GlowWorm 30CXI making loud noise

[spen10]

Hi,

I have a slight problem with my boiler, I'm sure it's not unique.

I moved into the house around 2 years ago, and inherited existing boiler. It works fine for the most part in that it produces hot water and heats the house fine.

From a year ago, it began to occassionally produce a loud noises - like the sound of a horn or an ever-growing humming. Once the sound dissappears, it goes back to normal (mild hum), and behaves quietly like a boiler should.

I'm still trying to figure out what triggers the noise - my current deduction - it makes this noise when the boiler has been idle for some time and hot water is 'suddenly' required - ie. early in the morning or evening after work. However at times the noise just appears and challenges this deduction.

Note - I have had a plumber in to service the boiler and no problem was found. He did suggest to leave on/running a radiator, or two, to let build-up heat 'escape' since the boiler is always on. Does this make sense? Though this was a general advise, not related to the above-described noise problem.

Additional info:
- boiler is switched ON all the time
- central heating is on timer

Any ideas will be much appreciated!!!

Thank you for reading!

 

[oph]

deleted

 

[naanbread]

Hi There,

This loud humming noise sometimes described as "trumpeting" (sound of a horn/trumpet) is often caused by the CO2% readings being out of calibration.

I would suggest getting a gas safe engineer into the property with an analyser to measure the readings that the appliance is producing. These are easy to adjust which could solve your problem.

There is a high and low rate reading that needs to be achieved. the reason you are experiencing the problem from idle is probably because the high rate is out. As the boiler fires from cold it immediately tries to fire on its highest rate to achieve the target temperature. If the air gas mixture (%) isnt correct it causes the noise.

I hope this helps

NB

 

[spen10]

Hi NB,

Thank you for your reply.

I'll be getting an engineer to look at the boiler this weekend hopefully, will make sure he checks CO2 reading as per your post.

cheers,
spen10

 

[Agile]

Engineers often charge more at a weekend.

But you dont just need "an engineer", you need a competent one who has a flue gas analyser.

Unfoprtunately there are still many who do boiler services on modern boiler with out using one.

They can cost nearly £1000 to buy which is another £1000 for those cowboys!

 

[naanbread]

Hi NB,

Thank you for your reply.

I'll be getting an engineer to look at the boiler this weekend hopefully, will make sure he checks CO2 reading as per your post.

cheers,
spen10

Your more than welcome. I hope it helps.

As stated by Agile, please ensure that you get someone thats fully qualified and understands the concept of what i have mentioned. It may be worth showing my answer to your engineer for guidance. If he/she refers to the Manual he/she should be able to find the information in there on what readings to look for.

NB

 

[Agile]

We are guessing that its a combustion related noise. That can be checked by listening outside by the flue where it will be very loud!

It could also be TRV noise because there is no or a wrongly set auto bypass valve!

Tony Glazier

 

[naanbread]

We are guessing that its a combustion related noise. That can be checked by listening outside by the flue where it will be very loud!

It could also be TRV noise because there is no or a wrongly set auto bypass valve!

Tony Glazier

Would the bypass not cause an issue if it was after the appliance had been running? The op stated it was on first fire up once its been idle for a while. I would look towards the air gas mixture as its on first fire.

I could be wrong but im 99% sure that this is the most likely cause

 

[naanbread]

Sorry Tony, iv just read my reply back and please dont think im doubting your knowledge im certainly not mate

NB

 

[Agile]

I also agree that its 99% a combustion related problem and suggested listening outside to confirm. I also pointed out that an auto bypass can also create TRV noises or even noises itself as well.

I was a little concerned by the OP's comment that the boiler is powered all the time. Although it then says the heating is timed.

By the way, if no one has posted in the meantime you can edit your last post.

Tony

 

[spen10]

Hi All,

Just to update everyone, the engineer came and fixed the problem (or sort of).

The culprit were CO2 (out of calibration) and irregular gas pressure/supply.

Since adjustments were made, the frequency of trumpetting have lessen and when it does occur it is significantly shorter. The engineer did agree to come back if problem still persist no matter how small.

Thanks again for everyone who contributed to this topic, sincerely appreciate it.

Thanks,
nev

 

[Agile]

It sounds as if you have an undersized gas supply pipe to the boiler!

Tony