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UNIT HEATER
4.2 Gas Supply
The whole of the gas installation including the meter should be inspected, tested for soundness and
purged in accordance with local regulations.
It will be necessary to ensure that the air is fully purged from the heater inlet pipe up to the main gas
valve inlet test nipple before the start gas burner will ignite.
4.3 Mechanical checks
1. Check that the fan(s) are free to run and delivery louvres are turned to give required air deflection.
2. Check that the flue is installed in accordance with these instructions and local regulations.
3. Check that the Settings of the Combination Fan/Limit thermostat are correct - see below.
Note: The limit thermostat is preset and sealed at the works and will need no adjustment.
To set the combination fan/limit thermostat first remove the cover by releasing the cover fixing screw
and pulling off the cover. The three hands from left to right should be set approximately as follows
subject to site conditions:- See Fig. 2.8.
Front combination thermostat (All Models) Rear thermostat on CUHD ... Only
HAND 1 FAN OFF SET TO 38°C SET TO 30ºC
HAND 2 FAN ON SET TO 57°C SET TO 55ºC
HAND 3 LIMIT SET TO 95°C SET TO 90ºC
Always refit the cover and tighten the cover screw after adjustments.
To continue with the Commissioning follow 4.4 for Automatic Ignition models or 4.5 for Manual
Ignition models. Then continue with 4.6 for all appliance types
4.4 Automatic Ignition Unit Heaters
4.4.1 Carry Out a “Dry Run”
To ensure that all the controls are in safe working order it is advisable to operate the fully automatic
controls for the first time with no main gas.
To do this unplug the electrical plug from the main gas valves (there are two plugs for Nova automatic
valves). Now, using the installed external control turn on the burner.
The automatic sequence will now begin as described in Section 2. The electric ignition will be heard
and the spark may be observed via the gas inlet port in the rear panel.
The start gas flame will then ignite on the opening of the start gas valve. If the flame does not ignite
then the control will go to the “lockout” condition.Wait one minute, then press in the control box reset
button, or the remote reset button if fitted and repeat until the start gas flame ignites.
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