Vaillant boiler 'howling' noises

[zeushermes]

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

The approach so far has been replace parts and see what happens. Which is fine until the warranty expires and I have to fund the bits that don't rectify the problem.

Meters have been attached and adjustments made on most visits. Unfortunately, I have no idea to what degree.

With regard to the installers competence. His general attitude was disappointing with much effing & blinding, damage to various items in the house, bodged repair to a CW cistern he replaced and old plumbing debris left in the loft. However, to be fair it all worked initially, apart from a fault caused by the Electrician.

Certainly power flushing wasn't done and I have no idea how much draining and refilling took place. An empty inhibitor container was left in the loft so I assume it's contents were added to the system.

I have been fairly consistent in draining down & replenishing the inhibitor every 2-3yrs, so assumed it to be reasonably clear. However, when the HEX was changed I was shown a container with muddy water in which was said to have been drained from the old one.

Incidentally, Is there any significance in the fact that the noise only occurs when CH is called for and not HW?

Thanks for your interest Tony.

 

[Stormboy]

I have the exact same model boiler and have had the howling pretty much as you describe soon after the thing was installed. After giving up on the 'installer' who powerflushed the system twice, I decided to attack it myself. Upon disconnecting the boiler from the heating circuit, I backflushed then flushed the boiler itself using the mains supply and got a fair amount of sludge out of it. Then I mains flushed the rest of the HW and CH circuits, connecting where the boiler was and isolating things as I went - again getting quite a bit of crud out. This was just before Xmas and I've had X400 in their since. I'm gonna give it a couple more weeks and flush everything again and fit a Magnaclean (R)(C)(tm).

Anyway, the howling has gone and all I have now is a what sounds like the fan combined with some faint kettling. If the kettling is still there when I re-flush I think I might try pouring some hot DS3 into the boiler when I have it disconnected and see what happens. Maybe the colour change will give me a clue as to whether there was any limescale?

Pretty happy with the results so far though!

 

[clairol]

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).

I have and Ecotec 415, is this well know as detailed above please?

I have had power flush, new hx and burner. Still have noise. Please advise any actions I can take to ascertain if it is air intake or flueing.

 

[clairol]

Why do these boilers start out ok and then develop howling? What is changing in the boiler?

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

 

[gaswizzard]

Why do these boilers start out ok and then develop howling? What is changing in the boiler?

Gas valve tends to drift due to 'weak' servo reg spring/WPD (gas/lean) also hex/hoses can tend to scale up over time.

Howling is usually combustion related.