GWA
Gas-Fired Water Boilers –Boiler Manual
10 Part Number 670 01 1001 00
Table 4 Water pipe size (based on 20 °F rise)
General
If installation is to comply with ASME or Canadian requirements,
anadditionalhightemperaturelimitisneeded.Installcontrolinsupply
piping between boiler and isolation valve. Set second control to
minimum20 °F abovesetpoint offirst control. Maximumallowable
setpointis 240 °F.See page19 forwiring.
Alow water cutoffdevice isrequired when boileris installedabove
radiation level or by certain state or local codes or insurance
companies. Use low water cutoff designed for water installations.
Electrodeprobe-typeis recommended.Purchaseand installintee
supplypiping above boiler.
Use backflow check valve in cold water supply if required by local
codes.
SeeTable4andFigure5(diaphragm-typeorbladder-typeexpansion
tank)orFigure6 (closed-type expansiontank)on page 11fornear-
boilerpiping forsystemsdesigned forreturn waterat least130 °F.
See page 12 (Figures 8 and 9) for near-boiler piping for low-
temperatureor high-volumesystems.
Seepage 11 (Figure7) forboilersused withrefrigeration systems.
Near-boiler piping
3 Install water piping
Relief valve
Installrelief valve verticallyin¾" tapping on side of boiler.See the
tagattached tothe relief valve formanufacturer’s instructions.
To avoid water damage or scalding due to valve
operation,dischargeline must beconnected to relief
valve outlet and run to a safe place of disposal.
Terminate the discharge line to eliminate possibility
of severe burns should the valve discharge.
•Discharge line must be as short as possible and be
the same size as the valve discharge connection
throughoutitsentire length.
•Discharge line must pitch downward from the valve
andterminate at least6" above thefloor drain where
any discharge will be clearly visible.
•Thedischargelineshallterminateplain,not threaded,
withamaterialserviceablefortemperaturesof375°F
orgreater.
•Donotpipethedischargeto any placewherefreezing
couldoccur.
•Noshutoff valve shallbe installedbetween therelief
valveandboiler,or inthe dischargeline.Do notplug
orplace anyobstruction in the discharge line.
•Failure to comply with the above guidelines could
resultinfailure of thereliefvalveto operate,resulting
in possibility of severe personal injury, death or
substantialproperty damage.
•Test the operation of the valve after filling and
pressurizing system by lifting the lever. Make sure
thevalve discharges freely.Ifthevalvefailstooperate
correctly, replace it with a new relief valve.
Water piping —multiple zone systems
Install system piping using either circulator zoning or zone valve
zoning.Install expansiontank onsuction side of system circulator.
Always connect fill line only at the expansion tank —never at
anotherpoint inthe system.
Circulator
The circulator is shipped loose (wiring pre-attached to boiler) to
allowyoutolocateiteither in thereturnorsupplypiping,as desired.
See page 11 for a typical installation. Pipe the expansion tank to
the suction side of the circulator whenever possible. Install an air
separator in the supply piping. Connect the expansion tank to the
air separator only if the separator is on the suction side of the
circulator.Alwaysinstallthesystemfillconnection at thesamepoint
as the expansion tank connection to the system. Figures 5 and 6
showtypical near-boiler piping connections.
Expansion tank
Diaphragm-type or bladder-type expansion tank —
Figure 5
1. Ensureexpansion tank sizewillhandleboilerandsystem water
volume and temperature.Tank mustbelocated inboiler return
pipingasclose toboileraspossible,beforeinletsideofcirculator.
Seetank manufacturer’s instructions fordetails.
2. Install an automatic airvent asshown.
Closed-type expansion tank —Figure 6
1. Ensureexpansion tank sizewillhandleboilerandsystem water
volumeand temperature.See tankmanufacturer’s instructions
fordetails.
2. Connect tank to ½" NPT tapping located behind supply outlet,
using ½" NPT piping. Pitch any horizontal piping up towards
tank1 inch per5 feet of piping.
Undersizedexpansion tankscause system water to
be lost from relief valve and makeup water to be
addedthrough fill valve.Eventual section failurecan
result.
Near-boiler piping continued
Boiler model
number To
system From
system
GWA052 ¾"¾"
GWA070 1" 1"
GWA105 1" 1"
GWA140 1" 1"
GWA175 1¼" 1¼"
GWA210 1¼" 1¼"
GWA245 1½" 1½"
GWA
Gas-Fired Water Boilers –Boiler Manual
27Part Number 670 01 1001 00
11 Troubleshooting
Verify proper operation after servicing. •See vent
dampermanufacturer’sinstructionspackedwith vent
damperforadditional information.Failure tocomply
could result in severe personal injury, death or
substantialpropertydamage.
Figure 15 Manually opening vent damper
Labelall wires priorto disconnectionwhenservicing
controls. Wiring errors can cause improper and
dangerousoperation.
Neverjumper (bypass)rollout thermalfuse element
orany other deviceexcept formomentary testing as
outlinedin“Chart1”,page28.Severe personal injury,
deathor substantialproperty damage can result.
Burneraccesspanelmustbein position during boiler
operation to prevent momentary flame rollout on
ignition of main flame. Severe personal injury or
substantialpropertydamage will result.
Before troubleshooting:
1. Have the followingitems:
a. Voltmeter that can check 120VAC and 24VAC.
b. Microammeterwith ascale range of 0-10.
c. Continuity checker.
d. U-tubemanometer.
2. Checkfor120VAC(minimum102VACto maximum 132VAC)
toboiler.
3. Makesure thermostatiscallingforheat and contacts(including
appropriate zone controls) are closed. Check for 24 VAC
betweenthermostat wire nuts and ground.
Troubleshooting sequence:
1. Before proceeding, check for:
•Loose connections, blown fuse or service switch off?
•Highlimit switchset below boiler water temperature?
•Thermostatset below roomtemperature?
•Gasnot turnedon atmeter or boiler?
•Incominggas pressure lessthan:
5" w.c.for natural gas? 11" w.c. for propane gas?
2. If all of the above check correctly, check gas pressures:
a. Withboiler off
•13" w.c. maximum natural or propane gas pressure
upstream of gas valve.
b. Withboiler on:
•5" w.c. minimum natural gas pressure or 11" w.c.
propane gas pressure upstream of gas valve.
•3.5" w.c. minimum natural gas pressure or 10" w.c.
propane gas pressure downstream tapping on gas
valve —Can be adjusted by regulator on gas valve.
c. If gas pressure is incorrector gasis notavailableto boiler,
contactgas supplierto correct beforeproceedingfurther.
3. Checkpilot operation-Follow “Lighting Instructions”,pages 20
and21.
•If gas is available and you cannot obtain a pilot flame, try
purgingthegas lineandcleaning pilotandpilot gastubing.
Follow“LightingInstructions”again. If youstillcannotobtain
aflame,replace pilot burnerandgastubing. Ifthisdoesnot
allowyou toobtain apilot flame, replace gas valve.
•Ifyouobtainapilot flame,butpilotwillnotremainon,replace
thermocouple.Ifthisdoes notcorrectproblem,replace gas
valveandpilot burner.
•Ifpilot stays on,but main gaswill not come on, proceed to
page 28.
In event of vent damper failure:
Effikal vent damper
Iftroubleshootingchartrecommendsreplacingactuatorandactuator
isnotimmediately available,damperblade can befixed in anopen
positiontoallowboileroperation. Manually turningbladecancause
actuatordamage. Follow theseinstructions onlyincase ofno heat
ordamper actuator malfunction.
1. Move damper service switch to Hold Damper Open position.
Applycallforheattoboiler.Damperbladeshould thenrotate to
Openposition and boiler will fire.
2. If step 1does notopen damper,manually rotatedamper blade
to open position using wrench or pliers on flat shaft between
damperand actuator.Boilerwill fire.Verify thatdamper service
switchis inHold DamperOpen position.(Figure 15)
3. Donot leave ventdamperpermanentlyinthisposition.Replace
actuator immediately. If vent damper is left in Open position,
boilerwill not operateat publishedefficiencies.
Johnson Controls vent damper
Iftroubleshootingchartrecommendsreplacingactuatorandactuator
isnotimmediately available,damperblade can befixed in anopen
positionto allowboiler operation.Follow theseinstructions onlyin
caseof no heator damperactuator malfunction.See Figure 15.
1. Turn offpowertoboiler.
Failure toturnoffpowerto boiler canresult in severe
personalinjury,deathorsubstantialpropertydamage.
2. See ventdamper manufacturer’s instructions for procedure to
fixvent damperin openposition.
3. Turn onpowertoboiler.
4. Using wrench or pliers on flat shaft section, manually rotate
damperbladeuntilgreenlightturnson.Boilerwillfire.(Figure 15)
5. Donot leave ventdamperpermanentlyinthisposition.Replace
actuator immediately. If vent damper is left in Open position,
boilerwill not operateat publishedefficiencies.
