Valiant Combi Water Pressure

[Tony13]

I have a valiant combi boiler. The heating circuit keeps losing pressure over a 2-3 hour period. This only started today. I have looked around the house for obvious signs of a leak but there are none.

Is it possible for a boiler malfunction to cause the loss of pressure or can it only be a leak?

If it is a leak any tips on trying to locate it?

 

[landyandy]

Have you checked the pressure relief valve?

 

[Tony13]

The boiler is off at the moment as I did think it may be the PRV, however the pressure is still dropping although slowly.

How do I check / reset the PRV?

 

[landyandy]

The prv should be terminated outside.

You could try tying a plastic bag under it.

In the boiler and central heating faqs there is an explination. Faqs 18.

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