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Central Heating - Gas Not Firing Up

Postby carrspaints » Mon Feb 21, 2011 5:59 pm

This may be a duplicate but my previous posting hasn't appeared even after waiting a while.....Hoping for some advice. I have a gas fired central heating system that is operated by a Potterton EP2002 programmer. The valve used for the hot water or central heating is a Honeywell V4073A 3-port mid position valve.

The problem I have is that the boiler won't fire up. I have switched on both the central heating & hot water, the red LEDs on the Potterton programmer are orange which is how it should be. The pilot light is working but the system is not igniting the gas to fire up and heat the water.

I thought perhaps our Grundfos recir pump had gone but I have tested that and it works fine. There is power to the Potterton controller, the room thermostat is set to high, the pump definitely works when connected to 230volts and the gas pilot flame is burning merrily away..

So I'm guessing that either the Potterton controller is faulty, or the Honeywell V4073A valve is faulty.

My question is this, can a faulty Honeywell valve cause the system not to call for gas, or heating? I would have thought that even with a faulty valve, the recirc pump would still switch on, or that the gas would ignite to boil the water, even if only briefly?

Can anyone suggest what might me the issue? Many thanks.
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