COMBAT CUHA - 4.5.2 Commissioning the Gas Valves - L.P.G.; Section 4.6 Commissioning Tests - All Heater Types

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UNIT HEATER
4.4.2 Commissioning the Gas Valves - Natural Gas
Depending on the model of the heater there will be an S.I.T Tandem valve, an S.I.T Nova valve or a
Johnson controls gas valve (see Data Table in Section 2 and Figs 4.1 to 4.4).
Connect a manometer to the outlet (burner) pressure test point of the gas valve after first removing its
screw cover.
To set the burner pressure remove the regulator cover 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 to allow correct burner setting 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.
To set the step opening adjustment, first turn off the burner at the external controls or unplug the
electrical connection to the main gas valve and wait for one minute for the valve to settle. Turn on the
burner again and as the main burner turns on set the step opening pressure to approximately 2.5 mbar.
As the step opening lasts for only a few seconds its setting may need to be checked two or three times
to ensure satisfactory starting of the main burner.
Following burner pressure adjustment, allow the heater to operate for at least 15 minutes and then re-
check settings. Remove the manometer and refit all covers to the valve.
Wherever possible a reading of the gas rate timed through the gas meter should be taken and compared
with the nominal rating in the Data Table, Section 2. The burner pressure should be adjusted to give
this nominal gas rate.
4.4.3 Commissioning the Gas Valves - L.P.G.
In all cases the gas valves for L.P.G either have no regulator or have the regulator put out of action (see
Section 10). The heater is therefore set on the inlet pressure to the gas valve which must be maintained
at 37 mbar (25 - 45) for G31 (Propane) or 29 mbar (20 - 35) for G30 (Butane).
Note: Although the appliances are tested to operate safely between the minimum and maximum pressures
shown, they are designed to give the correct heat input only at th especified inlet pressure.
No further adjustments are necessary.