gledhill Torrent GreenHeat TGH140-OV Design, Installation & Servicing Instructions page 42

SERVICING AND MAINTENANCE
The Torrent GreenHeat printed circuit control board/display has been designed to
be fully automatic whilst able to provide functional and diagnostic information to
the householder/installer.
The board works in conjunction with a number of sensors (thermistors) located as
shown in the diagram below.
Automatic Control Operation
The hot water temperature is controlled by sensors on the cold mains pipe to the plate
heat exchanger and the domestic hot water outlet from the plate heat exchanger.
The cold mains sensor checks for a drop in temperature every second and if the drop
is more than 2ºC, it switches on the hot water pump to raise the domestic hot water
temperature to 52ºC (± 2°C).
The control of the hot water temperature is carried out by sensor on the domestic
hot water outlet, adjusting the speed of the hot water pump.
The pump is stopped once the cold feed sensor reaches a temperature of above 30°C.
The following checks should be carried out by the installer before calling the manufacturer.
Noise When Hot Water Tap Is Opened/closed
If the plate heat exchanger pump is noisy when the hot water tap is opened, then
check the level of water in the F & E cistern and vent the pump if necessary.
Water hammer - loose pipework and/or tap washers and/or washing machine valves.
Causes of 'Unsatisfactory Hot Water Service'
See table opposite.
Overfl ow from Feed and Expansion Cistern
Check that the controlled level of water in the cistern is at the correct level. Adjust if
required and check the ballvalve is shutting off the water supply.
FAULT FINDING
Domestic Hot Water
Store Sensor
Hot Water
Sensor
Cold Water
Sensor
Page 42
Fault Condition Possible Causes
- Thermal store is cold/DHW
pump is permanently stuck
- Temperature sensor or
DHW temperature
printed circuit control
remains cold
exiting the taps. board is faulty.
- The water level is low in the
F&E Cistern
DHW temperature - DHW pump keeps sticking
fl uctuates wildly intermittently
when fl ow is - Hot & cold crossed at
steady appliance.
- DHW printed circuit control
DHW temperature board and/or temperature
exceeds and sensor is/are faulty.
remains well above - Immersion heater
60°C when the thermostat temperature
fl ow rate is low. setting too high should
be 70°C.
- Other heat sources failed
- Incorrect plumbing
arrangement
- No power supplies/fuses
Store not heating
are blown.
- Overheat stat has tripped.
- One or both immersion
heaters have failed.