Glow-worm Ultimate 50FF - buzzing sound

[DanielK]

Hi All,

I have been experiencing strange behaviour of my boiler.
After few hours of idle it starts buzzing.

Sound I recorded
http://exjs.home.pl/snd/boiler_strange_sound.wav

The buzzing is loud enough so it can wake my wife up when she sleeps at night.
The boiler is in the kitchen downstairs.

We have tried to switch CH and WH off completely, but it still does it.
Functionally it is fine. It runs as programmed, no problems with that.

The sound is quite annoying and and I am a bit nervous about it, I am not sure if it is safe.

I has already been seen by one "expert", but nothing was found. The buzzing is not coming on request.

What can it be?

 

[ianmcd]

that sounds like a relay chattering

 

[Poincare]

Identical symptoms in my 50FF pcb.

Saw a couple of capacitors looking a bit "old". One with bulge, one discoloured. Replaced both to no effect on the buzz. Then replaced the relay with identical one. For three days, the boiler worked without any buzz and I felt very pleased. Whilst putting it all back I may have accidentally turned the thermostat down slightly. I recalled that the boilermate tank I have requires the thermostat to be on full, so I turned it up to max. Within the hour the buzz returned and I'm back to turning off at night.

Now I might just replace the relay again, hoping, but if anyone knows what else might damage the relay I'd be very interested.

 

[Dextraneous]

Great name "poincare". Something to do with a geodesic disc?

 

[Agile]

Did you replace the smoothing capacitor on the PCB?

Tony

 

[Poincare]

Appreciation of username choice. Ta.

I replaced any suspect capacitors. If the smoothing capacitor is the one nearest the relay then no I didn't replace it as it looks OK. However I will do it as well. I take it the smoothing capacitor is the nearest?

 

[Agile]

Without seeing the PCB I don't know!

It would usually be larger and probably over 300 uF.

But the capacity needs to be measured! You cannot decide if a cap is OK without measuring the capacity.

They have a rated life of only about 2000 hours in most cases!

 

[45yearsagasman]

Is it me? but would it not be simpler to replace the pcb instead of faffing around with component changes, that appear not to work. Just a thought.

 

[Poincare]

if 150GBP is no object I would agree. 50p for a capacitor or 3GBP for a relay makes faffing quite rewarding.

Untitled

• Poincare
• 28 Aug 2013
• 1

Agile, you say "Without seeing the PCB I don't know!"

Any chance you can see it in the pic? a,b,c, or d or another?. The biggest Barrel Capac is 100uF.

 

[Agile]

I have one of those in stock somewhere. But I don't know where!

Has the 100 uF cap been changed?

But it may not be the main smoothing cap. If we knew what was buzzing then that would help to identify the fault!

 

[Poincare]

The relay next to cap d in the pic is the one buzzing. It only buzzes when the boiler has been idle for a while e.g. during night. I haven't replaced the 100uF caps (3 of them) yet, though have ordered some. In fact when they arrive and I fit these three I will have replaced all the caps. It'll be 5 days or so before I know if it was the capacitor! Sods Law says it'll be the last capacitor that is faulty.

 

[Poincare]

The 100uF caps arrived today. Relay buzzing merrily away when I got in from work.

Replaced all 3, turned the power back on, and not even a single buzz.

Eerie silence! It's golden!

Poincare is back to his maths now until the boiler strikes again. Agile - thanks, I reckon you were right-go for the large caps first.

 

[Boilerman2]

Lets hope the boiler fires up OK when heat is called for then!

 

[Agile]

Its not a matter of going for big caps but with buzzing its likely to be the main smoothing cap or a cap which has a similar function in respect of the buzzing relay!

Tony

 

[David1979]

Hi Poincare
I hope you remember this thread from 3 years ago.
I have the same symptom with my Glow worm Ultimate 55F - the buzzing/chattering is getting very bothersome - and I am hoping that replacing capacitor(s) will fix it, given the price of a new PCB.
I haven't yet opened the PCB to take a look. I can see from the manual that the part number is 900847. As capacitors are cheap, I was thinking of ordering a full set so I don't have to order more than once (it seems that it was a bit 'trial and error' for you, so I thought that might be sensible).
Do you happen to know what value capacitors you needed? You refer to three 100uF caps - what are the others? I haven't been able to find a list of what caps are on the 900847 PCB.
Thanks in advance!
David