Noisy boiler

15 Feb 2015
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United Kingdom
Hi I have a condensor boiler Gloworm Flexicom 18hxi, thermostat on boiler set to around 70 degrees.

I have found that when warming up from cold and the pump is starting fresh I see the temp on the boiler heat up rapidly until it reaches 48 degrees, the boiler then stops warming and turns off still displaying the temp.
Whilst it fires up you can often hear a bit of clanging.

Once it has tried to start once the main central heating pump upstairs is turning and remains on for 10-15 mins or so even though the boiler is off.

After 4-5 minutes of initially trying to fire up, the boiler then automatically restarts and fires up. Now the pump is already in action and not starting fresh the boiler works a dream and remains on for hours without problems. The pump seems to be working fine when in action and not to noisy.

So in summary the boiler works fine if the pump is already active, but seems to be noisy and clanging when starting fresh alongside a "cold" pump.

I have tried bleeding the radiators and the pump not alot of air in the system. At no point have any fault codes come on.

Would really appreciate your thoughts.

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This will be a circulation problem . And more than likely the main hex blocking up .
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