Installation manual

7
5 SERIES 500RO11 INSTALLATION MANUAL
Dual Fuel Systems
5 Series units can be connected to fossil fuel furnaces that
include an A-coil or slab coil. Dual fuel installations utilize
the 5 Series heat pump for heating until the point that
auxiliary heat is called for on the thermostat. At that point,
the furnace will be enabled and the heat pump will be
disabled. The 5 Series heat pump provides air conditioning
through the furnace’s refrigerant coils.
Refer to the furnace manufacturer’s installation manual
for the furnace installation, wiring and coil insertion. A
WaterFurnace Dual Fuel thermostat or a field-installed
DPST relay is required. See the Typical Split System Heat
Pump Coil Add-on Fossil Fuel Furnace illustration for
typical Dual Fuel application.
Thermostat
Wire From Furnace
Wire To
Thermostat
Up-Flow
Fossil Fuel
Furnace
Condensate
Drain
(must be trapped)
"A" or
Slab Coil
Supply Duct
Insulated
Suction Line
Return
Duct
Lineset To Air Handler
Disconnect
Typical Split System Heat Pump Coil
Add-on Fossil Fuel Furnace
In add-on 5 Series Split applications, the coil should
be located in the supply side of the furnace to avoid
condensation damage to the furnace heat exchanger. A
high temperature limit should be installed upstream of the
coil to de-energize the compressor whenever the furnace
is operating. Without this switch, the 5 Series Split will trip
out on high pressure. A dual fuel thermostat can remove
the Y1 and Y2 calls when a W call is energized to allow gas
furnace backup on a 5 Series Split application. Refer to the
Thermostat Wiring section for details.
General Installation Information cont.