AquaStar 125X 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 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 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.
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 turning on the heater ................... Page 8
Operating instructions........................................ Page 9
Setting water temperature ................................. Page 9
Maintenance & Service.................................... Page 10
Trouble Shooting ............................................. Page 10
Microswitch Adjustment................................... Page 11
Electrical Diagram ........................................... Page 12
Diagram of AquaStar ....................................... Page 13
Interior components diagram ........................... Page 14
Parts List ......................................................... Page 15
TABLE OF CONTENTS
6 720 605 566 PT 961 (01.99)

2
Principle of Operation:
Whenahot water 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 sensorconfirms the 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 hotwater faucet isshut off,the gas valve
automatically closes and the burners turn off. Your hot
waterfaucet is an ignitionkey to activate thewater 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(notthermocouple)
- On/Off Switch to activate system
- LEDindicatorflashesbeforebatteryneedsreplacement
AquaStar 125X LP and 125X 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 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 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
MINIMUM INSTALLATION CLEARANCES FROM COMBUSTIBLE AND
NON COMBUSTIBLE MATERIALS FOR ALCOVE INSTALLATIONS
FRONT VIEW SIDE VIEW
AQUASTAR MODELS 125B / 125BL / 125BS / 125X
D870_072
MODEL 125B / 125B LOW
PRESSURE / 125B SOLAR / 125 X
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.
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.
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
1. Maximum operating temperature of 125X: 130°F
2. Maximum heating capacity: 60°F rise 30°F rise
70,000 BTU/hr 35,000 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 advicefrom a professional properlylicensed in thelocality where theinstallation is made.

5
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 thathot water 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 125X 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 free area
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.
water heater installation in bathrooms, bedrooms or any
occupied rooms normally kept closed. See the section
below on locating the heater.
4. You must vent your heater. See section on Vent Pipe
Connections, Page 6.
5. The appliance must be disconnected from the gas
supply piping system during any pressure testing at
pressures in excess of 1/2 Psig (3.5 kPa).
Theappliancemust be isolated from thegassupply piping
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 must be leaktested
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 withyourlocal gas
supplier,andseethesectiononconnectingthegassupply.
8. Shouldoverheating occur orthe gas supplyfail to shut
off,turnoffthe gassupplyat the manualgasshut offvalve
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 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

6
CLEARANCES
TheAquastar 125 Xis design certifiedfor installation ona
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. For example: typeB-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 X 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 soas to develop apositive flow
adequatetoremove flue gasses totheoutdoors.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
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 125X 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.
Theincandescentparticletray(shippedlooseinthe carton
with the water heater) must be attached at the bottom of
thewater heater frontcover at the timeof installation. Use
the screws provided. See figure 2
WALL STUDS
1” X 4”
SPACE BOARD
SUPPORT BOARD
13 ¼”
SCREWS
INCANDESCENT PARTICLE TRAY

7
The flue connection for the AquaStar 125X is 5 inches.
However,in Canada, for installationsathighaltitude(2000-
4500feet above sealevel) a six inch flueis required. A 5"
by 6" flue adaptor must be affixed to the flue collar of the
AquaStar with at least two screws. See figure 3.
WARNING: Failure TO INCREASE THE VENT SIZE TO
SIXINCHES AND/orassure that the manifold pressure is
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 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 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
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
Fig. 3 - Flue Adaptor for High Altitude Installations
5” X 6” ADAPTOR
USED ON HIGH ALTITUDE
Above 4.500 ft consult your local gas provider.

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 the water flowsfreely and
alltheair has escapedfromthe system. The water heater
is now ready to work
FOR YOUR SAFETY READ BEFORE
OPERATING YOUR HOT WATER HEATER
Warning: If you do not follow these instructions
exactly, a fire or explosion mayresultcausingproperty
damage, personal injury or loss of life.
A. This appliance is equipped with electronic ignition for
lightingthe pilot andmainburners.Whenturningtheheater
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-down coverplate on the front panel strip. 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. Useonly your hand topush in the on/offcontrolbutton.
Neverusetools.Followthese instructions exactly.Ifcontrol
buttonisjammed, close thegassupply and call aqualified
servicetechnician. Attempted forcefulrepair may resultin
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.Rememberthatwaterpressuremustbesufficient
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. TheAquaStar 125X
is provided with two connectors that must be connected
to the inlet and outlet fittings of the water valve as shown
inFig 5. Thesefittings seal to thewater valve bymeans 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.
Becertain there areno loose particlesor dirt inthe piping.
Blow out or flush the lines 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 - top view
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. The location of the PRV must be readily accessible
forservicing or replacement.,and be mounted as closeto
thewaterheater as possible. See Fig6.To install 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
HWSHWS CWSCWS
Pressure
Relief
Valve
Pressure
Relief
Valve

9
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°F is 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 125X, 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
125B LPS or 125B NGS.
Fig. 8 - Temperature Adjustment Knob
LIGHTING AND OPERATING INSTRUCTIONS
1. STOP!Read thesafety information above onthis label.
2. The gas valve must be shutt off by putting the ON/OFF
switch to position “0”. Wait five (5) minutes to clear out
anygas.Ifyousmellgas,STOP!Follow “B” in the safety
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 plate onfrontal
panel strip) marked I/0totheIposition. In this position,
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 open andclose 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.
SETTING THE WATER TEMPERATURE
TheAquaStar125X LP and 125 XNGwaterheatershave
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 control on the front of the
heaterall the way to the right (clockwise). SeeFig 8.This
will produce a temperature rise of approximately 90°F at
flow rates between 0.5 and 2.0 gallons per minute. Given
that average incoming water temperatures are 50°F, this
heater will produce approximately 140°F water at these
flow rates. Turning the dial all the way to the left
(counterclockwise) will produce a temperature rise of
approximately 45°F 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.
TEMPERATURE
ADJUSTMENT 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
Align batteries as
shown
G667_091
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
G661_004
Temperature Adjustment Knob
Decrease temperature
and increase flow Increases temperature and decreases flow
Fig. 9 - Principles of Operation

10
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
MAINTENANCE AND SERVICE
Approximately once a year, the AquaStar should be
checked, cleaned and serviced as necessary. To remove
thefront cover,first remove theincandescentparticle tray,
thenpulloff the temperature adjustment knob and unscrew
and remove the plastic collar. Pull main cover out toward
youand lift upand out. THE FOLLOWINGOPERATIONS
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.Check that thewater inlet
filter (#28 on Figure 14, page 14) is clean.
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
mayneedto be cleaned orreplaced.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.
Main Burner Flames: The main burner flames should be
blue, with a more intense blue cone in the center core.
Yellowflames could be asign of wrong sizegas orifices 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 theburners,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.
TROUBLE SHOOTING
Introduction
The AquaStar 125X burners are activated by a water flow
valve. Numerous water related problems can cause this
watervalve tomalfunction suchas: 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
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 that the cover
betakenoff.Todo this, remove incandescentparticletray,
pulloffthe temperature adjustmentknobandunscrew and
remove the plastic collar. Pull main cover out toward you
and lift up and out.
To clean the pilot burner and/ or the pilot orifice : Turn
offthegasto the unit. Set theOn/OffswitchtoOff(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.Thepilotorificeshouldbe 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 rate of 1.1 gallons/minute is
required to activate the heater.
3. Water inlet filter is clogged
Water flow is restricted,preventingneededflowtoactivate
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.Water running is a signofaplumbing
cross-over. Consult your plumber.
5. Batteries are weak
TheLEDlight (seen through the peephole inthecoverplate
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 tank and the waterheater’sgasregulator
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
Ifthepilotorifice is clean, the watervalveassemblyshould
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
3. ECO (overheat sensor) tripped due to overheating
4. Minimum inlet pressure on well is inadequate
Check the inlet water pressure. On a private well, raise
the minimum pressure setting to 30 psi. Confirm that the
pressure tank is not water logged.
WATER IS TOO HOT
1.Temperature Selection too high
Turn thetemperature adjustment knobcounter-clockwise
(to the left) to lower the maximum water temperature.
Note: This will increase the activation flow rate.
2. Inlet water temperature is too hot (as with solar
preheated water or high ground water
temperatures)
Decrease gas pressure. Note: Only the Model “S”
AquaStar should be used if the inlet water is preheated.
WATER IS NOT HOT ENOUGH
1. Temperature selection too low.
Changethesetting.Turn the temperature adjustment knob
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 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 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
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 “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.
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 electrical 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
MAIN BURNERS GO OUT DURING HOT WATER USE
1. Flow rate diminished below activation rate
2. Unbalanced pressure in the water lines
The added restriction caused by the AquaStar in the hot
watersystem can result inuneven pressures between the
coldand the hot.In such cases when mixingcold water 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 and showerheads are free of minerals and dirt.
Do not add any flow restrictor to the shower head.

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 “NO SPARK AT THE PILOT”.
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.
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 cases when mixingcold water 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.
13

14
Fig. 15 - INTERIOR COMPONENTS DIAGRAM AND PARTS LIST

15
Fig. 15
INTERIOR COMPONENTS DIAGRAM
AND PARTS LIST 125X
1Front cover ¤ 8 705 421 255
2Temperature adjustment knob ¤ 8 702 000 111
3Plastic collar ¤ 8 700 403 008
4Back panel ¤ 8 705 402 164
5Draught diverter ¤ 8 705 505 354
6Heat exchanger ¤ 8 705 406 235
7Hot water pipe ¤ 8 700 705 556
8Washer ¤ 8 710 103 045
9Overheat sensor (ECO) ¤ 8 707 206 040
10 Cold water pipe ¤ 8 700 705 294
11 Main Burner Assembly NG 8 708 120 298
11 Main Burner Assembly LPG 8 708 120 296
12 Washer for burner assembly ¤ 8 710 103 060
13 Throttle disc LPG 8 700 100 174
14 Gas valve NG 8 707 011 729
14 Gas valve LPG 8 707 011 730
15 Diaphragm switch NG 8 708 504 021
15 Diaphragm switch LPG 8 708 504 049
16 Pilot burner assembly ¤ 8 708 120 491
17 Electrode ignition group ¤ 8 718 107 067
18 Injector pilot NG 8 708 200 069
18 Injector pilot LPG 8 708 200 312
19 Pilot gas tube ¤ 8 700 707 349
20 Washer ¤ 8 700 103 173
21 Ignition unit ¤ 8 707 207 060
22 Battery box ¤ 8 700 505 062
23 Set of cables complete ¤ 8 704 401 035
24 Water valve ¤ 8 707 002 532
25 Cover ¤ 8 705 500 076
26 Slow-ignition valve ¤ 8 708 503 061
27 Diaphragm ¤ 8 700 503 053
28 Water inlet filter ¤ 8 700 507 045
29 Selector screw ¤ 8 708 500 251
30 Volumetric water governor ¤ 8 707 402 015
31 Venturi ¤ 8 708 205 249

Replacement Parts available from North American Distributor
CONTROLLED ENERGY CORP.
340 Mad River Park Waitsfield
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]
INSTALLATION CHECKLIST
MODELS 125B / 125BL / 125BS / 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 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 obstructionwithin a 10 foot radius of vent pipe. Consult your
g
as utility or National Gas Fuel 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.