Bloody boiler, and bloody useless insurance company

[Rocksteadyeddie]

My boiler has stopped working. More specifically it will run for a little, the pressure gauge will increase into the red after about 20 minutes. The safety lockout will trip, and the boiler will turn off. Once it has cooled down it can be reset and you can repeat the process. With two small kids this is far from ideal.

I called my insurance company who look after the boiler, heating, plumbing etc on their direct line. It turns out that they are utter st and can't / won't get anyone out until tomorrow - despite my remonstrations with them about having small children, and no heating.

Has anyone got any ideas of simple things I might be able to try to sort it out ?

Thanks chaps.

[Rocksteadyeddie]

It is a Baxi 100HE boiler but not a combi. It is rigged up to a megaflow if that makes a difference? The gauge is definitely a pressure gauge and the red bit is when the pressure goes above 3 bar. Does that makes sense and/or help at all?

[Rocksteadyeddie]

Ferg said:

Sounds like the pressure vessel is fuggered. No-one's going to have one with them, I wouldn't imagine.

Worth bothering to recharge it?

[Rocksteadyeddie]

Checked the pressure. Seems fine. Reading about 1 and a bit Bar. Any other ideas?

[Rocksteadyeddie]

Good point. It may have had some residual pressure in it. Which presumably would just give the same reading from the pressure vessel?

[Rocksteadyeddie]

munroman said:

Is it the kids complaining of the cold, or maybe someone else, of the female type persuasion?

[Rocksteadyeddie]

Ricky_M said:

If its anything like the Baxi 105 combi, it will most definitely need replacing, quite a common fault on the 105 and a pig of a job to replace as most of the time, the boiler has to come off the wall.

Do you have space around the boiler? Will be a lot easier to have an external expansion vessel fitted next to the boiler, rather than replace the original one.

Plenty of space around it and easy to get to the expansion vessel if necessary. We shall see when the man turns up in the morning....

[Rocksteadyeddie]

Hereward said:

Expansion vessel - when you pressed the valve did it hiss air or leak water?

If it hissed air then that is encouraging - turn the boiler off and use a bike pump to replenish the air. You should really do this with the system drained down and open to atmospheric pressure, but I never bothered (I had an early Baxi Barcelona ). Pumping in air if the system is not drained down will raise the pressure so keep an eye on the gauge and drain off some water at a radiator to keep pressure between 1 and 1.5 bar. If you've pumped enough air into the EV then this should sort you out or at least buy you some time.

If it leaked water when you pressed the valve then it is bust and you need a new EV.

Edited by Hereward on Sunday 28th March 21:21

Air. And air at a decent pressure. Thanks for the tips.

[Rocksteadyeddie]

I have been away all week and the insurance company are refusing to cover the boiler as I do not have a certificate of servicing in the last 12 months. Tried the pressure in the expansion vessel this morning and it is about 1.5 bar and air coming out.

Ricky, the talked about the diaphragm on the diverter valve. Any way I can check this?

Thanks

[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.

[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?

[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.

[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.

[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?