lp-441 Rev. 002 Rel. 008 Date 8.23.18
24
3. Power Venting, Indoor Combustion Air in Confined or
Unconfined Space
This heater requires fresh, uncontaminated air for safe operation
and must be installed in a mechanical room where there is adequate
combustion and ventilating air.
NOTE: To prevent combustion air
contamination, see Table 2.
Combustion air from the indoor space can be used if the space has
adequate area or when air is provided through a duct or louver to
supply sufficient combustion air based on the water heater input.
Never obstruct the supply of combustion air to the water heater.
If
the water heater is installed in areas where indoor air is contaminated
(see Figure 13) it is imperative that the water heater be installed as
direct vent so that all combustion air is taken directly from the outdoors
into the water heater intake connection.
Unconfined space
is space with volume greater than 50 cubic feet per
1,000 Btu/hour (4.8 cubic meters per kW) of the total input rating of
all fuel-burning appliances installed in that space. Rooms connected
directly to this space, through openings not furnished with doors, are
considered part of the space.
Confined space
is space with volume less than 50 cubic feet per
1,000 Btu/hour (4.8 cubic meters per kW) of the total input rating of
all fuel-burning appliances installed in that space. Rooms connected
directly to this space, through openings not furnished with doors, are
considered part of the space.
When drawing combustion air from inside a conventionally constructed
building to a confined space, such space should be provided with two
permanent openings: one located 6” (15 cm) below the space ceiling,
the other 6” (15cm) above the space floor. Each opening should have a
free area of one square inch per 1,000 Btu/hr (22cm2/kW) of the total
input of all appliances in the space, but not less than 100 square inches
(645cm2).
If the confined space is within a building of tight construction, air for
combustion must be obtained from the outdoors as outlined in the
Venting section of this manual. See Figure 14.
DO NOT INSTALL
WATER HEATER,
BOILER, OR
APPLIANCE
NEAR DRYER
LP-325-X
Figure 13 - Do Not Place Appliance Near Dryer
ROOM OPENING
ROOM OPENING
6"
6"
EXHAUST
LP-325-S
09/29/11
Boiler,
Water Heater,
or Appliance
Indoor Combustion Air
(Single Pipe)
EXHAUST
UPPER
AIR DUCT
LOWER
AIR DUCT
LP-325-T
8/5/2010
Boiler,
Water Heater,
or Appliance
Outdoor Combustion Air
(Single Pipe)
Figure 14 - Indoor and Outdoor Combustion Air - Single Pipe
