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Andrew Smith
Andrew Smith, Plumber
Category: Plumbing
Satisfied Customers: 3757
Experience:  City and Guilds qualified plumber
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I have a potterton 220CF boiler. A central heating timer switches

Customer Question

I have a potterton 220CF boiler. A central heating timer switches on either the DHW or the CH or both. If either the DHW or the CH or both are left on CONSTANT, there is no problem. But if I put the system onto the timed programme, then the pilot light seems to go out at some point during the off period, so that the boiler cannot re-ignite for the next on session. I have had a new thermocouple put in and the gas valve cleaned, but the problem remains.

After a year of this problem, the DHW gave up altogether, so I have recently had fitted a new DHW pump and a new DHW motorised valve in. The DHW works again, but still has to be on constant for the boiler to be reliable.
Submitted: 4 years ago.
Category: Plumbing
Expert:  Andrew Smith replied 4 years ago.

Andrew Smith :

This is strange, because even when on constant the boiler is not running all the time.

Andrew Smith :

You have done right, first I would change the thermocouple, then the gas valve.

Andrew Smith :

I would strip and clean out the pilot next and make sure the flame is large enough to sustain the flame