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CTU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL
26
Figure 12: Gas Valve for Heater (Models 75 - 115)
Regulator
(Under Cover)
Inlet Pressure
Gas Outlet
Outlet Pressure
Plug for
Main Gas Valve
Gas Inlet
Plug for
Main Safety
Gas Valve
11.4.2 Commissioning the Gas Valves (all gases)
11.4.2.1 Check Burner Gas Pressure
1. Loosen the screw cover of the outlet (burner)
pressure test point and connect a manometer.
2. With the burner firing, measure the pressure on
the manometer. To adjust the burner pressure,
remove the regulator cover from the valve and
turn the regulator adjustment screw to set the
required burner pressure as stated in the Tech
-
nical Data Tables for the correct gas and model
on Page 8, Section 4.4.
NOTE: If the correct burner pressure cannot be
reached, then check the inlet pressure to the valve,
with the burner firing. See Technical Data Tables
on
Page 8, Section 4.4 for inlet pressure requirement.
Do not continue to adjust the regulator if the
pressure is not changing.
If the inlet pressure is too low to allow correct burner
pressure setting, then the gas inlet pressure must be
corrected before completing the commission.
Check Gas Rate
1. After burner pressure adjustment, allow the
heater to operate for at least 15 minutes and
then re-check settings.
2. Remove the manometer and refit all covers to
the valve and tighten the screw of the outlet
pressure tap.
3. Check gas flow rate at gas meter.
11.5 Combustion Testing
The only adjustment to alter combustion
performance is burner pressure. Combustion quality
must be tested to prove correct heater operation.
Incorrect results will indicate faults with the
installation or appliance.
Combustion testing must be carried out with all
covers in place. The flue gas is sampled in the flue,
within 1 meter of the heater. The values of CO
2
should be between 6.5% to 8.0% for natural gas and
7.0% to 9.1% for LPG dependant upon model.
The CO will be up to 80 ppm (0.008%) dry, air free
dependant upon model. Temperature rise of the flue
gases above ambient should be approximately
160° C to 180° C. Seal test hole in flue after testing.
Pressure Switch:The pressure switch is factory pre-
set for each model and is not adjustable.
11.6 Turning Off the Heater
Set the external controls to the off position and the
main burner will stop.
The fans will run until they are stopped automatically
by the fan thermostat.
Do not use electrical isolator for control of
heater. Electrical isolator will switch off the fan.
Heat exchanger could be damaged. Warranty will
not cover damage to the heat exchanger if
operated improperly.