Weil-McLain CGA 2 Series Product manual

Series 2
Gas-Fired Water Boilers
Boiler Manual • Installation • Maintenance
II
i!J._ 0 ·.1
Mobile Product
Ubrary
I AWARNING I
• Startup • Parts
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Thismanualmustonlybe used by a qualifiedheatinginstaller/service technician.
Before Installing, read
all instructions, including this manual, and any related
supplements. Perform stepsin the order
~ven. Failure to comply could result in
severe personal injury, death or substantial propertydamage.
PartNumber 550-142-779/0712

COa Series 2 Gas-Fired Water Boiler - Boiler Manual
2
How it works ...
(j) Control module
(2)
@
The co ntrol module responds to signals from the room thermostat and bo iler limitcircuit to operate the boiler
circulator,pilot burner,gasvalve
and ve nt damper.When room thermost at calls for heat, the control modulestarts
th e systemcirculator and activates the vent damper (causingit to driveopen).
When th e ve nt damper has opened completely, th e control module opens the pilot valve and activates pilot
ignition spark.
For natural gas,
th e control module allows up to ISseconds to establish pilot flame. If flante is no t sensedwithin
ISseconds,
the con trol module will turn off the gas valve, flash th e Flamelight, and immediately star t a newcycle.
Thiswill
co n tinue indefinitelyuntil pilotflante is established or poweris interrupted. Once pilotflante is proven,
the con trol module opens the gas valve to allow main burner flame.
For propanegas, the control moduleallows up
to ISseconds to establish pilotflante. If fl ame is no t sensedwithin IS
seconds,
th econtrol modulewill turn off the gas valve,flash th e Flamelight, wait I minute, thenstarta newcycle. If
flante is still
not sensed af t er the second trial, two more attempts are madewith Sminutewait periods in between.
Ifflame
is not sensed after 4 tries, control will lockout and flash all lights.Control must be manually reset to place
back into service. Oncepilot flame
is proven, th econtrol moduleopens the gas valve to allow main burner flante.
When the room therntostatis satisfied, the control module turns off the gas valve and deactivates th e vent damper
(causing it to dose ).
The control moduleindicatorlights shownormalsequence when th e lightsare on steady.Whena problemoccurs,
the control module flashes combinations of lights to indicate th e most likely reason for th e problem. See page 49
for details.
Tr41n s fonner
The control tran sformer reduces line voltage to 24 volts for the gasvalve and limit circuit.
Draft hood
The draft hood provides a minimum draft for the boiler, assuring adequate air for combusti on if installed in
accordancewith manual an d no t modified in anyway.
@ Spill switch
The sp i ll switch will shut down the bo il er (requiring manual reset of the switch reset button) if the ve nt system
becomesblocked.
@ Water temperature sensor
The watertemperaturesensor l?rovides a signal to th e control module to turn off the gas valve if the temperature
in the boilergoesabove its settmg.
(T he circula to r will continue to run as longas thereis a call for heat.)
@ Boiler circulator
The boiler circula to r circulat es wat er t hr ough the external (system) piping. The circula to r is sh ipp ed loose, and
can be moun ted on eith er the bo iler s uppf y or return piping. The factory-installed circulator wiring harness
pro vides ample length for eitherlocation. NOTE - The control module pro vides a pu mp exercising routine. If
th e boiler is no t operated for 30 da ys, th e control modulewill power the circula to r for 30se cond s, th en turn off.
® Vent damper
The vent damper closes during off cycles to reduceheatloss from the house up the vent.
Other boiler components:
a supp ly to system
b re turn from syst em
c flue outlet
d
burner manifold
e gasvalve
f pressure/temperature gauge
g reli
ef valve
h air ventconnection
i flame rollout switclt
j b urner orifice
k pilot burner, typical
I stainlesssteel burners
m cast ironboilersections
n flue collector
o junction box
PartNumber550-142-779/0712

CGa Series 2 Gas-Fired Water Boiler - Boiler Manual
CGa Series 2 Gas-Fired Water Boiler
Part Number 550 -142-779/0712 3

COa Series 2 Gas-Fired Water Boiler - Boiler Manual
4
Contents
How is works .................................................... 2-3
Hazard definitions ...............................................4
Please read before proceeding ............................ 5
1 Prepare boiler location ................................... 6-11
2 Prepare boiler ............................................... 12-15
3 Water piping ................................................. 16-25
~ Clas pipin!J ••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 26
fi ~ielcl wiring .••••...•••...•••...•••..••••...•••...•••...•••..••••.. 2~
6 Start-up ........................................................ 28-32
7 Check-out procedure ......................................... 33
8 Department of Energy Compliance ••••••••••••••••••• 34
9 Operation- spark-ignited pilot boilers ...•••...• 34-41
10 Service and maintenance ............................. 42-47
11 Troubleshooting:
Spark-ignited pilot boilers ............................ 48-56
12 Replacement parts ....................................... 58-63
13 Dimensions and ratings ................................ 64-65
14 Notes ............................................................ 66-67
Hazard definitions
The following defined terms are used throughout this manual to bring attention to the presence of hazards of
various risk le vels or to importantinformation concerning the life of the product.
I AWARNING I
lA CAUTlON I
NOTICE
Indicates presence of hazards that will cause severe personal injury, death or substantial
propertydamage.
Indicates presence
of hazards that can cause severe personal injury, death or substantial
propertydamage.
Indicatespresence
of hazards that will or can cause minorpersonalinjury or propertydamage.
Indicatesspecial instructionson installation,operati
on or maintenancethatareimportant but
not relat ed to personal injury or property dam age.
PartNumber550-142-779/0712

CGa Series 2 Gas-Fired Water Boiler - Boiler Manual
Please read before proceeding
Installer
!A WARNING I
User
Read all Instructions before In-
stalling. Follow
aU instructions in
proper order to prevent personal
injury
or death.
Considerpiping
and Installationwhen determining
boilerlocation.
Any
claims lor damage or shortage In shipment
mustbefiled immediatelyagainst the transportation
companyby the consignee.
This manual Is lor use only by your qualified
heating Installer/service technician.
Please refer to the user's Information Manual for
your reference.
We
recommend regular service by a qualified
service technician, at least annually.
I AWARNING I
The boiler contains ceramic fiber and fiberglass materials. Use care when handling these
materials per instructions
on page 57 of this manual. Failure to comply could result in severe
personal injury.
NOTICE
When calling or writing about the boiler- Please ha ve the boiler model number from the
boiler rating label
and the CP number from the boiler jacket.You may li st the CP number in
thespaceprovided
on theInstallation and service certificate found on page 33.
I AWARNING I
Fa ih1r e to ::.dhere to the Cl lidel ine.s on this p::.ce (":tn re.snlt in severe personal injury, de.ath
or substantial propertydamage.
When servicing boiler -
To avoid electric shock, disconnect electrical supply
beforeperforming maintenance.
To avoid severe burns, allow boiler
to cool before
performing maintenance.
Boiler operation -
Do not block flow of comb ustion or ventilation air
to boiler.
Should overheating occur or gas supply fail to shut
off, do
not turn off or clisconnect electrical supply to
circulator. Instead, shut offthegassupplyata location
external
to th e app li ance.
Do
not usethis boilerifany part has been under wa-
ter. Immediatelycall a qualified servicetec hni cian to
inspecttheboil er and to replaceany part of thecontrol
system
and anygascontrol that hasbeen under water.
Boiler water -
Do not us e petroleum -based cleaning or sealing
compounds
in boilersystem.Waterseal deterioration
will occur,causingleakage betweensections.Thiscan
result
in substantial propertydamage.
Do not us e "homema de cures" or "boiler patent
medicines".Seriousdan1age to boiler, personnel and/
or propertymayresult.
Part Number 550 -142-779/0712
Continual fresh makeup water will reduce
boiler li
fe. Mineral bui ldup in sections re-
duces heattransfer, overheatscastiron, and
causes section failure. Additi on of oxygen
and othergasescancauseinternal corrosion.
Leaks in boiler
or piping must be repaired
at once to prevent makeupwater.
Do
not addcoldwater to hot boiler.Thermal
shockcancausesections
to crack
Glycol -potential fire hazard -
All glycol is flan1mable when exposed to high
temperatures.lfglycol
is allowed to accumulate
in or around the bo iler or any ot h er potential
ignition source, a fire can develop.
In order to
preventpotential severe personal in ju ry , death
or substantial property damage from fire and/
or structuraldamage:
Neverstoreglycol
of anykind nearthe boiler
or anypotential igniti on source.
Monitor and inspect th e system and boiler
regularly for leakage. Repair any leaks im-
mediately to preventpossibleaccumulati on
of glycol.
Never useautomotiveantifreeze
or ethylene
glycol
in thesystem.Using these glycols can
lead to hazardous leakage
of glycol in the
bo ilersystem.
5

COa Series 2 Gas-Fired Water Boiler - Boiler Manual
6
1a Prepare boiler location -codes & checklist
Installations must follow these codes:
Local, state, provincial, and national codes, laws, regulations and ordinances.
National Fuel Gas Code,
AN SI Z223.!- latest edition.
Stand ar d for Contro ls an d SafetyDevices forAutomatically Fired Boilers, ANSI!
ASME CSD-
1, when required.
National Electrical Code.
For
Canada only: Bl49.! or Bl49.2 Install ation Co de, CSA C22.1 Cana d ian
Electrical Code Part I andany localcodes.
NO TICE The CGa boilergas manifold and controlsmeetsafeoperatingand
o
th er performancecriteriawhen bo il er und envent testsspecified
in AN SIZ21.13- latestedition.
Before locating the boiler,
check the following:
Check for nearbyconnection t o:
Systemwat er pi ping
Ventingconnections
Gas su
pp ly piping
Electrical power
Checkarea
aro und bo il er. Remove any combu s tible material s, ga s oline and
other flammable liquid s, or other contaminant s.
I AWARNING I Failure
to keepboilerarea dear and free of combustible material s,
ga s oline and other flammable liquid s and va por scanresultin
severe personal injury,
death or substant ial property damage.
Boil
er must be installed so that gas con trol syst em components are pro tected
from
dripp ing or sprayingwater or rain during operation or service.
If newboilerwi ll replace existingboiler, checkfor and correctsystem problems,
such as:
1. Systemleaks causing oxygen corrosion or section cracksfrom hard water
deposits.
2. Incorrectly-sizedexpansion tank.
3. Lack
of an tifreeze in bo ilerwat er causingsystem and boiler to freeze and
leak.
PartNumber550 -1 42 -779/0712

CGa Series 2 Gas-Fired Water Boiler - Boiler Manual
1b Prepare boiler location -clearances
Recommended SERVICE clearances
(Fig.1a)
1. Provide clearances for cleaning and servicing the boiler and for
access to controls and components.SeeFigure Ia for recommen·
dations.
2. Provideat least screwdriverclearance tojacketfront panelscrews
for removal
of fron t panel for inspection and minor service. 1f
unableto provide at leastscrewdriverclearance, instaU unions and
shu t off valves in system so boiler can be mo v ed for servicing.
Figure
1a
Recommended
service
clearances
(see WARNING
below)
IAWARNINGI
II any clearance is less than in Figure 1 a, pro-
vide openings fo r combustion and ventilation
air
located on the wall or door oppoalts the
boiler FRONT(aee Figure 1b) .
Theseopenings must be l ocated as shown in Figure lb to provide
!?roper
air flow around the boiler. The free area of each opening
{after deducting for louvers) must be at least one squa re inch
per 1,000 Btuh of boiler input. If the building is of un usually
tight construction (see page II for definition), the air openings
must connect direcdy to outside or the buildi ng must have air
openings to the outside as specified on page II.
If clearances
are equal to or greater than Figure Ia, see pages I0
and II for location and sizing of combustion air openings.
Failure
to comply can result in severe personal injury, death or
substantial property damage and reduced boiler life.
Required MINIMUM clearances (Fig .1b )
I AWARNING I Never Install
the boller In a space with clear-
ances less than the minimum clearances shown
In Figure 1b.Failure to comply can result in severe
personalinjury,death
or substantialproperty dam -
age and reducedboilerlife.
1. Hot water pipes: at least 'h Inch from combus tible material.
2. Single-wall vent pipe: at least Glnches from combustiblemate-
rial.
3. Type B double-wan metal vent pipe : refer to vent manufacturer's
recommenda t ion for clearances to combus tible material.
Part
Number 550-142-779/0712
Figure 1b Required MINIMUM cl ea ran ces
Flooring
The CGa boiler is approvedfor installation on comb ustible
flooring,
but must never be installed on carpeting.
IAWARNINGI
Do no t install boiler on carpeting even
if foundation is used. Fire can result,
causing severe personal injury,
death
or subs tantial property damage.
Foundation
I. Providea solidbrick or mini mum 2-inch th ickconcrete
foundation
pad if any of the fo ll owing is true:
floor
can become flooded.
the boiler mounting area is not level.
2.
Minimum dimensi ons are 25" length by:
Minimumfoundation width:
CGa-2513 1 2" CGa-6
CGa-i
15" CGa-7
CGa-5 18" CGa-8
21"
24 "
27"
Residential garage installations
Take the following specialprecautions when ins talling t he
boiler in a residential garage. If the boiler is l ocated in a
residential garage,
per ANSI Z223.1:
Mount the boilera minimum of 18 Inches above the
floor 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.
7

COa Series 2 Gas-Fired Water Boiler - Boiler Manual
lc
I AWARNING I
8
Prepare boiler location -vent system
Failure to follow all instructions can result in flue gas spillage and carbon monoxide emissions, causing severe
personal injury
or de ath.
Inspectexisting chimney beforeinstalling boiler. Failure to clean or replaceperforatedpipe or tileliningwill cause
severe personal injury
or de ath.
Do not alterboilerdraft hood or place any obstruction or non -approved vent damper in breeching or ventsystem.
CSAcertification will become void. Flue gas spillage and carbon monoxide emissions will occur causing severe
personal injury
or death.
When removing boiler from an
existing common vent system:
At the time of removal of an existing boiler, thefollowing
steps shall
be followed with each appliance remaining
connected
to the common ventingsystem placedin op-
eration,while the ot her app liances remainingconnected
to the
common ventingsys tem are not in operation.
a.
Seal any unused openings in the common venting
system.
b. VIsually
In s pect the venting system for proper
siu and ho•·izonral pitch and determinethereis no
blockage or restricti on, leakage, corrosion or other
deficiencies whichcouldcause an unsafecondition.
c.
Test vent s ystem- Insofar as ispractical,closeall
buildingdoors
and windows and all doors be twe en
the space in which the appliances remaining con-
nected to
the common venting system are located
and other spaces of the building. Turn on clothes
dryers
and anyapp liance no t connectedto the com-
mon ventingsystem. Turn on anyexhaustfans, such
as range hood s and bathroom exhausts, so theywill
operate at maximum speed. Do not operate a sum-
mer exhaust fan. Close fireplace dampers.
d.
Place In operation the app li ance being inspected.
Follow theoperatinginstructions.Adjustthermostat
so appliancewill operate
continuous l y.
e. Te s t lor spillage at draft h ood re li ef open in g after
5 minutes
of main burner operation.Use the flame
of a match or candle.
f. After it has been determined th at each appliance
remainingconnected to the common ventingsyst em
proper ly vents when testedas outl inedabove, return
doors, windows, exhaust fans, fireplace dampers,
and any other gas-b urnin g app liance to theirprevi-
ous conditions of use.
Any
im proper operation of common venting system
should be corrected so the installation conforms with
the NationalFuelGas Code,ANSI Z223.1-latestedition.
Correct by resizing to approach the minimum size as
de termined using the appropriate tables in Part II of
th at code. Canadian in stallations must comply with
Bl49.1
or Bl49.2 Installation Code.
Chimney or vent require-
ments
I. Venting must be installedaccording to Part 7,Vent-
ing
of Equipment, ofNational Fuel Gas Code,ANSI
Z223.1-latestedition
and applicable buildingcodes.
Canadianinstallations must comp ly withBl49.1 or
Bl49.2 InstallationCodes.
2. See Ratings table on page665for minimum chimney
or vent sizes. A chimney or vent without a li s ted
cap sho uld extend at least 31eet above the highe st
point where it passes through a roof of a building
and at lea st 2 feet higher than any portion ol a
building within a horizontal di s tance 0110 feet.
A
chimney or vent must not extend less than the
distancesstatedabove.
3. Alined
chimney is preferred and must be used when
required by local, state , provincial and national
codes,laws,regulations and ordinances.Vitreous tile
liningswithjointsthatpreventretenti
on of moisture
and linings made of noncorrosivematerials are best.
Advice for flueconnections and chimneylinings can
be obtained from local gas utility. Type B double-
wall
me t al vent pipe or single-wall vent pipe may
be usedas a liner.
4.
Cold masonry chimneys, also known as outs id e
chimneys, typically have
one or more walls ex-
posed to outsideair. When any atmospher ic gas-
fired boiler with
automatic vent damper is vented
through this
type of chimney, the po tential e:<ists for
condensation
to occur. Condensation can damage
a
masonry chimney. We il-M clain recommends the
following to prevent possible damage.
a. Line chimney with corrosion-resistant metal
liner
such as AL29-4C® single-wallstainless
steel
orB -vent.Size liner per National Fuel
Gas
Code ANSI Z223.1-latestedition.
b. Provide drain trap to remove any condensate.
5.
Where rwo or more gas appliances vent in to a
common chimney or vent,equivalent area should
be at lea st equal to area of vent outlet on largest
appliance
plu s 50 percent of vent outlet area on
additional appliance.
PartNumber 550-142-779/0712

CGa Series 2 Gas-Fired Water Boiler - Boiler Manual
1d Prepare boiler location - air contamination
Please review the fo ll owing information on potential
combus ti on air co nt amination problems.
Refer to Table 1 for pro du cts and areas which may cause
contaminated combus ti on air.
IAWARNINGI
To pr eve nt potential of severe personal injur y or death,che ck for products or areas listed
below before installing boiler. If any of these contaminant s are found:
remove contantinants permanently
-OR -
isolate boiler and provide outside combustion air. See national, provincial or local codes
for further information.
Table 1 Corrosive contaminants and li ke ly l ocations
Products to avoid Areas likely
to have contaminants
Spray cans containing ch lorolfluorocarbons Dry cleani
ngn au ndry areas and establishments
Permanent
wave so lutions Swimming pools
Chlorinatedwaxes/cleaners Metal fabrication olants
Chl or ine-based sw i mm i ng pool chemicals Beauty shops
Calcium chloride used f or thawing Refrigeralion
re pairs ho ps
Sod ium chloride usedfor wa te r softeni ng P ho to processing plants
Refrigerant l eaks
Autobody shops
Pa int or varnish r em overs Plas
ti c manufacturing plants
Hyd rochl oric ac id/muriatic ac id Furniture refinishing areas and establishments
Cements and gl
ues
New building construction
Antistatic fabricsofteners used in clothesdryers Remodeling areas
Chl
or ine-typebleaches, detergents, and cleaning
so lvents fou nd in household laundryroorns Garageswilh
worl<shops
Adhesiv es used to fasten building products and other
simil
ar products Buildings under construction
(Wh ereair is contaminated
with parti
cula tes)
Airborne particulates (drywall
dus t, fiberglass particl es ,
road
or gravel dust, lint, etc.)
Part Number 550-142-779/0712 9

COa Series 2 Gas-Fired Water Boiler - Boiler Manual
1e Prepare boiler location - air openings
IAWARNIN GI
Combu s tion air opening location and sizing
requirements
depend on the clearance s around
the boller.Checkthe bo ilerplacementcomparedto
Figure
La, page 7.
It all clearances are at least equal to Figure 1 a,
page 7,apply thesizing and placement of openings
givenon pages
10 and 11.
It ANY clearance Is les s than Figure 1 a, page 7,
you
must provide air openingssized and locatedas
shownin Figure
lb ,page7. DO NOT applythesizing
and locati on in formationshown on page 10 or 1 1.
Air openings must be provided
Com bustion air an d ventilation openings mustcomply theNational Fuel
Gas Code
ANSIZ223.1-latestedition, or applicablelocal buildingcodes. Ca-
nadianinstallationsmustcomplywithBl49.1 or Bl49.2InstallationCodes.
IA WA RNIN Gl Prov
id e adc::qualc wrnbw; tion and vc::ntila li on air to
assurepropercombustion and reduce the risk of severe
personal injury, death
or substantial propertydamage
c
aused by flue gas spillage and carbon monoxide
emissions.
Air opening options
Two op e ning s - Air s upply from in s id e th e buildin g *
I. If thebuilding is of unu sually tight con strucllon (seedefinition, next
page),the building
mu st also be provided with air opening s directly
to the out side,sized and locatedper Fig ure 3, Figure 4 or Figure 5.
2. Buildings
of typical co nstructionshould provideadequatecombustion
air from natural infiltration, soadditionalair openings to thebuilding
are
not required.
3. See Figure
2. Provide two opening s thro ugh the interior wall, within
12 inch es of th e ceiling and th e floor, sized perFigure 2.
Two op e ning s - Air s upply di re ctly from out s id e *
I. Air openings must bedirectly through an o ut sidewall, or into a space
thatconnectsdirectly to theoutside(suchas a ventilat
ed att ic or cr awl
space, for example).
2. See Figure 3- Openings directlythrough
an out side wall- provide
two
opening s within 12 inches of the ceiling an d the floor, sized per
Figure 3.
3. See Figure4 - Air supplied through vertical
duct s - provide two
opening s terminated within 12 inches of t he ceilingand th efloor,sized
per Figure 4.
4. See Figure 5 -
Air supplied through horizontal duct s - provide
two
opening s within 12 inch es of the floor and the ceiling, sized per
Figure 5.
Figure 2
Figure 3
Figure 4
Figure 5
Air openin gs to i nt erior spaces
Eac h opening fr ee ar ea =
1sq. inch per 1,000 Btu h
"
Air d ir ectly throu gh outsi de wa ll
Each op enfng free area =
1 sea. Inch per 4,000Btuh
"' "'
.... ,..
..
Ot 1r
Air from outdoors - vertical ducts
Outsi de or vent ilated attic
Each
ope ning tree arN =
1 sq . Inch per 4,000Btuh
-
Air fromoutdoors - h or izontal du cts
E.a c: h opening frM area •
1 sq. inch pa t ~000 Btuh
"'"' '
--· · 0
~
0
10
PartNumber 550 -1 42 -779/07 12

CGa Series 2 Gas-Fired Water Boiler - Boiler Manual
le
Prepare boiler location - air openings
NOTICE
FREE AREA of openings - the minimum areas
given
in this manual are free area (equals the area,
length times width of opening, after deduction for
louverobstruction).
Use the free area information provided by the louver manufacturer.
When this information is not available, assume:
Woodl
ouvers- assume free area is 20o/o of total;so th e actual area
of each opening with wood lou, •ers would be 5 times the r equired
free area.
Metal louvers- assume free area is 60o/o of actual area; so, forw ood
louvers, the actual area of each opening must be 1.67 times the re-
quired free area.
Single air ope ning option *
A single combustion air opening can be used in lieu of the two- opening
op ti ons on page 10, provided:
Clearances from boiler to walls
The boiler must have clearances of at least those sh own in Figure Ia,
page 7.
Op&ning must b& dir&et/y to outs i de
The opening must connect directly to the outdoors or to a space tha t
communicatesdirectly
to the outdoors (not to an interiorspace).
The air can be provided througha direct opening orthrougha horizontal
or vertical duct.
Op&ni ng p/ac&m&nt
The top of the air opening must be within 12 inches of the ceiling.
Op&ni ng siz&
The free area of the opening must be at least equal to the sum of the
area of all equipment vent connectors in the space, and ...
The free area of the opening must be at least I square inch per 3,000
BtuJhr input rating of all equipment located in the space.
Exception for la rg e spac es *
No combustion air openings are needed when the boiler (and ot her ap-
pliances) are installed in a spacewith a vol ume at lea s t 50 cubic feet per
1,000 Btuh of all installed appliances, provided:
the building must not have unu sually tight con s truction (seedefini-
tion, this page)
all clearances
around the boiler must must be no less th an sh own in
Figure Ia, page 7.
Todetermine if the space is large enoug h to quali fy:
Add the total input of aJI appliances in MBH (l,OOO's of Bt uh).
Multiply this number times 50 to determine min imum room vo lun1 e.
Example: For a total input of 1 00 MBH (100,000 Btull), mininlum
volun1e is 50 x 100 =5,000 cubic feet. At aceiling height of 8 feet, the
space must have at least 5,000 + 8 = 625 square feet (25 feet x 25 feet,
for instance).
Part Number SSQ-142 - 77910712
Unusuallyti ght construction
Unusuallytightconstruction means( per ANSI Z223.1)
buildings in which:
a. Walls and ceilings exposed to the outside atmo-
spherehavea continuous water vapor retarderwith
a rating
of I perm or less with openings gasketed,
and ...
b. Weather-stripping ha s been added on openable
windows and doors , and ...
c. Caulking or sealants are applied to areas such as
joints
around windows and door frames, between
sole plates
and floors, between wa ll -ceiling joints,
between wall
pane ls, at penetrations for plumbing,
electrical,
and gas lines, and in other openings.
Forsuch constructioncases, if appliances use insideair
forcombusti
on, provideair openings Into the building
f
rom outside . Size and locate these openings per the
appropriate
case in Figure 3, 4 or 5 on page 10.
l!xhaust fans and air movers
The appliance space must never be under a negative
pressure,even
if the appliance(s) are installedas direct
vent.Always provide airopenings sized
not only to the
dimensionsrequiredfor the firing rate of aU appliances,
but also to handle the air movement rate of the exhaust
fans
or airmovers using air from the building or space.
Motorized air dampers
If the air openings are fitted with motoriud dampers,
electrically interlock
the damper to:
Prevent
the boiler from firing if the damper is not
fully open.
Shut the boiler down should the damper dose dur -
ingboileroperation.
To accomplish thisinterlock, wire an Is olat ed contact
(p roving the damper open) in series witll the thermo -
stat input to the boil er. The boiler will not start if this
contact is open, and wi ll shut down s hould it open
d uring operation.
II

COa Series 2 Gas-Fired Water Boiler - Boiler Manual
12
2a Prepare boiler -placement and setup
Place boiler/crate near f1 M:!i@;l
position
Correc tly-sized manifold orifices
must be used. Failure to do so wi ll
result in severe personal injury,
1. Leave boiler In crate and on pallet until installa-
tion siteis read
y.
2. Moveentirecrate and pallet next toselectedlocation.
3. Remove crate. Leave boiler
on pallet.
4. Remove boiler from pallet as follows:
a. Tiltleftside
of boiler up and placea board under
left legs.
b. Tiltboil
er the otherway and placea board under
right legs.
c. Slide bo il er backwards offpallet and into pos i-
tion.
NOTICE I
5. Check level.
Do
no t drop boiler or bu mp jacket
on flo oror pallet.Damage to boiler
can result.
a. Shim legs, ifnecessar
y.
b. Do not alterle gs.
Inspect orifices and burners
I. Remove fro nt jacketdoor. Remove baseaccess pane l
(See Figure 32, it
em 4, page 60).
2. Check for corr ectly-sized manifold orifices. See
Table2 belowforsizing. (Theorificesize isstamped
on theorificespud barrel.)
Table 2 Ma
nif old orifice s izin g
Loca ti on Natural gas
u.s.
0-2,000 ft over 2,000 ft
2.00 mm (Note 1)
Canada
G-2,000 ft 2,00G-4,500 ft
2.00 mm
1.90 nvn
Location Propane gas
u.s.
0-2,000 ft over 2,000 ft
1.30 mm (Note 1)
G-2,000 ft 2,00G-4,500 ft
Canada 1.30
mm
1. 20 nvn
No te 1:
For elevations above 2,00 0 fee t, contact your
Wei i- Mclain sa l es office for details.
death
or substantial property dam-
age.
3.
Level and straighten burners.
Burners must beproperlyseated
in
slots in burner rest with their open-
in gs face up. Main burner orifices
must inject down center of burner.
Failure
to proper ly seat burners
will result in severe personalinjury,
death
or substantial property dam-
age.
4. Reinstalla cc ess panel.
lA CAUTlON I
Do not operate boiler wit hou t ac-
cess pane l secured in place. Failure
to complycould cause momentar y
flante rollout
on ignition of main
flante, resulting
in possible fire or
personal injury hazard.
Orifice replacement procedure
(when requ ir ed)
I. Remo ve access pane l.
2. On gas manifold, mark location of mainburnerwith
attached pilot assembl
y.
3. Remo ve ma in burner with attached pilot assembly
from manifold. Remove all remainingburners.
4. Remove and discard all main burner orifices in gas
manifo
ld .
5. Apply a s
maU amoun t of pipe dope to each of the
neworifices
and install in themanifold. Makesure
theorificesarealigned correc
tl y, not cross-threaded
in the manifoldtappings.
I AWARNING I Use onlypi pe dopecompatible with
propane gas, even if bo
il er is to be
operated
on natural gas. Failure to
comply could result in severe per-
sonal injury, death or s ub stan tial
propertydamage.
6. Reinstallmain burner withattached pilotassembly
at location marked
on gas manifold. Reinstall all
remaining burners.
7. Followcheck- out procedure,Section 7, page 33.
Part Number 550 -14 2-779/0712

CGa Series 2 Gas-Fired Water Boiler - Boiler Manual
2b Prepare boiler -pressure test
Hydrostatic pressure test
Pressure test boiler beforeattachingwater or gaspiping
or electrical supply(exceptas notedbelow).
Prepare boiler for test
I. Remove the shipping nipple (from CGa supply
tapping) and remove the boiler relief valve.
Temporarily plugthereliefvalve tapping with a%"
NPT pipeplug.
2. Remove I \14" nipple, reducing tee and drain
valve from accessory bag. InstaU in boiler return
connectionasshownonpage 3 or in Figure34,item
3, page62. Installcirculat
or on eitherthe return or
supply.
3. Remove I
\14" nipple, I \14" tee ,bushing and pressure/
temperature gauge from accessory bag. Pipe to
boil
er supply connection as shown in Figure 34 ,
page 62-. (Use pipe dopesparingly.)
4. Connecta hose to boilerdrainvalve, theother end
connectedto a fresh water suppl y. Make surehose
can also be used to drain boilerafter test.
5. Connecta nippleandshutoffvalve tosystemsupply
connection
on the I \14" tee. This valve will beused
to bleed a
ir during the fill. (Valve and nipple are
not includedwith boiler.)
6. Connect a nipple and shu toff valve to system
returnconnection
(at circulatorflange if circulator
installed
on return). This valve will be used to
bleed air during the
fill. (Valve and nipple are no t
included
wi th boiler.)
Fill and pressure test
1. Openthe sh utoff va l ves youinstalled on supply and
re turn connections.
2. Slowly open boiler drain valve and fresh water
supplyto fill boiler
wid1 water.
3. Whenwaterflows from shutoff
valves,closeboiler
drain valve.
Part Number 550 -1 42-779/0712
4. Closeshutoffvalves.
5. Slowly reopen boiler
drain valve until test pressure
of not more th an 45 psi is reached on thepressure/
temperaturegauge.
6. Test at no more than 45
psi lor no more than 10
minutes.
I AWARNING I
Do not leave boller unattended .
A cold water fill could
e>.-pan d and
cause excessive pressure, resulting
in severe personal injury, death
or
substantial propertydamage.
7. Make sureconst
ant gauge pressurehas been main-
tained throughout test. Check for leaks. Repair
if
found.
I AWARNING I
Leaks must be repaired at once .
Failure to do so can damage boiler,
resulting
in subs tantial proper ty
damage.
Donotusepetroleum-basedclean-
ing
or sealingcompo un ds in boiler
system. Severe damage
to boiler
will oc cur , resulting in substantial
propertydamage.
Drain and remove fittings
I. Disconnectfill water hose from water source.
2. Drain boiler
at drain valve or out hose, whichever
provides best access to drain. Remove hose after
draining ifused to drain boiler.
3. Remove nipples
and valves unless theywill remain
for use
in thesystem piping.
4. Removeplugfrom reliefvalvetapping.SeeSection 3
to replace reliefvalve.
13

CGa Series 2 Gas-Fired Water Boiler - Boiler Manual
2C Prepare boiler - draft hood & spill switch
Draft hood installation
Spill switch installation
1. Orient draft hood wi th spill switch mounting holes to front of boiler
as shown in Figure
7.
I. Fasten spill switch to drafthoodasshown in Figure 6
and Figure 7.
2. Securedraft hood
to outlet at top of boilerwith sheet metal screws.
2. SeeWiring diagram to connectwires:.
a_ Spark-ignited pilot boiler-
3. Bottom of draft hood or "skirt" must have clearancedimensionabove
jacket
top pane l as indicated on draft hood. see
pages 36 and 37
p
1
j 1 MHij@ ;I Do not alterboilerdrafthood or placeanyobstruction or
-- -···-· •• non-approvedventdamperin breeching or vent sys tem. I
AWARNING I Improperorientation
of spillswitch
maycause boiler to shutdown. The
loss of heatcan result in significant
dam age due to freezing.
2d
IAWARNING I
14
CSAcertificationwill become void. Rue gas spillage and
carbon monoxide emissions will occur causingsevere
personal injury
or death_
Figu re 6 Install spill switch
D"ft h ood _/
.....
Figure 7 Spill switch with wire harness
Sp ill switch wire
harness
Damper harness
knock out -- "'
•
Prepare boiler -install vent piping
LQng horizontal ventcoJmector,
excessive number of elbow or
tees, or other obstructions that
restrict the flow of combustion
gases should
be avoided. Severe
personalinjury,death or substan-
tial propertydamagecould result
I. Connect from draft hood or vent damper ou tlet to chimney or vent
with same size vent connector.
2. Where possible, vertical venting to theoutside from thedraft hood or
ventdamper outletwill offer bestperformance.
3. Wherehorizontalvent connectoris used, slopeupward atleast \4''
per
lineal foot towardchimney or vent and support withhangers to prevent
sagging.
4. Breechingmust no t beconnected to anyportion of a mechanical draft
system
that can opera te under positive pressure.
PartNumber 550 -1 42 -779/0712

CGa Series 2 Gas-Fired Water Boiler - Boiler Manual
2e Prepare boiler - vent damper installation
NOTICE
I AWARNING I
These systems are used on gas-fired boilers with vent
dampers
as shippedfrom factory. Boilerwill not operate
without ve nt damper installed.
Onlyvent dampers listed in the Replacement parts list
on page 58 are certified for use wid1 CGa boilers.Any
othervent
damper in stalledc ould causeseverepersonal
injury
or de ath.
Damper blade
Spark-Ignited pilot systems- Refer to vent manu-
facturer's instructions to install plug (s hi pped with
damper) in damper hole. For spark-ignited pilot
boilers only,
in stall plug with no hole in vent d amper
hole.
Minimum clearances
Providea minimum of 6" betweenfuevent damper and
any c omb ustible material.(Providea minimum of 36 "
be twe en jacket to p and combustible cei li ng.)
Do
not modify draft hood or vent damper, or make an-
other connectionbetween draft hood an d vent damper
or boiler except as no te d below. This will vo id CSA
certification and will no t be covered by Weil-McLain
warranty.Anychangeswill causesevere personal
in jury ,
death or s ub s tan tial property dam age.
Figure 8 Vent damper assemblies
Effikal or Field Controls Johnson Controls damper
damper
Refer to vent man ufacturer's instructions to insta ll
plug {shippedwith dampe r) in dampe r hole.
Hold-
open switch {Effika l on lyI -
Install vent damper so that switch
is vis
ib le and accessibleto user .
Part Number 550-142-779/0712
S932S
Installation
I. Install vent damper horiwntally or vertically as
shown in ve
nt damper manufacturer'sinstructions.
Vent dan1per
must be installedso that itserves only
one boiler and so damper blade indicat or is visible
to the user. See Figure 8.
2. Screws or rivets used to secure the vent damper to
the draft h ood must not interfere with rotation of
the damper blade.
3. Install damper harne ss be tw een damper actua t or
and knockout in jacket top panel. Use strain relief
conne ct ors and locknuts to secure both ends of
damper harness.
!A CAUTION I Keep
wiring harne ssclear of all ho t
surfaces.
WARNING
UNE UP KEYWAY WHEN
CO NN EC TING PLUGS.
FORCING A MISMATCH
CAN CAUSE A
HAZARDOUSCONDITION.
oo
OQ
Keyway~ -- ... ·· ··-···-······ -- L_ Key
59304
4. Read and apply the harness plug warning label
(s hown above) so that it is visible after installation.
5. Plugdamperharness receptacle
in to damperharness
plug.
!A CAUTION I
NOTICE
Bypassing(jumpering)vent damper
will ca use flue produc ts such as
carbon monoxide to escape in to
the house. This will cause severe
personal injury
or death.
Afterboiler
ha soperated once, if ei-
ther end of harnessis disconnected,
thesystem safety
shutdown will oc-
cur. The boilerwi ll not operateuntil
harne ss is reconnected.
E111kal or Field controls damper-
Dan1per hold open switch must be
in Automatic Operation position
for system to operate properly.
IS

COa Series 2 Gas-Fired Water Boiler - Boiler Manual
3a Water piping - general information
General piping information
If in stallati on is to comply with ASME or Canadian requirements, an ad-
ditional high temperature limitis needed. Install control in supp ly piping
between boiler and isolation valve. Set second control to minimum 20°F
abovesetpoint of first control. Maximum allowable setpoint is 240°F. See
page 36,for wiring.
A low water cutoff device is required when boiler is installed above ra-
diation level
or by certainst ate or local codes or insurancecompanies. Use
l ow water cutoff designed for water installations. Electrode probe-type is
recommended. Purchase
and install in tee in supply pipingaboveboiler.
Use backllow Check valve incold water supply as required by localcodes.
Pressure/temperature gauge
Install pressure/temperature gauge in tee on supp ly piping (as shown in
drawing on page 3).
Isolation valves
Isolationvalves are required to enable servicing of the boiler's te mperature
sensor. Install as shown in appropriate pipingdiagram.
Relief valve
Install reliefvalve vertically in %• tapping on side of boiler. See Figure 9
or 10, page 17, and the tag attached to the reliefvalve for manufacturer 's
instructions.
lA WARNING ! Toavoidwaterdamage or scalding due to reliefvalve
operation:
16
Discharge l ine must be connected to relief valve outlet and run to
a sa le place of disposal .Terminate the dischargeline to eliminate
possibility
of severe burns should the valve discharge.
Dischargel
ine must be as short aspossible and be the same size as
the valve di sc harge connection througho ut itsentire length.
Dischargel
ine must pitch downward from the valve and terminate
at least 6" above the floor drain where any dischargewill be clearly
visible.
The dischargel ine shall terminate plain, not threaded ,witha mate-
rial serviceable for temperatures of 375°F or greater.
Do
not pipe the discharge to any place where freezing could
occur.
No shuto ff valveshall be installedbetween the reliefvalve and boiler,
or in the dischargeline. Do not plug or place any obstruction in the
di scharge line.
Failure
to comply with the aboveguidelines could resultinfailure of
the reliefvalve to operate, resulting in possibility of severe personal
injury,
death or substantial property damage.
Test the operation of the valve afterfilling and pressurizingsystem
by lifting thelever. Make sure the valve discharges freely. If the valve
fails to operate correctly, replace
it with a new reliefvalve.
Circulator
T he circulator is shipped loose (wi ring pre-attached to
boiler) to allow you to locate it either in the return or
supp ly piping, as desired.See page3 for a typicalinstal-
lation.Pipe
the expansion tank to the suctionside of the
circula to r wheneverpossible. Install an air separator in
the supp lypiping. Connec t theexpansion tank to the air
separator only if the separator is on the suc ti on side of
the circulator. Always install the system fill connection
at the same point as the expansion tank connection to
the syst em. Figure s 9 and 10 show typical near-boiler
piping connections.
System water piping
See Figure 9 ( diaphragm-type or bladder-type expan-
sion tank ) or Figure 10 ( dosed-type expansion tank ),
and Table 3 below, for near-boiler and single-zone
systems designed for
return water at least 130°F.
See pages 18-19 to complete multiple-zone pip ing or
pages 20 -25 to comple te piping for radiant heating
systems or converted gravity systems (large- volume
systems originally designed for circulation by natural
convection rather t han a pump). Sec pa~;e 25 fur boiler>
used with refrigeration systems.
Table 3 Water pipe size (based on 20°F rise)
Boiler model To From
sy ste m sy ste m
CGa -25
:Y.."
%"
CGa-3, 4, 5 1" 1
..
CGa-6, 7 1%'' 1%"'
CGa-8 11h'' 1 V2"
Note: The bo iler supp ly and return connections, the re tuml
dra in tee and the supp l y/gauge tee supplied with
th e bo iler are 1 14'' NPT . One of t he c ir c ul ato r fla nge s
supplied with
th e boi l er is 114• . The othe rcir cula t or
fla ng e is t he si ze of th e r ecom mended sys te m pip in g
shown aboVe.
lA WARNING ! Chillers
or air handling unit s:
Install boiler such that-
Chilled medium , if used, is piped in parallel with
heating boiler. Use appropriate valves to prevent
chill
ed medium fromenteringboiler.Consult AHRI
Installation
and Piping Guides.
If boiler is connec ted to heating coils located in
air handling units where they can be exposed to
refrigerated air , use flow control valves or other
automatic means to prevent gravity circulati on
during cooling cycle. Circulation of cold water
through the bo ilercouldresult in damage to theheat
exchanger, causingpossiblesevere personal
in jury,
death or substantial property damage.
PartNumber550-142-779/0712

CGa Series 2 Gas-Fired Water Boiler - Boiler Manual
3b
Water piping -single-zone system
lA CAUTlON I Undersizedexpansiontanks causesystem water to belost from re
li ef valve and makeupwat er
to be added th ro ugh fill valve. Eventual section failure can result.
Diaphragm-type or bladder-
type expansion tank (Figure 9)
I. Ensure expansion tanksize will handle boiler and
system water volume and temperature. Tank must
be located in boiler returnpipmg as dose to bo il er
as possible, before inletside of circulator.See ta nk
manufacturer 's instructions for details.
2. Install an
automatic air vent as shown.
Closed-type expansion tank
(Figure 10)
I. Ensure expansion tanksi ze will handle boiler and
system water volume and te mpera tur e. See ta nk
manufacturer's instructions for details.
2. Connect tank to Ih" NPT tapping located behind
supply outlet, usi
ng W' NPT piping. Pitch any
horizontalpiping up towardsta nk I inch per 5 feet
of pipin g.
I AWARNING I
Use Figure 9 or Figure 10 only for single-zone systems designed for return water at least
130•F. For systems wi th low return water temperature possible, su ch as converted gravity
systems
and radiant h ea ting systems, refer to the special piping suggestions of pages 20-25.
Failure topreve nt lowreturn wa t er temperatureto theboilercouldcausecorrosion of the boiler
sections
or burners,resulting in severe personal injury,death or substantial propertydamage.
Figure 9 Diaphragm- or bladder-type expan-
sion tank - Single-zone system
us ing
diaphragm-type
or bladder-type expan-
sion tank.
See Table 3 for piping si zes .
Cold
F rom water
system fi ll
lsol ati/
va lve
To DI APHRAGM
expansion tank
and fittings
Relief
va lve
Circul
ator
To system
Circulator*
91,.__,."" ___ Automatic
air
vent
*Alt erna te
location
Figure
10 Closed-type expansion tank - Singl e-
zone system usi ng closed-type expa n-
sion tank.
See Table 3 for piping sizes.
I so lation
va l ve
Relief
va l ve
Circu lator
*Alt ernate
..,., location
I so l ation
va l ve
To system
Part Number 550 -142-779/0712 17

COa Series 2 Gas-Fired Water Boiler - Boiler Manual
3c
18
Water piping - multiple zones
Piping multiple zones
Follow instructions on pages 16 and 17 to install near-
boiler or single- zone piping. (A lso refer to Piping
tor radiant heating sys tem s or converted gravity
sys
tem s, below, if applicable.)
See Figure 11 or Figure 12, page 19, to complete in-
stallation.
Zoning with circulators (Figure 11)
(return temp over 130 "F)
I. Size each circulator to individual circuit require-
ments.
2.
Do not install circulator on boiler (except for
primary/secondarypiping).
3. Install isolation (balancing) valves to adjust flow to
distribute heat toall zones.
4. Install
and wire a separa te relay for each zone
circulator.
Zoning with zone valves (Figure 12)
(return temp over 130 •F)
I. Install isolation (balancing) valves to adjustflowto
distribute heat toall zones.
2. Provide aseparate 24-volt transformer to powerthe
zone valves.Size thetransformer to handlethe total
rated load of all connectedzonevalves.
I AcAunoN I DO NOT
connect directly fr o m
3-wire
zone valves to the T- T termi -
nals on the boiler . \¥hen using3-wire
zone valves, install
an isolation relay.
O:mnectthe zone va l ve endswitchwires
to the isolation relay coil. Connect the
isolation relaycontactacross theboiler
T-T terminals. Failure to comply can
result
in damage to boilercomponents
or causeunreliable operation, resulting
in severe propertydamage.
Piping for radiant heating
systems or converted gravity
systems
Converted gravity (or steam) systems
\¥henever possible, use the primary/secondary piping
shown
in Figures 13 or 14 on page21.Thispipingde-
sign allows changingboilerflow rate wi t hout af fecting
primarycircuit
fl ow rate.
If Figures 13 or 14 cannot be used,usetheboiler-bypass
pipingshownin Figure
15 or Figure 16 on page23. You
can also use the pifing sh own in Figure 17 on page25
(syst
em -bypass), i t he reduced fl ow rate in theheating
system
wi ll no t causeheat distribution problems.
I AWARNINGI
Failure to prevent low return water
temperature to the boiler could cause
corrosion
of theboilersections or burn-
ers, resulting in severe personal injury,
death
or substant ial propertydamage.
Radiant heating systems
Preferabl y, use primary/secondary piping, as shown
in Figures 13 or 14 on page 21. Alternatively, use the
method
of either Figure 15 or Figure 16 on page 23.
Do
not use the piping of Figure 17 (system-bypass),
because this met
hod does not control radiant system
supplytemperature.
If radiant system tubing has no oxygen barrier,a heat
exchanger must beused.
I AWARNING I
Ra diant heatingsystempipingshouldincludea means of regulating theboil er returnwat er
temperature and thesystemsupplytemperature(suchas provided byan injection pump in g
co
nt rol). Bo iler re tu rn wat er te mp era tu re wi ll be ad equately contro ll ed using the methods
shown in this
ma nualprovided the system supplytemperature is relatively constant.
DO NOT apply themethods in this man ual if the system is equippedw it h an outdoor reset
control. Instead, provide controls and piping which can regulate the boiler return wat er
temperature at no less t han 130"F regardless of system supply temperature. Con tact yo ur
Wei i-McLain representative for suggested piping and control met ho d s. Failure to prevent
cold retu
rn water temperaturetothe boiler c ould causecorrosion damage tothesecti ons or
burners,resulting in possiblesevere personal injury, death or substantialpropertydamage.
PartNumber 550 -1 42 -779/0712

CGa Series 2 Gas-Fired Water Boiler - Boiler Manual
3c Water piping -multiple zones <continued)
Figure 11 Zoning with cir cu l ators - return wate r
130 °F or higher.
++ ----------------~---~ e~N - e:z --1----------------- ++
' ______________ .. '
~ ZONE 1 ~
~ 1 ~
1 r .. 1
I L r•
I ~
~ ( )'
Lr l 2 1 ' T
~ ~ ~
10
C<Jid
water
fi l
15:1
iii
'"""
Figure 12 Zoni ng wi th zone val ves -return water
1 30 °F or higher.
r------------- ..
' 0 '
_,:'-------<--------, Z NE 2 r---------o----- +~ .
I --------------J I
I
!
I!
ZONE 1
6 6
13
C<Jid
wate .r
fill
il l
.,,,.
1 Boiler isola t ion (balancing)
valves
2 Flow/checkvalve
10 Aut omatic airvent (w ith diaphragm-typeexpansion t ank), or connect
to tank fitting (closed- type e:q>ansion tank). DO NOT use an automat ic
air vent
when usingclose d- type expansion tan k. It would allow air to
leave the system,causingwaterlogging of the expansion tank.
11 Fill valve
3
Sys t em or zone circulator
5
Zone valve
6
Drain valve
9 Reliefvalve
lA WARNING !
12 Diaphragm -type or bladder-type expansion tank, if used (For dosed -
type e>:pansion tank, pipefrom top of air separator to tank fitting as in
Figure 10 ,page 17.)
13 Airseparator and automatic vent, ifused ( Note that the fill valve must
always be connected to the exyansi on tank, regarclless of location of
expansion t ank circulat or or a1r separator.
Forsystems with possiblelow
return -watertemperature (s uch as con vertedgravitysystems,
racliant heatingsystems
and heat pu mp systems),refer to thespecial piping suggestions of
Figures 13 - 17 ,asapplies. Fa il ure to preventsustainedl ow return water temperature to
the boiler could causecorrosion of the boil er sections,resulting in severe personal injur y,
death or substantial property damage.
Part Number 550 -142-779/0712 19

COa Series 2 Gas-Fired Water Boiler - Boiler Manual
3d
20
Water piping- low temperature systems
Primary/secondary (preferred)
Bypass piping method
Primary /seco ndary bypass piping is preferredbecause
the flow rate
and te mperature drop in the heating
circuit(s)
is determined only by the heating circuit
circulator(s). So adju
stment of the bypass valves in
the boilercircuit wiU not cause a change in the heating
circuit ratea
nd temperature distribution.
Figures 13 and 14 , page21, show suggested bypass
arrangementsusing
primary/secondary bypasspiping
(preferred)forlowtemperaturesystemssuch as radiant
heating systems or converted gravity systems . For
alternatives,seepages22 through 25.
Thebypass valves (items
7a and 7b ) providemixing of
hot boiler outlet water withcooler system re turn water
-set to assure a minimum return water temperature
(atleast 130°F) totheboiler.Set thevalves as explained
below.
Temperature gauges
Gauge 4a is suggested, but optional on anysystem.
Gauge
4b is optional on converted gravitysystems, but
required on radiant heating systems -to display the
water tempera
tur ebeingsuppl ie d totheradiant tub in g.
Gauge8 is required on all systemsto assure the return
water temperature
is accurately set for a minimum of
I 30°F. If thisgauge is no t available however, adjustthe
valves
su ch thattheboiler -m oun ted temperature/pres-
sure gauge reads
at least Iso•F when thesystem retu rn
water is cold(approximately60°F water temperature).
Valve adjustment
(Figures 13 and 14 only)
I. Set the valves wh ile thesystem is cool,settingfor the
coldest expected water temperature (usuaUy 60°F
sin ce thesystem will often dr op to room tempera-
ture berweencycles).
2. Startwith valve 7a fully closed an d 7b fully open.
3. GraduaUyopenvalve 7a while closingvalve 7b until
thetemperatureatgauge8 reads I30°Fwhengauge
4a reads 60°F.
4. Note thatvalve 7a regulates the amount of hot wa-
ter from theboiler supplywhich mixes with return
water.
Valve 7b regulatesthe amount of systemwater
flowing th ro ugh the bo il er secondaryloop.
IAWARNINGI
Fai lure to prevent low return water temperature to the boiler could cause corrosion
of theboilersect ion s or burners, resulting in severe personal injury, death or substantial
propertydamage.
Radiant heating system piping should include a means
of regulating the boller return
water temperature and the system supply temperature (suchas provided by an InJec-
tion pumping control).
Boiler return water temperaturewill
be adequatelycontro ll ed using themethods shown
in this manual providedthe
system supply temperature is relatively constant.
DO NOT applythemethods of thismanualifthesystemisequippedwithan outdoor reset
control.Instead,provide controls and pipingwhich canregulate the bollerreturn water
temperature at no less than 130•Fregardless of systemsupplytempera tur e.Contact yo ur
Wei l- McLain representat ive for suggestedpiping and control methods.
Fai lure to prevent cold return water temperature to the boil er could cause corrosion
damage to the sections
or burners, resulting in possible severe personal injury, death or
substantialpropertydamage.
PartNumber 550 -1 42 -779/0712