Commercial Air to Water Heat Pump Water Heater
57
AUTOMATIC DEFROST
The Rheem Commercial Heat Pump installation can be
configured in a number of ways depending on the require-
ments of the individual installation.
Ice may begin to form on the evaporator when the air tem-
perature falls below 45°F (7°C), and this will reduce the
heat pump efficiency. The water heating system can be
designed to operate in one of two scenarios in low ambi-
ent temperature conditions.
When auxiliary heating mode is OFF, the heat pump will
use hot gas bypass to melt any ice that may form on the
evaporator coil when operating at air temperatures below
41°F (5°C) and there will be no auxiliary boost.
When auxiliary heating mode is ON, the heat pump will
use hot gas bypass to melt any ice that may form on the
evaporator coil when operating at air temperatures below
41°F (5°C) and auxiliary gas or electric water heater will
be activated. A pump circulates water from the storage
tanks through the auxiliary water heater until the set tem-
perature is reached.
The auxiliary heater should be set to 140°F (60°C).
For most applications, automatic defrost should be satis-
factory to meet the water heating demands.
The water heater can control an auxiliary heating source if
the ambient temperature falls below 41°F (5°C) or if 50%
or more of the water heaters are in fault mode.
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