Operation - Rheem 310 Series Service Instructions Manual

Operation

Operation – Water System:
The heat pump utilises a form of heating called 'top down' heating.
The circulator (1) draws cooler water from the bottom of the cylinder
via the long dropper tube (2). The water passes through the heat
exchanger (condenser) (3) where it is heated by the refrigerant and is
then returned to the top of the cylinder via a short dropper tube (4).
Operation – Heat Pump Mode:
During normal operation in 'heat pump' mode the electronic controller
(control board) holds a control relay in the energised state and power
for the compressor is passed to an electronic switch (called a triac) via
the normally open relay contact.
The operation of the compressor causes a pressure difference within
the sealed refrigeration system. This pressure difference causes the
refrigerant to move around the sealed system. The refrigerant enters
the evaporator (5) as a liquid, as the refrigerant absorbs heat from the
atmosphere it changes state, at low pressure, from a sub cooled liquid
to a super heated vapour or gas (evaporates). The vapour then enters
the compressor (6) and obtains more heat, known as heat of
compression, and passes into the heat exchanger as a super heated
vapour at high pressure.
As the refrigerant passes through the heat exchanger it gives off
heat which is absorbed by the water flowing through a separate
chamber inside the heat exchanger. As the refrigerant gives off
heat it cools and changes state back into a liquid (condenses). The
refrigerant then enters the evaporator again and the cycle is
repeated.
Operation – Boost Mode:
The controller will enter 'boost' mode when atmospheric conditions are unsuitable for heat
pump operation or a possible failure of the refrigeration or water circuits has been
detected. The following error conditions will initiate boost mode:
1. The temperature sensed by the ambient air sensor is below 0°C.
2. The water leaving the heat exchanger is greater than 80°C.
3. The compressor discharge temperature is greater than 110°C.
4. The evaporator temperature is less than -3°C.
5. The failure of sensors S3, S4 or S5.
6. The compressor is not running based on either of the following conditions:
a. After 2 minutes in controller sequence 3 the compressor discharge temperature has
not risen 15°C above ambient.
b. In controller sequence 4 the water temperature rise across the heat exchanger
(condenser) is less than 8°C.
In boost mode the electronic controller continues to control the temperature of the water in
the cylinder and the circulator however the control relay is de-energised switching the
power supply from the compressor triac to the element.
TM025 Rheem Heat Pump Service Instructions REV: B
Date of Issue: 02/08/07
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