Weil-McLain Ultra Electric Water Heater Installation and operating instructions

This addendum must only be used by a qualified heating installer/service technician. Read all instructions, including
the Ultra boiler 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.
Manual addendum — Venting
Gas-fired water boilers – Series 3
Featuring
Flexibility
Part number 550-100-103/1110
®
Contents
Venting & air — general. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Sidewall vent/air termination: 3” or 4” concentric . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Vertical vent/air termination: 3” or 4” concentric . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Concentric vent/air termination assembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
DIRECT VENT: Vertical vent / sidewall air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Install vent/air piping — boiler to termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
DIRECT EXHAUST venting — general . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
DIRECT EXHAUST — Boiler room air openings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
DIRECT EXHAUST — Sidewall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
DIRECT EXHAUST — Vertical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Supplementary instructions for:
Additional concentric vent/air termination kits, includings
IPEX System 636 in 3-inch and 4-inch sizes
(for information on IPEX, go to www.ipexinc.com)
Direct exhaust ventings (requires combustion air openings to boiler
room/building per this addendum).
Direct vent withs Roof exhaust and Sidewall air intake

Part number 550-100-103/1110
GAS-FIRED WATER BOILER — Manual addendum — Venting
A–2
Corrosive contaminants and sourcesFigure 1
Products to avoid
Spray cans containing chloro/fluorocarbons
Permanent wave solutions
Chlorinated waxes/cleaners
Chlorine-based swimming pool chemicals
Calcium chloride used for thawing
Sodium chloride used for water softening
Refrigerant leaks
Paint or varnish removers
Hydrochloric acid/muriatic acid
Cements and glues
Antistatic fabric softeners used in clothes dryers
Chlorine-type bleaches, detergents, and cleaning
solvents found in household laundry rooms
Adhesives used to fasten building products and other
similar products
Excessive dust and dirt
Areas likely to have contaminants
Dry cleaning/laundry areas and establishments
Swimming pools
Metal fabrication plants
Beauty shops
Refrigeration repair shops
Photo processing plants
Auto body shops
Plastic manufacturing plants
Furniture refinishing areas and establishments
New building construction
Remodeling areas
Garages with workshops
Venting & air — general
Do not install the Ultra boiler into a common vent with
any other appliance. This will cause flue gas spillage or ap-
pliance malfunction, resulting in possible severe personal
injury, death or substantial property damage.
Existing common vent systems may be too large for the
appliances remaining connected after the existing boiler
is removed.
Failure to follow all instructions can result in flue gas
spillage and carbon monoxide emissions, causing severe
personal injury or death.
When removing a boiler from an existing
common vent system
The Ultra boiler cannot be common vented with any other appli-
ance. When an existing boiler is replaced with an Ultra boiler, the Ultra
boiler CANNOT use the existing common vent. The Ultra boiler requires
its own vent and air piping, as specified in this manual. This may cause a
problem for the appliances that remain on the old common vent, because
the vent may be too large. The following test is intended to check for proper
operation of the appliances remaining on the old common vent system.
Vent system verification
At the time of removal of an existing boiler, the following steps shall be
followed with each appliance remaining connected to the common venting
system placed in operation, while the other appliances remaining connected
to the common venting system are not in operation. Seal any unused open-
ings in the common venting system.
Existing vent test procedure
(The following is intended to test whether the appliances
remaining on an existing vent system will operate
satisfactorily.)
Visually inspect the venting system for proper size and horizontal pitch1.
and determine there is no blockage or restriction, leakage, corrosion or
other deficiencies which could cause an unsafe condition.
Test vent system — Insofar as is practical, close all building doors and2.
windows and all doors between the space in which the appliances
remaining connected to the common venting system are located and
other spaces of the building. Turn on clothes dryers and any appliance
not connected to the common venting system. Turn on any exhaust
fans, such as range hoods and bathroom exhausts, so they will oper-
ate at maximum speed. Do not operate a summer exhaust fan. Close
fireplace dampers.
Place in operation the appliance being inspected.Follow the lighting in-3.
structions. Adjust thermostat so appliance will operate continuously.
Test for spillage at draft hood relief opening after 5 minutes of main4.
burner operation. Use the flame of a match or candle, or smoke from
a cigarette, cigar, or pipe.
After it has been determined that each appliance remaining connected5.
to the common venting system properly vents when tested as outlined
herein, return doors, windows, exhaust fans, fireplace dampers, and any
other gas-burning appliance to their previous conditions of use.
Any improper operation of common venting system should be corrected
so the installation conforms with the National Fuel Gas Code,ANSI Z223.1
— latest edition. Correct by re-sizing to approach the minimum size as
determined using the appropriate tables in Part 11 of that code. Canadian
installations must comply with B149.1 or B149.2 Installation Code.
REPLACES MANUAL PAGE 16
You must provide combustion air.
Direct vent — Install air inlet piping for the Ultra
boiler as described in the Boiler manual and this ad-
dendum. The air termination fitting must be installed
with the clearances and geometry relative to the vent
outlet depicted in this manual to ensure that flue
products do not enter the air intake.
Direct exhaust — Provide combustion air openings
to boiler room/building as specified in this adden-
dum and as required by all applicable codes.
Ensure that the combustion air will not contain
any of the contaminants in Figure 1. DO NOT
place combustion air supply opening or intake near
a swimming pool, for example. Avoid areas subject
to exhaust fumes from laundry facilities. These areas
will always contain contaminants.
Contaminated combustion air will damage the boiler,
resulting in possible severe personal injury, death or
substantial property damage.

Part number 550-100-103/1110 A–3
GAS-FIRED WATER BOILER — Manual addendum — Venting
Venting & air — general (cont.)
Ultra Boilers must be vented and
supplied with combustion and ven-
tilation air using piping and methods
described in this manual.
Every boiler must have its own vent.
DO NOT common vent with any other
appliance. See page A-2.
Inspect finished vent and air piping
thoroughly to ensure all are airtight and
comply with the instructions provided
and with all requirements of applicable
codes.
Failure to provide a properly-installed
vent and air system will cause severe
personal injury or death.
If the vent/air piping configurations cov-
ered in the Ultra boiler manual and this
addendum cannot be applied for a par-
ticular installation, contact Weil-McLain
for assistance. Other configurations may
be available.
Where vent piping is routed through an
unheated space, apply minimum 1 inch
of foil-faced fiberglass insulation on the
length of the vent pipe in the unheated
space.
Installations must comply with local
requirements and with the National
Fuel Gas Code, ANSI Z223.1 for U.S.
installations or CSA B149.1 or B149.2
for Canadian installations.
Use only the materials listed in the
Boiler manual and this addendum for
vent and air pipe and fittings. See Fig-
ure 5, page A-7. Failure to comply could
result in severe personal injury, death or
substantial property damage.
If used, a masonry chimney can
ONLY be used as a PIPE CHASE for
vent and air pipes — The vent and air
piping must be installed as instructed in
this manual and all joints must be sealed.
The chimney must be used only for Ultra
boilers. NO OTHER appliance or fire-
place can be connected to the chimney.
The chimney must be straight, with no
offsets, and the vent and air piping ma-
terials must comply with this instruction
manual. The chimney must be fitted
with a sealed access opening, through
which the interior of the chimney can
be inspected. The chimney (and liner, if
installed) must be inspected at least once
annually to verify condition.
Failure to comply could result in severe
personal injury, death or substantial
property damage.
Vent piping
Boiler flue gases must be piped from the boiler to outside, follow-1.
ing the instructions in the Boiler manual and this addendum, and
compliant with all applicable codes. The vent pipe must terminate
either through the sidewall or through the roof, located with the
correct separation from the air termination.
See2. Figure 2, page A-4 for location of instructions for the vent/
air system being used.
Each Ultra boiler requires a separate vent.3. Do not common
vent.
Combustion air piping
(direct vent installations)
For direct venting, combustion air must be piped from outside to1.
the boiler, following the instructions in the Boiler manual and this
addendum, and compliant with all applicable codes. Read the
warning in Figure 1, page A-2, and ensure the air intake
will not be likely to draw in contaminated air.
Combustion air can be piped individually for each boiler, or2.
it can be manifolded as shown in Boiler manual, page 55. Air
piping must always terminate on the same side (or roof ) of the
building as the vent, except for direct vent: vertical vent/sidewall
air installations.
Combustion and ventilation air openings
(direct exhaust installations)
Combustion and ventilation air are provided from the boiler room1.
on direct exhaust installations.Follow all instructions in the Boiler
manual and this addendum, plus all applicable codes, to provide
required air openings.
Vent and air pipe termination options
Vent and air piping must terminate out the sidewall or through1.
the roof of the building, using only one of the methods described
in the Boiler manual and this addendum.
See2. Figure 2, page A-4 for options.
Vent and air pipe diameters
Vent and air pipe diameters can be as specified in1. Fig-
ure 2, page A-4.
Vent and air pipe maximum length
Do not exceed vent and air piping MAXIMUM lengths given in1.
Figure 2, page A-4.
Vent and air pipe minimum length
Direct vent — vent pipe and air pipe must each be1. at least 2 feet
long, with 2 elbows if sidewall venting or 1 elbow if vertical vent-
ing.
Direct exhaust — no minimum.2.
REPLACES MANUAL PAGE 17

Part number 550-100-103/1110
GAS-FIRED WATER BOILER — Manual addendum — Venting
A–4
Venting & air — general (cont.)
Figure 2 DIRECT VENT APPLICATIONS — Vent and air termination options
DIRECT VENT
SIDEWALL termination
DIRECT VENT
VERTICAL termination
DIRECT VENT
VERTICAL vent and
SIDEWALL air
Weil-McLain
sidewall
termination
plate
(See Boiler
manual
page 18)
3” or 4”PVC
concentric
termination
(See addendum
page A-8)
Vertical
vent
termination
and
Sidewall
air
termination
(See
addendum
page A-15)
3” or 4” PVC
concentric
termination
(See addendum
page A-8)
Vertical
termination with
separate vent
and
air pipes
(See Boiler
manual
page 73)
Sidewall
termination with
separate vent
and
air pipes
(See Boiler
manual
page 66)
Direct vent
installation
sequence
Install the boiler.Step 1
Determine the termination method — sidewall or vertical, concentric or separate pipes, etc.Step 2
Determine proper location for wall or roof penetration for each termination.Step 3
Install termination assembly as described in this manual.Step 4
Install air and vent piping from boiler to termination.Step 5
Install pipe supports and brackets as required.Step 6

Part number 550-100-103/1110 A–5
GAS-FIRED WATER BOILER — Manual addendum — Venting
Venting & air — general (cont.)
Figure 3 DIRECT EXHAUST APPLICATIONS — Vent termination options (combustion air from room)
DIRECT EXHAUST
Sidewall termination
DIRECT EXHAUST
Vertical termination
Sidewall vent
termination
(See addendum
page A-19)
Vertical vent
termination
(See addendum
page A-19)
Direct
exhaust
installation
sequence
Install the boiler.Step 1
Determine the proper location for roof or wall penetration for each termination.Step 2
Prepare roof penetrations before installing vent piping.s
Finish by attaching external pipe and fittings as shown in the termination instructions.s
Vertical terminations only — Install terminations as described in this addendum.s
Support vertical runs on the outside of the building with brackets as shown in the termination instructions.s
Install vent piping from boiler to termination.Step 3
Install a hanger support within 6 inches of any upturn in the piping.s
Slope horizontal piping downward toward the boiler at least 1/4 inch per foot.s
Connect the vent piping at the boiler per manual instructions.Step 4

Part number 550-100-103/1110
GAS-FIRED WATER BOILER — Manual addendum — Venting
A–6
Venting & air — general (cont.)
Figure 4 Vent and air pipe options and maximum allowable piping lengths
Ultra model
Vent or air
pipe size
t.BYJNVNFRVJWBMFOUGFFUPGQJQJOH
t/VNCFSPGFMCPXTBMMPXFEBUUIFTFMFOHUIT
(All applications include allowance for the terminations.)
Direct vent
Sidewall
with
Weil-McLain
vent/air cap
Direct vent
Sidewall with
separate pipes
— or —
%JSFDUFYIBVTU
(sidewall or vertical)
3” PVC Concentric
Sidewall or Vertical
(Use only PVC pipe
DO NOT use CPVC
or ABS)
[Note 1]
4” PVC Concentric
Sidewall or Vertical
(Use only PVC pipe
DO NOT use CPVC
or ABS)
[Note 1]
Direct vent
Vertical
with separate
pipes
Direct vent
Vertical exhaust
Sidewall air
Direct vent
only Direct vent or Direct exhaust Direct vent only Direct vent only Direct vent only Direct vent only
Length Ells Length Ells Length Ells Length Ells Length Ells Length Ells
80/105
2” * 100 (ab) 2 100 (a) 2 100 (ab) 1 NA 100 (a) 1 100 (a) 1
3” 100 2 100 2 100 1 NA 100 1 100 1
155 3” 100 2 100 2 100 1 NA 100 1 100 1
230
3” 30 (c) 2 30 (c) 2 30 (c) 1 30 (c)(d) 1 30 (c) 1 30 (c) 1
4” 100 (d) 2 100 2 70 (d) 1 100 1 100 1 100 1
299 4” 100 2 100 2 70 (d) 1 100 1 100 1 100 1
310 4” 100 2 100 2 70 (d) 1 100 1 100 1 100 1
399 4” 100 2 100 2 NA 100 1 100 1 100 1
Note 1:
IPEX 3” and 4” PVC concentric vent kits can be used with standard PVC pipe, fittings and cement (ANSI/ASTM D1785) except
where ULC S636 compliance is required. For ULC S636 compliance, all pipe, fittings and cement must be IPEX System 636. When
using IPEX kits, use only IPEX product code 196006 for 3”venting or IPEX product code 196021 for 4”venting.
Contact Weil-McLain for ordering information and availability of Weil-McLain venting kits.
Additional
notes
a —
Use 3”x2”reducer at boiler
C Use 3”x2”reducers at termination
c — Use 4”x3”reducer at boiler
d — Use 4”x3”reducers at termination
* Ultra-80 and 105 boilers installed with 2-inch vent piping automatically derate due to the pressure loss in the vent and air pip-
ing. The derate ranges up to 10% for the Ultra-80 at 100 feet or 15% for the Ultra-105 at 100 feet.
Equivalent feet for elbows — deduct from maximum equivalent length of
piping:
tGFFUQFSGPSFBDIJODIFMCPXPSJODI¡MPOHSBEJVTPS¡FMCPX
tGFFUGPSFBDIPSJODITIPSUSBEJVTFMCPX
Stainless (AL29-4C) vent pipe
install an adapter at the boiler for all applications. Also install an
adapter at the termination unless using separate-pipe termina-
tion.

Part number 550-100-103/1110 A–7
GAS-FIRED WATER BOILER — Manual addendum — Venting
Venting & air — general (cont.)
Figure 5 Vent and air piping materials — Use only the materials listed below, ensuring that all materials meet local codes
Item Material Standards for installations in:
United States Canada
Plastic piping materials
Vent or air pipe
&
fittings
PVC schedule 40 ANSI/ASTM D1785
Plastic vent pipe must be certified to
ULC S636 when required. (Note 2)
Air pipe can be any of those listed at
left if acceptable for local codes.
PVC-DWV (Note 1) ANSI/ASTM D2665
CPVC schedule 40 (Note 1) ANSI/ASTM F441
ABS-DWV schedule 40 (Note 1) ANSI/ASTM D2661
PVC & ABS pipe
cement & primer
PVC ANSI/ASTM D2564
CPVC (Note 1) ANSI/ASTM F493
ABS (Note 1) ANSI/ASTM D2235
AL29-4C piping materials
Vent pipe
AL29-4C
stainless
steel
Heat Fab, Inc. — Saf-T-Vent®
Z-Flex, Inc. — Z-Vent II
Simpson Dura-Vent — FasNSeal™
Certified for Category IV and direct vent
appliance venting
Certified for Category IV and direct vent
appliance venting
Weil-McLain bird screens (purchase separately)
Weil-McLain
bird
screens
For 2” or 3” vent or air termination
(cut to size if necessary)
3” vent screen:
W-M part number 383-500-105
For 3” or 4” vent or air termination
(cut to size if necessary)
4” vent screen:
W-M part number 383-500-110
Note 1: DO NOT use DWV, CPVC or ABS when using concentric vent termination. Use ONLY PVC schedule 40.
Note 2: IPEX PVC concentric terminations utilize PVC pipe/fittings certified to ULC S636. Where ULC S636 compliance is required, use
only IPEX System 636 pipe, fittings and cement.
AL29-4C vent piping — Install a PVC-to-stainless adapter supplied by the vent pipe manufacturer at the boiler vent connection
and at the termination (when using Weil-McLain plate or concentric PVC termination). DO NOT mix piping from different vent
pipe manufacturers unless using adapters specifically designed for the purpose by the manufacturer.
Plastic piping — Do not attempt to connect different types of plastic piping together.
DO NOT use cellular core pipe.
All vent and air pipes require a bird screen at each termination where specified in the manual or vent supplement. Purchase
bird screens separately from Weil-McLain or vent kit supplier. Note that most kits do not include the screens.

Part number 550-100-103/1110
GAS-FIRED WATER BOILER — Manual addendum — Venting
A–8
Sidewall vent/air termination: 3” or 4” concentric
Termination kit — 3” or 4” PVC concentric
termination
The 3” or 4” PVC concentric termination kit must be purchased1.
separately. See below.
Use only the vent materials and kits listed in Fig-
ure 2, page A-4 and Figure 4, page A-6 for concentric
venting. Provide pipe adapters as specified in Fig-
ure 4, page A-6.
Commonwealth of Massachusetts
When the boiler is installed within the Commonwealth of Mas-
sachusetts:
This product must be installed by a licensed plumber or gass
fitter.
See instruction in the Boiler manual.s
Allowable vent/air pipe materials
Use only the materials listed in Figure 5, page A-7.
Maximum piping length
Locate the termination such that the total air piping and vent piping1.
from the boiler to the termination will not exceed the maximum
length given in Figure 4, page A-6.
Maximum lengths listed in2. Figure 4, page A-6 allow for 1 elbow.
Additional elbows required a reduction in maximum length as
explained in the table notes.
Connecting from termination to boiler
Install the termination as instructed in the following.1.
Then proceed to2. page A-18 to complete the air and vent piping
between the termination and the boiler.
The center lines between the air and vent are wider at the concentric3.
termination connections than at the boiler. See Figure 15, page A-13
for suggestions on adjusting the spacing when required. In addi-
tion to the method given there, you can rotate the Y-fitting slightly,
which will cause the air pipe to be slightly higher or lower than
the vent, but the center lines will match those at the boiler vent
and air connections.
Determine locations for terminations
A gas vent extending through an exterior wall shall not
terminate adjacent to the wall or below building exten-
sions such as eaves, parapets, balconies or decks. Failure
to comply could result in severe personal injury, death
or substantial property damage.
Locate the vent/air terminations using the following guidelines.
You must consider the surroundings when terminating the vent1.
and air:
Position the vent termination where vapors will not damagea.
nearby shrubs, plants or air conditioning equipment or be
objectionable.
Termination location — 3” or 4” PVCFigure 6
concentric termination — height above grade
or snow line
Termination location — 3” or 4” PVCFigure 7
concentric termination — clearances to
openings
All vent and air pipes require a bird screen
at each termination. Most kits do not
include the screens. Purchase separately
from Weil-McLain or vent kit supplier if
not included.

Part number 550-100-103/1110 A–9
GAS-FIRED WATER BOILER — Manual addendum — Venting
Sidewall vent/air termination: 3” or 4” concentric (cont.)
The flue products will form a noticeable plume as they con-b.
dense in cold air. Avoid areas where the plume could obstruct
window views.
Prevailing winds could cause freezing of condensate and water/c.
ice buildup where flue products impinge on building surfaces
or plants.
Avoid possibility of accidental contact of flue products withd.
people or pets.
Do not locate the terminations where wind eddies could affecte.
performance or cause recirculation, such as inside building
corners, near adjacent buildings or surfaces, window wells,
stairwells, alcoves, courtyards or other recessed areas.
Do not terminate above any door or window or under a deck.f.
Condensate can freeze, causing ice formations.
Locate or guard vent to prevent condensate damage to exteriorg.
finishes.
Maintain clearances as shown in2. Figure 6, Figure 7, Figure 8 and
Figure 9. Also maintain the following:
Vent must terminate:a.
At least 6 feet from adjacent walls.s
No closer than 5 feet below roof overhang.s
At least 7 feet above any public walkway.s
At least 3 feet above any forced air intake within 10 feet.s
No closer than 12 inches below or horizontally from anys
door or window or any other gravity air inlet.
Air inlet must terminate at least 12” above grade or snowb.
line.
Do not terminate closer than 4 feet horizontally (above or be-c.
low) from any electric meter, gas meter, regulator, relief valve
or other equipment.
Locate terminations so they are not likely to be damaged by foreign3.
objects, such as stones or balls, or subject to buildup of leaves or
sediment.
Multiple vent/air terminations
When terminating multiple Ultra boilers, terminate each vent/air1.
connection as described in this addendum.
All vent pipes and air inlets must terminate at the same
height to avoid possibility of severe personal injury, death
or substantial property damage.
Place wall penetrations to obtain minimum clearance as shown in2.
Figure 9 for U. S. installations. For Canadian installations, provide
clearances required by CSA B149.1 or B149.2 Installation Code.
The air inlet of an Ultra boiler is part of a direct vent connection.3.
It is not classified as a forced air intake with regard to spacing from
adjacent boiler vents.
Combustion air (NOT vent piping) can be manifolded as shown4.
in Boiler manual, page 55.
Termination location — 3” or 4” PVCFigure 8
concentric termination — clearances to
public walkway or forced air intake
Termination location — 3” or 4” PVCFigure 9
concentric termination — multiple boilers —
clearance from vent of one to air intake of the
next

Part number 550-100-103/1110
GAS-FIRED WATER BOILER — Manual addendum — Venting
A–10
Installing and supporting the concentricFigure 10
sidewall vent assembly
Install terminations — concentric pipes
Assemble the vent termination as described for vertical concentric1.
terminations, beginning on page A-12.
If necessary, you can shorten the lengths of the inner and
outer pipes for a shorter finished assembly. But you must
ensure the pipes butt correctly at both ends. Failure to
properly assemble the concentric termination can result
in flue gas recirculation,causing possible severe personal
injury or death.
Wall penetration:2.
3” termination: Preferably, use a thimble with a 4½-inch hole.a.
If not using a thimble, carefully use a hole saw to cut a hole
not larger than 4¾ inches in diameter through the wall. The
finished hole must provide a solid stop for the rain cap ribs,
as shown in the inset to Figure 10.
4” termination: Preferably, use a thimble with a 6-inch hole.b.
If not using a thimble, carefully use a hole saw to cut a hole
not larger than 6¼ inches in diameter through the wall. The
finished hole must provide a solid stop for the rain cap ribs,
as shown in the inset to Figure 10.
Secure the termination in place so the rain cap will butt against the3.
outside wall or outer thimble plate as shown in Figure 10.
Before beginning vent and air piping from the boiler to the con-4.
centric termination, mount and secure the concentric termination
as shown in Figure 10 and Figure 11.
The vent and air piping must be securely supported, and
must not rest its weight on the boiler fittings. Failure to
properly support the vent and air piping could result in
vent piping damage, resulting in possible severe personal
injury, death or substantial property damage.
The supports/bracing used must support the termination
assembly to prevent slippage or movement.
The clamps used on the outside of the termination pipe
must not cut into the pipe or contain sharp edges that
could cause a crack to form.
When inserting the partially-assembled termination
kit through the roof penetration, wrap plastic or other
protection over the end of the exposed assembly to pre-
vent debris from entering the pipes. If the air passages
become blocked, the boiler will not operate. Once the
rain cap has been cemented to the assembly, there is no
way to correct the problem. The assembly would have
to be replaced if it were cut to be removed and cleaned.
Altering the assembly in any way could result in severe
personal injury or death due to toxic flue product emis-
sions.
When using AL294C stainless vent pipe, use the vent
pipe manufacturer’s PVC adapter when connecting to
the concentric vent attachment.
After the assembly has been positioned in the opening and all sup-5.
ports have been attached,install a bird screen (purchased separately
if not included with the kit) and rain cap as follows:
Place the bird screen on the end of the inner pipe as ina. Fig-
ure 17, page A-14.
Cement the rain cap in place as shown.b.
Sidewall vent/air termination: 3” or 4” concentric (cont.)
Figure 11 Concentric termination requirements
Concentric termination
(installing termination — see
page A-8)
Install pipe supports every 5s
feet on both the horizontal and
vertical runs.
Install a hanger support withins
6 inches of any upturn in the
piping.
The concentric terminations
assembly must be installed
before piping from the
boiler to the termination.
Support the terminations
at the wall as shown in the
termination instructions.
Slope horizontal pipings
downward toward the boiler at
least 1/4 inch per foot.
Rotate the concentrics
termination Y-fitting about
30° to result in pipe centers the
same as at the boiler.
Ensure that the wall material is strong enough
to prevent the rain cap from being pushed
inward if struck or pushed from the outside.

Part number 550-100-103/1110 A–11
GAS-FIRED WATER BOILER — Manual addendum — Venting
Vertical vent/air termination: 3” or 4” concentric
Termination kit — 3” or 4” PVC concentric
termination
The 3” or 4” PVC concentric termination kit must be purchased1.
separately. See below.
Use only the vent materials and kits listed in Fig-
ure 2, page A-4 and Figure 4, page A-6 for concentric
venting. Provide pipe adapters as specified in Fig-
ure 4, page A-6.
Allowable vent/air pipe materials
Use only the materials listed in Figure 5, page A-7.
Maximum piping length
Locate the termination such that the total air piping and vent piping1.
from the boiler to the termination will not exceed the maximum
length given in Figure 4, page A-6.
Maximum lengths listed in2. Figure 4, page A-6 allow for 1 elbow.
Additional elbows required a reduction in maximum length as
explained in the table notes.
Connecting from termination to boiler
Install the termination as instructed in the following. Then proceed1.
to page A-18 to complete the piping between the termination and
the boiler.
Determine location
Locate the concentric vent/air termination using the following guide-
lines:
The concentric vent/air assembly must terminate as shown in1.
Figure 12.
The vent and air piping connected to the termination assembly2.
must comply with the instructions in this supplement.
You must consider the surroundings when terminating the vent3.
and air:
Position the termination where vent vapors will not damagea.
nearby shrubs, plants or air conditioning equipment or be
objectionable.
The flue products will form a noticeable plume as they con-b.
dense in cold air. Avoid areas where the plume could obstruct
window views.
Prevailing winds could cause freezing of condensate and water/c.
ice buildup where flue products impinge on building surfaces
or plants.
Avoid possibility of accidental contact of flue products withd.
people or pets.
Do not locate the termination where wind eddies could affecte.
performance or cause recirculation, such as inside building
corners, near adjacent buildings or surfaces, window wells,
stairwells, alcoves, courtyards or other recessed areas.
Locate or guard vent outlet to prevent condensate damage tof.
exterior finishes.
Figure 12 Vertical termination — 3” or 4” PVC
concentric
Figure 13 Vertical termination — 3” or 4” PVC
concentric — multiple boilers
All vent and air pipes require a bird screen
at each termination. Most kits do not
include the screens. Purchase separately
from Weil-McLain or vent kit supplier if
not included.

Part number 550-100-103/1110
GAS-FIRED WATER BOILER — Manual addendum — Venting
A–12
Vertical vent/air termination: 3” or 4” concentric (cont.)
Maintain clearances to termination as given below:4.
Vent outlet must be located:a.
At least 6 feet from adjacent walls.s
No closer than 5 feet below roof overhang.s
At least 7 feet above any public walkway.s
At lease 3 feet above any forced air intake within 10 feet.s
No closer than 12 inches below or horizontally from any doors
or window or any other gravity air inlet.
Air inlet must terminate at least 12 inches above the roof orb.
snow line as shown in Figure 12, page A-11. (For Canada, the
minimum is 18 inches.)
Do not terminate closer than 4 feet horizontally from anyc.
electric meter, gas meter, regulator, relief valve or other equip-
ment. Never terminate above or below any of these within
4 feet horizontally.
Locate termination so it is not likely to be damaged by foreign5.
objects, such as stones or balls, or subject to buildup of leaves or
sediment.
Do not connect any other appliance to the vent pipe or multiple6.
boilers to a common vent pipe.
Multiple vent/air terminations
When terminating multiple Ultra boilers, install the concentric1.
vent/air termination assemblies as described in this addendum.
All vent outlets must terminate at the same height to avoid
possibility of severe personal injury, death or substantial
property damage.
Place roof penetrations to obtain minimum of 12 inches between2.
centers of adjacent vent pipe of another boiler for U. S. installations
(see Figure 13, page A-11).
For Canadian installations, provide clearances required by CSA3.
B149.1 or B149.2 Installation Code.
The air inlet of an Ultra boiler is part of a direct vent connection.4.
It is not classified as a forced air intake with regard to spacing from
adjacent boiler vents.
Prepare roof penetrations
Roof penetration hole:1.
3”termination: Cut a 5-inch diameter hole to clear the 4½-incha.
termination outside diameter.
4”termination: Cut a 6.5-inch diameter hole to clear the 6-inchb.
termination outside diameter.
Insert a galvanized metal thimble in the vent pipe hole.c.
Follow all local codes for isolation of vent pipe when passing2.
through floors, ceilings and roofs.
Provide flashing and sealing boots sized for the concentric termi-3.
nation outside diameter.
Mount the termination as shown in4. Figure 15, page A-13.
Assembling the concentric termination
See1. Figure 18, page A-14 for the dimensions and details of the
termination assembly.
Prepare the bird screen (purchased separately if not included with2.
the kit). Cut the bird screen to size if required. If the bird screen
must be trimmed, cut the bird screen to fit the outside diameter of
the PVC inner pipe supplied with the termination kit.
Partially assemble the vent termination kit in the se-3.
quence shown in Figure 17, page A-14.
DO NOT install the rain cap and bird screen
until the assembly has been inserted through
the roof and all supports have been installed.
Follow instructions to cover the end of the
assembly with plastic before inserting through
the roof penetration to prevent debris from
blocking the air passages.
Use the following procedures to prepare termination4.
components and cement together.
Deburr inside and outside of pipe ends.5.
Chamfer outside of each pipe end to ensure even cement6.
distribution when joining.
Clean all pipe ends and fittings.7.
Dry thoroughly.8.
Dry assemble entire vent or air piping to ensure proper9.
fit before assembling any joint.
For each joint:10.
Handle fittings and pipes carefully to prevent con-a.
tamination of surfaces.
Apply primer liberally to both joint surfaces — pipeb.
end and fitting socket.
While primer is still damp, lightly apply approvedc.
cement to both surfaces in a uniform coating.
Apply a second coat to both surfaces. Avoid usingd.
too much cement on sockets to prevent cement
buildup inside.
With cement still wet, insert pipe into fitting, twist-e.
ing ¼ turn. Make sure pipe is fully inserted.
If necessary, you can shorten the lengths of the
inner and outer pipes for a shorter finished
assembly. But you must ensure the pipes butt
correctly at both ends. Failure to properly as-
semble the concentric termination can result
in flue gas recirculation, causing possible
severe personal injury or death.
Mount concentric termination
Before beginning vent and air piping from boiler, mount1.
and secure the concentric termination as shown in Fig-
ure 14, page A-13, and Figure 15, page A-13.
The vent and air piping must be securely
supported, and must not rest its weight on
the boiler fittings. DO NOT drill or screw
into either the vent pipe or air pipe. Failure
to properly support the vent and air piping
could result in vent piping damage, resulting
in possible severe personal injury, death or
substantial property damage.

Part number 550-100-103/1110 A–13
GAS-FIRED WATER BOILER — Manual addendum — Venting
Vertical vent/air termination: 3” or 4” concentric (cont.)
When inserting the partially-assembled termination kit
through the roof penetration, wrap plastic or other protection
over the end of the exposed assembly to prevent debris from
entering the pipes. If the air passages become blocked, the
boiler will not operate. Once the rain cap has been cemented
to the assembly, there is no way to correct the problem. The as-
sembly would have to be replaced if it were cut to be removed
and cleaned. Altering the assembly in any way could result
in severe personal injury or death due to toxic flue product
emissions.
When using AL294C stainless vent pipe, use the vent pipe
manufacturer’s PVC adapter when connecting to the con-
centric vent attachment.
After the assembly has been positioned in the roof opening and all sup-2.
ports have been attached, install a bird screen (purchased separately if
not included with the kit) and rain cap as follows:
Place the bird screen on the end of the inner pipe as ina. Fig-
ure 17, page A-14.
Cement the rain cap in place as shown.b.
Vent termination support
Support the concentric vent/air termination at the roof penetration1.
as shown in Figure 15.
The supports/bracing used must support the termination assemblys
to prevent vertical slippage or sideways movement.
The clamps used on the outside of the termination pipe must nots
cut into the pipe or contain sharp edges that could cause a crack
to form.
Concentric termination requirementsFigure 14
Concentric termination
(installing termination — see page A-11)
Install pipe supports every 5 feet ons
both the horizontal and vertical runs.
Install a hanger support withins
6 inches of any upturn in the piping.
The concentric terminations
assembly must be installed
before piping from the boiler to
the termination.
Support the termination at the ceilings
and above the roof as shown in the
termination instructions.
Slope horizontal piping downwards
toward the boiler at least 1/4 inch per
foot.
Use long-radius elbows for air pipings
when using 2” or 3” pipe to reduce
pressure drop.
Rotate the concentric terminations
Y-fitting about 30° to result in pipe
centers the same as at the boiler.
3” or 4” PVC concentric terminationFigure 15
supports
Alternate piping configuration, using (3)Figure 16
45-degree elbows to obtain closer pipe
centers

Part number 550-100-103/1110
GAS-FIRED WATER BOILER — Manual addendum — Venting
A–14
Concentric vent/air termination assembly
3” or 4” PVC concentric termination assembly (see kitFigure 18
manufacturer’s instructions for details)
3” or 4” PVC concentric termination assemblyFigure 17
— DO NOT attach the rain cap until the
termination has been inserted through the
roof or wall and all supports have been
installed.

Part number 550-100-103/1110 A–15
GAS-FIRED WATER BOILER — Manual addendum — Venting
DIRECT VENT: Vertical vent / sidewall air
Determine location
Locate the vent termination using the following guidelines:1.
The vent piping must terminate in an up-turned coupling as shown2.
in Figure 20, page A-16. The top of the coupling must be at least 1 foot
above the air intake.
You must consider the surroundings when terminating the vent and3.
air:
Position the vent termination where vapors will not damage nearbya.
shrubs, plants or air conditioning equipment or be objectionable.
The flue products will form a noticeable plume as they condenseb.
in cold air. Avoid areas where the plume could obstruct window
views.
Prevailing winds could cause freezing of condensate and water/c.
ice buildup where flue products impinge on building surfaces or
plants.
Avoid possibility of accidental contact of flue products with peopled.
or pets.
Do not locate the terminations where wind eddies could affecte.
performance or cause recirculation into building or appliance air
intakes, such as inside building corners, near adjacent buildings
or surfaces, window wells, stairwells, alcoves, courtyards or other
recessed areas.
Do not terminate above any door or window. Condensate can freeze,f.
causing ice formations.
Locate or guard vent to prevent condensate damage to exteriorg.
finishes.
Maintain clearances to vent termination as given below:4.
Vent must terminate:a.
At least 6 feet from adjacent walls.s
No closer than 5 feet below roof overhang.s
At least 3 feet above any forced air intake within 10 feet.s
No closer than 12 inches below or horizontally from any doors
or window or any other gravity air inlet.
Do not terminate vent closer than 4 feet horizontally from anyb.
electric meter, gas meter, regulator, relief valve or other equip-
ment. Never terminate above or below any of these within 4 feet
horizontally.
Locate terminations so they are not likely to be damaged by foreign5.
objects, such as stones or balls, or subject to buildup of leaves or sedi-
ment.
Do not connect any other appliance to the vent pipe. Do not connect6.
multiple boilers to a common vent pipe.
Prepare roof penetrations
Vent pipe penetration:1.
Cut a hole for the vent pipe. For either combustible or noncombus-a.
tible construction, size the vent pipe hole at least 0.4” larger than
the vent pipe diameter:
2¾” hole for 2” PVCs
4” hole for 3” PVCs
5” hole for 4” PVCs
Insert a galvanized metal thimble in the vent pipe hole.b.
Follow all local codes for isolation of vent pipe when passing through2.
floors, ceilings and roofs.
Provide flashing and sealing boots sized for the vent pipe and air3.
pipe.
Allowable vent/air pipe materials
Use only the materials listed in1. Figure 5, page A-7.
Purchase bird screens for vent and air termina-2.
tions separately. See the parts list at the end of this
manual.
Maximum piping lengths
Locate the terminations such that the total air pip-1.
ing and vent piping from the boiler to the termina-
tion will not exceed the maximum length given in
Figure 4, page A-6.
Maximum lengths listed in2. Figure 4, page A-6 allow
for 1 elbow in the air piping and 1 elbow in the vent
piping. Additional elbows required a reduction in
maximum length as explained in the table notes.
Direct vent: Vertical vent / sidewall airFigure 19

Part number 550-100-103/1110
GAS-FIRED WATER BOILER — Manual addendum — Venting
A–16
DIRECT VENT: Vertical vent / sidewall air (continued)
Termination and fittings
Prepare the vent termination coupling by inserting a bird screen.1.
Bird screens must be purchased separately. See the parts list at the
end of this manual for part numbers.
If using 3-inch piping for an Ultra-230, cut a 4-inch bird screena.
by placing 3-inch fitting on screen and cutting around it as a
template.
Maintain the required dimensions of the finished termination2.
piping as shown in Figure 20.
Multiple vent terminations
When terminating multiple Ultra boilers, terminate each vent/air1.
connection as described in this section.
Place adjacent terminations at least 6 inches apart.2.
For Canadian installations, provide clearances required by CSA3.
B149.1 or B149.2 Installation Code.
Connecting from vent termination to boiler
Install the termination penetration as instructed in the preced-1.
ing. Then proceed to page 18 to complete the piping between the
termination and the boiler.
Determine location for air inlet elbow
The air inlet of an Ultra boiler is part of a direct vent connection.1.
It is not classified as a forced air intake with regard to spacing from
adjacent appliance terminations.
Locate the air inlet elbow (termination) using the following2.
guidelines.
The air piping must terminate in a down-turned elbow as shown3.
in Figure 21.
Apply the configuration on the left side ofa. Figure 21 unless
the terminations would fail to meet minimum clearance to
grade or snow line.
Apply the configuration on the right side ofb. Figure 21 when
the terminations need to be raised higher to meet clearance to
grade or snow line.
The air pipe may run up the side of the building, as shown.c.
The vent and air pipes must be secured with braces, and all
clearances and lengths must be maintained. Space braces no
further than 24 inches apart.
You must consider the surroundings when terminating the air4.
connection:
Make sure there are no obstructions for air flow. DO NOTa.
locate the termination where plants could grow and cause
obstruction to air flow.
Do not locate the terminations where wind eddies could affectb.
performance or cause recirculation with exhaust from other
appliances, such as inside building corners, near adjacent build-
ings or surfaces, window wells, stairwells, alcoves, courtyards
or other recessed areas.
Locate the air inlet termination at least 12 inches below andc.
12 inches horizontally from any appliance or building vent
outlet.
Locate terminations so they are not likely to be damaged by foreign5.
objects, such as stones or balls, or subject to buildup of leaves or
sediment.
Vent termination (through the roof) for directFigure 20
vent: vertical vent / sidewall air
Sidewall air inlet (termination) for direct vent:Figure 21
vertical vent / sidewall air

Part number 550-100-103/1110 A–17
GAS-FIRED WATER BOILER — Manual addendum — Venting
DIRECT VENT: Vertical vent / sidewall air (continued)
Multiple air terminations
When terminating multiple Ultra boiler air connections,terminate1.
each air connection as described in this manual.
Place wall penetrations to obtain minimum clearances as instructed2.
in this manual.
Place adjacent air inlets for multiple Ultra boilers at least 6 inches3.
apart.
For Canadian installations, provide clearances required by CSA4.
B149.1 or B149.2 Installation Code.
Combustion air (NOT vent piping) can be manifolded as shown5.
in the Ultra boiler manual.
Prepare wall penetrations
Air pipe penetration:1.
a. Cut a hole for the air pipe. Size the air pipe hole as close as
desired to the air pipe outside diameter.
Seal exterior openings thoroughly with exterior caulk.2.
Termination and fittings
Prepare the air termination elbow (1. Figure 21) by inserting a bird
screen. Bird screens must be purchased separately. See the parts
list at the end of this manual for part numbers.
Use metal plates (by installer) at inside and ouside penetrations2.
as shown in Figure 22.
If extending the air pipe out from the wall, install a cou-
pling on each pipe. Mount the piping with the coupling
flush with the outer plate.
Connecting from air termination to boiler
Install the terminations as instructed in the following. Then pro-1.
ceed to page 18 to complete the air and vent piping between the
termination and the boiler.
Sidewall air inlet installation for direct vent:Figure 22
vertical vent / sidewall air
1 Air piping
2 Sidewall plates, by installer
3 Bird screen (air),by installer
4 Air inlet elbow

Part number 550-100-103/1110
GAS-FIRED WATER BOILER — Manual addendum — Venting
A–18
Install vent/air piping — boiler to termination
Complete termination preparation
Install vent and air terminations before proceeding. See previous1.
pages for instructions.
Installing vent and air piping
For reference in the following see:1.
Sidewall terminations: seea. Figure 11, page A-10.
Vertical terminations: seeb. Figure 14, page A-13.
Work from the boiler to vent or air termination. Do not exceed2.
the lengths given in the previous pages for either the air or vent
piping.
As shown in the maximum length tables, the Ultra-80 ora.
Ultra-105 may be installed with either 2-inch or 3-inch vent
and air piping.
As shown in the maximum length tables, the Ultra-230 may beb.
installed with either 3-inch or 4-inch vent and air piping.
You must install appropriate pipe reducers, where required, atc.
both the boiler and at the termination assembly.
See3. Figure 23 for attaching vent and air pipes at the boiler.
Cut pipe to required lengths.4.
Deburr inside and outside of pipe ends.5.
Chamfer outside of each pipe end to ensure even cement distribu-6.
tion when joining.
Clean all pipe ends and fittings. Dry thoroughly.7.
Dry assemble entire vent or air piping to ensure proper fit before8.
assembling any joint.
For each joint:9.
Handle fittings and pipes carefully to prevent contaminationa.
of surfaces.
Apply primer liberally to both joint surfaces — pipe end andb.
fitting socket.
While primer is still damp, lightly apply approved cement toc.
both surfaces in a uniform coating.
Apply a second coat to both surfaces. Avoid using too muchd.
cement on sockets to prevent cement buildup inside.
With cement still wet, insert pipe into fitting, twisting ¼ turn.e.
Make sure pipe is fully inserted.
Wipe excess cement from joint. Check joint to be sure a smoothf.
bead of cement shows around the entire joint.
Install pipe supports as shown in10. Figure 11, page A-10 or Fig-
ure 14, page A-13.
Slope vent and air piping continuously toward boiler, with at least11.
1/4 inch drop per foot of run. Do not allow sags at any point.
Maintain minimum clearance of12. 6QE inch between vent pipe and
any combustible wall or material.
Seal wall or floor penetration openings following local code re-13.
quirements.
Boiler vent and air connectionsFigure 23
Inserting/securing vent or air
pipe into boiler connectors
AL294C vent pipe — If using AL294C
stainless vent pipe, you must install a
PVC-to-vent pipe adapter at the boiler
vent connection (and at the termination
if using the Weil-McLain plate or the
concentric termination). Use only the
adapter made by the vent pipe manufac-
turer.
PVC/ABS pipe — Clean and chamfer insertion end1.
of pipe. Deburr inside of insertion end. Clean and
deburr inside and outside of other end of pipe.
The pipe end must be smooth and
chamfered to prevent possible damage to
sealing gasket in vent or air pipe adapter.
Failure to comply could result in leakage,
causing possible severe personal injury or
death.
Inspect vent or air adapter (above) — verify no2.
obstructions or foreign objects inside.
Loosen clamp screw.3.
Measure 3½ inches from end of pipe and make a4.
mark with felt-tip pen.
Loosen adapter clamp screw.5.
Apply small amount of silicon grease to end of pipe6.
to ease insertion.
Insert pipe into adapter.7.
Slide pipe down until the 3½-inch mark is8.
reached.
Do not apply excessive force or bend the
adapter or flue/air pipe when inserting.
The adapter or seal could be damaged.
Secure vent or air pipe by tightening the adapter9.
clamp securely. Do not overtighten. The seal is ac-
complished with the internal gasket. The clamp is
only to hold the pipe in place.

Part number 550-100-103/1110 A–19
GAS-FIRED WATER BOILER — Manual addendum — Venting
DIRECT EXHAUST venting — general
Vent and air piping materials
See1. Figure 5, page A-7 for approved vent and air piping materials,
for both direct exhaust and direct vent.
Use the same vent or air piping material through-
out. — Do not connect different types of piping to-
gether.
Vent piping
Boiler flue gases must be piped from the boiler to outside, following1.
the instructions in this manual, and compliant with all applicable
codes. The vent pipe must terminate either through the sidewall
or through the roof, located with the correct separation from the
air termination. See the associated instructions in the following
pages.
Each Ultra boiler requires a separate vent.2. DO NOT common
vent.
Combustion air openings for direct exhaust
Provide combustion air openings to boiler room
and building. Combustion and ventilation air for direct
exhaust boilers is provided from the boiler room. Follow
all instructions in the Boiler manual and this addendum
plus all applicable codes, providing combustion air open-
ings as specified. Failure to comply could result in severe
personal injury, death or substantial property damage.
Combustion air must be supplied through openings into the boiler1.
room, following the instructions in this manual, and compliant
with all applicable codes. Read the warning in Figure 1, page A-2,
and ensure the air and boiler room will not contain contaminated
air.
Where the Ultra boiler shares a space with other appliances, the2.
combustion air openings must be sized to handle the combined
requirements of all appliances in the space.
SIDEWALL direct exhaust option
Read and follow instructions in Boiler manual, including page 611.
for Massachusetts installations when applicable.
Read and follow instructions in Venting addendum2. page A-2
through page A-7.
Then go to Venting addendum3. page A-22.
VERTICAL direct exhaust option
Read and follow instructions in Boiler manual, including page 611.
for Massachusetts installations when applicable.
Read and follow instructions in Venting addendum2. page A-2
through page A-7.
Then go to Venting addendum3. page A-25.
SIDEWALL
DIRECT EXHAUST
VERTICAL
DIRECT EXHAUST
Every vent pipe requires a bird screen at its termi-
nation. Bird screens are not supplied with the Ultra
boiler. Purchase separately from Weil-McLain.

Part number 550-100-103/1110
GAS-FIRED WATER BOILER — Manual addendum — Venting
A–20
DIRECT EXHAUST — Boiler room air openings
Special considerations
Tight construction
ANSI Z223.1 defines unusually tight construction
where:
Walls and ceilings exposed to the outside atmo-1.
sphere have a continuous water vapor retarder with
a rating of 1 perm or less with openings gasketed,
and . . .
Weather-stripping has been added on openable2.
windows and doors, and . . .
Caulking or sealants are applied to areas such as3.
joints around windows and door frames, between
sole plates and floors, between wall-ceiling joints,
between wall panels, at penetrations for plumbing,
electrical, and gas lines, and in other openings.
For buildings with such construction, provide air
openings into the building from outside, sized per the
appropriate case in Figure 24, page 21 if appliances are
to use inside air for combustion and ventilation.
Exhaust fans and air movers
The appliance space must never be under a negative
pressure unless all appliances are installed as direct
vent. Always provide air openings sized not only to
the dimensions required for the firing rate of all appli-
ances, but also to handle the air movement rate of the
exhaust fans or air movers using air from the building
or space.
Motorized air dampers
If the air openings are fitted with motorized dampers,
electrically interlock the damper to:
Prevent the boiler from firing if the damper is nots
fully open.
Shut the boiler down should the damper close dur-s
ing boiler operation.
To accomplish this interlock, wire an isolated contact
(proving the damper open) in series with the thermo-
stat input to the boiler. The boiler will not start if this
contact is open, and will shut down should it open
during operation.
Combustion air provision
The Ultra boiler can use inside air if no contaminants are present in the
boiler space. (If contaminants are likely to be present, install the boiler
as a direct vent appliance, using the appropriate vent instructions in this
manual.)
The boiler room must be fitted with combustion air openings large enough
to provide air for all appliances in the room. Use the following information
to size the openings. Ensure the installation complies with all applicable
codes and standards.
Sizing combustion air openings
Air openings provide for ventilation (as well as combustion air) to prevent
overheating of the boiler controls and boiler space. Air is also needed for
other appliances located in the same space.
Use Figure 24, page A-21, selecting the appropriate installation condi-
tions.
Air openings must be sized to handle all appliances and air
movers (exhaust fans, etc.) using the air supply.
The sizing given in Figure 24, page A-21 is based on the National Fuel Gas
Code, ANSI Z223.1, allowing adequate air openings for gravity-vented gas
appliances (Category I) in addition to that needed for the Ultra boiler.
The air openings recommended in Figure 24, page A-21 will allow adequate
ventilation and combustion air provided the boiler room is not subjected
to negative pressure due to exhaust fans or other mechanical ventilation
devices.
Refer to the National Fuel Gas Code for dealing with other conditions.
Free area — louver allowance
The free area of openings means the area after reduction for any installed
louvers or grilles. Be sure to consider this reduction when sizing the air
openings.