heating and boiler problems – lovekin.net
We found 230V present but the solenoid wasn’t operating, so we knew we had a failed gas valve (multifunctional gas control). You can normally hear the solenoid give a sharp click or clunk when the voltage is applied across the terminals. This is the solenoid valve opening to allow gas to pass to the main burner where it would be lit by the pilot flame.
We fitted a new Honeywell V4600C gas valve, checked the burner pressure was within normal range and ran a combustion analysis on the boiler. Everything checked out correctly with the boiler working fine.
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We found the pilot present and a normal shape and size so eliminated thermocouple problems or a problem with gas supply. We could hear the old electro-mechanical time clock running on the wall beside the boiler so we eliminated the possibility of a blown fuse in the main isolating switch for the heating circuit.
We tested for power on the flex to the gas valve using a non-contact "Volt stick" (Fluke VoltAlert 1AC-E II) and found power present. This does not prove a complete circuit as it does not check the Neutral return so we used a multimeter set at 750V AC to check between Live and Neutral at the gas valve solenoid.
Honeywell V4600C gas valve (also called a multifunctional gas control)