Bosch AquaStar 38B 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.
In the Commonwealth of Massachusetts this product
must be installed by a licensed plumber.
INSTALLATION AND OPERATING INSTRUCTIONS FOR AUTOMATIC
INSTANTANEOUS TYPE WATER HEATERS FOR USE WITH NATURAL AND
LIQUEFIED PETROLEUM GAS
MODEL 38B LP and NG
Suitable for heating potable water only
Not approved for space heating purposes
Intended for low flow domestic hot water applications with steady cold water inlet temperatures
WARNING
If the information in this manual is not followed
exactly, a fire or explosion may result causing property
damage, personal injury or death.
FOR YOUR SAFETY
Do not store or use gasoline or other flammable,
combustible or corrosive vapors and liquids in the
vicinity of this or any other appliance.
WHAT TO DO IF YOU SMELL GAS
-Do not try to light any appliance.
-Do not touch any electrical switch; do not use any
phone in your building.
-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
Rulesforsafeoperation...................................... Page4
Locating theHeater ............................................ Page 4
CombustionAirRequirements ............................ Page5
MountingtheHeater........................................... Page5
Ventingthe Heater ............................................. Page6
GasConnections ............................................... Page6
WaterConnections ............................................ Page 7
Safetybefore lighting thepilot ............................ Page8
Lightinginstructions ........................................... Page 8
Settingwatertemperature .................................. Page9
Maintenance&Service....................................... Page9
TroubleShooting .............................................. Page10
DiagramofAquaStar......................................... Page13
Componentsand Parts List.............................. Page 14
TABLE OF CONTENTS
6 720 606 446 (02.01) AL

2
This well engineered, gas water heater has all the fea-
tures a water heater should have:
Itoperatesontheprincipleof heatingwaterinstantaneously
“on demand”. When a hot water faucet is opened, cold
waterflows through the coils of the heat exchanger in the
Aquastar. This same flow opens the gas valve, and the
burnersareignited by the pilot flame.Theheatexchanger
coils absorbthe heat generated bythe burners andtrans-
fer heat to the water. When the hot water faucet is shut
off, the gas valve automatically closes and the burners
turn off.Your hot water faucet is an ignition key to turn on
the water heater, giving you control over your hot water
energyuse. Each time you turn off yourhotwaterfaucet,
you also shut off the water heater.
FEATURES
- High Quality Materials for Long Working Life.
- Copper heating coils for endless supply of hot water.
- Safety thermocouple at pilot burner.
- Automatic overheating protection shut-off sensor.
- Stainless steel burners with stabilized blue flame.
- Built-in corrosion resistant draft inducer.
- Compactspacesaver:mountsonawallwithtwohooks.
- Easily removable one-piece cover.
- Easy one person installation.
- Adjustablewaterflowrestrictortoensurethat water flow
demand will not exceed the heating capacity of the
heater.
- Easypilot flame lighting withpush button piezoignition.
BOSCHisconstantly improvingourproducts,therefore
specifications are subject to change without prior
notice.
AquaStar 38B LP and 38B NG Specifications
Gas Input max.: 40,000 Btu/hr
min.: 20,000 Btu/hr
WaterConnection1/2”Thread fitting NPT
H x W x D 25 3/8” x 10 5/8” x 9 1/8"
Vent 4”
Gas Connection 1/2” NPT thread
Min. Water Pressure 13 Psi at 1.3 GPM
Max. Water Pressure 150 Psi
Shipping Weight 20 LB
Net Weight 18 LB
0.5 GPM at 90°rise
1.3 GPM at 45°rise
Min. Water Flow 1/2 gal/min
LP GAS Supply Pressure
(beforeAquastar regulator) min.: 11” W.C.
max.: 14”W.C.*
Required LP GAS Pressure at inlet tap while
Aquastaris operating: 10.5” W.C.
LPGASBurnerManifold pressure whileAquastaris
operating atmaximuminput: 9.0” W.C.
NaturalGas Supply Pressure
(beforeAquastarregulator) min.: 7” W.C.
max.: 14” W.C.*
RequiredNatural Gas Pressureat inlettap
whileAquastaris operating: 5.7” W.C.
NaturalGas Burner Manifold pressurewhileAquastaris
operating atmaximuminput: 3.3” 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
This heater is packed securely. The box includes two water connection fittings, a gas pressure regulator, a gas supply
elbowwithgasket, a gas shutoffvalve,apressurereliefvalve,twohooks for hanging theheater,thismanual,a warranty
statement and a warranty registration card. Do not lose this manual, as there is a charge for replacement. Please
completeand return theenclosed warranty registrationcard.

3
MINIMUMINSTALLATIONCLEARANCESFROM COMBUSTIBLEAND
NONCOMBUSTIBLE MATERIALS
FRONTVIEW SIDEVIEW
AQUASTAR MODEL 38B
* Some local codes require 18” in garage installations
MODEL 38B
TOP (A) 12 "
FRONT (B) 4 "
BACK 0 "
SIDES 4 "
FLOOR (C) 12 " *
VENT DIAMETER 4 "

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 absenceof local codes,
the National Fuel Gas CodeANSI 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
gasfiredwaterheater installation in bathrooms,bedrooms
or any occupied rooms normally kept closed. See the
section below on locating the heater. The 38B is not
approvedforboat or RVinstallations.
4. You must vent your heater. See section on VENTING,
Page6.
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 fromthegas supply piping
systembyclosingitsindividual manual shutoffvalveduring
any pressure testing of the gas supply piping system at
test pressures equal to or more than 1/2 Psig (3.5Kpa).
Theappliance and its gas connectionmust be leak tested
beforeplacingthe appliance in operation.
6. Keep water heater area clear and free from
combustibles and flammable liquids. Do not locate the
heateroverany material whichmight burn.
7. Correct gas pressure is critical for the optimum
operation of this heater (see specifications on page 2).
Gaspipingmust be sizedto provide therequiredpressure
at the maximum output of the heater, while all the other
gasappliancesare in operation. Checkwithyour local gas
supplier,andseethesectiononconnectingthegassupply.
8. Shouldoverheating occur or the gassupply fail to shut
off,turnoffthegassupplyat the manualgas shut 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 INSTALLINGYOUR
HEATER
Carefully select the location of your new heater. For your
safety and for proper heater operation, you must provide
anabundantsupplyofcombustionairandaproperventing
installation.
Theheatermaystilloperateevenwhenimproperlyvented.
It will, however, be less efficient and could eventually
damagetheheater.It could even resultinhuman sickness
or death due to oxygen deprivation and carbon monoxide
poisoning. Follow the guidelines below:
1. Place your heater as close to a vent or chimney as
possible.
2. National building codes require that you do not install
this appliance in bathrooms, bedrooms, unvented closet
or any occupied rooms normally kept closed. The 38B is
notapproved for boat orRV installations.
3. Simultaneous operation of other appliances such as
exhaustfans,ventilationsystemsclothesdryers,fireplaces
orwoodstoves couldcreateavacuum effectinyourhome
which could cause dangerous combustion by-products to
spillbackinto your home ratherthanventing to the outside
through the flue. Confirm that your Aquastar is venting
properlywhen all these otherappliances are running.See
section on venting.
Donotobstructtheflowofcombustionand 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,leadingtoadangerousconditionofventblockage
andpoorunsafe combustion.
4. Yourhotwaterlinesshouldbekept shorttosaveenergy.
It is always best to have hot water lines insulated.
WARNING: The water in this water heater is cold
andalwaysremainscoldexept for the times thathotwater
isbeingused DO NOT INSTALL IN AN AREAWHERE IT
COULDFREEZE.
This heater is neither designed for nor approved for
outside installation.
Draintheheater entirely iffreezingtemperatures are
anticipated in area where heater is installed by discon-
necting both the inlet and outlet water connections.
Additionally, remove the drainplugunderthe water valve.
See Fig 0.
Fig. 0 - Water heater drain plug
WATERVALVE
DRAIN PLUG
TOHEAT
EXCHANGER
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
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 REQUIREMENT
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.
ThisInstallationManualspecifiestheminimum vertical vent
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 are not beingsupplied with asufficient amount
ofmake-upair.Awood stove orfurnacecan rob themake-
upairintheAquaStar’sventpipe,leavingthecoldinfiltrating
aircapable of freezingthe cold water in theAquaStarheat
exchanger. More make up air is the solution. Follow the
instructionsonventingandcheckingadequacyofmakeup
air. AHVAC specialist should be used to design solutions
forprovidingmore make-up air ifnecessary.
Observethefollowing instructions concerning combustion
air.
Applianceslocated in confined spaces:
Theconfinedspace must beprovidedwith two permanent
openings,onecommencingwithin12inchesofthetop 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/hrifallairistaken fromtheoutsidebyhorizontal
ducts.
- 4000 Btu/hr if all air is taken from the outside by direct
openingsor vertical ducts.
Ortheconfinedspacemustbeprovidedwithonepermanent
openingor duct that iswithin 12 inchesofthe ceiling ofthe
enclosure. Thisopeningmusthaveaminimumfreeareaof
onesquare inch per:
-3000 Btu/hr if all air is taken from the outside by a direct
openingorvertical duct.
Louvers, grills and screens have a blocking effect. If the
effectivefree area is notknown, increase thesizes of your
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. That would be 2000
cubic feet for theAquastar 38B alone.
CLEARANCES
The Aquastar 38 B is design certified for installation on a
combustible wall and for installation in an alcove or closet
with the minimum clearances to combustible and non -
combustibleconstruction listed below
A. Top 12 inches ( 305 mm)
B. Front4inches (102mm)
C. Back 0 inches
D. Sides 4 inch (102mm)
E. Bottom 12 inches (306 mm)
Clearancefromventisdependentupontheclearancerating
oftheventing material used. Forexample: type B-1 ventis
approvedfor1inchclearance.
Note: Minimumclearancetocombustiblematerialsshould
not be less than 6" for single wall flue pipe. Note that this
clearance can be reduced if combustible material are
protectedaspertableVIofthe National fuel Gas Code orif
Type B gas vent is used.
MOUNTING INSTALLATION
The Aquastar 38 B is design certified for mounting on a
wall.
Securethe two Lshaped hooks, which are providedwith
heater, to a wall surface. Place them 5 ½” apart as
shown in Fig. 1.
Donotinstallthisapplianceona carpeted wall or over floor
coveringwhichis combustible, suchascarpet. The heater
must be mounted on a wall using appropriate anchoring
materials.Ifwall is astudwall sheathed withplasterboard,
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 causefailure of mounting.
Inearthquake-pronezones, CEC recommends that
installersuse a large washer and lag screw through the
existing holes used to hang the heater to affix the upper
third of the heater to the mounting board. To affix the
lowerthird of the heater, CECrecommends that two new
holes be drilled in the heater’s frame, each one 16 inches
below the top two holes, and that washers and lag
screws be used to secure the lower portion of the heater
to a spacing board.
Before installing the unit, be certain you have the correct
heaterfor your type of Gas – Propaneor Natural Gas

6
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 developa positive flow
adequatetoremovefluegassestotheoutdoors.Minimum
vent size must be 4". Minimum height must be 6 feet,
provided there are no elbows. Termination of vent
must be 2 feet above any obstruction within a 10 foot
radius. Consult your gas utility or National Fuel Gas
Code if vent will have elbows or share venting with
another appliance. The vent connector should have
asmuchverticalriseaspossible(minimum 12”) before
any horizontal run. The appliance must be located as
close as practicable to a chimney or vent. The vent pipe
sections must be secured to each other with sheet metal
screws. Keep in mind the minimum clearance from the
top of your heater. Remember also that single wall vent
pipe connectors require a 6 inch clearance from
combustibles. National Fuel Gas Code specifies double
wall — Type “B” — vent pipe be used in cold climates and
for gas vents running through attics. We consider double
wall vent pipe preferable in all circumstances. Any vent
sectiongreaterthan45degreesfromverticalisconsidered
horizontal. Horizontal sections of vent connectors must
slope upwards at least 1/4 inch for every foot of its
horizontal length. Keep the horizontal section short and
avoidtoomany elbows.
Applianceslocated in unconfinedspaces:
a) An unconfined space is one whose volume is greater
than50cubicfeetper1000Btuper hour ofthecombined
ratingofallappliancesinstalledinthespace.Thatwould
be2000 cubic feet for theAquaStar 38B alone.
b)Inunconfinedspacesinbuildingsofconventionalframe,
masonry, or metal construction, infiltration is normally
adequateto provide airforcombustion, ventilation, and
dilutionof flue gasses.
Identificationlabels are foundon the shippingbox, and on
the rating plate which is located on the right side panel of
thecover.Also,eachburnerorificeisstampedwithanumber
(79for LPG and120 for NaturalGas).
WARNING
Note: Theburnersofaninstantaneous“ondemand” water
heater such as the AquaStar are only on at the time that
hotwater is actually being used,the ventpipe is therefore
coldexceptfor the short durationswhen hot water isbeing
used,itis therefore veryimportant that the venting andair
supplybeadequatetoprovideagood positivedraftassoon
as the burners turn on.
TheAquaStar 38B instantaneouswaterheatershavebuilt-
in draft diverters and are designed for indoor installation
only.Thedraftdiverteroutletmustbeconnectedtoa clear,
unobstructedvent of the same size,or larger.
InCanada,CAN/CGA-B149InstallationCodefordetailed
requirements
In U.S.A., ANSI Z223.1 - NFPA 54, national Fuel Gas
Codefordetailedrequirements.
GAS CONNECTIONS and Gas Regulator
Before connecting the gas supply, check the rating plate
ontherightsideofthefrontcover to be sure that the heater
is rated for the same gas to which it will be connected.
In the United States: The installation must conform with
local codes or, in the absence of local codes, the National
FuelGasCodeANSIZ223.1/NFPA54.
InCanada:TheInstallationshouldconformwithCGAB149
INSTALLATION CODESand /or local installationcodes.
NOTE: The Aquastar 38 B is supplied with a gas
pressureregulatorthat must be installed on the heater
before attaching the gas supply line. See figure 2.
Place the gas regulator between the gas supply
connection(whichcomeswithamanual shutoff valve)
and the gas fitting wich is connected to the heater’s
gas inlet. There is a pressure tap on this gas fitting.
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.
Fig. 1 - Mounting the Heater
WALLSTUDS
1” X 4”
SPACEBOARD
SUPPORTBOARD
5 ½”
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.
Runthe unit for atleast 10 minutes.Then hold anordinary
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
theheaterandfreezing of the heatexchangerinafreezing
environment.
Themirrorwillremainclearwith aproperlyfunctioningdraft.

7
Connecting the pressure relief valve (PRV)
Alistedpressure relief valve suppliedwiththe heater must
be installed at the time of installation. Should a discharge
linebe added to thePRVnovalve is to beplaced between
the PRV and the heater. No reducing coupling or other
restriction may be installed in the discharge line. The
dischargelinemustbeinstalledsuch thatitallowscomplete
drainage of both the PRV and the line.The location of the
PRV must be readily accessible for servicing or
replacement.,andbemountedasclosetothewaterheater
as possible See Fig 4. To install the PRV, a suitable fitting
connected to an extension on a “T” fitting can be sweated
to the hot water line.
NationalFuelGasCoderequires that a sediment trap (drip
leg) be installed on gas appliances not so equipped. The
drip leg must be accessible and not subject to freezing
conditions.Installinaccordancewiththerecommendations
of the serving gas supplier.
WARNING: The heater and its individual shutoff
valvemustbedisconnected from the gassupplypiping
system during any pressure testing of that system at
test pressures in excess of 0.5 psig.
The water heater must be isolated from the gas supply
piping system by closing the manual shutoff valve during
any pressure testing of the gas supply piping system at
test pressures equal to or more than 0.5 psig.
Thewaterheater,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 gaslines or malfunctionof
Thepressureregulatorprovidedwiththeheaterisadjusted
to deliver the proper gas pressure (as indicated on the
rating plate and in the manual for altitude up to 2000 feet
(660 meters) above sea level. On appliances being
installed above 2000 ft (660 meters) elevation, the inlet
gas pressure should be set at installation to the value
shown below.
NOTE: The gas pressures specified below refer to
pressures taken at the pressure tap on the gas inlet
pipe just above the regulator (See Fig 2). These
readings should be taken while the heater is operating
at full input — i.e. maximum water flow with the
temperature dialselectorturnedallthewayclockwise.
MAXIMUM INLET GAS FLOW PRESSURE SETTING
Above 4.500 ft consult your local gas supplier.
Fig. 3 - Water connections
HOT OUTLET LINE
(CONNECTED TO HEAT
EXCHANGER)
3/8” WASHER
3/8” x 1/2”
BRASSFITTING
COLD WATER
INLET
the supply system, the gas valve and regulator must be
checkedforsafe operation.
Make sure that the regulator vent is protected against
blockage.
When your connections are made, check for gas leaks at
all joints (not just the ones you made).Apply some soapy
water to all gas fittings and gas valve. Soap bubbles are
a sign of a leak.
NOTE: Do not apply soap solution to pilot filter screen or
pilot orifice area. If you have a leak, shut off the gas.After
verifying that required gaskets are in place, tighten
appropriatefittingstostopleak. Turn the gasonandcheck
againwithasoapysolution.Never testforgasleaks using
a match or flame.
WATER CONNECTIONS
When facing the heater, the cold water inlet is on your
right and the hot water outlet is on your left
Although water piping throughout your structure may be
otherthan copper,werecommendthatcopper 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.
Threadedconnectorsaresuppliedwith this heater forboth
the hot and cold water fittings. See fig. 3. These fittings
permit1/2” NPT connectionsto be made.Be certain there
arenoloose particles ordirtin the piping.Blow out or flush
thelinesbeforeconnectingtotheAquaStar.Fullportvalves
shouldbeinstalledonboth the cold waterfeedlineandthe
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.
Fig. 2 - Gas Pressure Regulator
APPLIANCEGAS
REGULATOR
1/2” BRASS
BUSHING
GASSHUT-OFF
COCK
INLETGASFITTTING
WITHGASKET
PLASTICVENTCAP
PRESSURE
REGULATOR
(with directional
arrow on reverse
side pointing upward)
PRESSURETAP
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"

8
LIGHTING INSTRUCTIONS (as seen on front
cover of heater)
1. STOP! Read the safety information on the front panel
of the heater.
2. The Gas valve must be turned off by sliding the gas
valvebutton ( ) to the far left under the OFF( ) mark.
3. Wait five (5) minutes to clear out any gas. If you smell
gas, STOP! Follow “B”in the safety information above
on this plate. If you don’t smell gas, go to next step.
4. The pilot burner is located behind the peephole in the
front center of the jacket directly below the lighting
instructions on the front panel of the heater.
5. Slidethegasvalvebuttontotheright,tothe pilot position
( ).
6. Fully depress gas valve button ( )and light pilot by
pressing hard on pilot igniter button ( ). This step
may have to be repeated.
7. Observe the pilot flame through the peephole. The gas
valve button should be held down at least 15 seconds
withpilotburning.Whenthegas valvebuttonisreleased,
the pilot should continue to burn.
- If the gas valve button does not pop up when released,
stopand immediately call yourservice technician orgas
supplier.
- If pilot does not stay lit, repeat steps 1 through 7.
- If pilot will not stay lit after several tries, slide the gas
valvebutton to theleft, under theOFF ( ) mark and call
service technician or gas supplier.
8. Whenthe pilot remainson, slide thegas valve button to
the right, to the ON ( ) position. The heater will now
fire when water is drawn at a rate of 1/2 gallon or more
per minute.
NOTE: If main burner should fail to ignite, make sure pilot
is burning. If not, repeat lighting steps 1 through 7.
TO TURN OFF GAS TO APPLIANCE
Slide the gas valve button ( ) to the far left, under the
OFF ( ) mark and close the heater’s individual shut-off
valve.
OPERATING INSTRUCTIONS
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.
Openahotwaterfaucettopermitthewatertofilltheheater
andthepipingandtoeliminatetheair trapped inthesystem
Closethe hot water faucet afterthe waterflows freely and
allthe air has escaped fromthe system.The water heater
is now ready to operate.
FOR YOUR SAFETY READ BEFORE
LIGHTING THE PILOT
WARNING: If you do not follow these instructions
exactly, a fire or explosion may result causing property
damage,personal injury or loss of life.
A. This appliance has a piezo-igniter for lighting the pilot
burner. When lighting the pilot, follow these instructions
exactly.
B. BEFORE LIGHTING smell all around the appliance
area for gas. Be sure to smell next to the floor because
some gas is heavier than air and will settle on the floor.
WHAT TO DO IF YOU SMELL GAS
- Do not try to light any appliance.
- Do not touch any electric switch; do not use any phone
inyour building.
Fig. 5 - Water Piping
Fig. 4 - Pressure Relief Valve
- Immediately call your gas supplier from a neighbor’s
phone. Follow the gas supplier’s instructions.
- If you cannot reach your gas supplier, call the fire
department.
C. Use only your hand to push in or turn the gas control
buttons.Never use tools. Ifa button willnot push in, check
to make sure the buttons are being pushed in the proper
sequence. Follow these instructions exactly. If control
button(s) are jammed, close the gas supply and call a
qualifiedservicetechnician.Attempted forceful repairmay
result in a fire or explosion.
D. Do not use this appliance if any part has been under
water. Immediately call a qualified service technician to
inspecttheapplianceand to replace any partofthecontrol
system and any gas control which has been under water.

9
Fig. 6 - Water Flow Control Knob
Thepositionyouselectonthetemperatureadjustmentknob
willdependonthetemperatureof theincomingwater (50°F
is average in the U.S.). If you plan to supply theAquaStar
38B, with preheated water (i.e.)solar installation, the unit
could overheat. It will then shut off on safety when the
outlettemperaturereaches185°F.Foralowertemperature
rise, the heater can be set for minimum burner output by
slidingthegas valve control tothepilot setting symbol( ).
MAINTENANCEAND SERVICE(see maintenance
table on back)
Approximatelyonceayear,theAquaStarshouldbechecked
and cleaned. To remove the front cover, first remove the
incandescent particle tray, then pull off the temperature
adjustment knob, unscrew and remove the plastic collar
andunscrewthecentral screw locatedatthebottom of the
front cover. Pull main cover out toward you and lift up and
out. THE FOLLOWING OPERATIONS SHOULD BE
PERFORMEDBYAQUALIFIED SERVICEPERSON:
VentSystem:Shouldbecheckedannually.Cleanandrepair
asneeded.
Water Valve(Part#8707002497):Thewatervalveon this
heater should be serviced periodically. Lubricate compo-
nent#19 on page14 with asmall amount ofsilicon, faucet
or lithium grease every two years to keep its o rings fresh
andpushrodslidingsmoothly. Every3-5yearsreplacecom-
ponents #19 and #21 on page 14. The frequency will de-
pendon the mineral contentof the waterand conditions of
useor whenever signs of corrosionappear atthe gas and
water valve joint. Periodically check that the water inlet
filter (#25 on page 14) is clean as well.
3mm
Correct gap between pilot
burner tip and electrode tip
PiezoElectrode
Air screen filter
Fig. 7 - Characteristic Pilot Flame
10mm
3/8”
Piezo
Electrode
Thermocouple
To clean the pilot burner and/ or the pilot orifice :
Turnoffthegasattheunit.Removethecoveroftheheater.
To do so,removetheincandescent particletray, pull offthe
temperatureadjustmentknobandunscrewand remove the
knobcollar.Unscrewthecentral screwlocatedatthebottom
ofthefrontcover. Pull main coverouttowardyouandliftup
andout.Pull the airscreenoff, wash it andblowany lint off
(See Fig 8). The pilot orifices should also be cleaned or
replaced. Do not enlarge the orifice. Do not use any
wire or sharp object to clean orifices. Natural gas orifices
arelargeenoughthatyoucanusuallycleanthembyblowing
throughthem.LP orifices, ontheother hand, aretoo small
tocleanandshouldbereplaced.See#3inTroubleShooting
Section.Toaccessthepilotorifice,remove2screwsholding
pilot assembly in place. Then loosen compression fittings
to expose pilot orifice.
Pilot Flame: Thepilotflameshouldburnwith a clean sharp
blueflameandshouldresemble the diagram inFig7.Ifthe
flameisyellow, or if the pilotknobhastoremaindepressed
for a long time in order to keep the pilot lighted, the pilot
burnerandorthepilotburnerorificemayneedtobecleaned,
the orifice may need to be replaced, and or the air screen
orpilotgasfiltermayneed cleaning. The pilot flameshould
envelop approximately 10 mm (3/8") of the tip of the
thermocouple. If it is too small, the pilot burner must be
cleaned.Theposition of thePiezoigniter electrode should
be approximately 3 mm (1/8") from the pilot.
SETTING THE WATER TEMPERATURE
To adjust the temperature on your AquaStar, turn on a hot
waterfaucet to its maximum flow.Atthe water heater, turn
the large temperature adjustment knob located beneath
the maingascontrols on thefrontof the heaterall the way
to the right (clockwise). See Fig 6. This will produce a
temperaturerise of approximately 90°Fata flow rate of .5
gallons per minute (gpm). Turning the dial all the way to
the left (counterclockwise) will increase the water flowing
throughthe heater, and will produce a temperature rise of
approximately 45°F at a flow rate of 1.3 gpm. Given that
averageincomingwatertemperaturesare50°F,thisheater
willproducewaterbetween140°and95°attheseflowrates.
Thus one can obtain a higher flow rate, but at cooler
temperatures.

10
PILOT DOES NOT LIGHT
1. No gas to the Aquastar
A. Gas cock on gas line may not be open.
B. Gas valve button has not been moved to “PILOT
POSITION”.Slidebuttontorightto single flame position
( ).
2. In-line Aquastar gas regulator jammed (usually on
LP gas)
Replace or unlock the regulator. Note: The regulator
furnishedwiththeheater is designed forlowgas pressure.
Excessive pressure will lock it up (propane only). Locking
usuallyhappens if thegas pressure between the gastank
(propane)andthewaterheater’sgasregulatorhasnotbeen
reduced.Seepage2forrecommendedcorrectgaspressure
andcheck with gas service person.
To unlock a regulator, consult your gas supplier.
3. Pilot orifice clogged and/or air screen dirty
Clogging of the pilot burner can be caused by dust and
any suspended matter contained in the ambient air.
Although the filters can lengthen the cleaning intervals,
they can never completely prevent such clogging. In
consequence the gas jet issuing from the pilot orifice is
reduced and or the air mixture is reduced. The pilot flame
is weak and thus can no longer heat the thermocouple
sufficiently. For cleaning purposes, the air filter screen is
pulled off, washed and blown out. The pilot orifice has
likewise to be cleaned or exchanged. See page 9.
4. Air in the Gas Line
Note: Normally this is a problem only at the time of initial
installation, after the pipes have been worked on, or after
a propane tank has been allowed to empty, or after the
heater has been shut down for a long time.
Bleed all the air trapped in the gas line. Because of the
very small pilot orifice (especially on LP gas models),
bleeding out all the air could take several minutes. Slide
the gas valve button ( ) to pilot position ( ) and depress
this button until all the air has escaped, and the gas has
arrived. During this process, press on the piezo ignition
button separately until the pilot flame has ignited.
Main Burner Flames: Themain burnerflames should be
blue, with a more intense blue cone in the center core.
Yellowflamescould be asign of wrongsize gas orificesor
dirty burners, or a blockage on the heat exchangers fins.
Ifsomeburnershaveyellowflameswhileothershavegood
flames,itislikelythatdust,lintorspiderwebshavepartially
clogged the burner venturis.To clean the burners contact
a gas service person.
Mineral Scale Build-up: The AquaStars heater, when
operatedatlowertemperaturesettings,donot accumulate
mineralbuild-up.Ifhowever, theheaterisusedatthehigher
temperature settings and the water has a high mineral
content,periodicdescalingmay benecessary.Theheating
coilsshould be flushed with a descalingsolution. Consult
yourdealer or ControlledEnergy for instructions.
TROUBLE SHOOTING (see maintenance table on
back)
Introduction
TheAquaStar38burnersare ignited by a waterflowvalve.
Numerous water related problems can cause this water
valvetomalfunctionsuchas: Insufficientwater flowvolume
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;
Unevenpressuresbetweencoldandhot. (with single lever
faucets) Plumbing cross overs. These water flow related
problems can cause the heater to deliver less than its full
output, or to fail to ignite or to shut down completely.
Problemsarestatedinuppercase,boldface.Mostcommon
causes for the problems follow in order of likelihood. The
suggestedsolutions require that thecover be takenoff.To
this, remove incandescent particle tray, pull off the
temperatureadjustmentknobandunscrewand remove the
plasticcollarand unscrew the central screwlocated at the
bottom of the front cover. Pull main cover out toward you
and lift up and out.
Fig. 8 - Pilot burner with air screen/ pilot orifice
PILOTORIFICE
AIRSCREEN

11
BURNERS DO NOT IGNITE WHEN HOT WATER IS
TURNED ON
1. Pilot is not on.
Light the pilot. See lighting instructions.
2. Pilot lighting push button not turned to proper
position
Be sure that once the pilot flame is on, that the gas valve
button( )isslidall the wayto the rightto the ON position
( ).
3. Cold incoming water connection made to wrong
side of heater
Make sure cold water inlet connection is on the right side
of heater when you are facing heater.
4. Water flow rate at hot water tap is too low.
With the control knob set fully clockwise theAquastar
model38B requires ½gallonper minuteflow to activate
the burners. This is a flow which would fill a quart jar in
30 seconds.
5. Cold water inlet filter on heater is dirty.
Remove the filter and clean. This screen filter is located
at the inlet side of the brass water valve (fig. 10, #25).
Check and clean faucet aerators too.
6. Crossover in household plumbing
The AquaStar burner activates when there is sufficient
waterpressuredropintheAquaStarwater valve assembly
—ie. when a hot water faucet is opened. If there is a
crossover in the plumbing, the necessary pressure drop
in theAquaStar will be insufficient, or totally eliminated.A
plumbing crossover can be caused by a bad washer at a
singlelever faucet or incorrect plumbingor amixing valve
in the line, etc. which permits hot and cold water to mix in
the plumbing. The crossover will create a back pressure
inthesystempreventingthepressure drop in the Aquastar
(i.e.coldwaterisentering the water heaterfrombothsides
and the burners will not come on). To confirm there is no
crossover in the plumbing, shut off the cold water supply
to the AquaStar. Open your hot water taps. There should
not be any water flowing. If there is water flowing, there is
a crossover in the plumbing. This is a plumbing problem,
not an Aquastar problem. Please contact your plumber.
7. Water valve parts may be dirty or components
damaged.
Water valve and component parts must be totally free of
dirt. First check that the venturi is free of dirt particles. In
hard water areas, mineral deposits can eventually (3 to 5
years in hard water areas) corrode the water valve parts
to a point where they will need replacing. Any sign of
moisture or corrosion at the joint of the water valve and
the gas valve is a sign that the water valve assembly
components need to be replaced immediately. (Contact
serviceperson to cleanwater valveor replace ifcorrosion
ispresent).
PILOTLIGHTSBUT FLAMEGOESOUTWHENBUTTON
ISRELEASED
1. Pilot push button was not pushed in far enough or
was not held in long enough
Slide the gas valve button ( ) to pilot position ( ) and
depress this button. Hold it pushed in for at least 15
seconds to give time for the pilot flame to properly heat
the tip of the thermocouple.
2. Pilot flame improperly aimed or is too weak so it is
not properly heating the tip of the thermocouple.
The Pilot flame should be a sharp blue flame and aimed
at the tip of the thermocouple so that it envelops 10 mm
(3/8“)of thethermocoupletip.Pilotflamehastobeproperly
aimed at the thermocouple. See Fig 7.
3. Poor thermocouple connection at the
electromagnet
Note: Electromagnet is part #8707201012 located on the
right side of the gas valve behind the piezo pushbutton
assembly. Check the tightness of the thermocouple
connectionnut at the electromagnet: TheElectro-magnet
connection is a large aluminum 17mm hex head nut. The
thermocouple end is a 5 mm brass nut which screws into
the 17 mm nut. Tighten the thermocouple nut snugly but
not too tight.
4. Poor circuit connections at the ECO. (Energy Cut-
Off overheat protection)
Oxidation or looseness of the ECO terminal connections
canresultinmillivoltcurrentlossthroughthethermocouple
safetycircuit. Clean terminalswith very fine sandpaper or
an eraser and reconnect ECO leads.
5. Faulty ECO (part #8707206040)
If cleaning the terminals attached to the ECO did not fix
the problem,connectajumperwirebetweenthe two wires
and try to relight the pilot. If the pilot flame now remains
on, replace the ECO. If the flame still goes out when the
button is released, the ECO is not defective. Go to next
step.
6. Faulty thermocouple (part #8747202083) or
electromagnet ) Unless these 2 parts are at least 8
to10yearsold,itisveryunlikelythattheyare faulty.
Before testing, reconfirm that #2 is absolutely
correct,andthatallconnectionsarecleanand tight.
Totestthethermocouple,disconnectthethermocouplelead
totheECO.Insertamulti-meterprobeintothethermocouple
lead and attach or hold the other lead to the metal gas
valve(DC common). Lightthe pilot flame and holdbutton,
meterreading should be 24 mVDCor more.If the reading
is24 mVDC ormore the thermocoupleis good.Totest the
electromagnet, re-connect the thermocouple lead to the
ECO, light pilot and hold button while taking a reading
between the ECO leads and the metal gas valve (DC
common).The reading shoulddrop to 19mVDC or less.If
it does not, replace the electromagnet.

12
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
ComparewatertemperatureatoutletoftheAquaStar(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 “BURNERS DO NOT IGNITE
WHEN HOT WATER IS TURNED ON”paragraph # 6).
Whereautomatic“anti-scald”valvesare required bycode,
lowerthetemperature setting ontheAquaStarasmuchas
possible and balance the pressure between cold and hot
wateraftertheAquaStar.
6. Parts in water flow valve are corroded so that the
gas passage is not fully opening.
HOT WATER TEMPERATURE FLUCTUATES
1. Unbalanced pressure in waterlines
The added restriction caused by the Aquastar in the hot
watersystem can resultin uneven pressuresbetween the
coldand the hot. In such cases when mixing cold water at
thetap,thelower hot water pressuremaybeoverpowered
by a much higher cold water pressure, which may cause
the Aquastar burners to shut down. Make sure faucet
aerators or shower heads are free of minerals. Do not
add any flow restrictor to the shower head.
2. Cold water is mixing with the hot water between
the AquaStar and the outlet
See # 6 under “Burners do Not Ignite When Hot Water is
TurnedOn”.
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. Insufficient gas pressure
Check gas pressure requirements (page 2) and consult
gas service person.
PILOT LIGHT GOES OUT DURING OR IMMEDIATELY
AFTER HOT WATER HAS BEEN USED
1. Gas pressure too low
Very low gas pressure may be caused by low delivered
gas pressure, a jammed gas regulator or undersized gas
lines.If the gaslines are undersized,there may stillbe the
specifiedstaticgaslinepressure.Howeverwhenthewater
valveopens,andgasenterstheburners, thepressurecould
dropsharply, causingthe pilot flameto go out.Have a gas
technician confirm the gas pressure both static and at
maximum Btu output. Specifications for your heater are
on page 2.
2. Pilot may be dirty or weak
See Page 9 for instructions on pilot maintenance.
3. Burners are not shutting down immediately when
hot water is turned off
Note: If burners don’t shut down immediately when the
hot water is turned off, the heater will overheat and the
ECOwillshut-off thegas.Rebuildthewatervalveassembly
repair kit from CEC (part#8 703 406 204).
4. Water is too hot causing overheat sensor to shut
heater down
Reduce burners by sliding gas control to single flame
position or set control knob to a lower setting.
WATER IS TOO HOT
1.Burners are too strong
Note:Iftheinletwaterisquitewarm,slidegasvalvecontrol
to single flame symbol ( ) and the heater will function on
a minimum burner output.
2. Temperature selection is too hot
Turn the temperature adjustment knob to the left.
WATER IS NOT HOT ENOUGH
1. Temperature adjustment knob is set too low.
Changethesetting.Turnthetemperatureadjustmentknob
clockwise (to the right).
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 too low due to insufficient gas pressure
It is extremely important for a tankless
instantaneous water heater to have the right size
gas line to obtain the correct gas pressure
See specifications on page 2. Unlike storage tank water
heaters, the burners of a tankless water heater must be
verypowerful to heat water instantaneouslysince they do
this only at the time hot water is actually being used. It is
thereforeimperativethat the gaspressurerequirement be
met exactly. Insufficient gas pressure will directly affect
the water temperature at the time of usage. See pages 2
and 6 respectively for correct gas pressure settings and
wheregas pressures aretaken.

13
Fig. 9 - Diagram of AquaStar 38 B
2
4
8
10
1
7
9
11
1. Heat exchanger
2. Pilot assembly
3. Burner manifold gas
pressure test nipple
4. Pilot gas tubing
5. Main gas burner
6. Inlet gas pressure test nipple
7. Gas valve
8. Gas control slide
9. Piezo igniter
10. Temperature adjustment knob
11. Water valve
3
5
6

14
Fig. 10 - INTERIOR COMPONENTS DIAGRAM AND PARTS LIST

15
Fig. 10
INTERIOR COMPONENTS DIAGRAM
AND PARTS LIST 38B
1Cover ¤8 705 421 021
2Temperatureadjustmentknob ¤8 702 000 182
4Draftdivertor ¤8 705 505 361
5Heatexchanger ¤8 705 406 149
6Overheat sensor (ECO) ¤8 707 206 040
7Hot water pipe ¤8 700 703 038
8Main burner assembly LPG 8 708 120 301
Main burner assembly NG 8 708 120 011
9Burnerassemblywasher ¤8 700 103 008
10 Piezo electrode ¤8 708 107 002
11 Pilotburner assembly ¤8 708 105 337
11a Pilot air screen ¤8 700 507 055
12 Pilot orifice NG 8 708 200 005
“LPG 8 748 200 173
13 PilotTube ¤8 700 707 334
14 Thermocouple ¤8 747 202 083
15 Gas valve LPG 8 707 011 456
Gas valve NG 8 707 011 466
16 Electromagnet ¤8 707 201 012
17 Thermocable ¤8 747 202 209
18 Water valve assembly ¤8 707 002 497
19 Water valve repair kit ¤8 703 406 204
20 Water valve diaphragm ¤8 700 503 050
21 Slowignition valve ¤8 708 503 063
22 Water valvewater governor ¤8 707 402 018
23 Water valveselector screw ¤8 708 500 166
25 Water inletfilter ¤8 700 507 001
26 Watervalve venturi ¤8 708 205 210
27 ThrottleDisc NG 8 700 100 169

GAS LINE SIZE
Natural Gas
Nominal Iron Pipe Size* 3/8" 1/2"
MAXIMUM LENGTH 20' 80'
Liquid Propane
Semi-rigid Tubing 3/8" 1/2"
MAXIMUM LENGTH 10' 60'
* Flex tubing greatly reduces capacity and, therefore, is not recommended.
Minimum Vent Size* and Height
Minimum Diameter Minimum Height**
4 inches 6 feet**
* NOTE: Vent size must not be restricted. Installation must comply with national fuel gas code venting requirements
for a 40,000 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: 6 feet, provided there are no elbows. Termination of vent must be 2 feet above any obstruction within a
10 foot radius. Consult your gas utility or National Fuel Gas Code if vent will have elbows or share venting with
another appliance. The vent connector should have as much vertical rise as possible (minimum 12") before any
horizontal run.
INSTALLATION CHECKLIST
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]
VULCANO Termodomésticos S.A.
Estrada de Cacia
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