Set Appliance State:
Mains Power Off
Set Multimeter to AC Volts 
Turn Hot Water Tap On
Ensure appliance is cool at start of test
Set flow rate at hot tap to approx. 4ltr/min
CH Temp Selector min
DHW Temp Selector max
Set flow rate at hot tap to approx. 4ltr/min
CH Temp Selector min
DHW Temp Selector max
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Allow burner to ignite and appliance to run in DHW mode.
Monitor the AC voltage on the black and white wires to the
gas valve as the DHW heats and the demand is met.
Does the voltage decrease as the temperature demand is met?
Monitor the AC voltage on the black and white wires to the
gas valve as the DHW heats and the demand is met.
Does the voltage decrease as the temperature demand is met?
