Cracking noise coming vaillant ecotech plus 415 after servicing (Ed.)

[confused56789]

Hi
I have a conventional boiler (non combi) with flue coming out the top and then going out through the wall.

A couple of weeks ago I had a gas engineer service my boiler as part of my boiler cover. It was identified that a couple of seals/gaskets needed replacing and these were replaced a few days later. Since then I have been hearing a noise and have just realised tonight that is coming from top of boiler around area of flue I think. Not sure if it's just a coincidence that is started after these seals were replaced.

The noise happens intermittently when the boiler is cycling and can happen a few times after each cycle too.

If its something expansion/contraction related I don't understand how it has never happened in all the years we've lived here.

Totally stumped what it is and it's really annoying loud sound
I've tried to upload a 10 second mp4 file of the sound but it's not letting me do so

The sound is a singular loud crack type noise. Similar to the sound of a flap slamming shut

 

[BlueLoo]

.

 

[confused56789]

I will call in the morning. Trouble is, in the past they have refused to come out for 'noises' and i have an excess on my policy that I need to pay for them to come out.
The noise is getting ridiculous. Happens every 30 seconds while the boiler is firing and goes on for a few minutes after it goes off too

 

[muggles]

And the make & model is........?

 

[confused56789]

It's a vaillant ecotech plus 415

 

[confused56789]

They have just been to look and said its the heat exchanger expanding and contracting. So nothing can be done. Really ****ed off as it never made this noise before they replaced the burner seal and now it constantly making loud cracking noises

 

[ianmcd]

Call your so called boiler insurance company and tell them you are getting Vaillant out on a fixed price repar and if they find a fault they have to refund you the cost of the visit, they will soon sort it then, I know what is wrong but cant give gas advice on this part of the forum

 

[confused56789]

Please give me a clue as the noise is driving me round the bend. Could it possibly be anything to do with the way the nuts have been tightened up on the front of the heat exchanger?

 

[Gasguru]

Did they put the grease around the burner threads and mating faces?
It was supplied in a sachet along with the graphite burner seal. unless that changed.

 

[confused56789]

I don't know. I know it was a gasket kit 0020038679 and electrode kit 0020153950 that was fitted. That's all.
He checked the bolts when he came earlier and they were all done up correctly

 

[Gasguru]

The noise may be due to the differing expansion rates of the stainless steel front of the heat exchanger and the aluminium burner manifold that bolts to it....the grease alleviates the problem.

 

[confused56789]

Thanks. My insurance is through domestic and General who use a 3rd party heating company. The 3rd party company have said they can't do anything about it and to call my insurer. But that's pointless as they will just charge me an excess to send someone out who will probably say the same thing. They will probably refuse to send someone out anyway as its a noise, not a fault

 

[confused56789]

Well I've called and they are sending out an engineer from a different company that they use, so hopefully they will be able to sort it, but not holding my breath

 

[confused56789]

@ianmcd I PMd You earlier. Would be really grateful if you could let me know before they come out tomorrow. Thanks in advance

 

[ianmcd]

@ianmcd I PMd You earlier. Would be really grateful if you could let me know before they come out tomorrow. Thanks in advance

Sorry been out all day , I have answered you