Glow Worm Ultimate boiler firing up but no CH or HW

If the boilers fires up, then what is it heating up? You say you've tried running HW and CH individually, so the actuator is working, if the boiler/flame starts. Find out what pipes are getting warm when the boiler starts, then reply back.

Pump?

Oh! One other thing to check.

Make sure the system is full of water, cold feed could be blocked. Have a look at the F&E (probably in the loft). Is there water there?

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Allan Mac wrote in news: snipped-for-privacy@c19g2000vbb.googlegr oups.com:

Agree on this. No pump. No circulation = no heating, no hot water.

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How long does the boiler run for before it cuts out on its own thermostat?

You've clearly got no circulation. Prime suspect has to be the pump but, as someone else has suggested, if the water level has dropped, you could have air locks.

Is is a vented system, with a small fill & expansion tank (in addition to the large header tank for the hot water system) in the attic. If so, make sure it's got 2 or 3 inches of water at the bottom and hasn't dried up. [This can happen if water is lost due to a leak - or evaporation - and then the ball valve fails to open to top it up].

If it's a non-vented (pressurised) system, with a pressure vessel and fill loop, make sure that it's running at the correct pressure.

In message , amarh writes

So where is the heat going?

The ultimate has no modulation valve, so it just pumps full heat into the heat exchanger. First thought would be that the pump has failed, but if the pump is not circulation the water, then the water in the HE would start boiling and you WOULD notice that unless its running dry

No such thing as a CORGI engineer - if he showed you his card, then it's out of date and he's breaking the law working on a boiler for financial reward