Groaning boiler !! Savio/Biasi 428S

[steviebobs]

I have a groaning boiler !! After running DHW for a while, on closing
the DHW tap, the boiler seems to have a big groan as it turns off. It
doesn’t do it on CH turning off, so I have ruled out the pump or fan,
but can only think that the other ‘moving parts’ are the gas valve and
the diverter. The diverter was ‘overhauled’ with the ‘seals/diaphram
kit’ last winter.

Any ideas?

Ta

SjH

 

[joe-90]

It's the fan bearings wearing out.

On hot water the fan is at full tilt, on heating it spins slower so doesn't get a wobble on.

 

[1983]

Sounds more like residual heat making the noise in the heat exchanger. Usually due to a part blocked exchanger. Other problem could be a slow moving diaphragm on the diverted, it sometimes takes just a second longer to shut off the hw demand switch and the boiler keeps firing on high, overheating and causing the noise. What to do is get someone to switch off the hot water tap while you stand at the boiler and see if it goes off straight away. Doubt it's the fan.

 

[bengasman]

It's the fan bearings wearing out. On hot water the fan is at full tilt, on heating it spins slower so doesn't get a wobble on.

More Joe-90 nonsense.
The human ear can not hear the difference in speed between the fan running in dhw mode or ch mode on this boiler.

Your description of "groaning" noise is not clear enough to allow for an accurate diagnosis.

 

[1983]

Joe just cause your boiler did it doesn't mean this one is doing it. To state that is definitely the problem is ridiculous. We can all only offer advice here as none of us are standing in front of the boiler.
Perhaps the op could post when boiler fixed to confirm fault and we will see.

 

[1983]

I would have described fan noise as more of a rattling than a groaning. In 22 years at this I've never heard a fan on an se boiler groaning. Question for the op does it sound a bit like a plane landing?

 

[Dan Robinson]

Joe. The combo version of my boiler can make one hell of a groaning noise under several fault conditions. Only one of those is the fan. The rest are hydraulic.

 

[ChrisR]

The noise that I refer to

So you heard one noise on one boiler once.
Irrelevant.

The symptoms the OP describes are far more likely to be diverter/water related. I can remember Biasi diverters doing it.
I've long since lost count of how many noisy fans I've heard. We (boiler people) all would have done.
A boiler mender sees and hears dozens of boilers every week.

Why do you have to ejaculate the first thing - or only thing - you can think of?
Why don't you do what you're told and stop mis-directing people based on simplistic guessing?

Wind yer neck in or they'll ban you.

 

[joe-90]

They can ban me if they like.

 

[ChrisR]

I don't claim to know what the fault is.
I have already given my advice based on experience and knowledge.
Yet you have the answer, based on one noise in one boiler.

Boiler people have heard hundreds of noises, and know that from a keyboard they can only give advice, not clairvoyance.

Several things could be making this particular noise, the fan is way way down the list.

Changing a fan is not something a hapless diyer is allowed to do. It would be expensive, probably do this fellow no good, and is dangerous if you don't know what to check for.

 

[steviebobs]

Thanks all for the replies, I didnt mean to start WW3. The fan was changed last year, so unless a poor build, I doubt the bearings, but, it is something to check. It happens all the time after a long hot water run.
Sorry, but groaning is exactly what it sounds like. Aeroplane landing, possibly, yes.

As mentioned the diverter was 'reconned' last year with the kit available, but that doesn't necesarily mean it is not the diverter.

If possible I will try and record the noise and add it as an attachment!!

Regards to all helpers.

 

[Agile]

Ok so I have paused to allow Joe to give his guesses.

Now its time for me to tell the OP what it is!

The main heat exchanger is fouled by lime compounds and causes the latent heat in the copper to boil the water when the demand is suddenly stopped ( there is no pump overun on that model ).

The cure is to introduce sulphonic acid ( Fernox DS3 ) into the boiler ONLY and circulate it for a short time in alternating CH and DHW modes.

It is not very soluble and will need to be repeated a few times.

For a DIYer its not quite so easy to introduce but perhaps from the flow pipe where it enters the top of the diverter valve.

Tony

 

[Agile]

On this occasion Joe was right on the acid spelling. Thank you for pointing out my error.

But its of little consequence as the OP would buy it as DS3 as its not likely to be available easily in small quantities.

Tony

 

[sooey]

Ok so I have paused to allow Joe to give his guesses.

Now its time for me to tell the OP what it is!

The main heat exchanger is fouled by lime compounds and causes the latent heat in the copper to boil the water when the demand is suddenly stopped ( there is no pump overun on that model ).

The cure is to introduce sulphonic acid ( Fernox DS3 ) into the boiler ONLY and circulate it for a short time in alternating CH and DHW modes.

It is not very soluble and will need to be repeated a few times.

For a DIYer its not quite so easy to introduce but perhaps from the flow pipe where it enters the top of the diverter valve.

Tony

I'd be surprised if it was scaled up Tony, that's a problem we don't have round here, very soft water.

 

[sooey]

NO, we've had diverter and heat exchanger, the fan was your suggestion which doesn't count for reasons stated by chrisr.
Seeing as the man has already said that the diverter was stripped and rebuilt not long ago that's where I would be looking.