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UNIT HEATER
2.4.2 Second Limit Thermostat
This is a manual reset device - see Figs. 2. 1 to 2.7.
Note: On CUHB and CUHC models 340 and 380 there are two of these fitted.
To reset this thermostat:
a) Remove the screw on cover of the thermostat where it protrudes from the cabinet side.
b) Push in the button in the centre of the thermostat. Note: the heat exchanger must be cooled to
allow this to happen.
c) Replace the cover.
Fan Thermostat
The fan thermostat controls the operation of the main fan during the heater operating cycle. This
control also ensures that the main fan continues to run after the burner turns off to dissipate the residual
heat from the heat exchanger.
The white button on the fan thermostat should be pulled to its “out” position for normal operation. In
the “pushed in” position the fan will run continuously. However, when connected to CD100 type
control consoles this feature is catered for by the fan on position of the control switch.
Limit Thermostat
The limit thermostat operates in overheat conditions caused by insufficient air passing over the heat
exchanger. This is a manual reset device and is reset by pressing in the red reset button on the thermostat.
Note the heat exchanger must have cooled to below the operating temperature for reset to be possible.
Fig. 2.8 Combination Fan/Limit Thermostat
WARNING: IT IS ESSENTIAL THAT THE BREAK OFF LINK SHOWN IS REMOVED
IN THE EVENT OF THERMOSTAT REPLACEMENT
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