralbuild-up.Ifhowever,theheaterisusedat thehigher
temperature settings and the water has a high mineral
content,periodic descalingmay benecessary.Theheating
coilsshould be flushed witha descaling solution. Consult
yourdealer or Controlled Energyfor instructions.
TROUBLE SHOOTING (see maintenance table)
Introduction
TheAquaStar 125X burners are activated by a water flow
valve. Numerous water related problems can cause this
watervalve to malfunctionsuch as: Insufficientwater 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
waterflow related problems can cause theheatertodeliver
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 that the cover
betakenoff.To dothis, remove incandescent particletray,
pulloffthe temperature adjustment knobandunscrewand
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
offthegas to the unit.SettheOn/Offswitch to Off(position
0). Remove the cover of the heater. To do so, pull off the
temperature adjustment knob and unscrew and remove
the plastic collar. Pull main cover out toward you and lift
upandout.Thepilotorificeshould be cleaned or replaced.
Do not enlarge the orifice.
3mm
Correct gap between pilot
burner tip and electrode tip
Piezo Electrode
Flame sensor
Piezo
Electrode

11
NO SPARK AT THE PILOT
1. On/Off switch is not ”On” (Position I).
The On/Off switch is located behind the flipdown cover
plate on the front panel strip. See fig. 9.
2. Water flow is not sufficient to activate heater.
Water flow rate at faucet is below minimum flow needed
to activate heater. When temperature adjustment knob is
turned all the way clockwise, the AquaStar model 125X
requires 1/2 gallon per minute flow to activate the heater.
As a reference, this is a flow which would fill a quart jar in
30 seconds. If the temperature adjustment knob is turned
fullycounterclockwise, aflow rateof 1.1 gallons/minute is
required to activate the heater.
3. Water inlet filter is clogged
Waterflowisrestricted,preventing needed flow to activate
heater. Clean water inlet filter screen.
4. Cross over in water lines
To confirm there is no cross-over in the plumbing, shut off
the cold water supply to the AquaStar water heater and
open a hot water faucet. There should not be any water
flowingatthatfaucet.Waterrunning isa sign of aplumbing
cross-over. Consult your plumber.
5. Batteries are weak
TheLED light (seen through thepeepholeinthecoverplate
on the front panel) flashes when the batteries are less
than 1.2 volts. Replace batteries with D cell (1.5 volt) long
life alkaline batteries as shown in fig. 9.
6. Microswitch needs to be adjusted or replaced.
If you do not hear a click when a tap is opened, the
microswitch needs to be adjusted. See Fig. 12 for
adjustment, or replace the microswitch if the heater has
been in use for some time.
G871_212
Adjusting screw
Pilot does not spark with
water flow Pilot is always sparking without water flow
1Close water tap 1 Close water tap
2 Remove screw cap and
unscrew adjusting screw till
sparking starts
2 Screw in adjusting screw,
till it stops sparking
3 Screw in turning one and
half turns 3 Continue to screw in turning one and half turns
more
7. 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.
8. Water valve parts may be dirty or components
damaged
Firstcheck that venturiis free of dirtparticles.Watervalve
and component parts must be totally free of dirt. In hard
waterareas, mineral deposits caneventually (3-5 years in
hard water areas) corrode the water valve parts to a point
where they will need replacing. Any sign of moisture at
the bleed hole is a sign that the water valve
components need to be replaced immediately.
9. Loose connection at the ECO
Ignition sparker will not operate if the electrical circuit is
interrupted. Check that the connections to the ECO are
secure and tighten if necessary.
SPARKS APPEAR AT PILOT WHEN HOT WATER TAP
TURNED ON, BUT PILOT AND BURNERS WILL NOT
IGNITE
1. Air in the Gas Line
Normallythisisaproblem at time of initial installation,after
the pipes have been worked on, or after a gas supply line
has been allowed to empty. Bleed the air trapped in the
gasline by turningthe hot water faucet onand off until the
air has been cleared from the line.
2. No gas to the AquaStar
A. Gas cock on gas line may not be open
B. Gas regulator may be shut or damaged. Replace or
unjam the regulator. Note: The regulator furnished with
the heater is exclusively designed for low gas pressure.
Excessive pressure will lock it up. Jamming usually
happens when using propane gas if f the gas pressure
betweenthegas tankandthewater heater’sgas regulator
has not been reduced. See Page 2 for recommended
correct gas pressure. To unjam a regulator, consult your
gas supplier or call CEC.
3. Pilot orifice or gas valve is dirty
Clogging of the pilot burner can be caused by dust in the
airor dirt inthe gas. Thepilot orifice orgas filter mayneed
to be cleaned or replaced.
4. Water valve assembly needs to be checked
Ifthepilotorificeis clean, the water valveassemblyshould
be checked. The adjustment screw on the water valve
micro-switch may not be tight enough (Fig. 12). Remove
central cap beneath micro-switch assembly, carefully
loosen the adjustment screw until the pilot light ignites. At
that point retighten the screw one and a half turns.
5. Pilot electrovalve switch may need to be replaced
(See Fig 13).
Call CEC.
6. Electronic Control Box may need to be replaced
(See Fig 13).
Call CEC.
Fig. 12 - microswitch adjustment

12
Fig. 13 - Electrical wiring diagram
E661_002
WATER IS NOT HOT ENOUGH
1. Temperature selection too low.
Changethe setting.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.
3. Btu input is toolowdue 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
verypowerful to heatwater instantaneously sincethey do
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
for correct gas pressure settings and fig. 14 for locations
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
Comparewater temperature at outlet of the AquaStar(hold
theAquaStar’s outlet pipe with your hand) and at the tap.
If these two are very different, check for mixing valve or
plumbing crossover (see “NO SPARK AT THE PILOT”
paragraph #4). Where automatic “anti-scald”valves are
required by code, lower the temperature setting 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.
HOT WATER TEMPERATURE FLUCTUATES / UNIT
DEACTIVATED
1. Unbalanced pressure in waterlines
The added restriction caused by the Aquastar in the hot
watersystem can result inuneven pressures betweenthe
coldand the hot. In suchcases when mixing cold waterat
thetap,thelowerhot water pressure may beoverpowered
by a much higher cold water pressure, which may cause
theAquastar burners to shut down (deactivate). Make sure
faucetaeratorsor shower headsarefree of minerals.
Do not add any flow restrictor to the shower head.
Typically this deactivation symptom is a result of the
hot water being too hot to use comfortably. Warm inlet
water generally causes this. Lowering the control
knob setting and/or reducing the inlet gas supply to
the heater should correct this deactivation symptom.
PILOT SPARKS CONTINUOUSLY WITH NO WATER
RUNNING
1. Microswitch needs adjustment
If no water is running, but pilot electrode continuously
sparks, the microswitch screw to the water valve needs
adjustment. See Figure 12.
PILOT LIGHTS BUT BURNERS WILL NOT COME ON
1. Confirm water valve assembly is working properly.
2. Confirm the flame sensor is in its proper position.
3. Confirm the burner electrovalve switch is
functioning properly.
Call CEC
4. The electronic Control Box (Fig. 13) may need to
be replaced.
Call CEC.
114 gas control valve
115 burner electrovalve
116 battery compartment
1.5V D batteries (2)
119 overheat sensor
4 electronic control box
43 pilot electrovalve
51 pilot electrode
52 flame sensor
96 microswitch assembly
99 on/off switch
WATER IS TOO HOT
1.Temperature Selection too high
Turnthe temperature adjustmentknob counter-clockwise
(tothe left) tolower the maximum water temperature.
Note: This will increase the activation flow rate.
2. Inlet water temperature is very warm (60º-75ºF)
Reduce inlet gas supply to lower the heaters degree rise.
Note: Only the Model 125BS should be used if the inlet
waterispreheated.

13
5
11
1
4
9
10
3
12
2
6
7
8
Fig. 14 - Diagram of AquaStar 125 X
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. Electronic control box
8. Battery box
9. on/off switch
10. Temperature adjustment selector
11. Microswitch
12. Gas inlet gas pressure test nipple
13. LED
2. Cold water is mixing with the hot water between
the AquaStar and the outlet
See#4 under “NOSPARKATTHEPILOT”.
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 and 7 for correct specifications.
13

14
Fig. 15 - INTERIOR COMPONENTS DIAGRAM AND PARTS LIST

15
Fig. 15
INTERIOR COMPONENTS DIAGRAM
AND PARTS LIST 125X
1Frontcover ¤8 705 421 255
2Temperatureadjustmentknob comp. ¤8 702 000 219
3Temperatureadjustment knob ¤8 702 000 111
4Water connectiongasket ¤8 710 103 043
5Draughtdiverter ¤8 705 505 354
6Heatexchanger ¤8 705 406 235
7Hot water pipe ¤8 700 705 556
8Washer ¤8 710 103 045
9Overheatsensor (ECO) ¤8 707 206 040
10 Cold water pipe ¤8 700 705 294
11 MainBurnerAssembly NG 8 708 120 298
11 MainBurnerAssembly LPG 8 708 120 296
12 Washer forburnerassembly ¤8 710 103 060
13 Throttledisc LPG 8 700 100 174
14 Gasvalve NG 8 707 011 729
14 Gasvalve LPG 8 707 011 730
15 Diaphragmswitch NG 8 708 504 021
15 Diaphragmswitch LPG 8 708 504 049
16 Pilotburner assembly LPG 8 708 105 491
16 Pilotburner assembly NG 8 708 105 337
17 Electrodeignition group ¤8 718 107 067
18 Injectorpilot NG 8 708 200 069
18 Injectorpilot LPG 8 708 200 312
19 Pilot gas tube ¤8 700 707 349
20 Washer ¤8 700 103 173
21 Electroniccontrol box ¤8 707 207 011
22 Batterybox ¤8 700 505 062
23 Set of cables complete ¤8 704 401 035
24 Watervalve ¤8 707 002 534
25 Water valverepair kit ¤8 705 500 076
26 Slow-ignitionvalve ¤8 708 503 063
27 Diaphragm ¤8 700 503 053
28 Water inletfilter ¤8 700 507 059
29 Selectorscrew ¤8 708 500 251
30 Volumetric watergovernor ¤8 707 402 015
31 Venturi ¤8 708 205 249
32 LED Control 8 707 305 001
33 On/OffSwitch 8 707 200 014
34 PilotElectrovalve 8 708 501 249
35 BurnerElectrovalve 8 708 501 250
36 Water elbowfitting 8 700 703 114

01egapeesELBATECNANETNIAM
RAEYYREVESRAEY2YREVESRAEY5-3YREVE
EVLAVRETAWETACIRBUL
†
EVLAVRETAWDLIUBER
†
NEERCSRETLIFRETAWTCEPSNI
†
YLBMESSATOLIPTCEPSNI
†
YLBMESSATNEVTCEPSNI
†
RENRUBNIAMTCEPSNI
†
Replacement Parts available from North American
Distributor
CONTROLLED ENERGY CORP.
340 Mad River Park
Waitsfield, Vermont 05673
Phone[phone]
Fax [phone]
www.controlledenergy.com
[e-mail]
VULCANOTermodomésticos S.A.
Estrada de Cacia
3801 - 856 Aveiro - PORTUGAL
INSTALLATION CHECKLIST
MODEL 125X
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 capacityand, 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 gas code venting
requirements for a 117,000 Btu Category 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 height must be 6 feet, provided there are no elbows. Termination of the vent must be
2 feet above any obstructionwithin a 10 foot radius of vent pipe. Consult your gas utility or National Gas Fuel
Code if vent will have elbows or share venting with another appliance. The vent connector should have as much
vertical rise as possible (minimum 12") before any horizontal run.
Recycled paper © 2001 Controlled Energy Corporation, Waitsfield, VT
all rights reserved