Boiler Noise (Biasi Riva compact HE combi boiler)

[macflapper]

Hi,

I have a Biasi Riva compact HE combi boiler, approximately 6 years old. We moved in about 4 years ago and had no problems with it till recently
About 9 months ago we had a problem with the timer not working, a plumber came out and just turned it off at the plug and reset it and it was all fine.

Shortly afterwards, I’m not sure if was related, the boiler started making some low humming noises, that the suddenly crescendoed and went. Over the past 6 months that has increased significantly – to the point where it lasts over 2 minutes and happens 4 or more times a day, typically in the evening (when we are usually in) after 7pm. It happens when the heating is on or off, and regardless of hot water use. The noise sounds like it is humming for a couple of minutes then suddenly building up pressure for a few seconds then suddenly releases it – the noise comes from the boiler, not any radiators. The missus describes it as like a jet taking off.

We called out a plumber who said the heat exchanger would need replacing. I wasn’t in at the time but the missus said he had a poke about and then left and is giving us a quote for replacing the heat exchanger (£400) and fitting a new boiler (£1200 - £1800 dependant on type and length of warranty). Anyway, after he left the boiler never made the noise since for 3 nights in a row, the one thing I noticed is that he must have increased the pressure as it used to sit below 1 bar when the heating was off, but is now at about 1.2/3.

Tonight though it made the noise 3 times, 7pm about 8pm and 9pm. The heating hasn’t been on since 6.15pm and we haven’t used the hot water. I also noticed the pressure had dropped again below 1 bar, I’m hesitant to up the pressure as I’m not 100% sure which lever to release!

Anyway, wondered if anyone could shed any light on the noise? The actual boiler itself seems to work fine.

Thanks in advance for any advice.

 

[Homesafe]

If it sort the problem when the pressure is topped up to 1.2 bar then keep it at that , and problem solved

 

[macflapper]

Hmmm. I put the pressure up to just over 1 bar again, and I thought that solved it but then this afternoon it made the noise again. Again it happened well after any heating had been on (happened at 2pm - heating went off at 7am - and no hot water use pior to it happening).

Just to be clear could this noise be caused by the heat exchanger as the plumber said, even though the heating and hot water are not on?

The only other thing i have noticed is that the frost protection light is always flashing on the panel.....the noise couldnt be the frost protection could it?

 

[Agile]

No.

The boiler obviously has a fault although thats not likely to be causing the noise.

Can you say EXACTLY what lights are doing? There is no single frost protection light!

Have you ever had the boiler serviced? That will need a flue gas analyser!

If its an M110 then the mains transformer makes a 100 Hz hum when the boler is not operating.

I am guessing its a combustion related matter because its not been serviced properly!

Tony

 

[macflapper]

Thanks for the advice.

Looking at it the only light that is flashing (out of the 3) is the first one, pulsing every 2 seconds - the manual states this is normally operating boiler. I think the flashing i saw on the second light looking at it again is just a reflction from the first (as its very faint) - but apparently the two flashing at the same time indicates frost protect operation.

We had someone service it two years ago, who advised it should only need doing once every two years. Think i'll get someone out to service it and explain the issue then.

But is reassuring its possibly not the heat excahnger - i dont have £400 just after christmas! But can probably muster enough for a service.

Thanks