Electronic Controller - Rheem 310 Series Service Instructions Manual

Boost mode allows 220 litres of 60ºC hot water to be provided by electric boosting. During
this mode the circulator will cycle on and off periodically allowing for the 220 litre boost
capacity rather than just the amount of water above the element as is the case with a
conventional electric boost system.
Once a heating cycle is completed the error is cleared and normal operation is resumed on
the next call for heat.
Note: If sensor S4 fails the system will operate on boost mode however the temperature
will in this case be controlled by the mechanical thermostat and 220 litres of 70ºC water
will be available.
Operation – Limp Mode:
Limp mode will only occur due to the failure of both sensors S1 and S4.
In limp mode the electronic controller no longer controls the operation of the heat pump
and both 'heat pump' mode and 'boost' mode are rendered inoperable. The control relay is
de-energised switching the power supply from the compressor triac to the element.
Limp mode allows 111 litres of hot water to be provided by electric boosting and the water
temperature is controlled by the mechanical thermostat which is set to 70°C; in this
condition only the water in the zone above the element is heated as the circulator does not
operate.
It should be noted that if sensor S1 fails and sensor S4 is operational the system operates
in boost mode however the circulator cannot operate. In this case the end result is an
operation similar to limp mode in which 111 litres of water is heated by the booster and the
temperature controlled to 70ºC by the Robertshaw thermostat.

Electronic Controller

The main features of the electronic controller
(control board) are shown on the diagram opposite.
The inputs to the software are shown in blue and
the outputs that control the heat pump are shown in
red.
The connection marked "relay element" energises
or de-energises a relay that switches from heat
pump heating to electric element heating when the
system operates in "boost" or "limp" mode.
The "Compressor TRIAC" switches the power to the
compressor on and off.
The "Communication port" can be used in
conjunction with a computer to read the inputs and
outputs from the software. This information may be
logged using specially designed logging software
(Contact Rheem Service for more information
regarding this software).
The "Software loading port" is only used for loading
software on to the control board.
The green and red LED's indicate the condition of
the heat pump (refer to the section titled "LED
Indication" on page 12).
TM025 Rheem Heat Pump Service Instructions REV: B
5
Date of Issue: 02/08/07
This document is stored and maintained electronically by Service. All printed copies not bearing this statement in RED are deemed "uncontrolled".