RC845 Manuals


RC845 - Installation Instructions
Heat Pump Add-On Fossil Fuel Relay
RC845
Application
• RC845 red wire must be connected to the fan side.
Connect the RC845 low voltage terminals W, G and C to the
The RC845 is designed to control either a gas, oil furnace burner or
corresponding terminals on the heat pump thermostat.
an electric furnace as well as the fan when adding a heat pump on
Connect the RC845 Auxiliary Heat dry contact outputs (T, T) to:
an existing heating system.
• oil burner terminals T and T; or
The RC845 includes a low voltage dry contact output to activate the
• gas control terminals TH and TH; or
auxiliary heating system, and a line voltage contact output to control
• electric heat furnace terminals R and W.
the fan operation.
Once mounting and wiring have been completed, return power
When installed with an Aube heat pump thermostat (TH144HP), the
installer can configure the auxiliary heat sequence to turn OFF the
to the heating system and proof installation. 
compressor (Y) on a cal  for auxiliary heat.
To proof installation, select the Emergency Heat mode on your
The RC845 combined with the TH144HP thermostat offers a
thermostat. Increase the thermostat setpoint to activate the
complete integrated solution that simplifies installation and provides
auxiliary heating system. 
proper equipment operation.
Allow system operation long enough to proof relay operation.
Once installation has been proofed, disable the Emergency
Instal ation
Heat mode and define setpoint for normal operation.
Operating Sequence
All wiring must comply with national and local electrical
code regulations. 
Installation should be carried out by an electrician. 

On a call for heat or cool, the heat pump thermostat (TH144HP)
Disconnect power supply before installing the relay to
activates the G terminal; the RC845 activates the fan.
prevent electrical shock. 
When auxiliary heat is required, the heat pump thermostat activates
Secure relay in or on the electrical enclosure using the
the W terminal; the RC845 dry contact outputs T, T closes to
provided lock-nut (see Figure 1).
activate the auxiliary heat system.
Wire the RC845 line voltage side as per Figure 2. The line
NOTE: The RC845 line voltage contact is connected in parallel with
voltage contact must be connected in parallel with the Plenum
the furnace fan and limit controller (fan side). When the thermostat
setpoint has been reached, the fan may continue to run until the fan

Thermostat, usually known as the Fan and Limit Controller (fan
and limit controller setpoint is reached. 
side). Connect as follows:
• RC845 black wire must be connected to L1 (hot).
FIGURE 1
FIGURE 2
Installation on the side of
an electrical box
1/2
400-277-000-B


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