COMBAT CUHA - Section 4.7 Combustion Testing - All Heater Types; Section 4.8 Pilot Drop-Out Test - Manual Ignition Models

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UNIT HEATER
4.5 Manual Ignition Unit Heaters
All CUH manual ignition unit heaters are controlled by an S.I.T Nova 0.820.054 multifunctional gas
valve (see Fig 4.3).
First remove the electrical plug from the multifunctional gas valve to ensure that main gas cannot be
released.
To ignite the pilot press in the manual control button of the gas valve and turn anticlockwise to the star
symbol. Press the button fully in and hold whilst continuously pressing and releasing the Piezo ignition
device to create the spark ignition.
Note: IF AT ANY TIME THE PILOT FAILS TO LIGHT OR GOES OUT, EITHER
INTENTIONALLY OR UNINTENTIONALLY, WAIT A FULL 3 MINUTES BEFORE
ATTEMPTING TO RELIGHT.
Once the pilot flame has been seen to light continue to hold in the control valve button for a further 30
seconds, and then release. The pilot flame should now remain on.
Should the pilot flame go out check that the limit thermostats have not operated and that there is an
electrical supply to the main terminal block. Also ensure that the leads to the thermocouple interrupter
relay are connected to their connections on the gas valve (see Fig 4.3). Observe the 3 minute waiting
time and retry.
Once the pilot flame has been established it will remain on constantly providing that the gas or electricity
supplies are not interrupted and the limit thermostats do not operate.
To Operate the Main Burner
Replace the electrical plug onto the gas valve. Press in slightly and turn the valve control knob a
further quarter turn anticlockwise to the "flame" symbol. With the external controls in an on position
and calling for heat the main burner will now fire
Connect a manometer to the outlet (burner) pressure test point of the gas valve after first removing its
screw cover (see Fig. 4.3).
To Set the Main Burner - Natural gas
To set the burner pressure remove the regulator cover screw and with the burner firing, turn the regulator
adjustment screw to set the required burner pressure as stated in the Data Tables in Section 2.
Note: If any difficulty is found in obtaining the correct burner pressure then check that there is a
sufficient inlet pressure available to the valve, with the burner firing.
Under no circumstances should a regulator be set to a pressure over that where the pressure is
no longer being changed.
If the inlet pressure is too low then the problem will be on the installation and must be corrected before
completing the commission. The inlet pressure must be 20mbar with the main burner firing.