Rheem RUUD Iraining, Руководство пользователя

Страница: 13 / 29

Heat Pump Water Heater
12
Water Pump Flow Rates
Water pump operation will be allowed whenever the compressor or
electric heat is operational. The basic water pump motor will be a
single speed 240 volt AC motor. Water pump speed will be controlled
via the control board based on Triac motor voltage control. (Triacs
are widely used in AC power control applications. They are able to
switch high voltages and high levels of current, and over both parts of
an AC waveform. This makes triac circuits ideal for use in a variety of
applications where power switching is needed.)
The triac control will output full voltage for approximately 2 seconds to allow motor start-up
before the voltage to the motor is reduced. During compressor operation the water pump will
utilize at least two (2) stages of control. A low pumping rate (about 1 GPM) will be used when
the measured tank water temperature is 110º F or below or when the electric heat is operational.
A high pumping rate (about 3 GPM) will be used at all other tank water temperature conditions.
The water pump will remain energized for 30 seconds once the compressor is de-energized to
allow the residual hot water in the heat exchanger to be returned to the water tank.
Evaporator Fan Speed
The default fan speed is low. Low fan speed is obtained by power output to two fan leads (the
3
rd
lead is common). High speed operation is obtained by de-energizing the low speed fan lead.
Operational Safety Controls – all Modes
The following controls are utilized to provide reliable heat pump operation for all operational
Modes:
•
Thermistors will measure temperatures of both water and pressurized refrigerants during
the water heater cycle. For the first 90 seconds no operational control will be polled for
temperature values to prevent false reporting.
•
Compressor has an anti-short cycle timer of 120 seconds. If the compressor is shutdown
for any reason, it will not be able to restart for 120 seconds.
•
If the compressor suction temperature is below 37ºF, following the appropriate delays at
start-up or anytime thereafter, compressor operation is stopped.
This will prevent coil
freeze-up.
•
If compressor operation is stopped 3 times for suction temperatures below 37ºF,
compressor operation will be terminated for that run cycle. Once the run cycle is
terminated electric heat will be used to fulfill the water heating requirement. Compressor
operation will again be allowed.
•
If the compressor discharge temperature rises to 195ºF or higher, compressor operation is
terminated. Should this occur 3 times during a run cycle, compressor operation will be
terminated for that run cycle and electric heat will fulfill the operational requirements.