- 6 -
5.3 C
ONNECTING
AND
A
DJUSTING
THE
L
OW
V
OLTAGE
T
HERMOSTAT
(Use only class 1 wires inside furnace compartments.)
Attach thermostat wires to the low voltage terminal block located on the inside of the furnace. Follow the diagrams supplied with the thermostat. As a
general guide, remember that the R & W terminals control single stage heating; the R & Y terminals control cooling. Single stage cooling uses “Y/Y2”
as first and only stage.Two-stage cooling uses “Y1” as first stage and “Y/Y2” as second stage. Make sure the thermostat is levelled on the wall and in
appropriate location as per instructions supplied with the thermostat.
Before turning the furnace on, the heat anticipator in the thermostat must be properly set.
CAUTION
Because each installation is different an accurate reading of the current draw should be made with an AC meter. Set the meter at 2 A range for
furnaces through 20 kW, and at 4 A range for larger units.
A. Set the anticipator at its highest setting.
B. Disconnect the “W1” thermostat wire from the furnace low voltage terminal connections.
C. Connect the AC meter between the “W1” terminal on the board and the loose “W1” wire.
D. Turn the thermostat up to start the furnace and allow it to run,with all elements on, for three or four minutes.
E. Read the current draw on the meter and reset the anticipator to match the meter reading.
6. U
SE
IN
M
OBILE
H
OMES
Models 21B10M, 21B15M, 21B18M & 21B20M are certified for “L”-shape
and “T”-shape shallow duct installation with model FSB-1 sub-base in
downflow applications when the supply air ducts pass through the floor
of the structure. Recommended size of a floor opening: 14¼” x 14¼”
(362 mm x 362 mm). The duct system must be designed so that the external
static pressure of the system does not exceed the maximum external static
pressure of 0.50” W.C. (125 Pa).
SHALLOW DUCT AREA REQUIREMENTS
D
UCT
D
EPTH
D
UCT
W
IDTH
4” (102 mm)
16” (406 mm)
5” (127 mm)
13” (330 mm)
6” (152 mm)
10” (254 mm)
5. I
NSTALLATION
N
OTES
5.1 C
OLD
A
IR
R
ETURN
The duct can be attached to either side, rear or the bottom of the furnace.
For side return there are four 1½” (38 mm) knockouts which can be removed and used as an outline for cutting a 18” x 18” (457 mm x 457 mm)
return air opening in the furnace left or right side. Mount the filter frame to the furnace over the opening with the open side of the frame facing front.
Then attach the 19” x 19” (483 mm x 483 mm) air duct to the flanges on the filter frame.
For bottom mounting, remove the screws holding the bottom plate to the furnace, discard the bottom plate and attach the filter frame to the bottom
flanges with the open side of the frame facing front.
5.2 E
LECTRICAL
W
IRING
- P
OWER
S
UPPLY
The furnaces are completely factory wired. From a separate breaker, a two-wire plus ground supply wire is required for single phase units, and a
three-wire plus ground supply wire for three phase units. The ground conductor must be firmly attached to the ground lug in the furnace and the supply
wires to the terminal block in the furnace.
NOTE: On single-phase furnaces, when a FK120 kit is used to supply an air cleaner and/or humidifier, a third (neutral) conductor must be brought
into the furnace.
WARNING
For all installations, we only recommend appropriate gauge good quality copper wire(s). However, it is the electrician’s
responsibility to ensure that the wiring and connections are compliant to the latest editions of the Canadian Electrical Code
and local codes.
