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General Requirements and Specifications
CAUTION
This unit must be installed in a dry place, in a non-corrosive, well-ventilated environment, without excessive dust.
The ambient temperatue must be over 10°C and under 27°C. If the ambient temperatue is 10°C or less, the plenum
must be insulated on 10 ft linear minimum length.
1. LOCATION – The furnace should be centrally located to the heating area.
2. POSITIONS – It can be installed for vertical, horizontal or downflow operation. When installed horizontally, the
furnace should be positioned such as the door will not end up being on the top. The door should be on the side of
the furnace, to ensure that the motor bearings are in their designed position. In vertical downflow installations, use
only “L”- or “T”-shaped plenum with no openings or registers directly below furnace.
3. INSTALLATION CLEARANCES – As shipped from the factory, each unit is approved for “zero inch” clearance. If
additional clearance is required, it will be indicated on the data label attached to the furnace.
4. TEMPERATURE RISE – Furnaces are shipped to operate at 0.20” W.C. (50 Pa) external static pressure. They are
certified for operation up to 0.50” W.C. (125 Pa). Check below for temperature rise table on specification chart and,
if necessary, adjust the unit to match.
5. SERVICE CLEARANCE – Units are serviced from the FRONT. Leave at least 24” (610 mm) clearance in front of
the door.
240 VOLTS - SINGLE PHASE
TEMPERATURE RISE
@ 0.20" W.C.
MODEL NO.
KW
BTUH
AMPS INCL. MOTOR
HP
°C
°F
SPEED*
21D10
10
34121
46
1/3
18
32
LOW
21D15
15
51182
67
1/3
21
38
MED
21D18**
18
61419
77
1/3
25
46
MED
21D20**
20
68243
86
1/3
28
51
MED
21D23**
23
78479
97
1/3
33
59
MED
21D25**
25
85304
107
1/3
35
64
MED
STATIC PRESSURE
FLOW
(INCHES OF WATER COLUMN)
SPEED
RATE
0.2
0.3
0.4
0.5
0.6
LOW
CFM
980
950
925
905
880
L/s
462
448
436
427
415
MED
CFM
1240
1220
1190
1165
1135
L/s
585
576
562
550
536
HIGH
CFM
1420
1395
1360
1330
1280
L/s
670
658
642
628
604
WARNING:
* FACTORY SETTINGS.
** These models must NOT be setup to run continuously at LOW speed as it will cause overheating conditions. These
models are certified to run only at HIGH and MED speeds.
SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE
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