HTP 199-55SA User Manual
Page 36
36
LP-179 REV. 3.21.14
VENT / AIR INLET SIZE
MINIMUM EXISTING VENT / CHASE SIZE
2”
4”
3”
5”
4”
7”
Table 9
– Minimum Vent / Chase Sizing
VENTING AS A CHASE
When venting as a chase, follow all instructions included in Part 5
– Venting of this
manual, as well as the previous Concentric Venting section. See Figure 17 for
chase venting demonstration.
NOTES:
A. For every 1” of overhang, the exhaust vent must be located 1” vertical below overhang
(overhang means top of building structure and not two adjacent walls [corner of building]).
B. Typical installations require 12” minimum separation between bottom of exhaust outlet
and top of air intake.
C. Maintain 12” minimum clearance above highest anticipated snow level or grade
(whichever is greater).
D. Minimum 12” between vents when installing multiple vents.
E. 12” minimum beyond air intake.
F. Maintain 12” minimum clearance above highest anticipated snow level or grade
(whichever is greater).
3. INDOOR COMBUSTION AIR INSTALLATION 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 1
Contaminant Table on page 12.
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 18) 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
(22cm
2
/kW) of the total input of all appliances in the space, but not less than 100
square inches (645cm
2
).
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 18
– LP-325-X
Figure 17
– Venting as a Chase