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8- COMMISSIONING OF GAS UNIT HEATERS
A precise engineering study must be carried out on the diameters of the piping depending on the nature of the gas
flow and the length of the piping.
Make sure that the pressure drops in the piping do not exceed 5 % of the supply pressure.
The gas connections must be carried out in conformity with the requirements concerning interior installations
regardless of the type of gas.
7-1 Connection of unit heaters
The unit heaters operate with a pressure of between 20 and 25 mBar for Natural gas and 37 mBar for the Propane
versions.
1/
The gas supply network pressure corresponds to the entry pressure of the device
:
- in this case, connect each device with a dam valve item 1 and the gas filter item 2.
2/
The gas supply network pressure is higher than the intake pressure of the device
:
- in this case, connect each device with a dam valve item 1, a gas filter item 2 and a pressure regulator item 2, to
reduce the supply pressure to the unit heater.
CAUTION Any supply pressure which is higher than the maximum intake pressure tolerated by the gas solenoid valve
will cause irreparable damage to that solenoid valve.
To connect the unit heater to the gas network, use the union item 4 with the seal item 5 delivered with the device.
Tighten the union onto the network before connecting it to the unit heater.
Check that the gas supply circuit is correctly sealed upto the gas solenoid valve.
(see schematic).
8-1 Operating principle:
1- For the commissioning of the device, turn the regulation to demand.
The inspection box tests the air pressure switch contact switch in its ‘at rest’ position, and then triggers the smoke
extractor. Its correct functioning is controlled by the differential air pressure switch which, if there is not enough air, will
prevent the control box from following its cycle.
2- After pre-ventilation, the ignition electrode lights up and the gas solenoid valve allows the gas to pass to the
injectors.
3- If the air/gas mixture is not ignited or is not detected by the ionisation sensor, the flame control box tries once more
and then changes to safety position.
4- Once the burner is ignited, the blowing fan is triggered when the air temperature is higher than the fan airstat
regulation value (35°C to 40°C).
5- In the case of a fan malfunctioning, the excess heat safety thermostat cuts off the unit heater burner if the
temperature exceeds 90 °C.
CAUTION :
Never stop the device before the fan has totally stopped. The lack of cooling can necessitate the excess
heating airstat to be reset and can damage the heat exchanger over the long term.
7- GAS CONNECTION
Check the sealing up to the gas solenoid valve input
4
5
1
2
3
Network
