Indoor Combustion Air Installation In Confined Or Unconfined Space - American Standard TCWH-199-AS Installation Start-Up Maintenance Parts

TANKLESS WATER HEATER
Figure 10 - Screen Installation
NOTE: Vent termination elbow is meant to be installed open end facing the ground.
Orientation in Figure 10 is meant to demonstrate proper Vent Screen installation ONLY.
SAFETY INSTRUCTIONS

4. INDOOR COMBUSTION AIR INSTALLATION IN CONFINED OR UNCONFINED SPACE

This tankless condensing water heater requires fresh, uncontaminated air for safe operation and must be
installed in a mechanical room where there is adequate combustion and ventilating air.
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 ob-
struct the supply of combustion air to the water heater. If the water heater is installed in areas where indoor
air is contaminated (see Figure 11) 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).
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NOTE: To prevent combustion air contamination, see Table 2.