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UNIT HEATER
9.3.1 Burner Lockout Reset Button
This manual reset button which is built into the burner control box, and will illuminate the red warning
light on the elctrical terminal box when the control has gone to safety shut down ‘lockout’.
This may be caused by flame failure.
After lockout has occurred, a waiting time of one minute must be observed before an attempt to reset
the control is made by pressing in the reset button on the side of the heater.
Note: On some fully ducted heaters the fan will come on during the burner firing cycle and not wait for
the temperature rise. This is to ensure that there is always a proper operation of the heater under all
possible duct conditions.
When the remote controls turn off the heater, the burner turns off immediately leaving the fan(s) to run
on to cool the heat exchanger. When cooled sufficiently the fan thermostat will turn off the fan(s).
9.2.1 Combination Fan/Limit Thermosatat
This is located on the top right hand side of the heater, see Fig.1.1.
This control ensures the heater does not blow cold air in the normal heating cycle and protects the heat
exchanger against overheating.
Fan Thermostat (White Button)
Although it should not be necessary for the user to touch this control, it is worth noting that pressing in
the White button on the combination fan limit thermostat causes the main fan(s) to run continuously.
For normal operation this button should be pulled to the out position.
Limit Thermostat (Red Button)
If for any reason the main fan should fail or the air flow is reduced the built in limit thermostat will
cause the burner to go to safety shut down ‘lockout’. This condition will persist until the fault is
corrected and the red manual reset button is operated. The combination fan/limit thermostat is preset
during commissioning (see 4.3). Note: the heat exchanger must have cooled for reset to be possible.
9.2.2 Secondary Limit Thermostat
There is also a secondary limit thermostat situated on the heater side panel at the rear.There are two of
these thermostats on models 340 and 380 which are sited on the rear panel below the fans. These are
hand reset devices designed to fail safe and give further protection against fan failure. To reset this
thermostat unscrew the plastic cover and press in the central reset button.
Note: the heat exchanger must have cooled for reset to be possible.
9.2 User Controls Common to All Versions
9.3 User Controls Automatic Ignition Versions
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