Hubbell TXA Series Operating and installation instructions

INSTALLATION, OPERATION, AND
MAINTENANCE MANUAL FOR THE
HUBBELL MODEL TXA / ETXA/
MTXA TANKLESS WATER HEATER
ELECTRICHEATERCOMPANY
Edition 2019

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HUBBELL
ELECTRICHEATERCOMPANY
P.O.BOX288
STRATFORD,CT06615-0288
PHONE: [phone]
FAX: [phone]
INTERNET: http://www.hubbellheaters.com
Important Safety Information
1. You must read and follow allinstructions. Serious bodily injuryordeath couldoccur
if youignorethiswarning.
2. All circuit breakers and/or disconnect switches servicingtheheatermust beturnedoff
when installing, uninstalling, orrepairingthis water heater.
3. TheHubbellTankless WaterHeatermust begrounded.
4. Theunit mustbeinstalled bya licensed electrician and plumber.
5. Theunit must bewired in accordancewith thecurrentversionoftheNational
ElectricalCode(US)orCanadianElectricCode(Canada).
6. This installationmustcomply withallnational, state,and localplumbingand
electricalcodes.
7. When theheater is notwithin sightoftheelectricalcircuit breakers, anadditional
localmeans ofdisconnectionofallungrounded conductorsmustbeprovidedthatis
within sight oftheapplianceora circuit breakerlockout mustbeused. (Ref.NEC
422.31)
8. If theHubbellTanklessWater Heater is installed in a locationwherewater damage
could occur in theevent ofa leak, it is recommended thata drip panbeinstalled and
connected toa suitabledrain.Alternatively, anactivewaterleak detectorandshutoff
valvecan beinstalled toturnoffyourwater supply in theevent a leak is detected.
9. It is recommended that water hardnesslevels in excess of 12 grains per gallon
[approx. 200ppm(mg/l)] be treated priorto enteringthewater heater. Unless treated,
water at or abovethis hardnesslevelwill causescaling which will significantly impact
thewater heater performance.
10. When theheater is installed in a well water systemor iftheplumbingsystemis prone
tointroducingair intotheheater, it is highly recommendedthatanair separatorbe
installed in thecold water feed totheheater toavoid possiblefailureoftheheating
element and/or heatingchamber.

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TABLE OF CONTENTS
Table of Contents
HUBBELL ELECTRICHEATERCOMPANY...................................................................................2
SECTION I –TANKLESS WATER HEATER OPERATING PRINCIPLE................................4
•How the Hubbell Tankless Water Heater Works:.................................................................................. 4
SECTION II –GENERAL DESCRIPTION AND CONSTRUCTION......................................5
•Technical Specifications Common to All Models: .................................................................................. 5
•Tankless Water Heater Maximum Flow Rates:...................................................................................... 7
•Formulas:............................................................................................................................................... 8
SECTION III –INSTALLATION............................................................................................9
•Locating and Mounting Instructions:..................................................................................................... 9
•Plumbing Installation Instructions:...................................................................................................... 10
•Flushing the Line:..............................................................................................................................10
•Checking for Leaks and Purging Air.................................................................................................10
Typical Accessory Piping......................................................................................................11
ElectricalInstallation Instructions:........................................................................................12
WIRING DIAGRAMS:............................................................................................................13
SECTION IV –OPERATION AND MAINTENANCE ..........................................................27
•Maintenance:...................................................................................................................................... 27
•First Use of your Hubbell Tankless Water Heater:............................................................................... 27
•Temperature Controller User Interface Instructions:.......................................................................... 28
•Configuration Menu.............................................................................................................................28
Power and Triac Wiring.......................................................................................................32
SECTION V –TROUBLESHOOTING................................................................................34
InitialEvaluation:................................................................................................................34
•AdvancedTroubleshooting:................................................................................................................. 35
SECTION VII –PARTS LIST .............................................................................................46
SECTION VIII –WARRANTY.............................................................................................47
•WARRANTYPROCEDURE..................................................................................................................... 48
NOTES:...............................................................................................................................49

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SECTION I –TANKLESS WATER HEATER OPERATING PRINCIPLE
HowtheHubbellTanklessWaterHeaterWorks:
For the most part, operating the new tankless water heater is very similar to using any
traditionalwaterheater system.However, itis very importantthat,alltheset-up procedures
and operating instructions are carefully read to ensure maximum performance and energy
savingsfrom the new waterheater.
TheHubbellTXA Series Water Heaterdoes not storehotwaterlikea conventional tank-type
water heater. It contains high powered heatingelementsthat are capable ofheating water
instantlyon-demand asneeded. Dueto thesehigh poweredelements, dry firing the TXA
series heater is a possibility.To preventthis,a low water detection systemhasbeen installed
to keep theelements from turningon if theunit has not been properlypurged ofair.
Once theair has been purgedand as soonasthereis a hotwater demand,a sophisticatedflow
sensor within theheaterrecognizes thedemandandinitiates theheatingprocess. This sensor
measures thewaterflow ratewhiletwo othersensorsmeasure the incoming and outgoing
water temperature. This information is transmitted continually to the microprocessor
controller which determinesthepreciseamountofpower tosend tothe heatingelements to
heat thewater tothedesired temperature. TheHubbelltankless water heater only uses as
much powerasis needed tomeet thedemandbyfully modulatingthe heatingelements from
0 to100%.
It is importanttokeep in mind thatalltankless waterheaters aresubject toa maximum flow
rate. Ifthis flow rateis exceeded, theheater willnotbecapableoffully heating water. The
amount of water that can be heated by the tankless water heater at any given time will
depend onthemodelselected and theincomingwater temperature. Seethechartsin Section
II todeterminethemaximumflowrates.
Moreover, since a tankless water heater eliminates the ongoing thermal losses caused by
storing hot water in a tank, there will be a significant energy savings compared to a
conventional tank typewaterheater.

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SECTION II –GENERAL DESCRIPTION AND CONSTRUCTION
TechnicalSpecificationsCommonto AllModels:
Materials:
StainlessSteel
Exchanger andCasing
Plumbing
Connection:
Low
Flow
1”FNPT
Energy
Efficiency:
98%
High
Flow
1”FNPT
Voltage:
208-600Volts
OperatingRange:
5 –150psi
Frequency:
50/ 60Hz
Protection:
ThermalAutoReset
ProductOverviewTXA/MTXA:
Notes:
1. Transformersareonlyinstalledon3-phasemodelsover240volts.
2. Systemcomponentsandlayoutaresubjecttochangewithoutnotice.
Hi-Limit Switches
Heating Elements
ElementSwitching
Devices (Triacs)
Transformer
Flow Meter
Control Board
Control Fuse
GroundLug
PowerDistribution
Block
Magnetic
Contactor
Heating Chamber
VentDrain
Cold Water Inlet
Hot Water Outlet
InletThermistor
Outlet Thermistor

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ProductOverviewETXA:
Notes:
1. ConstructionofETXA is similar to TXA, with theadditionofa mechanicaltempering
valve, factory set at85°F.
2. System componentsand layoutaresubject to changewithoutnotice.
Mechanical
Tempering Valve

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TanklessWaterHeater MaximumFlowRates:
1. For alternatepower(kW)values,themaximumflow ratecan becalculatedusingthe
formulasonthefollowingpage.

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Formulas:
WattageDe-ratingFormula:
Applied Voltage2
Rated Voltage2× Rated Wattage = ActualWattage
For example:Ifinstallinga 27kWunit when actualvoltageis 212V,
2122
=
44,944
= 0.78 × 27,000W=21,060 W @ 212V
2402
57,600
AmperageFormula:
Watts
= Amps(SinglePhase)
Watts
÷1.73 = Amps(3-Phase)
Volts
Volts
FlowRateFormulas:
Todeterminepower(kW)requirement
GPM×°FT×0.1465=kW
Todeterminetemperaturerise
kW× 6.824÷GPM=°FT
Todetermineflowrate
kW× 6.824÷°FT =GPM

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SECTION III –INSTALLATION
WARNING: SERIOUS BODILY INJURY OR DEATH MAY
OCCUR IF THE FOLLOWING WARNINGS ARE IGNORED.
•All circuit breakersand/or disconnect switches servicingthis heater mustbeturned
off before installing,repairingoruninstallingthis water heater.
•InstallationMUST bedoneby a licensed electrician and licensed plumber.
Locating andMountingInstructions:
TheHubbellTXA series tanklesswater heater can beinstalled justaboutanywhere.
However, therearesome importantguidelines tofollow thatwillensurethattheinstallation
is both safeand convenient iffutureservicingis required.
Theunit may beinstalled in either indooror
outdoorlocationsduetotheNEMA4 -12
enclosurerating,thatprotectsit fromrain, splashed water, directsunlight,debris, and
insects.Thisproduct should NOT beinstalled in a location where it may be
subjected to freezing temperatures. If thewater insidethe tanklesswater heater
freezes, it can causesevereand permanentdamagethatis notcovered under thewarranty.
If yoususpect thatthetanklesswaterheater mayhavefrozen,donot turnontheheateruntil
it has thawed,and it has been inspected for damage. (Hubbellhas optionsfor internal
heaters for low ambient conditions.)
When selectinganinstallation location, consider theexistingplumbing
configuration, the
location ofyourmain electricalpanel, andlocationofthepointofuse. Try to choosea
location thatdoes notrequiremajor plumbingalterations, thatis closetothemain electrical
panel(this willreducetheamountofwireneeded toinstall),and thatis physically closeto
thehot water fixtures. By locatingtheheater closetothepointsofuse, this will reducethe
amount oftimeit takes for thehotwatertotravelfrom thewaterheater to the pointofuse.
Consideration should alsobegiven tofutureservicing. Do NOT locate the water
heater in a locationthat is difficult to access or on a horizontalsurface, like the
ceiling or floor. This will affect the operation of the high limits.
Avoid installing the tankless water heater in a location proneto excessive
humidity, moisture, or dust, orin an area where it may be splashed with
corrosive liquids. DO NOT install under water pipes or air conditioning lines
that might leak or condense moisture that could then drip onto the heater. Do
NOT install aboveelectrical boxes or junctions.
If installation ofthewaterheateris such,thatleaks may causewaterdamage, makesure
that allcode requirementsfor such installationsasrequiredfor yourareaarefollowed.
Hubbell recommendsthata drip pan(connectedtoa drain)is installed belowthewater
heater to avoid propertydamagein theunlikely event ofa leak. Alternatively,anactive
water leak detector andshut-offvalvedesigned toturnoffthewater supply ifa leak is ever
detected may beinstalled.
Mounting theunit:
•Leave a minimumof12”tobothsides 11”onthebottomand 36” in front of the unit.
•Mount thewaterheatersecurelytothewallbyputtingfour (4)screwsthrough the
mountingholes.
•Installa ¼” diameter beadofsealingcaulk aroundtheentireperimeter oftheheater
between theheater back panelandthewall. This prevents any moistureordebris
fromaccumulating.

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Plumbing InstallationInstructions:
IMPORTANTINFORMATION:
•Ensureallfittinginstallationscomply withlocalplumbingandbuildingcodes.
•This water heater does notrequirea temperatureand pressure(T&P)relief valve.
You may installa T&P relief valve if thecounty, city orstateplumbingcoderequires
it.
•Installationsin theCommonwealth ofMASSACHUSETTS and KENTUCKY require
a T&P relief valve.
•It is recommended that this unit be installed in plumbing systemsusecopper or
stainless steel pipingonly. If usingplasticpipingsuch as PEX or PVC is
required, then contacttheHubbellHeater for moreinformation.
•WARNING: DO NOT SOLDER ANY PIPING WHILE THE UNIT IS
CONNECTED TO THE PIPING. DOING SO WILL DAMAGE THE
FLOW METER AND VOID YOUR WARRANTY.
•Before energizing theheater, run water for a minimum of three(3) minutes and
verify that allair has been removed.
•Installationofanair separatordeviceis recommended for installationswhereair can
beeasily introduced into thewater system (i.e. Well water systems,lakepumps, and
other municipalsystems).
•Shutoff valves MUST be installed onboth the inlet side and outlet piping of
unit.
•WARNING: DO NOT SUPPLY WATER TO THE UNIT THAT IS
HOTTER THAN 130°F.
Flushing theLine:
•Before connectingthe copper pipetothewater heater,it is extremely important to
flush the lines toeliminateall plumbingpaste, residue, ordebrisin thelines and
damagingthe flow meter.
•After completingplumbinginstallation,open thehotwater faucet and allow water
to run through the water heater for at least three(3) minutes, cyclingtheflow on
and off every minute.This processclears allthe air from the lines and must be
performed prior toturningonthepower at the unit. WARNING: FAILURE
TO DO THIS MAY DAMAGE THE FLOW METER AND/OR HEATING
ELEMENTS AND WILL VOID YOUR WARRANTY.
Checking forLeaksand Purging Air:
•Verify circuit breakersandservicedisconnectsupplyingpower totheunit are
turned off.
•Open allhot water tapssupplied bytheunit and inspect water connectionsfor leaks.
•With all hotwater tapsstill open,allow the waterto run fora minimum of 3
minutes. Inspect each tap toensureallair in thelines has been purged.This process
purges alltheair from thewater lines and MUST beperformed priortoturningonthe
power attheunit. WARNING: FAILURE TO FOLLOW THIS STEP CAN
CAUSE PERMANENT DAMAGE TO THE HEATING ELEMENTS.
•Closeall hotwater taps.

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TypicalAccessory Piping
Water Hammer
Arrestor(Optional)
Temperature and
Pressure Gauge
(Optional)
Ball Valve
(Recommended)
Pressure Relief Valve
(If requiredby code)
Tankless Hot Water
Valve with Purge valve
Connection (Optional)
Union Fittings
Strainer
(Recommended)
Water Treatment
(Optional)
Air Separator
(Recommended)

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Electrical Installation Instructions:
IMPORTANTINFORMATION:
• Theunitmust bewired in accordancewith thecurrentversionoftheNational
ElectricalCode(US)or CanadianElectricCode(Canada).
• Theunit must haveits ownindependent circuits.
• When theheater is notwithin sightoftheelectricalcircuit breakers, anadditional
localmeans ofdisconnection(service disconnect) ofall ungrounded conductors must
beprovided thatis within sight oftheapplianceora circuit breaker lockoutmustbe
used.(Ref.NEC 422.31)
• For Canada,per Canadian ElectricCode, C22.1-02, theunitmustbewired bya single
feed installationwithone(1)three-polecircuit breaker.
• For US,theunit maybewired bya single feed installationwith one(1)three-pole
circuit breaker orbya multiplefeed installation with multipledouble-polecircuit
breakers.
Wiring to thewater heater:
• Connect the power wire from the main panel to the power distribution block or
magneticcontactor asapplicable.
• Connect themain groundwire to the ground lug in the heater.
• Make surethe connections aresecurely tightened.
Electrical Specifications:
• Tanklesswaterheatersareconsidered a non-continuousload.
• If a multiplefeed installation is used,it is acceptabletoinstalluptotwoconductorsin
one-line side port.Additionally, whena power distributionblockis supplied,
additionalconductors maybeinstalled in anopenload sideportofthepower
distributionblock.
• Wiringsizing listed is for 75°C THHN.60°Cor90°Cwiremay beused. Refer to
NFPA70table310.15(B)for propersizing.
• Wiring penetrationsarerecommended in bottom ofheater.
• Conductorsshouldbesized tomaintain a voltagedrop ofless than3%under load.

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WIRING DIAGRAMS:
Tankless Wiring Diagram 1B

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Tankless Wiring Diagram 1C (Delta)

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Tankless Wiring Diagram 1C (Wye)

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Tankless Wiring Diagram 1F

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Tankless Wiring Diagram 1G (Delta)

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TanklessWiring Diagram1G (Wye)

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TanklessWiring Diagram 2C

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TanklessWiring Diagram 2D