Reznor X Unit Installation Manual - Manual (Page 4)

Form I-X, P/N 150491 R10, Page 4
2.2 Combustion Air
Requirements
for a Heater
Located in a
Confined Space
Confined
Space
(1) (2) (3)
(3) (2) (1)
FIGURE 1 - Confined
Space: A space whose
volume is less than
50 cubic feet per 1000
BTUH of the installed
appliance input rating
3.0 Uncrating and
Preparation
3.1 Uncrating and Inspecting
This furnace was test operated and inspected at the factory prior to crating and was in
operating condition. If the furnace has incurred any damage in shipment, document the
damage with the transporting agency and immediately contact an authorized Reznor
distributor. If you are a Reznor distributor, follow the FOB freight policy procedures as
published by Reznor for Reznor products.
Check the rating plate for the gas specifications and electrical characteristics of the
furnace to be sure that they are compatible with the gas and electric supplies at the
installation site.
2.0 Furnace
Location
(cont'd)
WARNING
These furnaces are designed to take combustion air from the space in which the unit is installed
and are not designed for connection to outside combustion air intake ducts. Connecting outside air
duct voids the warranty and could cause hazardous operation. See Hazard Levels, page 2.
These duct furnaces are designed to take combustion air from the space in which the
furnace is installed. The air that enters into the combustion process is vented to the
outdoors. Sufficient air must enter the equipment location to replace the air exhausted
through the vent system. Modern construction methods involve the greater use of insu-
lation, improved vapor barriers and weather-stripping, with the result that buildings
generally are much tighter structurally than they have been in the past. The combus-
tion air supply for gas-fired equipment can be affected by these construction conditions
because infiltration that would have existed in the past may not be adequate. Exten-
sive use of exhaust fans aggravates the situation. In the past the filtration of outside
air assumed in heat loss calculations (one air change per hour) was assumed to be
sufficient. However, current construction methods may now require the introduction of
outside air into the space through wall openings or ducts.
Requirements for combustion air and ventilation air depend upon whether the unit
is located in a confined or unconfined space. An "unconfined space" is defined as a
space whose volume is not less than 50 cubic feet per 1000 BTUH of the installed
appliance. Under all conditions, enough air must be provided to ensure there will not
be a negative pressure condition within the equipment room or space. A positive seal
must be made in all return-air connections and ducts. Even a slight leak can create a
negative pressure condition in a confined space and affect combustion.
Do not install a unit in a confined space without providing wall openings leading to and
from the space. Provide openings near the floor and ceiling for ventilation and air for
combustion as shown in FIGURE 1, depending on the combustion air source as noted
in Items 1, 2, and 3 below the illustration.
Add total BTUH of all appliances in the confined space and divide by figures below for
square inch free area size of each (top and bottom) opening.
1. Air from inside the building -- openings 1 square inch free area per 1000 BTUH.
Never less than 100 square inches free area for each opening. See (1) in FIGURE 1.
2. Air from outside through duct -- openings 1 square inch free area per 2000
BTUH. See (2) in FIGURE 1.
3. Air direct from outside -- openings 1 square inch free area per 4000 BTUH. See
(3) in FIGURE 1.
NOTE: For further details on supplying combustion air to a confined space, see the
National Fuel Gas Code ANSI Z223.1a (latest edition ).
Hazards of Chlorine The presence of chlorine vapors in the combustion air of gas-fired heating equipment
presents a potential corrosion hazard. Chlorine will, when exposed to flame, precipitate
from the compound, usually freon or degreaser vapors, and go into solution with any
condensation that is present in the heat exchanger or associated parts. The result is
hydrochloric acid which readily attacks all metals including 300 grade stainless steel.
Care should be taken to separate these vapors from the combustion process. This may
be done by wise location of the furnace with regard to exhausters or prevailing wind
direction. Remember, chlorine is heavier than air. This fact should be kept in mind when
determining installation locations of heating equipment and building exhaust systems.