How Your Water Heater Works - Rheem HPHD-135HNU-483 Owner's Manual And Installation Instructions

HOW YOUR WATER HEATER WORKS

The commercial heat pump is an instantaneous type and
does not have an integral storage tank. The unit is de-
signed to be installed indoors or outdoors, model depen-
dent. The water heater's evaporator absorbs heat from the
surrounding air and transfers this heat into the water. A
circulator transfers the heated water to a bank of storage
tanks. The heat pump produces a sound level of up to 69
dBA (measured at 9.8 ft) when it is operating. The prin-
ciple of operation and sound level are similar to that of an
air conditioner.
When hot water is drawn off and cold water enters the
storage tanks, a remote thermostat activates the fan,
compressor and circulating pump of the water heater. Air
is drawn in through the inlet louvers on the side of the
water heater and then past the evaporator, where heat
is transferred from the air to a refrigerant fluid. The fluid
is compressed and passes to the condenser (heat ex-
changer) where heat is transferred into the water. The
pump circulates water from the bottom of the storage
tanks through the heat exchanger and the heated water is
circulated back into the storage tanks. The fan discharges
the cooled air through the fan grilles on the top of the
water heater. This process continues until the water in the
storage tanks reaches the set temperature.
Even on cold days, heat is drawn from the surrounding air.
The heat pump will operate most efficiently at tempera-
tures between a minimum of 41°F (5°C) and maximum of
113°F (45°C). The efficiency of the water heater is relative
to the surrounding air temperature and the incoming wa-
ter temperature.
Automatic safety controls are fitted to the water heater to
provide safe and efficient operation.
AUXILIARY BOOST OPERATION
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.
OPERATION AT LOW AMBIENT
TEMPERATURE
Ice may begin to form on the evaporator when the ambi-
ent air temperature falls below 45°F (7°C), and this will
reduce the heat pump efficiency. In this case, the heat
pump will use hot gas bypass to de-ice the evaporator
7
Commercial Air to Water Heat Pump Water Heater
coil. Should the ambient temperature continue to fall be-
low 41°F (5°C), the heat pump will enter Low Ambient
mode. The water heating system can be designed to op-
erate in one of two scenarios when ambient temperature
falls below 41°F (5°C).
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. Auxiliary heater will remain active until the
air temperature reaches 45°F (7°C).
OPERATION IN FAULT MODE
If fitted, the auxiliary booster will operate instead of the
heat pump if the heat pump is in fault.
For multiple heat pump (Primary/Secondary) configura-
tion, the auxiliary booster will operate instead of the heat
pumps if fifty percent (50%) or more heat pumps are in
fault.
The auxiliary boost will operate until the set temperature
is reached. The auxiliary boost should be set to 140°F
(60°C).
The auxiliary boost will remain active until the water heat-
er fault is cleared.
WARNING: Rheem nor its subsidiaries will
not be responsible for higher utility bills due
to excessive use of auxiliary boost heater. It
is the customers' responsibly to monitor the
system regularly for its correct operation.
We recommend monitoring via BMS (modules
supplied separately).
MAINS PRESSURE
The water heater is designed to operate at mains pres-
sure by connecting directly to the mains water supply. If
the mains supply pressure in your area exceeds, a pres-
sure limiting valve must be fitted.