Vaillant boiler 'howling' noises

[zeushermes]

A Vaillant 'EcoMax Pro 18E' Condensing Boiler, installed 18 months back, has begun to make a horrendous howling noise when starting up from cold. Initially, HW is called for and there is no noise. However, half an hour later when CH is called for, the howling starts and continues for about 5 mins. All is then ok until the next programmed period starts it up again. Vaillant's Service Engineers have changed both Burner & Heat Exchanger without success and have given up (in spite of a 2yr warranty) blaming the water condition and suggest the system needs the inevitable 'power flush'. Before embarking on that, I wondered if anyone may have come across the problem and have other suggestions.

 

[andsam]

Why not get a magna clean installed on the return. This should collect the dirt ( if there is any ).

I have found that adjusting the systems by-pass can have an effect on the boiler performance and noise.

I am assuming he's checked the obvious things like gas air ratio and gas pressure.

Andsam.

 

[ChrisR]

Did the new hex improve it? If it were dirty water doing it, that's practically the only wet part!

What I would do - though I haven't tried this or thought about it much - is try partly closing the flow valve (use a small spanner) and see if it makes an immediate effect. If the problem is do do with the water flow it will, but if it's to do with the burner/fan, it won't. Then open it fully.

Next, do the same with the gas isolating valve (under the boiler). That will affect the burner first, then of course the temperatue in the hex, so may not be so useful. Neither is a textbook thing to do but I can't see any harm in doing it for the few seconds I'm talking about.

Make sure you leave them fully open - even if having them part closed shuts it up!

 

[Agile]

The problem here is that we cannot know if this "howling" is a combustion noise or a water or kettling noise.

I never assume that a manufacturers service engineer necessarily knows how to diagnose boiler problems. Some are still just parts changers.

Did they ever check the combustion setup with a Flue Gas Analyser? ( Sometimes a rather bright green expensive looking instrument with a black tube that connects to the flue at the top of boiler?

Was the installer totally competent and what power flushing did he do or was it a fit in in one day job with no water treatment?

Tony

 

[pannierstan]

I would agree with Agile regarding the noise and would steer the original post being down to incorrect combustion ratio.

I have installed 6 Vaillants in the last year and may I add commisioned them correctly including combustion analyser.

One started to make the noise after only 3 weeks and the other I did just before Christmas having been in for 6 months.

When checked the CO2 ratio was lean at about 7.8%. Now the manufacturers instructions stipulate 9.0% +/- 1.0% which would make you think that 8.0% is acceptable.
I can tell you it still made a hell of a noise at 8.0% and only shut up at 9.0% or above.

Zeushermes I suggest getting someone out who ISNT going to try and sell you a Bloody Magnaclean
I am sick of hearing about them as good as they might be they are not the answer to every noise related post on this forum that many seem to think it is.
This is not a jibe at anyone on this post by the way so please dont take offence.

Stan

 

[Agile]

I think that is a little unfair to Chris Abney. His Magnaclean is a useful device to deal with an existing problem or to pick up what the power flushing misses.

The problem is that many installers use them as a cheap alternative to power flushing.

Only last week I had a sensible sounding installer whose new boiler's pump had worn out because he admitted he had not power flushed the system "because the landlord would not pay for it". He ended up having to pay out over £100 for a new pump.

I would say if the landlord will not pay for the job to be done properly then why do it badly?

Tony

 

[pannierstan]

I think that is a little unfair to Chris Abney. His Magnaclean is a useful device to deal with an existing problem or to pick up what the power flushing misses.
Tony

Hi Tony I agree with all you say and I am not criticizing the item itself or Chris, rather some peoples implementation of it, or suggested implementation.

I actually use the powerflush version of the Magnaclean to save having to clean all the crap out of my delicious Jetflush 4 all the time and to get every last bit I can out of the system.

Stan

 

[Softus]

IHis Magnaclean is a useful device to deal with an existing problem or to pick up what the power flushing misses.

Magnaclean ® ?

 

[kevplumb]

magnaclean

 

[Softus]

Magnaclean ® !

 

[zeushermes]

Why not get a magna clean installed on the return. This should collect the dirt ( if there is any ).

I have found that adjusting the systems by-pass can have an effect on the boiler performance and noise.

I am assuming he's checked the obvious things like gas air ratio and gas pressure.

Andsam.

Thanks for your interest 'andsam'.

I must confess I was unaware of magnetic filters before posting the problem but having read the general enthusiasm for them in the forum, plan to fit one but only after I'm convinced the sytem is reasonably clean beforehand.

If the by-pass is causing the noise, would it emanate from the valve area or the boiler? (The boilers in the garage & the valve in the airing cupboard). In this case the noise is definately from the boiler.

The gas/air ratio & pressure were checked and as far as I understood, were adjusted to a point where the noise was eliminated, temporarily, until the replacement HEX was acquired. However, I was advised that at that level the system would be 'inefficient'.

 

[croydoncorgi]

Dear, oh dear!

We're STILL not clear whether this is combustion, heat exchanger or pipe noise!!

It's absolutely vital to work out which it is BEFORE trying to fix it!

IF it REALLY IS a 'howling noise' and ALWAYS happens IMMEDIATELY with a cold boiler, as soon as the burner lights up, it's PROBABLY combustion noise from the air intake or flueing of the boiler. As it happens, certain Vaillant models are well-known for this.

If it sounds more like a singing kettle and starts as the boiler warms up then possibly dies down a bit, it's probably from the heat exchanger. IF it continues for a short period AFTER the burner has turned off but while the pump is still running, then it's 90% certain to be the heat exchanger causing it.

If its 'white noise', hissing or humming which continues WHENEVER and ONLY when the CH is ON and the pump is running, whatever the burner is doing, it's more likely to be pipe noise, from outside the boiler altogether (bypass valve, zone valve(s), loose pipes, radiator valve (a lot of 'possibles' but best found by trying to localise the noise to its loudest point).

 

[zeushermes]

Dear, oh dear!

We're STILL not clear whether this is combustion, heat exchanger or pipe noise!!

It's absolutely vital to work out which it is BEFORE trying to fix it!

IF it REALLY IS a 'howling noise' and ALWAYS happens IMMEDIATELY with a cold boiler, as soon as the burner lights up, it's PROBABLY combustion noise from the air intake or flueing of the boiler. As it happens, certain Vaillant models are well-known for this.

If it sounds more like a singing kettle and starts as the boiler warms up then possibly dies down a bit, it's probably from the heat exchanger. IF it continues for a short period AFTER the burner has turned off but while the pump is still running, then it's 90% certain to be the heat exchanger causing it.

If its 'white noise', hissing or humming which continues WHENEVER and ONLY when the CH is ON and the pump is running, whatever the burner is doing, it's more likely to be pipe noise, from outside the boiler altogether (bypass valve, zone valve(s), loose pipes, radiator valve (a lot of 'possibles' but best found by trying to localise the noise to its loudest point).

Thanks 'croydoncorgi'.

Would my boiler 'ecoMAX Pro 18e' be one of those 'certain Vaillant models' by any chance?

 

[Agile]

Virtually any premix condensing boiler can make a noise if the combustion gas/air mix is wrong, usually too weak!

A clue to this is the noise will be particularly apparent at the flue outlet often to the point of annoying neighbours more than the occupants.

Water/heat exchanger noises are more apparent in front of the boiler even though they can still be heard from the flue.

Many people are not very experienced at setting up boilers according to the analyser readings. If the gas supply pipe is undersized then it can be difficult or impossible to set up the boiler correctly.

Tony

 

[zeushermes]

Did the new hex improve it? If it were dirty water doing it, that's practically the only wet part!

What I would do - though I haven't tried this or thought about it much - is try partly closing the flow valve (use a small spanner) and see if it makes an immediate effect. If the problem is do do with the water flow it will, but if it's to do with the burner/fan, it won't. Then open it fully.

Next, do the same with the gas isolating valve (under the boiler). That will affect the burner first, then of course the temperatue in the hex, so may not be so useful. Neither is a textbook thing to do but I can't see any harm in doing it for the few seconds I'm talking about.

Make sure you leave them fully open - even if having them part closed shuts it up!

Changing the HEX did alter the symptoms a bit in that, instead of the 'howling' being a continuous note, it is now on/off at about 3sec intervals but runs for about the same amount of time.

As a layman in the subject, I'm reluctant to interfere with the boiler settings, especially as the warranty is still valid. However, I might be tempted if all else fails.

Your mention of the Burner/Fan reminds me that I failed to point out that both were replaced on separate occasions prior to the HEX being diagnosed as the likely cause of the problem. The Printed Circuit Board has been renewed twice, also the Wiring Harness, although for other problems caused by the installer incorrectly wiring the Airstat to the Boiler and a 'suck it and see' approach applied to rectify the problem.

Appreciate your help Chris.