Wiring Guide

C-2
6-446 — MODELS PDP/BDP TYPICAL SUMMER/WINTER SWITCH WIRING
Before proceeding with wiring the accessories described,
make sure the unit has been installed, vented piped and wired
according to the Installation/Service Manual and Standard Wiring
Diagram furnished with the unit heater.
CAUTION
Turn off all power and gas to unit before wiring. Failure to
wire this unit according to this wiring diagram may result in
injury to the installer or user. For deviations, contact factory.
1. Turn off gas and power supply to unit.
2. Determine which method of summer/winter control is desired, Figure 1, 2 or 3.
3. Wire unit according to the method selected. Note: If the method selected is as
described in Figure 3, the factory supplied buss bar between terminals "T2"
and "F" must be removed prior to wiring in thermostat and subbase.
4. Check wiring using the Check-Out Procedure.
Check-Out Procedure
With the power and gas supply turned off, set the thermostat to its lowest setting and
place the summer/winter switch to the winter position. After making these adjustments
proceed as follows:
1. Turn on gas and power supply to the unit. Nothing should happen.
2. Place the summer/winter switch in the summer position. The fan motor should start,
except when wired as shown in Figure 3. In that case, after a delay of
30 to 90 seconds, the fan motor should start.
3. While the summer/winter switch is still in the summer position, and with the fan motor
running, turn the thermostat up to call for heat. The power exhauster motor should
come on, the pressure switch should close, and the main burner should fire. Allow
burner to fire for 1 to 2 minutes.
4. Turn the thermostat down again. The main burner should shut off and the fan motor
should continue to run. During this step, allow the fan to run at least 90 seconds to
make sure it will continue running. Modine units are equipped with a time delay relay
and the motor will run 30 to 90 seconds after the time delay relay has been de-
energized.
5. After insuring that the fan motor will continue to run in the summer position, and with
the thermostat set to its lowest setting, place the summer/winter switch in the winter
position and wait for the time delay relay to turn the fan motor off.
6. After the fan motor has stopped, and with the summer/winter switch in the winter
position, turn the thermostat up to call for heat. The power exhauster motor should
come on, the pressure switch should close, the main burner should fire and after a
delay of 30 to 90 seconds, the fan motor should run.
If the above sequence of operation does not occur, recheck all wiring until the
necessary correction to the wiring is found and corrected. Set the thermostat to the
desired set point and place summer/winter switch in desired position. Unit is now ready
for use.
Robertshaw
CM260 T-Stat
w/ Subbase
System
Auto
Auto
Off
On
Fan
T1
C
V
F
G
To Thermostat
TD Relay
Terminals In Unit
J-Box
Terminal
Board
On J-Box
To Combination
Gas Control or
Ignition Control
T2
2
4
BK
Summer/
Winter Switch
Blue
or
Red
Figure 1
Typical Wiring – Summer/Winter Switch (Modine # 78727)
(24v Thermostat, 115v or 200/230v Summer/Winter Switch)
T1
C
V
F
G
To thermostat
Terminal
Board
On J-Box
To Combination
Gas Control or
Ignition Control
Relay
T2
2
4
Summer/Winter Switch
Relay By Others
(24v Relay Coil,
Line Volt Contacts)
TD Relay Terminals
In J-Box
Figure 2
Typical Wiring – Summer/Winter Switch (Modine # 78727)
(24v Thermostat, 24v Summer/Winter Switch)
T1
C
V
F
G
Terminal
Board
On J-Box
To Combination
Gas Control or
Ignition Control
Wire to Hot
Lead of Power
Exhauster
Motor
TD RelayTerminal
In J-Box
Relay By Others
(24v Relay Coil,
Line Volt Contact)
T2
Figure 3
Alternate Wiring Using Robertshaw CM260
Thermostat w/SB-3A-1 Subbase
(25v Thermostat and Subbase)
(Modine #79187 and #78785 respectively)
3
Relay
W
G
R