American Water Heater BCG3 - Manual (Page 23)

23
gas piping
Contact your local gas service company to ensure that adequate gas
service is available and to review applicable installation codes for
your area.
Size the main gas line in accordance with Table 9. The figures shown
are for straight lengths of pipe at 0.5 in. W.C. pressure drop, which is
considered normal for low pressure systems. Note: fittings such as
elbows, tees and line regulators will add to the pipe pressure drop. Also
refer to the latest version of the National fuel Gas 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 latest version of the National fuel Gas Code if Corrugated Stainless
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 GAS, (1/2 PouND PeR SquARe iNCH
GAGe) SuPPLY GAS PReSSuRe. eXPoSuRe To HiGHeR SuPPLY
PReSSuRe mAY CAuSe DAmAGe To THe GAS VALVe WHiCH
CouLD ReSuLT iN fiRe oR eXPLoSioN. if oVeRPReSSuRe HAS
oCCuRReD SuCH AS THRouGH imPRoPeR TeSTiNG of GAS
LiNeS oR emeRGeNCY mALfuNCTioN of THe SuPPLY SYSTem,
THe GAS VALVe muST Be CHeCKeD foR SAfe oPeRATioN. mAKe
suRE THaT THE ouTsIDE VENTs oN THE suPPlY REGulaToRs
AND THe SAfeTY VeNT VALVeS ARe PRoTeCTeD AGAiNST
BLoCKAGe. THeSe ARe PARTS of THe GAS SuPPLY SYSTem, NoT
THe HeATeR. VeNT BLoCKAGe mAY oCCuR DuRiNG iCe SToRmS.
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 Specific 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 eXPLoSioN.
if CoPPeR SuPPLY LiNeS ARe uSeD THeY muST Be iNTeRNALLY
TiNNeD AND CeRTifieD foR GAS SeRViCe. BefoRe ATTACHiNG
THe GAS LiNe, Be SuRe THAT ALL GAS PiPe iS CLeAN oN THe
iNSiDe.
To TRaP aNY DIRT oR FoREIGN MaTERIal IN 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 ACCeSSiBLe AND NoT SuBJeCT
To fReeZiNG CoNDiTioNS. iNSTALL iN ACCoRDANCe WiTH
ReCommeNDATioNS of SeRViNG GAS SuPPLieRS. RefeR To
THE laTEsT VERsIoN oF THE NATioNAL fueL GAS CoDe.
To prevent damage, care must be taken not to apply too much torque
when attaching gas supply pipe to gas valve inlet.
Apply joint compounds (pipe dope) sparingly and only to the male threads
of pipe joints. Do not apply compounds to the first two threads. use com-
pounds resistant to the action of liquefied 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 iGNiTioN foR THiS PuRPoSe.
DiSCoNNeCT THe HeATeR AND iTS mANuAL GAS SHuToff VALVe
FRoM THE Gas suPPlY PIPING sYsTEM DuRING aNY suPPlY
PReSSuRe TeSTiNG eXCeeDiNG 1/2 PSiG. GAS SuPPLY LiNe
muST Be CAPPeD WHeN DiSCoNNeCTeD fRom THe HeATeR.
foR TeST PReSSuReS of 1/2 PSiG oR LeSS THe APPLiANCe
NeeD NoT Be DiSCoNNeCTeD, BuT muST Be iSoLATeD fRom
THe SuPPLY PReSSuRe TeST BY CLoSiNG THe mANuAL GAS
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 sufficient capacity to supply the full
rated gas input of the water heater as well as the requirements of
all other gas fired 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 regulator is built into the gas valve and is
equipped to operate on the gas specified 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 specified in Table 10, refer to flow 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)