Weil-McLain Ultra Electric Water Heater Installation and operation manual

This manual must only be used by a qualified heating installer/service technician. Read all instructions, including this
manual and all other information shipped with the boiler, before installing. Perform steps in the order given. Failure to
comply could result in severe personal injury, death or substantial property damage.
s)NSTALLATION
s3TARTUP
s-AINTENANCE
s0ARTS
Boiler Manual
Gas-fired water boilers
Featuring
Flexibility
Part number 550-100-086/0809
®

Part number 550-100-086/0809
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
2
The COMMERCIAL gas-fired water boiler, Featuring Flexibility
 #ASTALUMINUMSECTIONALHEATEXCHANGER
 (EATEXCHANGERCLEANOUTPLATE
 "LOWER
Air enters the boiler enclosure through the air intake adapter (18), flows
through the enclosure, enters the air inlet silencer (5), then enters the
venturi (6). The blower pulls air and gas through the venturi and pushes
the mixture into the burner. The advanced blower design and air inlet
silencer yield very quiet operation.
A"LOWERMOTOR
 !UTOMATICGASVALVE
The automatic gas valve incorporates two solenoid-operated valve seats.
The valve senses the vacuum in the venturi (item 6) caused by flowing
air. Gas flows in proportion to air flow, so fuel/air ratio remains constant
as blower speed/air flow changes.
 !IRINLETSILENCER
The horn-shaped air inlet silencer significantly reduces fan noise,providing
exceptionally quiet operation.
 6ENTURI
When air flows through the venturi, it creates a vacuum that is sensed by
the gas valve to regulate gas flow (see item 4).
 5#ONTROLMODULE
The U-Control Module responds to signals from the room thermostats,
DHW aquastats (when used), boiler sensors (boiler return, boiler sup-
ply, heat exchanger, system return, system supply, flue temperature, and
outdoor temperature, if used). The control module automatically adjusts
blower speed (and gas flow rate) to match boiler output to space heating
and/or DHW heating demand.
 %XPANSIONMODULE
The expansion module operates the gas valve, monitors gas pressure
switches and provides a dry contact for the boiler circulator (suitable for
up to 10 amps).
 4EMPERATUREANDPRESSUREGAUGE
 %LECTRONICDISPLAYBUTTONS
The electronic display is used to configure boiler settings and monitor
boiler operation. The buttons allow changing display mode, entering set-
ting values, and resetting after lockout.
 &LUEPIPEADAPTERINCH06#SIZEFEMALE
 0REMIXGASBURNERNOTSHOWN
Made with high-grade stainless steel and fiber mesh construction, the
burner uses pre-mixed air and gas. The burner and control provide
modulating firing.
 7ATEROUTLETPIPESYSTEMSUPPLY
 7ATERRETURNPIPESYSTEMRETURN
 'ASCONNECTIONPIPE
 -ANUALGASSHUTOFFVALVE
 3WINGAWAYCONTROLPANELASSEMBLY
The Ultra control panel is mounted to a hinged subpanel, allowing the
panel to be swung forward and down for easy access to the electrical
connections.
 !IRINTAKEADAPTERINCH06#SIZEFEMALE
 %LECTRICALENTRANCESKNOCKOUTS
Knockouts are provided in the jacket top panel, allowing con-
duit entry directly behind the control panel or near the wall.
 !IRPRESSURESWITCH
 ,OWWATERCUTOFF
 &LUEADAPTERCONDENSATECOLLECTORDRAINTUBE
 (EATEXCHANGERmUEGASCONDENSATEDRAIN
 &LUEGASCONDENSATEDRAINlELDCONNECTION
 &RONTDOOR
The front door is sealed to the boiler assembly around its
entire perimeter.
 *ACKETDOORLATCHES
 )GNITIONELECTRODEmAMESENSOR
The burner flame is ignited by applying a high voltage to the
ignition electrode. This causes a spark (from electrode to
ground). After ignition, the electrode measures flame signal.
 &LAMEINSPECTIONWINDOW
The quartz glass window provides a view of the burner surface
and flame.
 ,INEVOLTAGETERMINALSTRIPVOLTPOWER
 /./&&SWITCH
 (IGHGASPRESSURESWITCH
 ,OWGASPRESSURESWITCH
 4RANSFORMER
 "LOWERRELAY
 5#ONTROLTEMPERATURESENSORWELL
 04GAUGEPRESSURESENSORTAPPING
 04GAUGETEMPERATURESENSORWELL
 7IREHARNESSCONNECTORLINEVOLTAGE
 7IREHARNESSCONNECTORLOWVOLTAGE
 "LOWERPLATE
A blower plate is used on Ultra-550 for both natural gas and
propane applications.The Ultra-750 propane requires a blower
plate, but does not use a blower plate on natural gas.
 0ROPANEGASORIlCELOCATION
Boilers are shipped with no orifice installed (not required for
natural gas). The propane orifice must be installed to operate
on propane.
 "OILEROUTLETTEMPERATURESENSORWELL
 40GAUGETEMPERATURESENSORWELL
 4APPINGPLUGGEDNOTUSED
 40GAUGEPRESSURESENSORTAPPING
Located in bottom of supply manifold.
 &LUEINSPECTIONPLUG

Part number 550-100-086/0809 3
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
The COMMERCIAL gas-fired water boiler, Featuring Flexibility

Part number 550-100-086/0809
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
4
#ONTENTS                  4
(AZARDDElNITIONS                4
0LEASEREADBEFOREPROCEEDING           5
0REPAREBOILERLOCATION              6
0REPAREBOILER                9
)NSTALLWATERPIPING               13
-ULTIPLEBOILERWATERPIPING           21
6ENTINGCOMBUSTIONAIRGENERAL         26
6ENTINGCOMBUSTIONAIROPTIONS         27
!PPLIANCESREMAININGONANEXISTINGVENTSYSTEM   28
6ENTINGAIRPIPING-ASSACHUSETTSINSTALLATIONS  29
$)2%#4%8(!534"OILERROOMAIROPENINGS   30
$)2%#4%8(!5343IDEWALL          32
$)2%#4%8(!5346ERTICAL            35
$)2%#46%.4"OILERROOMAIROPENINGS     37
$)2%#46%.43IDEWALL            39
$)2%#46%.46ERTICAL             43
)NSTALLVENTAIRPIPINGFROMTERMINATIONTOBOILER   46
)NSTALLCONDENSATECOMPONENTS           47
'ASPIPING                  49
&IELDWIRINGSEE&IGURE&IGURE      51
5#ONTROLOPERATIONANDSETUP          58
3TARTUPlLLTHESYSTEM             70
3TARTUPlNALCHECKS             72
#HECKOUTSTARTUPVERIlCATION          76
!NNUALSTARTUPANDGENERALMAINTENANCE       77
!NNUALSTARTUP                  78
4ROUBLESHOOTING                83
-AINTENANCE                  93
2EPLACEMENTPARTS                96
$IMENSIONS                  108
2ATINGS5LTRABOILERS             109
2ATINGSMULTIPLE5LTRABOILERS          110
)NSTALLATIONAND3ERVICE#ERTIlCATE        112
Contents
The following defined terms are used throughout this manual to bring attention to the presence of hazards of various risk
levels or to important information concerning the life of the product.
Indicates presence of hazards that will cause severe personal injury, death or
substantial property damage.
Indicates presence of hazards that can cause severe personal injury, death or
substantial property damage.
Indicates presence of hazards that will or can cause minor personal injury or
property damage.
Indicates special instructions on installation, operation or maintenance that are
important but not related to personal injury or property damage.
Hazard definitions

Part number 550-100-086/0809 5
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
Failure to adhere to the guidelines on this page can result
in severe personal injury, death or substantial property
damage.
When servicing boiler —
To avoid electric shock, disconnect all electrical supplies to thes
boiler before performing maintenance.
To avoid severe burns, allow boiler to cool before performings
maintenance.
This boiler contains ceramic fiber and fiberglass materials. Refers
to the WARNING and instructions on page 78.
Boiler operation —
Do not block flow of combustion or ventilation air to boiler.s
Should overheating occur or gas supply fail to shut off, do not turns
off or disconnect electrical supply to circulator. Instead, shut off
the gas supply at a location external to the appliance.
Do not use this boiler if any part has been under water. Immedi-s
ately call a qualified service technician to inspect the boiler and to
replace any part of the control system and any gas control that has
been under water.
Boiler water —
The Ultra heat exchanger is made of aluminum, and requires thats
system pH always be between 7.0 and 8.5 and water chemistry be
checked. Chemical treatment may be necessary. See page 70 for
details.
Thoroughly flush the system (without boiler connected) to removes
sediment. The high-efficiency heat exchanger can be damaged by
build-up or corrosion due to sediment.
Do not use petroleum-based cleaning or sealing compounds ins
boiler system. Gaskets and seals in the system may be damaged.
This can result in substantial property damage.
Continual fresh make-up water will reduce boiler life. Minerals
buildup in heat exchanger reduces heat transfer, overheats the
aluminum heat exchanger, and causes failure. Addition of oxygen
carried in by make-up water can cause internal corrosion. Leaks
in boiler or piping must be repaired at once to prevent make-up
water. Use this boiler ONLY in a closed-loop system.
Do not add cold water to hot boiler. Thermal shock can cause heats
exchanger to crack.
Freeze protection fluids —
NEVER use automotive or standard glycol antifreeze, even glycol made
for hydronic systems. Use only freeze-protection fluids recommended
in this manual (see page 70). Follow all guidelines given. Thoroughly
clean and flush any replacement boiler system that has used glycol
before installing the new Ultra boiler.
Please read before proceeding
)NSTALLER— Read all instructions,
including this manual and all other
information shipped with the boiler,
before installing. Perform steps in the
order given.
5SER— This manual is for use only
by a qualified heating installer/service
technician. Refer to User’s Informa-
tion Manual for your reference.
5SER — Have this boiler serviced/
inspected by a qualified service tech-
nician, at least annually.
Failure to comply with the above
could result in severe personal injury,
death or substantial property dam-
age.
Write in the CP number in the
space provided on the Installation
certificate on page 112 if not already
shown.
When calling or writing about the
boiler— Please have the boiler model
number from the boiler rating label
and the CP number from the boiler
jacket.
Consider piping and installation
when determining boiler location.
Any claims for damage or shortage in
shipment must be filed immediately
against the transportation company
by the consignee.
Commonwealth of Massachusetts
When the boiler is installed within the Common-
wealth of Massachusetts:
This product must be installed by a licenseds
plumber or gas fitter.
If antifreeze is used, a reduced pressure back-s
flow preventer device shall be used.
Sidewall vent air installations — see instructions
on page 29.

Part number 550-100-086/0809
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
6
Clearances&IGURE
Prepare boiler location
Installations must comply with:
Local, state, provincial, and national codes, laws, regulations ands
ordinances.
National Fuel Gas Code, ANSI Z223.1 – latest edition.s
Standard for Controls and Safety Devices for Automatically Fireds
Boilers, ANSI/ASME CSD-1, when required.
National Electrical Code.s
For Canada only: B149.1 or B149.2 Installation Code, CSA C22.1s
Canadian Electrical Code Part 1 and any local codes.
The Ultra boiler gas manifold and controls met safe
lighting and other performance criteria when boiler
underwent tests specified in ANSI Z21.13 — latest edi-
tion.
Before locating the boiler, check:
Check for nearby connection to:1.
System water pipings
Venting connectionss
Gas supply pipings
Electrical powers
Location of drain for condensates
Check area around boiler. Remove any combustible materials,2.
gasoline and other flammable liquids.
Failure to keep boiler area clear and free of combustible
materials, gasoline and other flammable liquids and
vapors can result in severe personal injury, death or
substantial property damage.
The Ultra boiler must be installed so that gas control system com-3.
ponents are protected from dripping or spraying water or rain
during operation or service.
If new boiler will replace existing boiler, check for and correct4.
system problems, such as:
System leaks causing oxygen corrosion or heat exchanger crackss
from hard water deposits.
Incorrectly-sized expansion tank.s
Lack of freeze protection in boiler water causing system ands
boiler to freeze and leak.
Provide clearances:
Clearances from combustible materials
Hot water pipes — at least ½” from combustible materials.1.
Vent pipe — at least2. 6QE” from combustible materials.
See3. Figure 1 for other clearance minimums.
Clearances for service access
See1. Figure 1 for recommended service clearances. If you do not
provide minimum clearances shown, it might not be possible to
service the boiler without removing it from the space.
#LEARANCE
FROM
-INIMUM
CLEARANCETO
COMBUSTIBLE
SURFACES
INCHES
2ECOMMENDED
SERVICEACCESS
CLEARANCES
INCHES
,%&4 00
2)'(4 012
4/0 20 20
"/44/-
&LOOR 00
&2/.4 1⁄224
"!#+ 00
6%.40)0% 3⁄16 ** NA
(/47!4%2
0)0%3 1⁄2NA
Openings in combustible floors, walls, ceilings or
roofs must be 3⁄8” larger in diameter than the vent pipe
and must be lined with steel thimbles and designed for
fire stopping as required by applicable codes.
Provide air openings for combustion air and/
or ventilation of the room as specified in this
manual and as required by applicable codes.

Part number 550-100-086/0809 7
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
Prepare boiler location (continued)
Placing multiple boilers
Locate multiple boilers in boiler room to provide1.
the clearances shown in:
a. Figure 2 (side-to-side), or
b. Figure 3 (back-to-back).
Provide indicated clearances around boilers for ac-2.
cess and servicing. If recommended dimensions are
not possible, provide at least the minimum clear-
ances given on page 6. Also follow local codes.
Construct boiler foundation if boiler room floor3.
is uneven or if there is a danger of flooding. Size
foundation to allow for clearance and spacing di-
mensions shown in either Figure 2 or Figure 3.
Chalkline boiler locations on foundation or boiler4.
room floor.
Uncrate, assemble and mount boilers according to5.
instructions in this manual.
Provide clearance for installation of venting, air6.
piping, gas piping, condensate piping and compo-
nents, expansion tank, boiler circulator and other
accessories.
Side-to-side mounting of multiple Ultra boilers&IGURE
Back-to-back installation of multiple Ultra boilers&IGURE

Part number 550-100-086/0809
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
8
Prepare boiler location (continued)
Flooring and foundation
Flooring
The Ultra boiler is approved for installation on1.
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
The boiler mounting surface must be level and1.
suitable for the load.
Provide a solid foundation pad, at least 2 inches2.
above the floor, if any of the following is true:
floor can become flooded.s
the floor is dirt, sand, gravel or other looses
material.
the boiler mounting area is severely unevens
or sloped.
The minimum foundation size is:3.
48 inches wide x 20 inches deep.s
Foundation may be of wood, brick or concrete4.
(minimum 2 inches thick) construction.
If flooding is possible, elevate boiler sufficiently to5.
prevent water from reaching boiler.
Garage installation
Precautions
Take the following special precautions when install-1.
ing the boiler in a garage. If the boiler is located in
a garage:
Mount the boiler at a height above the floor ass
specified in the National Fuel Gas Code, ANSI
Z223.1 for U. S. installations, or CSA B149.1
and B149.2 for Canadian installations.
Locate or protect the boiler so it cannot bes
damaged by a moving vehicle.
Ensure that the installation complies with alls
applicable codes.
Provide air openings to room
Air openings — General
Follow the National Fuel Gas Code (U. S.) or CSA B149.1 and B149.2
(Canada) and all applicable codes to size/verify size of the combustion/
ventilation air openings into the space. See the venting instructions section
of this manual for required air openings and sizing for either direct vent
or direct exhaust installation.
Air openings — Ultra boiler alone in boiler room
DIRECT VENT —1. For direct vent installations (air piped to boiler),
no air ventilation openings into boiler room are needed if clearances
around the Ultra boiler are at least equal to the SERVICE clearances
shown in Figure 1, page 6. For spaces that DO NOT supply the mini-
mum service access clearances, see the direct vent venting instructions
in this manual for required openings.
DIRECT EXHAUST —2. For direct exhaust installations (combustion
air from inside), provide air openings as specified in the direct exhaust
venting section of this manual.
Air openings — Ultra boiler in same room with other
gas or oil-fired appliances
DIRECT VENT —1. For direct vent installations (combustion air piped
to boiler), size openings only on the basis of the other appliances in
the space. No additional air opening free area is needed for the Ultra
boiler because it takes its combustion air from outside.
For direct vent installations, when the Ultra boiler is located
in the same room as other appliances, provide combustion
air openings correctly sized for all appliances in the room
except the Ultra boiler.
Reinstall the boiler jacket front door after servicing. The boiler
front door must be securely fastened to the boiler to prevent
the boiler from drawing air from inside the boiler room.This
is particularly important if the boiler is located in the same
room as other appliances.
Failure to comply with the above warnings could result in
severe personal injury, death or substantial property dam-
age.
DIRECT EXHAUST —2. For direct exhaust installations, combustion air
openings into the room must be sized to handle the Ultra boiler and
all other appliances. See the direct exhaust venting instructions in this
manual for required openings.
For direct exhaust installations, when the Ultra boiler is lo-
cated in the same room as other appliances, provide combus-
tion air openings correctly sized for all appliances, including
the Ultra boiler.
Failure to comply with the above warnings could result in
severe personal injury, death or substantial property dam-
age.

Part number 550-100-086/0809 9
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
Vent and air piping requirements (page 26)
The Ultra boiler requires a special vent system, designed for pres-1.
surized venting.
Ultra boilers are rated ANSI Z21.13 Category IV (pressurizeda.
vent, likely to condense in the vent).
Ultra commercial boilers can be eitherb. DIRECTEXHAUST (vent
to the outside, combustion air from inside) or DIRECTVENT
(vent and air piped outside).
See instructions beginning onc. page 26 for vent/air configura-
tion options and installation requirements.
Note “Prevention of combustion air contamination” on2. page 26
when considering vent/air terminations and boiler room conditions
when using inside air (direct exhaust installation).
Be sure to locate the boiler such that the vent and air piping can3.
be routed through the building and properly terminated. The
vent/air piping lengths, routing and termination method must
all comply with the methods and limits in instructions beginning
on page 26.
Remove boiler from crate
Cold weather handling — If boiler has been stored in a very
cold location (below 0°F) before installation, handle with care
until the plastic components come to room temperature.
Do not lift or handle the boiler by the water or gas
pipes.
Leave boiler on crate base until ready to place in final location.1.
Cut the retaining straps. Make sure the boiler is sitting securely.2.
Remove outer shipping carton from boiler.3.
Leave the plastic cover on the boiler vent outlet until ready to
attach vent piping. This will prevent debris from falling into
the vent adapter.
&LUECOVER
After removing the packaging, lift boiler from the skid and place4.
in position.
Do not drop the boiler. Damage to boiler components
can result.
)NSPECTTHEBOILERBASEFORCRACKSORPOSSIBLEDAM
AGEINHANDLING. The base must be in good condition
and sealed tightly for proper operation of the boiler.
Placing the boiler
Set the boiler in place and check level. Use shims if necessary to1.
level the boiler (and condensate pump, if used).
Prepare boiler
Prepare boiler for propane
(when required)
5LTRABOILERSMUSTBECONVERTED
FORPROPANEOPERATIONALLBOIL
ERSARESHIPPEDREADYFORNATURAL
GAS OPERATION AND MUST BE
lTTEDWITHAPROPANEORIlCETO
BEUSEDONPROPANE-ODEL
BOILERSALSOREQUIREINSTALLATION
OFAPROPANEBLOWERORIlCESUP
PLIEDINTHEPROPANECONVERSION
KIT
 (IGHALTITUDEINSTALLATIONS
No orifice change is required for high-
altitude installations. The U-control
automatically adjusts boiler operation
for altitude when set properly. Select
“9%3” in the U-Control setup for the
(IGH!LTITUDE option (see Figure 65,
page 63).
6ERIFYORIlCESIZE
See Figure 4, page 11. Verify when
installing the propane orifice that the
orifice size marking matches boiler
size.
Model 750 boilers also require instal-
lation of a blower orifice for propane
operation. The orifice is supplied in
the propane conversion kit.
#ONVERTINGEXISTINGNATURALGAS
lREDBOILERFORPROPANE
For a boiler already installed, you must
turn off gas supply, turn off power and
allow boiler to cool before proceed-
ing.
6ERIFY OPERATION AFTER CONVER
SION
You must completely test the boiler
after conversion to verify performance.
Start up the boiler following instruc-
tions in this manual.
&AILURETOCOMPLYWITHTHEABOVE
COULDRESULTINSEVEREPERSONALIN
JURYDEATHORSUBSTANTIALPROPERTY
DAMAGE

Part number 550-100-086/0809
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
10
Install propane orifice — Ultra-550 or -750
)FBOILERISALREADYINSTALLED — You must turn off electrical
supply to the boiler and close the external manual gas shut-
off valve to isolate the boiler during conversion. Allow the
boiler to cool if it has been operating. Following conversion
of an installed boiler, follow all instructions in this manual
to start up the boiler and verify operation of the boiler and
all system components.
Ultra-550 boilers are shipped with a blower plate that is used
for natural gas and propane. The blower plate must be left in
place for propane applications.
Locate propane orifice disc from conversion kit bag shipped with the1.
boiler.
Verify that the stamping on the orifice disk matches the model size2.
(see Figure 4, page 11).
Remove jacket front door by rotating the two rotary latches.3.
Lift the door away from boiler.4.
See5. Figure 4, page 11.
Disconnect the gas train adapter flange (see item 12) from the venturi6.
gas line flange (see item 7):
Use a 4 mm Allen wrench and 8 mm open-end or box wrench toa.
loosen the four screws and nuts (items 10 and 11).
Remove the gasket (item 9).b.
Inspect the gasket between the gas train adapter flange (see
item 12) and the venturi gas line flange (see item 7). The
gasket must be in good condition and must be installed.
Failure to comply could result in a gas leak, resulting in severe
personal injury, death or substantial property damage.
The gas train is connected with a flexible gas line. Pull the gas trainc.
forward and support it temporarily.
Insert the propane orifice into the counterbore in the ventured.
flange.
Reposition the gasket and gas train adapter against the venturi gase.
line flange.
Secure with the four screws and nuts.Do not over-tighten, but makef.
sure the joint is secure (torque to 1.5 N-m/13 in-lbs/1 ft-lb).
Ultra-750 propane only — Install the propane
blower plate and gaskets
See1. Figure 4, page 11.
Disconnect the two wire harnesses connected to the blower.2.
Ultra-750 natural gas boilers do not use a blower plate. The boiler is3.
shipped with a blower plate and gaskets that must be installed to oper-
ate the boiler on propane.
Obtain the two gaskets (item 3) and blower plate (item 4) shipped4.
with the boiler.
Check the blower plate to ensure it says “750 LP.”5.
Turn off all power sources to the boiler.6.
Prepare boiler (continued)
Disconnect the two wiring connectors on the7.
blower.
Disconnect the blower flange (see item 6) from the8.
mixing tube flange (see item 5) as shown.
Use a 13 mm nut driver or ratchet for the screws9.
and a 13 mm open-end wrench for the nuts.
Support the weight of the blower and gas train10.
temporarily.
Insert the top two bolts through the mixing tube11.
flange.
Slide on the two gaskets and blower plate, with one12.
gasket on each side as shown.
Position the blower.13.
Align all parts and start the nuts on the top two14.
bolts.
Insert the remaining two bolts and fasten with nuts.15.
Be careful not to tear the gasket.
Secure the flanges together with the bolts and16.
nuts, being careful not to over-tighten (torque to
15 N-m/132 in-lbs/11 ft-lbs).
Reconnect the two blower wiring harnesses.17.
Legend for Figure 4, page 11
(see Figure 93, page 104 for part numbers)
Hex bolts (4), M8 x 30 mm — requires 13 mm open-1.
end wrench, box wrench or ratchet.
Hex nuts (4), M8 keps — nylon lock nuts — requires2.
13 mm open-end wrench, box wrench or ratchet.
Blower plate gasket (one on each side of blower plate).3.
One gasket is used on Ultra-750 natural gas, because
this unit does not use a blower plate — blower plate is
only used for the Ultra-750 propane. Ultra-550 boilers
use a plate for natural gas and propane (same plate is
used for both fuels).
Blower plate — used on all Ultra-550, natural gas and4.
propane; used on Ultra-750 propane only (not on
Ultra-750 natural gas).
Mixing tube.5.
Blower motor and blower.6.
Venturi — with gas line flange and inlet air connec-7.
tion.
Propane orifice — shipped with boiler — verify the8.
model number stamped on the orifice.
Gasket — venturi gas flange to gas line adapter9.
flange.
Hex nuts (4), M5 keps — requires 8 mm open-end or10.
box wrench.
Hex bolts (4), M 5 x 20 mm — requires 4 mm Allen11.
wrench.
Gas line adapter flange.12.
Manual gas valve.13.
Automatic gas valve.14.

Part number 550-100-086/0809 11
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
Prepare boiler (continued)
&IGURE A BLOWERPLATE is used on all Ultra-550 boilers, for both natural gas and propane.
A BLOWERPLATE is used on Ultra-750 propane, but NOT on natural gas.
A PROPANEORIlCE MUST be installed on both the Ultra-550 and Ultra-750 to operate on propane.
See opposite page for legend
"LOWERPLATEMOUNTWITH)$STAMPINGLOCATEDASSHOWN
Verify model number & fuels .',0or ,0
Install plate with I. D. stamping toward front of boiler and facing blowers
0ROPANEORIlCE
Verify model number
,0or ,0
Heat
exchanger
BACK
SIDE
1
89
13
12
11
10
14
3 4
5
6
7
3 2

Part number 550-100-086/0809
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
12
Prepare boiler (continued)
$/./4INSTALLARELIEFVALVEWITHAPRESSUREHIGHER
THAN  03)'. This is the maximum allowable relief
valve setting for the Ultra boiler. The boiler is shipped
with a 30 PSIG relief valve. See Replacement parts in the
back of this manual for alternate pressure setting relief
valves.
Perform hydrostatic pressure test
Pressure test boiler before permanently attaching water or gas piping
or electrical supply.
Prepare boiler for test
See1. Figure 5 for reference in following steps. Use pipe dope spar-
ingly.
Remove 2” supply line tee, 2x¾” bushing and ¾” nipple from ac-2.
cessory bag.
Pipe 2” tee, bushing and ¾” nipple to boiler supply connection3.
as shown.
Temporarily plug the end of the 2” supply tee.4.
Attach a ¾” shut-off valve (by others) to the ¾” nipple.5.
Attach a 2-inch tee (by others) to the boiler return pipe.6.
Install a bushing and a ¾-inch boiler drain valve off of the tee as7.
shown. Temporarily plug the end of the tee. (All fittings by oth-
ers.)
Connect a hose to the boiler drain valve, with the other end con-8.
nected to a fresh water supply. Make sure the hose can also be used
to drain the boiler after test.
To avoid getting water on the boiler, you may want to pipe street el-9.
bows on top of shutoff valves and attach catch-buckets beneath.
If convenient, install any other piping compatible with10. Figure 5
that would still allow bleeding air from shutoff valves.
Fill and pressure test
Open the shutoff valves you installed on supply and return con-1.
nections.
Slowly open boiler drain valve and fresh water supply to fill boiler2.
with water. The boiler will fill quickly because of its low water
content.
When water reaches the shutoff valve on top, allow water to flow3.
long enough to ensure all air is out of the heat exchanger. Then
close the boiler drain valve.
Close shutoff valve on top.4.
Increase test pressure until the pressure/temperature gauge reaches5.
120 psig, but no higher. DO NOT exceed 120 psig.
Hold at test pressure for 10 minutes.6.
Do not leave boiler unattended. A cold water fill could
expand and cause excessive pressure, resulting in severe
personal injury, death or substantial property damage.
Make sure constant gauge pressure has been maintained through-7.
out test. Check for leaks. Repair if found.
Do not use petroleum-based cleaning or seal-
ing compounds in boiler system. Gaskets and
seals in the system may be damaged. This can
result in substantial property damage.
Drain and remove fittings
Disconnect fill water hose from water source.1.
Drain boiler through drain valve. Remove hose after2.
draining.
Remove pipe fittings unless they will remain for use in3.
the system piping.
Remove the ¾” shut-off valve from the ¾” relief valve4.
nipple.
See5. page 13 to install relief valve on the ¾” nipple.
Hydrostatic test piping connections&IGURE
,EAKSMUSTBEREPAIREDATONCE Failure
to do so can damage boiler, resulting in
substantial property damage.

Part number 550-100-086/0809 13
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
Install water piping
Use two wrenches when tightening water piping at boiler,
using one of the wrenches to prevent the boiler interior
piping from turning. Failure to support the boiler piping
connections to prevent them from turning could cause
damage to boiler components.
General piping information
Additional controls, when required
The U-Control module uses temperature sensors to
provide both high limit protection and modulating tem-
perature control, and is UL353 Limit Controls certified
to meet ASME CSD-1 and Section IV requirements. The
U-Control module also provides low water protection,
both with a low water cut-off inside the boiler jacket
and by sensing the temperature of the heat exchanger.
Some codes/jurisdictions may require additional external
controls.
Additional limit controls
Consult local requirements for other codes/standards to determine1.
if additional limit devices are needed.
-ULTITEMPERATURESYSTEMS — If the heating system
includes circuits that require lower temperature water
(radiant slab circuits, for example) as well as higher
temperature circuits, it is recommended to protect low-
temperature circuits with limit controls that are wired to
a U-Control external limit circuit (P13 terminals 1 and 2
for manual reset, or P13 terminals 3 and 4 for automatic
reset).
See instructions beginning on2. page 51 for wiring information.
Manual reset operation: If external limit controls are to causea.
MANUALRESET of the U-control module, connect series-wired
isolated contacts to P13 terminals 1 and 2 (see page 51 for wir-
ing information).
Automatic reset operation: If external limit controls are tob.
cause AUTOMATIC RESET of the U-control module, connect
series-wired isolated contacts to P13 terminals 3 and 4 (see
page 51 for wiring information).
Low water cutoff
A push-to-test low water cutoff is included with the boiler. The1.
low water cutoff is mounted on the boiler supply manifold, and is
available for test by removing the boiler jacket.
Operation of the low water cutoff is manual reset through the2.
U-control.
Backflow preventer
Use backflow check valve in cold water supply as re-1.
quired by local codes.
Install relief valve
Install relief valve on the ¾” nipple in the 2x¾” bush-1.
ing on the boiler supply piping tee (Figure 5, page 12).
The relief valve must be piped with no smaller than ¾”
pipe and fittings.
Connect discharge piping to safe disposal location, fol-2.
lowing guidelines in the 7!2.).' below.
4OAVOIDWATERDAMAGEORSCALDING
DUETORELIEFVALVEOPERATIONASPER
LOCALORSTATECODES:
Discharge line must be connected to re-
lief valve outlet and run to a safe place
of disposal. Terminate the discharge
line in a manner that will prevent
possibility of severe burns or property
damage should the valve discharge.
Discharge line must be as short as pos-
sible and be the same size as the valve
discharge connection throughout its
entire length.
Discharge line must pitch downward
from the valve and terminate at least
6” above the floor drain where any
discharge will be clearly visible.
The discharge line shall terminate
plain, not threaded, with a material
serviceable for temperatures of 375 °F
or greater.
Do not pipe the discharge to any place
where freezing could occur.
No shutoff valve shall be installed be-
tween the relief valve and boiler, or in
the discharge line. Do not plug or place
any obstruction in the discharge line.
Test the operation of the valve after
filling and pressurizing 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.
Failure to comply with the above guide-
lines could result in failure of the relief
valve to operate, resulting in the pos-
sibility of severe personal injury, death
or substantial property damage.

Part number 550-100-086/0809
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
14
Install water piping (continued)
System water piping methods
All piping methods shown in this manual use PRIMARY
SECONDARY CONNECTION TO THE BOILER LOOP. These
designs ensure proper flow through the Ultra boiler, for
the most efficient and reliable operation of the boiler and
the heating system. For other piping methods, consult
your local Weil-McLain representative or see separate
Ultra boiler piping guides.
Recommended pipe sizing
Connect minimum 2” pipe to the supply and return connections
Ultra-550 and Ultra-750 boilers.
Size the piping and the boiler circulator to provide the required tem-
perature rise through the boiler loop. See Figure 6 for the head loss
through the boiler and minimum/maximum flow rates.
$/./4 design the piping and components for a boiler
loop flow rate above or below the range given in Figure 6.
Insufficient flow will cause nuisance outages due to limit
operation. Excessive flow can damage to the boiler heat
exchanger from erosion.
Circulators
The boiler circulator must be supplied by others. Locate the boiler
circulator in the return piping, as shown in the appropriate piping
diagram in this manual.
$/./4 use the boiler circulator in any location other
than the ones shown in this manual. The boiler circula-
tor must be selected to ensure adequate flow through the
Ultra boiler.
Install the boiler circulator only on the boiler return pip-
ing. This ensures the pressure drop through the boiler
will not cause low pressure in the circulator intake.
Failure to comply could result in unreliable performance
and nuisance shutdowns from insufficient flow.
A Taco model 1400-50 (or 2400-50) or equivalent will work for most
boiler loop circulator applications.
Boiler head loss vs flow rate for Ultra-550&IGURE
& Ultra-750
5LTRA 5LTRA
GPM Temp.
Rise °F
Boiler head loss
Feet w.c. GPM Temp.
Rise °F
Boiler head loss
Feet w.c.
25 41.0 6.3 30 46.4 6.3
30 34.1 8.1 35 39.8 7.6
35   40 34.8 9.2
40 25.6 12.5 45  
45 22.8 15.1 50 27.8 13.0
50 20.5 18.1 55 25.3 15.3
55 18.6 21.3 60 23.2 17.9
DO NOT design for flow rates
above or below the range listed
above.
65 21.4 20.7
70 19.9 23.6
DO NOT design for flow rates
above or below the range listed
above.
* Suggested design flow rates (30°F temperature rise)

Part number 550-100-086/0809 15
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
Install water piping (continued)
Expansion tank and make-up water
Ensure expansion tank size will handle boiler and system water1.
volume and temperature. Allow 7 gallons per boiler for the boiler
and its piping.
Undersized expansion tanks cause system water to be
lost from relief valve and make-up water to be added
through fill valve. Eventual boiler failure can result due
to excessive make-up water addition.
Tank must be located as shown in this manual, or following rec-2.
ognized design methods. See tank manufacturer’s instructions
for details.
Connect the expansion tank to the air separator only if the separa-3.
tor is on the suction side of the circulator. Always install the system
fill connection at the same point as the expansion tank connection
to the system.
Most piping drawings in this manual show diaphragm expansion4.
tanks. See Figure 7 for piping from air separator to expansion tank
and make-up water line using a closed-type expansion tank.
Most chilled water systems are piped using a closed-type tank, as5.
shown in Figure 12, page 20.
Diaphragm (or bladder) expansion tank
(1. Figure 7) Always install an automatic air vent on top of the air
separator to remove residual air from the system.
When using diaphragm or bladder tanks only — when the
boiler is installed above the system main piping, install
an automatic air vent in the top of the outgoing boiler
piping to prevent air pocketing.
Closed-type expansion tank
See1. Figure 7,Alternate,for piping connections when using a closed-
type expansion tank.
Pitch any horizontal piping up towards tank 1 inch per 5 feet of2.
piping. Connect to tank with at least ¾” piping to allow room for
air to rise.
DO NOT install automatic air vents on closed-type
expansion tank systems. Air must remain in the system
and return to the tank to provide its air cushion. An au-
tomatic air vent would cause air to leave system, resulting
in water-logging the expansion tank.
Expansion tank piping&IGURE
Install a union on the boiler supply and return
connections as close as possible to the boiler to al-
low disconnection for service when required. See
Figure 7.

Part number 550-100-086/0809
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
16
Legend — Figure 8
1 Ultra boiler
2 Indirect water heater (DHW), if used
3 Boiler relief valve (see page 13 for piping details)
4 Relief valve discharge piping (see page 13 for details)
5 DHW circulator)
6 Isolation valves
7 System circulator (see information above for wiring)
8 Diaphragm (or bladder) type expansion tank (see page 15 for piping of
closed-type expansion tank, if used)
9 Air separator [with automatic air vent only on systems using diaphragm
(or bladder) type expansion tank]
10 Flow/check valves
11 Purge/drain valves
12 Boiler circulator
13 Zone valves, typical
20 Make-up water supply
21 Primary/secondary connection
24 Strap system supply and return sensors to lines as shown, at least 6 pipe
diameters (but no more than 3 feet) from boiler connection tees.
25 Systems using high-head pumps may require a bypass pressure regulator
to prevent damage to control valves.
26 Boiler drain valve, ¾” or larger
31 Install a union on the boiler supply and return connections as close as
possible to the boiler to allow disconnection for service when required.
Items supplied with boiler
Items supplied by others
NOTE 1: Use at least the following pipe sizes on all boiler
loop piping (connecting boiler to and from the
primary/secondary connection, item 21). Pipe sizing is based on a temperature
rise of 30°F, corresponding to the recommended maximum flow rate. Use only
primary/secondary piping as shown. Failure to follow these guidelines could
result in system problems.
s5LTRAnvORLARGER
s5LTRAvORLARGER
Install water piping (continued)
Zone valve zoning plus optional DHW&IGURE
piping
Zoning with zone valves
Connect boiler to system as shown in1. Figure 8 when zone valve
zoning. The primary/secondary piping shown ensures the boiler
loop will have sufficient flow. It also avoids applying the high head
of the boiler circulator to the zone valves.
When using a closed-type expansion tank, connect the expansion2.
tank and make-up water piping as shown in Figure 7, page 15.
Connect DHW (domestic hot water) piping to indirect storage3.
water heater as shown.
If DHW input is priority 1: With factory default, on a
call for DHW heating, the U-Control turns circulator 1
(DHW) and circulator 4 (boiler) ON and turns circula-
tors 2 and 3 OFF (so there is no space heating during
DHW operation). For the system shown in Figure 8, you
can set the U-Control to turn the boiler circulator off
during DHW heating. It is not needed. (The flow/check
valve shown on the boiler outlet piping prevents gravity
circulation in the boiler loop.)
Controlling the circulators4.
The U-Control can control up to four circulators (boiler cir-a.
culator and three others). Refer to Field wiring, beginning on
page 51, for instructions on wiring to circulators.
The factory default settings are: DHW circulator as Circula-b.
tor 1, system circulator as Circulator 2, and boiler circulator
as Circulator 4. See Field wiring instructions, beginning on
page 51, for details. ("YDEFAULTCIRCULATORIS/.FORALL
PRIORITIES

Part number 550-100-086/0809 17
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
Legend — Figure 9
1 Ultra boiler
2 Indirect water heater (DHW), if used
3 Boiler relief valve (see page 13 for piping details)
4 Relief valve discharge piping (see page 13 for details)
5 DHW circulator
6 Isolation valves
7 System circulator (see information above for wiring)
8 Diaphragm (or bladder) type expansion tank (see page 15 for piping of
closed-type expansion tank, if used)
9 Air separator [with automatic air vent only on systems using diaphragm
(or bladder) type expansion tank]
10 Flow/check valves
11 Purge/drain valves
12 Boiler circulator
13 Zone valves, typical
20 Make-up water supply
21 Primary/secondary connection (tees no more than 8 pipe diameters
apart)
23 DHW secondary connector piping — no more than 8 pipe diameters
apart
24 Strap system supply and return sensors to lines as shown, at least 6 pipe
diameters (but no more than 3 feet) from boiler connection tees.
25 Systems using high-head pumps may require a bypass pressure regulator
to prevent damage to control valves.
26 Boiler drain valve, ¾” or larger
31 Install a union on the boiler supply and return connections as close as
possible to the boiler to allow disconnection for service when required.
Items supplied with boiler
Items supplied by others
NOTE 1: Use at least the following pipe sizes on all boiler
loop piping (connecting boiler to and from the
primary/secondary connection, item 21). Pipe sizing is based on a temperature
rise of 30°F, corresponding to the recommended maximum flow rate. Use only
primary/secondary piping as shown. Failure to follow these guidelines could
result in system problems.
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s5LTRAvORLARGER
Install water piping (continued)
Zone valve zoning plus optional DHW&IGURE
piping
Zoning with zone valves — alternate
High-flow-rate/high-head-loss DHW circuits
For applications requiring DHW circuit flow rates higher than al-1.
lowable for the boiler, or for high pressure-drop coil-type DHW
tanks, connect the piping as in Figure 9. The DHW water only flows
through the secondary circuit connection piping. NOTE: Make
sure to size the connection piping (Figure 9, item 23) to handle
the total flow it must handle.
Connect boiler to system as shown in2. Figure 9 when zone valve
zoning. The primary/secondary piping shown ensures the boiler
loop will have sufficient flow. It also avoids applying the high head
of the boiler circulator to the zone valves.
When using a closed-type expansion tank, connect the expansion3.
tank and make-up water piping as shown in Figure 7, page 15.
Connect DHW (domestic hot water) piping to indirect storage4.
water heater as shown.
Controlling the system circulator and boiler circulator5.
If DHW input is priority 1: With factory default, on a call fora.
DHW heating, the U-Control turns circulator 1 (DHW) and
circulator 4 (boiler) ON and turns circulators 2 and 3 OFF (so
there is no space heating during DHW operation). Read the
instructions on U-Control operation and setup, beginning on
page 58 for further information.
For systems with low-temperature radiant heating, the
system circulator (item 7) MUST be OFF during DHW
heating to prevent possible overheating in the radiant
system.

Part number 550-100-086/0809
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
18
Legend — Figure 10
1 Ultra boiler
2 Indirect water heater (DHW), if used
3 Boiler relief valve (see page 13 for piping details)
4 Relief valve discharge piping (see page 13 for details)
5 DHW circulator
6 Isolation valves
7 System circulator (see information above for wiring)
8 Diaphragm (or bladder) type expansion tank (see page 15 for piping of
closed-type expansion tank, if used)
9 Air separator [with automatic air vent only on systems using diaphragm
(or bladder) type expansion tank]
10 Flow/check valves
11 Purge/drain valves
12 Boiler circulator
14 Zone circulators, typical
20 Make-up water supply
21 Primary/secondary connection (tees no more than 8 pipe diameters
apart)
24 Strap system supply and return sensors to lines as shown, at least 6 pipe
diameters (but no more than 3 feet) from boiler connection tees.
26 Boiler drain valve, ¾” or larger
31 Install a union on the boiler supply and return connections as close as
possible to the boiler to allow disconnection for service when required.
Items supplied with boiler
Items supplied by others
NOTE 1: Use at least the following pipe sizes on all boiler
loop piping (connecting boiler to and from the
primary/secondary connection, item 21). Pipe sizing is based on a temperature
rise of 30°F, corresponding to the recommended maximum flow rate. Use only
primary/secondary piping as shown. Failure to follow these guidelines could
result in system problems.
s5LTRAnvORLARGER
s5LTRAvORLARGER
Install water piping (continued)
Circulator zoning plus optional DHW&IGURE
piping
Zoning with circulators
Connect boiler to system as shown in1. Figure 10 when circulator
zoning. The boiler circulator cannot be used for a zone. It must
supply only the boiler loop.
Install a separate circulator for each zone.2.
When using a closed-type expansion tank, connect the expansion3.
tank and make-up water piping as shown in Figure 7, page 15.
Connect DHW (domestic hot water) piping to indirect storage4.
water heater as shown.
If DHW input is priority 1: With factory default, on a
call for DHW heating, the U-Control turns circulator 1
(DHW) and circulator 4 (boiler) ON and turns circula-
tors 2 and 3 OFF (so there is no space heating during
DHW operation). For the system shown in Figure 8, you
can set the U-Control to turn the boiler circulator off
during DHW heating. It is not needed. (The flow/check
valve shown on the boiler outlet piping prevents gravity
circulation in the boiler loop.)
Controlling the circulators5.
The U-Control can control up to four circulators (boiler cir-a.
culator and three others). Refer to Field wiring, beginning on
page 51, for instructions on wiring to circulators.
The factory default settings are: DHW circulator as Circula-b.
tor 1, system circulator as Circulator 2, and boiler circulator
as Circulator 4. See Field wiring instructions, beginning on
page 51, for details. ("YDEFAULTCIRCULATORIS/.FORALL
PRIORITIES)
The zone circulators inc. Figure 10 must be controlled by
circulator relays activated by the zone thermostats or zone
controller.

Part number 550-100-086/0809 19
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
Legend — Figure 11
1 Ultra boiler
2 Indirect water heater (DHW), if used
3 Boiler relief valve (see page 13 for piping details)
4 Relief valve discharge piping (see page 13 for details)
5 DHW circulator
6 Isolation valves
7 System circulator (see information above for wiring)
8 Diaphragm (or bladder) type expansion tank (see page 15 for
piping of closed-type expansion tank, if used)
9 Air separator [with automatic air vent only on systems using
diaphragm (or bladder) type expansion tank]
10 Flow/check valves
11 Purge/drain valves
12 Boiler circulator
13 Zone valves, when used (zoning may also be done using
manifold-mounted valve actuators)
20 Make-up water supply
21 Primary/secondary connection (tees no more than 8 pipe diameters apart)
22 Optional high limit temperature control, set to protect radiant tubing
24 Strap system supply and return sensors to lines as shown, at least 6 pipe diameters
(but no more than 3 feet) from boiler connection tees.
25 Systems using high-head pumps may require a bypass pressure regulator to prevent
damage to control valves.
26 Boiler drain valve, ¾” or larger
31 Install a union on the boiler supply and return connections as close as possible to
the boiler to allow disconnection for service when required.
Items supplied with boiler
Items supplied by others
NOTE 1: Use at least the following pipe sizes on all boiler loop piping
(connecting boiler to and from the primary/secondary
connection, item 21). Pipe sizing is based on a temperature rise of 30°F, corresponding
to the recommended maximum flow rate. Use only primary/secondary piping as shown.
Failure to follow these guidelines could result in system problems.
s5LTRAnvORLARGER
s5LTRAvORLARGER
Typical radiant heating system piping plus&IGURE
optional DHW
Radiant heating applications
The Ultra boiler is ideal for use in radiant heating. The Ultra1.
boiler’s unique heat exchanger design allows it to work well even
in condensing mode. So there is no need to regulate boiler return
water temperature in radiant heating applications.
Connect boiler to system as shown in2. Figure 11 for typical radiant
heating applications. The primary/secondary piping shown ensures
the boiler loop will have sufficient flow. Size the system piping and
circulator to provide the flow and pressure drop needed for the
radiant system.
Adding the recommended high limit control (3. Figure 11, item 22)
can help ensure supply water temperature will not exceed the
maximum allowable for the radiant system.Wire this limit control
in either the manual reset or automatic reset external limit circuit
of the U-Control.
When using a closed-type expansion tank, connect the expansion4.
tank and make-up water piping as shown in Figure 7, page 15.
Connect DHW (domestic hot water) piping to indirect storage5.
water heater as shown.
If DHW input is priority 1: With factory default, on a
call for DHW heating, the U-Control turns circulator 1
(DHW) and circulator 4 (boiler) ON and turns circula-
tors 2 and 3 OFF (so there is no space heating during
DHW operation). For the system shown in Figure 8, you
can set the U-Control to turn the boiler circulator off
during DHW heating. It is not needed. (The flow/check
valve shown on the boiler outlet piping prevents gravity
circulation in the boiler loop.)
Controlling the circulators6.
The U-Control can control up to four circulators (boiler cir-a.
culator and three others). Refer to Field wiring, beginning on
page 51, for instructions on wiring to circulators.
The factory default settings are: DHW circulator as Circula-b.
tor 1, system circulator as Circulator 2, and boiler circulator
as Circulator 4. See Field wiring instructions, beginning on
page 51, for details. ("YDEFAULTCIRCULATORIS/.FORALL
PRIORITIES)
Install water piping (continued)

Part number 550-100-086/0809
COMMERCIAL GAS-FIRED WATER BOILER — Boiler Manual
20
Legend — Figure 12
1 Ultra boiler
2 Indirect water heater (DHW), if used
3 Boiler relief valve (see page 13 for piping details)
4 Relief valve discharge piping (see page 13 for details)
5 DHW circulator
6 Isolation valves
7 System circulator (see information above for wiring)
8 Diaphragm (or bladder) type expansion tank (see page 15 for
piping of closed-type expansion tank, if used)
9 Air separator [with automatic air vent only on systems using
diaphragm (or bladder) type expansion tank]
10 Flow/check valves
11 Purge/drain valves
12 Boiler circulator
13 Zone valves, typical
15 Closed-type expansion tank
16 Water chiller
17 Check valve
18 Strainer
19 Balancing valve
20 Make-up water supply
21 Primary/secondary connection (tees no more than 8 pipe diameters apart)
24 Strap system supply and return sensors to lines as shown, at least 6 pipe diameters
(but no more than 3 feet) from boiler connection tees.
25 Systems using high-head pumps may require a bypass pressure regulator to prevent
damage to control valves.
26 Boiler drain valve, ¾” or larger
31 Install a union on the boiler supply and return connections as close as possible to the
boiler to allow disconnection for service when required.
Items supplied with boiler
Items supplied by others
NOTE 1: Use at least the following pipe sizes on all boiler loop piping
(connecting boiler to and from the primary/secondary con-
nection, item 21). Pipe sizing is based on a temperature rise of 30°F, corresponding to the
recommended maximum flow rate. Use only primary/secondary piping as shown. Failure
to follow these guidelines could result in system problems.
s5LTRAnvORLARGER
s5LTRAvORLARGER
Chilled water systems
Install boiler so that chilled medium is piped in parallel with the1.
heating boiler. Use appropriate valves to prevent chilled medium
from entering boiler. See Figure 12 for typical installation of bal-
ancing valve and check valve.
The space heating system may be zoned with circulators if a separate2.
circulator is supplied for the chilled water loop.
If antifreeze is used in the system, consider the effects of
antifreeze on circulator sizing and DHW performance.
Some local codes may require double-wall DHW heat
exchanger design.
Chilled medium, if used, is piped in parallel with heating
boiler as shown in Figure 12. Use appropriate valves to
prevent chilled medium from entering boiler.
If boiler is connected to heating coils located in air han-
dling units where they can be exposed to refrigerated
air, use flow control valves or other automatic means to
prevent gravity circulation during cooling cycle.
If DHW input is priority 1: With factory default, on a
call for DHW heating, the U-Control turns circulator 1
(DHW) and circulator 4 (boiler) ON and turns circula-
tors 2 and 3 OFF (so there is no space heating during
DHW operation). For the system shown in Figure 8, you
can set the U-Control to turn the boiler circulator off
during DHW heating. It is not needed. (The flow/check
valve shown on the boiler outlet piping prevents gravity
circulation in the boiler loop.)
Controlling the circulators3.
The U-Control can control up to four circulators (boiler cir-a.
culator and three others). Refer to Field wiring, beginning on
page 51, for instructions on wiring to circulators.
The factory default settings are: DHW circulator as Circula-b.
tor 1, system circulator as Circulator 2, and boiler circulator
as Circulator 4. See Field wiring instructions, beginning on
page 51, for details. ("YDEFAULTCIRCULATORIS/.FORALL
PRIORITIES)
Chilled water system plus optional DHW&IGURE
piping
Install water piping (continued)