Williamson-Thermoflo GWS-090E User manual

Part Number 550-110-737/1108
Contents Page
1 Prepare boiler location .......................................................2
2 Prepare boiler.....................................................................8
3 Install water piping..............................................................9
4 Venting and combustion air..............................................12
5 Gas piping........................................................................12
6 Field wiring.......................................................................13
7 Start-up ............................................................................14
8 Checkout procedure.........................................................16
9 Sequence of operation.....................................................17
10 Operating instructions ......................................................19
11 Service and maintenance.................................................20
12 Troubleshooting................................................................25
13 Replacement parts...........................................................33
14 Dimensions.......................................................................38
15 Ratings.............................................................................39
Boiler Manual
GWS- 090 E
Gas-Fired Water Boiler
This manual must only be used by a qualified heating installer/service technician. Failure to comply could result in
severe personal injury, death or substantial property damage.
 When calling or writing about the boiler— Please have:  •  boiler model number from the boiler rating label  and
•CPnumberfromtheboilerjacket.YoumaylisttheCPnumberinthespaceprovidedonthe“Installationandservice
certificate” found on page 16.
Hazards that will or can cause minor personal
injury or property damage.
Special instructions on installation, operation or
maintenance that are important but not related to
personal injury or property damage.
INSTALLER —Read all instructions before
installing. Read page 2 first. Follow all instruc-
tions in proper order to prevent personal injury or
death.
• Considerpipingandinstallationwhendetermining
boiler location.
• Anyclaimsfordamageorshortageinshipment
must be filed immediately against the transporta-
tion company by the consignee.
USER — Please read the following. Failure to
comply could result in severe personal injury,
death or substantial property damage.
• This manual is for use only by your qualified
heating installer/service technician.
• PleaseseetheUser’sInformationManualforyour
reference.
• Have the boiler serviced by a qualied service
technician, at least annually.
Hazards that will cause severe personal injury,
death or substantial property damage.
Hazards that can cause severe personal injury,
death or substantial property damage.
Hazard definitions

GWS-090E Gas-Fired Water Boiler – Boiler Manual
2Part Number 550-110-737/1108
Codes & checklist
When servicing boiler —
1. To avoid electric shock, disconnect electrical supply
before performing maintenance.
2. To avoid severe burns, allow boiler to cool before per-
forming maintenance.
Boiler operation —
3. Do not block flow of combustion or ventilation air to
boiler.
4. Shouldoverheatingoccurorgassupplyfailtoshutoff,do
not turn off or disconnect electrical supply to circulator.
Instead, shut off the gas supply at a location external to
the appliance.
5. Do not use this boiler if any part has been under water.
Immediatelycalla qualifiedservice technicianto inspect
the boiler and to replace any part of the control system
and any gas control that has been under water.
Boiler water —
6. DONOTuse petroleum-based cleaning orsealing com-
poundsinboiler system.Watersealdeterioration will oc-
cur, causing leakage between boiler sections, circulator
flanges, diaphragm tanks or other system components.
This can result in substantial property damage.
7. DO NOT use“homemade cures” or “boiler patent
medicines”. Serious damage to boiler, personnel and/
or property may result.
8. Continualfreshmakeupwaterwillreduceboilerlife.Min-
eralbuildupinsectionsreducesheattransfer, overheats
castiron,andcausessectionfailure.Additionofoxygen
and other gases can cause internal corrosion. Leaks
in boiler or piping must be repaired at once to prevent
makeup water.
9. Do not add cold water to hot boiler.Thermal shock can
cause sections to crack.
Glycol — potential fire hazard —
Allglycolisammablewhenexposedtohightemperatures.If
glycolis allowedtoaccumulateinoraroundthe boilerorany
other potential ignition source, a fire can develop.In order to
preventpotentialsevere personalinjury, deathor substantial
property damage from fire and/or structural damage:
• Never store glycol of any kind near the boiler or any
potential ignition source.
• Monitorandinspectthesystemandboilerregularlyfor
leakage. Repair any leaks immediately to prevent pos-
sible accumulation of glycol.
• Neveruse automotiveantifreezeor ethyleneglycolin
thesystem.Usingtheseglycolscanleadtohazardous
leakage of glycol in the boiler system.
1 Prepare boiler locationRead this first!
Installations must follow these codes:
• Local,state,provincial,andnationalcodes,laws,regulations
and ordinances.
• NationalFuelGasCode,ANSIZ223.1–latestedition.
• StandardforControlsandSafetyDevicesforAutomatically
FiredBoilers,ANSI/ASMECSD-1,whenrequired.
• NationalElectricalCode.
• ForCanadaonly:B149.1orB149.2InstallationCode,CSA
C22.1CanadianElectricalCodePart1andanylocalcodes.
Readand followthespecialinstructions fortheCom-
monwealthofMassachusetts,locatedonpage40
of this manual.
Certification
 TheGWS-090Eboilergasmanifoldandcontrolsmet
safe lighting and other performance criteria when
boilerunderwenttestsspeciedinANSI Z21.13–
latest edition.
Before locating the boiler:
❏ Check for nearby connection to:
• Systemwaterpiping
• Ventingconnections
• Gassupplypiping
• Electricalpower
❏ Checkarea around boiler.Removeany combustiblematerials,
gasoline and other flammable liquids.
Failure to keep boiler area clear and free of com-
bustible materials, gasoline and other flammable
liquids and vapors can result in severe personal
injury, death or substantial property damage.
❏ Boilermust beinstalledsothatgas control system components
are protected from dripping or spraying water or rain during
operation or service.
❏ If new boiler will replace existing boiler, check for and correct
system problems, such as:
1. System leaks causing oxygen corrosion or section cracks from
hard water deposits.
2. Incorrectly-sized expansion tank.
3. Lackof antifreeze(when required)in boilerwatercausingsystem
and boiler to freeze and leak.
The boiler contains ceramic fiber and fiber-
glassmaterials.Usecarewhenhandlingthese
materials per instructions on page 21 of this
manual.Failuretocomplycouldresultinsevere
personal injury.
Failure to adhere to the guidelines below can
result in severe personal injury, death or sub-
stantial property damage.

3
Part Number 550-110-737/1108
GWS-090E Gas-Fired Water Boiler – Boiler Manual
1 Prepare boiler location continued
Service clearances
1. Provide minimum clearances for cleaning and servicing the
boiler and for access to controls and components as listed in
Table 1 below:
2. Provide at least screwdriver clearance to jacket front panel
screws for removal of front panel for inspection and minor
service. If unable to provide at least screwdriver clearance,
install unions and shutoff valves in system so boiler can be
moved for servicing.
Clearances
Flooring and foundation
Flooring
TheGWS-090Eboilerisapprovedforinstallationoncombustible
flooring, but must never be installed on carpeting.
Do not install boiler on carpeting even if foundation
is used. Fire can result, causing severe personal
injury, death or substantial property damage.
Foundation
1. Providea solidbrickor minimum2-inchthickconcretefounda-
tion pad if any of the following is true:
• oorcanbecomeooded.
• theboilermountingareaisnotlevel.
2. See Table 2, below, for minimum foundation dimensions.
Residential garage installations
Takethefollowingspecialprecautionswheninstallingthe boilerin
aresidential garage.If theboiler is located ina residential garage,
perANSIZ223.1,paragraph5.1.9:
• Mounttheboileraminimumof18inchesabovetheoorof
the garage to assure the burner and ignition devices will be
no less than 18 inches above the floor.
• Locateorprotect the boiler so it cannot bedamaged bya
moving vehicle.
Minimum clearance to combustible materials
1. Hot water pipes must be at least ½” from combustible mate-
rial.
2. Vent pipe must be at least 2 inches from combustible material
exceptwhereotherwisenotedinGWSVentingManual.
Small space installations
1. When the boiler is located in a closet or small space, provide
clearances no less than those shown in Figure 1.The clear-
ances are required to any surface, whether combustible or
non-combustible.
Table 2 Minimum foundation size
Boiler
model
number
Minimum
foundation
length
Minimum
foundation
width
GWS-090E 25” 18”
Figure 1 Minimum clearances in small spaces
Table 1 Minimum service clearances

GWS-090E Gas-Fired Water Boiler – Boiler Manual
4Part Number 550-110-737/1108
1 Prepare boiler location continued
Failure to followall instructionscanresultin flue gas
spillage and carbon monoxide emissions, causing
severe personal injury or death.
 DonotinstalltheGWS-090Eintoacommonvent
with any other appliance. This will cause flue gas
spillage or appliance malfunction, resulting in pos-
sible severe personal injury, death or substantial
property damage.
 GWS-090Eboilerscanonlybedirect-ventvented.
They cannot be chimney-draft vented or direct-ex-
haustvented.SeeGWSVentingManualfordetailed
installation instructions.
If you are removing an existing boiler from a shared
ventingsystem,theGWS-090Eboilercannotshare
theventsystem(itrequiresitsownvent).Youmust
test each appliance remaining on the old common
vent system individually to verify the vent system
still operates adequately. Follow guidelines below.
When removing boiler from existing common vent
system:
Atthetimeofremovalofanexistingboiler,thefollowingsteps
shall be followed with each appliance remaining connected to
the common venting system placed in operation, while the other
appliances remaining connected to the common venting system
are not in operation.
a. Seal any unused openings in the common venting system.
b. Visually inspect the venting system for proper size and hori-
zontal pitch and determine there is no blockage or restriction,
leakage,corrosionor other deficiencieswhichcouldcausean
unsafe condition.
c. Test vent system — Insofar as is practical, close all building
doors and windows and all doors between the space in which
the appliances remaining connected to the common venting
system are located and other spaces of the building. Turn
on clothes dryers and any appliance not connected to the
common venting system.Turn on any exhaust fans, such as
range hoods and bathroom exhausts, so they will operate at
maximumspeed.Donotoperatea summerexhaustfan.Close
fireplace dampers.
d. Place in operation the appliance being inspected. Follow the
lighting/operatinginstructions.Adjustthermostatsoappliance
will operate continuously.
e. Test for spillage at draft hood relief opening after 5 minutes of
mainburneroperation.Usetheameofamatchorcandle.
f. Afterithasbeendeterminedthateachapplianceremaining
connectedtothecommonventingsystemproperlyventswhen
testedasoutlinedabove,returndoors,windows,exhaustfans,
fireplace dampers, and any other gas-burning appliance to
their previous conditions of use.
Any improper operation of common venting system should be
corrected so the installation conforms with the National Fuel
GasCode,ANSIZ223.1–latestedition.Correctbyresizingto
approach the minimum size as determined using the appropriate
tables in Part 11 of that code.Canadian installations must comply
with B149.1 or B149.2 Installation Code.
GWS-090E special vent system required
Vent system
TheGWS-090Eboilerrequiresaspecialventsystem,designed
forpressurizedventing.ModelGWS-090EisratedANSIZ21.13
Category IV (pressurized vent, likely to condense in the vent).
You may use any of the direct vent systems (combustion air
ducted to boiler) covered in GWSVenting Manual included in
the boiler envelope assembly.The GWS vent starter is a special
item,designedonlyforGWSandGWS-90E,availablefromeach
vendor.DonotattempttoconnecttheventtoaGWS-090Eboiler
with any other means.
DO NOT mix components from different systems.
The vent system could fail, causing leakage of flue
products into the living space.
Vent termination and combustion air supply
TheGWS-090Eboilermaybeventedthroughtherooforthrough
asidewall.FollowtheappropriateinstructionsintheGWSVenting
Manualfortheventsystemchosen.Themaximumventlength
depends on boiler size. Refer to the GWSVenting Manual to
determine acceptable vent length.
CombustionairfortheGWS-090Eboilermustbeducteddirectly
to the boiler from outside. For outside air (direct vent installa-
tion), two options are available for the flue/air termination. The
air supply must ALWAYS terminate at the same location as the
flue, using either:
1. Vertical direct vent installation — Obtain theThrough-Roof or
Through-UnusedChimneyTerminationKit.RefertotheGWS
VentingManual,packedwiththekitandtotheventmanufac-
turer’sinstructionsfortheventmaterialchosen.
2. Sidewall direct vent installation — Use theVent/Air Intake
Termination Kit shipped with the boiler. Refer to the GWS
VentingManualshippedwiththeboiler.
Vent system

5
Part Number 550-110-737/1108
GWS-090E Gas-Fired Water Boiler – Boiler Manual
Table 3 Corrosive contaminants and likely locations
 TheGWS-90Eboiler must be direct vented (using
ducted outside air).
The vent/air termination must be installed in a
location that is free of the contaminants listed in
Table 3.
Allowingtheboilertooperatewithcontaminatedair
can cause damage to the boiler and vent system,
resulting in possible severe personal injury, death
or substantial property damage.
Please review the following information on potential combustion
air contamination problems.
See Table 3 for products and areas which may cause contami-
nated combustion air.
Air contamination
1 Prepare boiler location continued

GWS-090E Gas-Fired Water Boiler – Boiler Manual
6Part Number 550-110-737/1108
Air openings
Using outside air — direct venting
Combustion air can be ducted directly from outside to the GWS-
090Eboilerairintaketting.Thismethodisdenedasdirect vent
(also referred to as sealed combustion).Refer to the appropriate
instructionsintheGWSVentingManualandtheinstructionsin
this manual.Two options are available: sidewall or vertical direct
vent.Eachrequiresaspecialventcomponentkit.
Sizing air openings
Airopeningsprovideforventilationtopreventoverheatingofthe
boilercontrolsandboilerspace.Airisalsoneededforotherap-
pliances located in the same space.
UseFigure2,page7,selectingtheappropriateinstallationcondi-
tions.Note that the sizing given in Figure 2 applies only to GWS-
090EinstallationswithclearancesnosmallerthanshowninTable
1, page 3 of this manual. For smaller clearances, regardless of
how the air openings are arranged, two openings providing free
area of 1 square inch per 1,000 Btuh input of all appliances in
the space are required.
 Airopeningsmustbesizedtohandleallappliances
and air movers (exhaust fans, etc.) using the air
supply.
The sizing given in Figure 2 is based on the National Fuel Gas
Code,ANSI Z223.1,allowingadequateairopeningforgravity-
vented gas appliances.The air openings recommended in Figure
2 will allow adequate ventilation and combustion air provided the
boiler room is not subjected to negative pressure due to exhaust
fansorothermechanicalventilationdevices.Referto the National
Fuel Gas Code for dealing with other conditions.
Louver allowance
The free area of openings means the area after reduction for any
installedlouversor grilles.Be sure to consider this reductionwhen
sizing the air openings.
Special considerations
Tight construction
ANSIZ223.1denesunusuallytightconstructionwhere:
a. Walls and ceilings exposed to the outside atmosphere have
a continuous water vapor retarder with a rating of 1 perm or
less with openings gasketed, and .. .
b. Weather-stripping has beenaddedonopenablewindowsand
doors, and . . .
c. Caulking or sealants are applied to areas such as joints
around windows and door frames, between sole plates and
floors, between wall-ceiling joints, between wall panels, at
penetrations for plumbing, electrical, and gas lines, and in
other openings.
For buildings with such construction, provide air openings into
the building from outside, sized per the appropriate case in
Figure 2.
Exhaust fans and air movers
The appliance space must never be under a negative pressure,
unlesstheappliancesareinstalledasdirectvent.Alwaysprovide
air openings sized not only to the dimensions required for the
firing rate of all appliances, but also to handle the air movement
rate of the exhaust fans or air movers using air from the building
or space.
Motorized air dampers
If the air openings are fitted with motorized dampers, electrically
interlock the damper to:
• Preventtheboilerfromringifthedamperisnotfullyopen.
• Shuttheboilerdownshouldthedampercloseduringboiler
operation.
To accomplish this interlock, wire an isolated contact (proving the
damper open) in series with the thermostat input to the boiler.
The boiler will not start if this contact is open, and will shut down
should it open during operation.
1 Prepare boiler location continued

7
Part Number 550-110-737/1108
GWS-090E Gas-Fired Water Boiler – Boiler Manual
Figure 2 Provide minimum air openings for GWS-090E boiler installations based on following:
1 Prepare boiler location continued

GWS-090E Gas-Fired Water Boiler – Boiler Manual
8Part Number 550-110-737/1108
Perform hydrostatic pressure test
Pressure test boiler before attaching water or gas piping or elec-
trical supply (except as noted below).
Prepare boiler for test
1. Removetheshippingnipple(fromGWS-090Esupplytapping)
and remove the boiler relief valve.Temporarily plug the relief
valve tapping with a ¾” NPT pipe plug.
2. Remove 1¼” nipple, reducing tee and drain valve from ac-
cessory bag. Install in boiler return connection as shown on
in Figure 18, item 3, page 36. Install circulator on either the
return or supply.
3. Remove 1¼”nipple, 1¼”tee, bushing and pressure/tempera-
turegauge from accessorybag.Pipe toboiler supply connec-
tionasshowninFigure18,item2,page36.(Usepipedope
sparingly.)
4. Connect a hose to boiler drain valve,the other end connected
toafreshwatersupply.Makesurehosecanalsobeusedto
drain boiler after test.
5. Connect a nipple and shutoff valve to system supply connec-
tion on the 1¼”tee.This valve will be used to bleed air during
the fill. (Valve and nipple are not included with boiler.)
6. Connect a nipple and shutoff valve to system return connec-
tion (at circulator flange if circulator installed on return).This
valve will be used to bleed air during the fill.(Valve and nipple
are not included with boiler.)
Fill and pressure test
1. Open the shutoff valves you installed on supply and return
connections.
Pressure test 2. Slowly open boiler drain valve and fresh water supply to fill
boiler with water.
3. When water flows from shutoff valves, close boiler drain
valve.
4. Close shutoff valves.
5. Slowlyreopenboilerdrainvalve untiltestpressureofnotmore
than 45 psi is reached on the pressure/temperature gauge.
6. Test at no more than 45 psi for no more than 10 minutes.
 Donotleaveboilerunattended.Acoldwaterllcould
expand and cause excessive pressure, resulting in
severepersonalinjury,deathorsubstantialproperty
damage.
7. Make sure constant gauge pressure has been maintained
throughout test. Check for leaks.Repair if found.
Leaks must be repaired at once. Failure to do so
candamage boiler,resulting in substantial property
damage.
Do not use petroleum-based cleaning or sealing
compounds in boiler system. Severe damage to
boiler will occur, resulting in substantial property
damage.
Drain and remove fittings
1. Disconnect fill water hose from water source.
2. Drain boiler at drain valve or out hose, whichever provides
best access to drain. Remove hose after draining if used to
drain boiler.
3. Remove nipples and valves unless they will remain for use in
the system piping.
4. Removeplug from relief valvetapping.SeeSection3, page 9,
to replace relief valve.
2 Prepare boiler
Table 4 Manifold orifice sizing
Location Natural gas Propane gas
U. S.
Sea level –
2,000 ft over 2,000 ft Sea level – 2,000 ft over 2,000 ft
2.55 mm (Note 1) 1.60 mm (Note 1)
Canada
Sea level –
2,000 ft 2,000 – 4,500 Sea level – 2,000 ft 2,000 – 4,500
2.55 mm # 41 1.60 mm 1.45 mm
Note1: ForU.S.elevationsabove2,000feet,contactyourlocalsupplierfor
details.
Place boiler/crate near position
1. Leave boiler in crate and on pallet until installation site is
ready.
2. Moveentirecrateandpalletnexttoselectedlocation.
3. Remove crate.Leave boiler on pallet.
4. Remove boiler from pallet as follows:
a. Tilt left side of boiler up and place a board under left legs.
b. Tilt boiler the other way and place a board under right legs.
c. Slide boiler backwards off pallet and into position.
Do not drop boiler or bump jacket on floor or pallet.
Damage to boiler can result.
5. Check level.
a. Shim legs, if necessary.
b. Do not alter legs.
Inspect orifices and burners; connect air adapt-
er
1. Remove front jacket door. Remove air adapter fitting from air
inlethose(seeFigure17, page 35, items 9 and10)and screw
into opening on jacket top. Reconnect air hose to bottom of
air adapter fitting.Remove inlet air box top panel.(See Figure
16, item 13, page 34).
2. Checkforcorrectly-sizedmanifoldorifices.SeeTable4forsiz-
ing. (The orifice size is stamped on the orifice spud barrel.)
Placement and setup
Correctly-sized manifold orifices must be used.
Failure to do so will result in severe personal injury,
death or substantial property damage.
3. Reinstall inlet air box top panel and jacket door.
Do not operate boiler without inlet air box top panel
secured in place. Failure to comply could result in
severepersonalinjury,deathorsubstantialproperty
damage.

9
Part Number 550-110-737/1108
GWS-090E Gas-Fired Water Boiler – Boiler Manual
Table 5 Water pipe size (based on 20 °F rise)
Boiler
model
number
To
system From system
GWS-090E 1” 1”
Circulator
The circulator is shipped loose (wiring pre-attached to boiler) to
allow you to locate it either in the return or supply piping, as de-
sired.See Figures 3 and 4, page 10, 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.Alwaysinstallthesystemll
connection at the same point as the expansion tank connection
to the system.
Expansion tank
Diaphragm- or bladder-type expansion tank — Figure 3,
page 10
1. Ensure expansion tank size will handle boiler and system
watervolumeand temperature.Tankmust be located in boiler
return piping as close to boiler as possible, before inlet side
ofcirculator.Seetankmanufacturer’sinstructionsfordetails.
2. Install an automatic air vent as shown.
Closed-type expansion tank — Figure 4, page 10
1. Ensureexpansiontanksizewillhandleboilerandsystemwater
volumeandtemperature.Seetankmanufacturer’sinstructions
for details.
2. Connect tank to ½”NPTtappinglocatedbehindsupply outlet,
using ½” NPT piping. Pitch any horizontal piping up towards
tank 1 inch per 5 feet of piping.
 Undersizedexpansiontankscause system water
to be lost from relief valve and makeup water to be
addedthroughllvalve.Eventualsectionfailurecan
result.
Water piping — multiple zone systems
Install system piping using either circulator zoning or zone valve
zoning. Install expansion tank on suction side of system pump.
Alwaysconnectlllineonlyat the expansiontank—neverat
another point in the system.
3 Install water piping
General
IfinstallationistocomplywithASMEorCanadianrequirements,
an additional high temperature limit is needed. Install control in
supply piping between boiler and isolation valve. Set second
controltominimum20°Fabovesetpointofrstcontrol.Maximum
allowable setpoint is 240 °F. See page 18 for wiring.
Alowwatercutoffdeviceisrequiredwhenboilerisinstalledabove
radiation level or by certain state or local codes or insurance
companies.Uselowwatercutoffdesignedforwaterinstallations.
Electrodeprobe-typeis recommended.Purchase andinstallin
tee in supply piping above boiler.
Usebackowcheckvalveincoldwatersupplyifrequiredbylo-
cal codes.
See Figure 3 (diaphragm-type or bladder-type expansion tank)
or Figure 4 (closed-type expansion tank) on page 10, and Table
5, for near-boiler and single-zone systems designed for return
water at least 130 °F.
See page 9 for multiple zone systems.
See page 10 for boilers used with refrigeration systems.
Near-boiler piping
Relief valve
Installrelief valvevertically in¾”tapping on side ofboiler.Seethe
tagattachedtothereliefvalveformanufacturer’sinstructions.
To avoid water damage or scalding due to valve
operation, discharge line must be connected to re-
lief 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
throughout its entire length.
• Dischargelinemustpitchdownwardfromthevalve
andterminateatleast6”abovethefloordrainwhere
any discharge will be clearly visible.
• Thedischargelineshallterminateplain,notthread-
ed, with a material serviceable for temperatures of
375 °F or greater.
• Donotpipethedischargetoanyplacewherefreez-
ing could occur.
• Noshutoffvalveshallbeinstalledbetweentherelief
valveand boiler, or in thedischargeline.Donotplug
or place any obstruction in the discharge line.
• Failuretocomplywiththeaboveguidelinescould
result in failure of the relief valve to operate, result-
ing in possibility of severe personal injury, death or
substantial property damage.
• Testtheoperationofthevalveafterllingandpres-
surizingsystembyliftingthelever.Makesurethe
valve discharges freely. If the valve fails to operate
correctly, replace it with a new relief valve.
Near-boiler piping continued

GWS-090E Gas-Fired Water Boiler – Boiler Manual
10 Part Number 550-110-737/1108
Figure 3 Diaphragm- or bladder-type expansion tank:
Piping to single-zone system using
diaphragm-type or bladder-type expansion
tank. See Table 5, page 9, for piping sizes.
Figure 4 Closed-type expansion tank: Piping to single-
zone system using closed-type expansion
tank. See Table 5, page 9, for piping sizes.
Figure 5 Piping refrigeration systems
3 Install water piping continued
Water piping — refrigeration systems
Prevent chilled water from entering boiler
Install boiler so that chilled medium is piped in parallel with the
heatingboiler.Useappropriatevalvestopreventchilledmedium
fromentering boiler. SeeFigure 5 fortypical installation ofbalanc-
ing valve and check valve.
Install boiler so that chilled medium is piped in par-
allelwithheatingboiler.Useappropriatevalvesto
preventchilledmedium from enteringboiler.Consult
I=B=R Installation and Piping Guides.
If boiler is connected to heating coils located in
air handling units where they can be exposed to
refrigerated air, use flow control valves or other au-
tomatic means to prevent gravity circulation during
cooling cycle.Circulation of cold water through the
boilercouldresultin damagetothe heatexchanger,
causing possible severe personal injury, death or
substantial property damage.
If system includes radiant heating circuits, provide
pipingandcontrolsto regulate the temperature sup-
plying the radiant circuits. Failure to comply could
result in substantial property damage.
 UseFigure3orFigure4onlyforsystemsdesigned
for return water at least 130 °F. For systems with
lowreturn watertemperaturepossible,suchascon-
verted gravitysystemsand radiantheatingsystems,
install bypass piping (see page 11) to protect boiler
against condensation.Failure to prevent low return
water temperature to the boiler could cause corro-
sion of the boiler sections or burners, resulting in
severepersonalinjury,deathorsubstantialproperty
damage.