Boiler whine when cold.

[Darren Blake]

Hi, its my first post on here

I've got an annoying problem with my oil boiler which has manifested itself within ithe last couple of days.

First off, its a Beta oil boiler with an Ecoflam Monoflame Minor burner inside. The whole thing is 10 years old, but has never been any trouble apart from having to have a new motor starter capacitor, oil pump and hose earlier this year. Its not a combi boiler, but heats my central heating rads and hot water tank.

Two days ago I was awoken by what sounded like a jet engine spooling up in my kitchen as the boiler fired up. What seems to be happening is that when the boiler fires up from stone cold, it is making a loud whine which is echoing around inside the boiler casing. When my boiler starts up it runs for a few seconds without any oil feed to pre-purge the system. This whine is there right from the start - not just when the boiler actually ignites.

My hot water pump is in the airing cupboard on an adjacent wall. This also runs during the pre-purge but the noise does not seem to be coming from there. It definately sounds like it is originating in the boiler or burner.

I'm a mechanical engineer by trade and to me it sounds like maybe a bearing in the motor or fan has worn out. Alternatively something might have come slightly loose inside the boiler and is vibrating ata high frequency, and the boiler casing is amplifying the noise. Incidentally it sounds just as bad with the front of the boiler on or off.

One final vital bit of info: As the boiler warms up the noise dies off, until after about 10 minutes you cannot hear it at all. Let the boiler cool down again and hey presto - its back.

Any ideas?

 

[wilhelm]

i would isolate the water pump first....ie take cover off and pull a wire.
just to eliminate it , then i would separate oil pump from burner motor and listen to motor .

 

[Darren Blake]

That's a good idea. CHeers

Actually, I had a proper investigation tonight and my original description was a bit off. Its not a whine, its a very high pitched rattle that you can hear through the pipes and rads...

 

[Darren Blake]

*Bump*

Right - last night I ran the boiler without the water pump, and the water pump without the boiler, and both together. The only combination that didn't make the noise was just the water pump on its own. I also went from the loft tank to the boiler grabbing onto all the pipework as I went. I could feel vibration in the pipes but nothing I did stopped or changed the noise at all.

I didn't separate tha oil pump from the motor on the burner assembly but I did do some listening using a long screwdriver against my ear and the sound doesn't seem to be coming from that end of the burner. In fact its very difficult to say just by lisetning around the boiler where it is originating from, but one thins is for sure: Since it does it from cold and before the flame lights, it must be something to do with the actual burner motor or fan, or the motion of the air itself through the burner. I'm not sure how this could be transmitting so much noise into the pipes though.

When I removed the inspection covers off and took the burner assembly out I excpeted to find something obviously loose but nothing really jumped out at me.

Unless someone on here can give me a reasonable lead, I'm going to leave it be until it either settles down or deteriorates to a point where its easier to diagnose.