Drolet HeatPack DF00500 Installation And Operating Instructions Manual page 38

HeatPack Furnace Installation and Operation Manual
Step 2. From the thermostat connected to the existing furnace, connect 2 new wire (H)
on the Rh and W terminals of your thermostat and fix them to the terminal on the circuit
board labeled "I" (interlock) of the Add-On furnace.
When the wood furnace receives the signal from the existing furnace's thermostat calling
for heat, it will disconnect the existing furnace damper motor, sending the wood furnace in
low burn until the call for heat from that thermostat is satisfied.
After the existing furnace's thermostat is satisfied, the wood furnace will return under the
control of its own thermostat.
Use in thermostat mode
To ensure proper operation of the air inlet damper while connected to a thermostat, the
manual control switch must be maintained in the closed position. However, when a
thermostat is connected to the furnace, it is still possible to use the manual control switch
to open the air damper if desired. Even though you chose to control the furnace with a
thermostat it is still possible to use the manual control switch to open the air intake damper
if desired.
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