Combi thumping noise on firing up!

stressedofdevon

My combi boiler has begun making a tremendous thumping noise when it fires up. Doesn't do it every time and no pattern to when it happens, but about 1/3 fire ups are a problem.

I am worried there is an underlying issue and things may suddenly give up. Has anyone had a similar problem? The hot water and radiators are all working fine at the moment.

I have no DIY experience whatsoever, bleeding the radiator is about my limit. Pressure in boiler is correct at 15 (?) but beyond that I don't have a clue.

Any advice please?

WestonDave

There are some clued up heating guys around so if you post the make and model of boiler, how long you've had it (or its been in if you moved in) you may get some useful advice. Without knowing what actual boiler it is, it will be hard to give specific advice.

Is it being allowed to get colder the times when it makes the noise - could be expansion noises which are probably OK. Alternatively if you get scaling then you can get banging noises as that expands at a different rate to the metal.

stressedofdevon

Thanks WestonDave. The boiler is an Ideal isar! It was in the house when I purchased it, so is about four years old and has been maintained regularly. We are a soft water area so don't have any problems caused by limescale.

Hopefully you are right that a heating guy may see this post and be able to advise. The noise is so loud it wakes you up at dawn when the heating kicks in, and gives you a shock at other times. I dread to think if it packs up altogether.

ormus

make sure the external condesate pipe is not iced up. very common right now!
and then check the pump is working ok.

stressedofdevon

ormus wrote: »

make sure the external condesate pipe is not iced up. very common right now!
and then check the pump is working ok.

Hmm, the place where all the steam vents from the boiler into the garden is all fine, no ice or obstructions and plenty of condensation coming out. Can't see any other outlets to do with the boiler, so am guessing this is not the issue.

Thanks for the suggestion though

deefadog

I think what ormus means is the small wipe pipe that comes out of the bottom of the boiler and goes into the drain pipe outside. I have a similar boiler and i have been geting the F/L flashing lights the past few weeks and this is what i have discovered is that it may be that pipe. I have not clean it out yet though.

Razor

You need to get an RGI out to check the ignition electrodes they are extremely prone to failure on the Isar (most parts are actually). If the explosive ignition continues you will have damage to the boiler.

stressedofdevon

Just thought I would update as it may help someone searching for answers in the future. RGI came and checked the boiler and the problem was with the ignition slow firing, too much of a gap between electrodes (?) and easily fixed with minimum hassle.

Hope this may help someone else to resolve a problem in the future.

Thanks all for your advice - at least I didn't look a total dummy when talking to the plumber.

elle45

This has happened to me!! Mine is an 'Ideal' About 18 months ago it sounded like it was backfiring!! Bloke came and said it was a carbon build up!! It has just started again, got warmfront out as warranty finishes tomorrow!! The guy took one look at my boiler (did not even take the front off) and said he was not touching it and phoned Ideal direct!! The guy on the other end said it could be a hundred and one reasons why its like that and could cost alot to rectify!! Basically what it came down to was Ideal are BAD and I should get a new boiler!! So I phoned Ideal myself and they are coming out on Saturday with a computer to diagnose what the fault is!! Under warranty cos I phoned today!! But I am fuming as they all tried to pass the buck to each other!!:mad:

arfurrrr

check ignition electrodes , gap may be too big , causing build up of gas and then explosive ignition . sometime you can bend them back , sometimes they snap/crack when trying . Call a RGI

bambibashercol

i agree check the electrodes, rgi job though.
i would then start saving for a new boiler as they are the most unreliable boiler ever manufactured.