23
gas piping
Contact your local gas servic e company to ensure that adequate ga s
service is available and to review applicable installation codes for
your area.
Size the main gas line in acco rdance with Table 9. The gures s hown
are for straight lengths of pipe at 0.5 in. W.C. pressure drop, which is
considered nor mal for low press ure systems. Note: fit tings such as
elbows, tees and line regulators will add to the pipe pressure drop. Also
refer to the latest version of the National fuel G as Code.
Schedule 40 metallic Pipe is the preferred material for the gas line of
this water heater. it is imperative to follow the sizing recommendations in
the la test vers ion of the Na tio nal fu el Gas Code if Cor rug ated Stai nle ss
Steel Tubing (CSST) is used as the gas line for this water heater.
THE HEaTER Is NoT INTENDED FoR oPERaTIoN aT HIGHER
THAN 14.0” W.C.- NATuRAL G AS, (1/2 PouND PeR SquAR e iNCH
GAGe) SuPPLY G AS PReS SuR e. eXP oSuR e To HiG HeR Su PPLY
PReSSuRe mAY CAuSe DAm AGe To THe GAS VALVe WH iCH
CouLD ReSuLT iN fiRe oR eXPLoSioN. if oVeRPReSSuRe HAS
oCCuRReD SuCH AS THRouGH im PRoPeR TeSTiNG of GAS
LiNeS oR emeRGeNCY mALfuNCTioN of THe SuPPLY SYSTem,
THe GA S VALVe muST B e CHeC KeD foR SAf e oPeR ATi oN. m AKe
suRE THaT THE ouTsIDE VENTs oN THE suPPlY REGul aToRs
AND THe SAfeTY VeNT VALVeS ARe PRoTeCTeD AGAiNST
BLoC KAG e. THe Se AR e PART S of THe GAS Su PPLY SYS Tem , NoT
THe He ATeR . VeNT BLoC KAG e mAY oC CuR Du RiN G iCe ST oRm S.
taBle 9 - gas supply pipe lengths (in feet)
maximum eQuiValent pipe length (feet)
natural gas only
Input Rate
(BTu/HR)
Schedule 40 iron Pipe - Nominal Diameter
1/2" 3/4" 1" 1 1/4" 1 1/2"
120,000 20 70 200 200 200
154,000 10 40 150 200 200
180,000 - 30 100 200 200
199,000 - 30 90 200 200
250,000 - 20 60 200 200
275,000 - 10 50 200 200
310,000 - 10 40 150 200
366,000 - - 30 100 200
390,000 - - 20 100 200
Natural Gas 0.60 Specic Gravity, 0.50" W.C. Pressure Drop
IT Is IMPoRTaNT To GuaRD aGaINsT Gas ValVE FoulING FRoM
CoNTAmiNANTS iN THe GAS WAYS. SuCH fouLiNG mAY CAuSe
imPRoPeR oPeRATioN, fiRe oR eXPLoSi oN.
if CoP PeR Su PPLY Li NeS ARe uS eD THe Y muS T Be iN TeRN ALLY
TiNNeD AND CeRTifieD foR GAS SeRViCe. BefoRe ATTACHiNG
THe GAS LiNe, Be SuRe THAT A LL GAS PiPe iS CLeAN o N THe
iNSiDe.
To TRaP aNY DIRT oR FoREIGN MaTERIal I N THE Gas suPPlY
LiNe, A DiRT LeG (SomeTimeS CALLeD SeDimeNT TRAP oR DRiP
LeG) muST Be iNCoRPoRATeD iN THe PiPiNG (See fiG. 21). THe
DiRT LeG muST Be ReADiLY ACC eSSiBLe AND NoT SuBJeCT
To fReeZiNG CoNDiTioNS. iNSTALL iN ACCoR DANCe WiTH
ReCommeNDATioNS of SeRViNG GAS SuPPLieRS. RefeR To
THE laTEsT VERsIoN oF THE NATioNAL fueL GAS Co De.
To prevent damage, care must be taken not to apply too much to rque
when attaching gas supply pipe to gas valve in let.
Apply joint compounds (pipe dope) sparingly and only to the male threads
of pip e join ts. D o not ap ply c ompo und s to the rst two th read s. use com-
pounds resistant to the action of lique ed petroleum gases.
BefoRe PLACiNG THe HeATeR iN oPeRATioN, CHeCK foR GAS
LeAKAGe. use soap and water solution or other material acceptable for
the purpose in locating the leaks. Do NoT uSe mATCHeS, CANDLeS,
fLAme oR oTHeR SouRCeS of iGNiTi oN foR THiS PuRPoSe.
DiSC oNN eCT TH e HeAT eR AN D iTS mA NuA L GAS SH uTo ff VALV e
FRoM THE Gas suPPlY PIPING sYsTEM DuRING aNY suPPlY
PReSSuRe TeSTiNG eXCeeDiNG 1/2 PSi G. GAS SuPPLY LiNe
muST Be CAPPeD WHeN DiSCoNNeCTeD fRom THe HeATeR.
foR TeST P ReSSuReS of 1/2 PSiG oR LeSS THe APPLiANCe
NeeD NoT Be DiSCoNNeCTeD, BuT muST Be iSoLATeD fRom
THe SuPPLY PReS SuRe TeST BY CLoSiNG THe mANuAL G AS
SHuToff VALVe.
gas piping and dirt leg installation
figure 21.
purging
Gas line purging is required with new piping or systems in which
air has entered.
PuRGING sHoulD BE PERFoRMED BY PERsoNs
eXPeRieNCeD iN THiS TYPe GAS SeRViCe. To AVoiD RiSK
of fiRe oR eXPLoSioN, PuRGe DiSCHARGe muST NoT
eNTeR CoNfiNeD AReAS oR SPACeS WHeRe iGNiTioN CAN
oCCuR. THe AReA muST Be WeLL VeNTiLATeD AND ALL
SouRCeS of iGNiTioN muST Be iNACTiVATeD oR RemoVeD.
gas meter siZe — natural gases only
Be sure the gas meter has sufcient capacity to supply the full
rated gas input of the water heater as well as the requirements of
all other gas red equipment supplied by the meter. if gas meter
is too small, ask the gas company to install a larger meter having
adequate capacity.
gas pressure regulator
The gas pressure regulato r is built into the gas valve and is
equipped to operate on the gas specied on model and rating
plate. The regulator is factory adjusted to deliver gas to burner at
correct water column pressure allowing for a nominal pressure
drop through the controls.
The minimum gas supply pressure for input adjustment must not
be less than 5.2" w.c. (1.12 kPa) for natural gas.
Do not subject the combination gas valve to inlet gas pressures
of more than 14.0” W.C. (3.48 kPa) - natural gas. A supply gas
regulator is necessary if higher gas pressures are encountered. if a
supply gas regulator is installed on the gas supply line, the maximum
recommended pressure for the regulated gas supply is 11" W.C.
Gas pressure specied in Table 10, refer to ow pressure taken
at pressure tap of automatic gas valve while heater is operating.
taBle 10.
manifold gas pressure in inches
of water column (all models*)
type of gas
natural
3.5 (0.87 kPa)