Set Appliance State:
Set Multimeter to DC Volts 
CH Demand
Isolate Mains Power to appliance as per TOPs P4
On/Off Switch in ON position
Mode Selector Switch to Constant
C/H Thermostat to MAX
Connect a U-Gauge to the Gas Valve outlet pressure point
On/Off Switch in ON position
Mode Selector Switch to Constant
C/H Thermostat to MAX
Connect a U-Gauge to the Gas Valve outlet pressure point
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Measure DC Voltage across terminals P1 (Pink) and 1 (Red) on the C/H Thermostat.
Is the voltage measured greater than 1V DC?
NOTE:
Max Heating Rate Potentiometer (located on the main PCB) must be turned to MAXIMUM. If adjustment necessary, please note setting before adjusting the heating rate potentiometer and corresponding burner gas pressure.
After the test, adjust the potentiometer to provide original burner pressure.
Note:
When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.
Is the voltage measured greater than 1V DC?
NOTE:
Max Heating Rate Potentiometer (located on the main PCB) must be turned to MAXIMUM. If adjustment necessary, please note setting before adjusting the heating rate potentiometer and corresponding burner gas pressure.
After the test, adjust the potentiometer to provide original burner pressure.
Note:
When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.
Isolate as per TOPs P4
and refit as necessary