Bloody boiler, and bloody useless insurance company

[Vipers]

I would also change from Direct Line to British Gas, they provide a better call out service, at least so far.

[Ferg]

Hmmmm... having read this again (properly) you say it's going out on the overheat? Manual reset? That means it's getting MUCH too hot.
This means that either the pump is failing to get heat away (pump failing, sludge, air) OR the control stat has failed allowing it to keep burning until overheat is reached. This would explain why your pressure is increasing so much, simply expansion. Try turning the control stat (on the boiler) right down and see if that is capable of turning the burner off.

Edited by Ferg on Friday 2nd April 10:09

[Rocksteadyeddie]

Ferg said:

Hmmmm... having read this again (properly) you say it's going out on the overheat? Manual reset? That means it's getting MUCH too hot.
This means that either the pump is failing to get heat away (pump failing, sludge, air) OR the control stat has failed allowing it to keep burning until overheat is reached. This would explain why your pressure is increasing so much, simply expansion. Try turning the control stat (on the boiler) right down and see if that is capable of turning the burner off.

Edited by Ferg on Friday 2nd April 10:09

Thanks Ferg. To expand (no pun intended) on what I said above. All the following is based on this morning. The pressure in the boiler when cold is 1.5 bar. The pressure in the expansion vessel is 1.5 bar. The red fault light is flashing. I turned it on this morning after reseting the fault button. The boiler fires fine and goes on its merry, if slightly noisy, way. It ran fine for about 5-10 minutes over which time the pressure rises to about 3 bar, and then trips itself out again. The expansion vessel is warm (but not hot) at the water end only and cold at the air end.

Given my knowledge of boilers (which is next to nothing) this does not sound like an expansion vessel issue - given it has air in it, its not all boiling as it would be with water in both ends, and the time in which it is tripping out. Not getting the heat away sounds much more likely. Any way of checking this / easy repairs that I would be able to try over a bank holiday weekend?

Thanks again for your time.

[Rocksteadyeddie]

Just tried again. The pump "appears" to be working, in that I can feel it spinning.
I only have the CH on, with the HW being heated by immersion.
Boiler fires. Lots of piping hot water comes out, through the motorised valve and up to the upstairs. First rad begins to get hot. Temperature starts to go up. The water coming back to, and through, the pump is warm (but not hot) as it would be having been pumped round a freezing cold system.
10 mins later the boiler trips again.

[Ricky_M]

Can you bleed some water out of the pump? What colour is it? Sounds like you may have a sludged up heat exchanger or possibly a blocked pipe leading to the expansion vessel.

[Rocksteadyeddie]

Ricky_M said:

Can you bleed some water out of the pump? What colour is it? Sounds like you may have a sludged up heat exchanger or possibly a blocked pipe leading to the expansion vessel.

OK, had the pump out and checked. The water was slightly dirty but not sludgey. I flushed it through, and it flushed through clear.

Have to wait for the system to cool before I can check the expansion vessel.

Edited by Rocksteadyeddie on Saturday 3rd April 18:56

[Rocksteadyeddie]

OK. I have changed the expansion vessel and the PRV. Expecting it to solve the problem - it hasn't....

Next stop power flush the boiler. Any better ideas?

[john_p]

I had a temperature sensor knocked off a pipe on my Worcester boiler by an incompetent engineer. This meant that the boiler would overheat and trip once CH was run for more than a few minutes. Is your sensor faulty or disconnected in some way?

[Rocksteadyeddie]

john_p said:

I had a temperature sensor knocked off a pipe on my Worcester boiler by an incompetent engineer. This meant that the boiler would overheat and trip once CH was run for more than a few minutes. Is your sensor faulty or disconnected in some way?

I don't think it has a temperature sensor, just a pressure sensor.

Thanks anyway.

[john_p]

It's worth checking, if you have a circuit diagram or can get one off the net ? On mine it's just after the heat exchanger on the primary circuit. I would have thought the pressure would change too much from installation to installation for it to be a reliable way of testing it's at the right temperature?

[Rocksteadyeddie]

So the boiler man finally came over the weekend. He had lots of probes and sensors and checked lots of things. He thought that the boiler housing seal had gone and was leaking heat and causing the issue. So he replaced the seal, and the old seal was indeed perished. The boiler all worked fine. 24 hours on and the problem is the same. He is suggesting that it is not worth spending any more money on, but can't diagnose what might be wrong with it. It is 4 years old for Christ's sake...

Any more suggestions chaps? Power clean the whole system? I am at a bit of a loss.

[Ricky_M]

Just remembered a similar job with the same boiler I think. There was no issue with pressure rising, but it did keep going into to overheat lockout.

Turned out that the combustion chamber had corroded badly and had a hole in it. Does it start with an explosive bang?

Sadly the one I mentioned was replaced by a Worcester Bosch as it was uneconomical to repair.

[Rocksteadyeddie]

Ricky_M said:

Just remembered a similar job with the same boiler I think. There was no issue with pressure rising, but it did keep going into to overheat lockout.

Turned out that the combustion chamber had corroded badly and had a hole in it. Does it start with an explosive bang?

Sadly the one I mentioned was replaced by a Worcester Bosch as it was uneconomical to repair.

It certainly starts with a "whoosh" but I don't really have a benchmark to judge it by. Surely the heating engineer would have spotted a hole in the combustion chamber?

[dirkgently]

Rocksteadyeddie said:

So the boiler man finally came over the weekend. He had lots of probes and sensors and checked lots of things. He thought that the boiler housing seal had gone and was leaking heat and causing the issue. So he replaced the seal, and the old seal was indeed perished. The boiler all worked fine. 24 hours on and the problem is the same. He is suggesting that it is not worth spending any more money on, but can't diagnose what might be wrong with it. It is 4 years old for Christ's sake...

Any more suggestions chaps? Power clean the whole system? I am at a bit of a loss.

Has the P.C.B been changed? If not change it and I believe your problems will disappear.
E&OE