Reznor SHH (Indoor PreevA) Unit Installation Manual - Manual (Page 22)

Form I-PDH/SDH/PEH/SHH/PXH, Page 22
Confined Space:
A space whose
volume is less than
50 cubic feet per 1000
BTUH of the installed
appliance input rating.
FIGURE 14 - Definition
of Confined Space and
Required Openings for
Combustion Air
(3)
(3)
(1)
(1)
(2)
(2)
Confined
Space
6.4 Unit Inlet Air
(Supply Air)
FIGURE 15 - Optional Inlet Air Duct Flange
on the Blower Cabinet, Option AR5
X
Blower Cabinet
Inlet Air Opening
with Duct Flange
Option AR5 Y
3/4”(19mm) 3/4”(19mm)
3/4”
(19mm)
3/4”
(19mm)
TABLE 12 - Dimensions of Optional Inlet Air Duct Flange
PDH/SDH PEH SHH PXH X Y
75/100
10A/ 20A/
40A
N/A 000A
inches 24-1/2 25-1/16
mm 622 636
125/150
15B/30B/
60B
N/A 000B
inches 34-1/2 25-1/16
mm 876 636
175/200/
225
N/A 130/180 000C
inches 24-1/2 37-5/16
mm 622 948
250/ 300 30D/ 60D/
90D/120D
260 000D
inches 40-3/4 37-5/16
mm 1035 948
350/400A 40E/80E/
120E
350 000E
inches 48-3/4 37-5/16
mm 1238 948
Combustion Air Requirements for a Heater Located in a Confined Space
Do not install a PDH 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 14, depending on the combustion air source
as noted in Items 1, 2, and 3 below.
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
14.
2. Air from outside through duct -- openings 1 square inch free area per 2000
BTUH. See (2) in FIGURE 14.
3. Air direct from outside -- openings 1 square inch free area per 4000 BTUH. See
(3) in FIGURE 14.
NOTE: For further details on supplying combustion air to a confined space, see the
National Fuel Gas Code NFPA54/ANSI Z223.1 (latest edition).
6.0 Mechanical
(cont’d)
WARNING
Model PDH power-vented 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.
Depending on the Model and how the unit was ordered, the blower can have a variety
of factory-installed inlets. The cabinet end can be full open with or without a screen;
the cabinet end can have a duct flange for attaching inlet air ductwork; or the cabinet
end can have a two-position damper with duct flange. If filters were ordered, the inlet
will have a filter rack with filters.
Or, the unit can have an attached combination of modules including a mixing box with
either one or two inlets with duct flanges and a variety of controls, a cooling coil mod-
ule, and/or an evaporative cooling module.
6.4.1 Optional Inlet
Duct Flange (factory
installed), Option AR5
Dimensions for attaching ductwork are shown in TABLE 12. The optional duct flange
is 1-1/2” (38mm) long with a 3/4” (19mm) wide flange on all sides. The inlet air duct
should be attached and sealed. Ductwork must have a free area equal to the duct con-
nection.
6.3 Combustion Air
Requirements
(cont’d) - Model
PDH