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UNIT HEATER
7.4.4 Thermocouple
The thermocouple is fitted into the pilot burner body by pushing fully home against the shoulder and
then tightening the retaining nut to hand tight plus ¼ turn with a spanner.
The thermocouple must be bent gently into its original path being careful not to kink or crack it.
The valve end of the thermocouple is connected using the screw nut. This connection is an electrical
one and must be clean and without the use of compounds.
The Connecting nut must be screwed hand tight plus no more than ¼ turn with a spanner to create a
sound electrical connection.
7.4.5 Thermocouple Interrupter Relay
All manual ignition heaters are fitted with a thermocouple interrupter relay to interface between the
limit thermostats and the thermocouple. This relay is fully encapsulated and if faulty must be replaced
with the same type, as it specially produced to operate with burner thermocouples.
It is important that the 230v supply to the relay is provided from the specified terminals in the terminal
block, and that following replacement the operation of the limit thermostats is checked to ensure that
on operation the pilot is extinguished.
NO ATTEMPT SHOULD BE MADE TO OPERATE THE HEATER WITHOUT THIS RELAY.
FAILURE TO COMPLY WILL CAUSE A SEVERE FIRE HAZARD
7.5 CUHA Axial Fan/Guard/Motor Assembly
The Axial fan unit for the CUHA range of heaters is supplied completely assembled and balanced.
These components are not replaceable separately
7.5.1 To Remove the Fan Assembly:
Disconnect the electrical cables from the fan terminal box at the rear or side of the heater, carefully
noting the colour code of the wires to the fan.
Remove the four screws securing the fan guard to the heater carefully retaining the rubber washers.
7.5.2 To Replace the Fan Assembly:
To replace the fan assembly reverse the above procedure ensuring that the rubber washers are fitted to
the guard mountings to reduce vibration.
Check that the fan blades are free to rotate without catching before turning on the power to the fan.
It is also most important that the colour code of the fan wires is strictly observed to ensure correct
operation.
It is sound practice to replace the fan capacitor when changing a fan.
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