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Form I-UDA, P/N 195673 R24, Page 16
Conned Space:
A space whose volume is
less than 50 cubic feet per
1000 BTUH of the installed
appliance input rating
Combustion Air
Requirements for a
Heater Located in
a Conned Space -
applies to Model UDAP
and Model UDAP-CV
FIGURE 11 - Denition
of Conned Space and
Required Openings for
Combustion Air
6.2 Combustion Air - Models UDAP and UDAP-CV
This heater must be supplied with the air that enters into the combustion process and is
then vented to the outdoors. Sufcient air must enter the equipment location to replace
that exhausted through the heater vent system. In the past, the inltration of outside air
assumed in heat loss calculations (one air change per hour) was assumed to be suf-
cient. However, current construction methods using more insulation, vapor barriers,
tighter tting and gasketed doors and windows, weather-stripping, and/or mechanical
exhaust fans may now require the introduction of outside air through wall openings or
ducts.
The requirements for combustion and ventilation air depend upon whether the unit is
located in a conned or unconned space. An “unconned space” is dened 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.
WARNING
Model UDAP and UDAP-CV power-vented unit heaters 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 ducts voids
the warranty and could cause hazardous operation. See Hazard
Levels, page 2.
Do not install a unit in a conned space without providing wall openings leading to and
from the space. Provide openings near the oor and ceiling for ventilation and air for
combustion as shown in FIGURE 11, depending on the combustion air source as noted
in Items 1, 2, and 3 below.
Add total BTUH of all appliances in the conned space and divide by gures below for
square inch free area size of each (top and bottom) opening.
(Note: For Model
UDAS, see
Venting Manual
for combustion air
requirements.)
1. Air from inside the building -- openings 1 square inch free area per 1000 BTUH.
Never less than 100 square inches of free area for each opening. See (1) in
FIGURE 11.
2. Air from outside through duct -- openings 1 square inch free area per 2000
BTUH. See (2) in FIGURE 11.
3. Air direct from outside -- openings 1 square inch free area per 4000 BTUH. See
(3) in FIGURE 11.
NOTE: For further details on supplying combustion air to a conned space, see the
National Fuel Gas Code ANSI Z223.1a (latest edition).
6.0 Mechanical
(cont’d)
7.1 General
All electrical wiring and connections, including electrical grounding MUST be made in
accordance with the National Electric Code ANSI/NFPA No. 70 (latest edition) or, in
Canada, with CSA Standard C22.1. In addition, the installer should be aware of any
local ordinances or gas company requirements that might apply.
CAUTION: If any of the original wire as supplied with the appliance must
be replaced, it must be replaced with wiring material having a temperature
rating of at least 105°C, except for limit control, ame rollout, and sensor
lead wires which must be 150°C. See Hazard Levels, page 2.
7.0 Electrical
Supply and
Wiring
CAUTION: Route
wires so that they do
not contact the ue
wrapper or venter
housing.
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