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Noisy oil-fired boiler


Nev
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Our oil-fired boiler is not quiet at the best of times, and I suspect this is why they're usually located in outhouses etc as ours is, but lately is has become VERY noisy, especially when it just fires up. It makes a vibrating sound as though it's trying to shake itself to pieces! There aren't many moving parts, an just injector pump probably, but I'm worried that it may be a flame problem.

Any ideas anyone? I'm hoping Opal Fruit will come along with some suggestions! Can I check the flame colour?

It was serviced earlier this year, April I think, and we've recently had the flue swept (4 weeks ago). No fuel delivery since January (but we will need one soon).

When it makes this racket, if I turn it off and then on again it usually fires-up and runs correctly.

Nev

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Nev.Noisy burner operation could be many things,ie, worn pump,air in pump,worn motor bearings,Fan out of balance.If pulsating on startup it could mean flue draft incorrect, combustion settings wrong, or even a faulty nozzle etc etc.I strongly suggest your service eng checks it out, setting or checking burners is not is not one of those diy jobs when health is involved.Have a nice day.
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Thanks Michael. I'll have to get a service guy to look at it, I realise that, but was wondering if there was anything obvious to check first. The whole installation is only just over 12 months old so I wasn't expecting major replacements yet. It seems coincidental that this starts when the flue has been recently swept. After posting my query I noticed anothe thread a bit lower down 'banging old boiler' and Opel Fruit' mentions a dirty filter, maybe I should check that first because it doesn't sound too difficult.

Nev

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It's the "Banging old boiler" syndrome, by the sound of it.

It's normally caused by the injector (gicleur) chattering/spluttering due to low oil pressure. I suspect the gicleur is running at its low pressure limit.

If the filter is clean......

I can only suggest you get a chauffagiste with the correct equipment to check the pump aspiration and pump pressure. The pump aspiration check will verify that the pump is able to draw fuel correctly and that the filters are not choked. The pump pressure check and adjustment will ensure that the gicleur is operating in its correct pressure band. I would also be tempted to fit a new gicleur.

If you want to observe the flame, open the boiler window. Be aware that if the burner is coughing, you may get sparks and fumes flying out...

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Thanks Opel.

Looking at the filter bowl (which I must admit I've never really closely examined before) I can see that the oil level is about 1 cm from the top. When the boiler fires, this drops to between halfway and two-thirds full. The filter is a kind of gold colour and looks clean at the top but may be a bit blocked lower down; I'm sorry if I sound a bit vague, but it's hard to tell if it's just the effect of the oil. Anyway, I'm confident enough to take this apart so I'll do that later this morning. You mention in another thread that there is another filter, at the inlet to the burner unit I think. I've got the installation manual and documantation somewhere so I'll see if I can locate that too.

As I said, the boiler is only just over a year old. I have to say that I'm not overjoyed with the workmanship. You note in you excellent 'heating funnies' thread that many installations are not correctly set up, and that was certainly the case with ours. By April this year it had become completely full of soot due to incorrect burning. I got a more reputable (hindsight is wonderful) engineer to set it up correctly, but we didn't use it much over the summer. I had the flue swept (belatedly) on his advice and everything seemed fine. It has definitely been running more economically. The whole thing reminds me of the engine room of the QE2 and there's a lot of manual intervention required to get just hot water for example. Vanne Melageuse - some sort of mystical French apparatus!

Anyway, I'll let you knowwhat I find.

Nev

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I doubt the filter in the pump inlet is blocked. I would certainly clean the supply filter. To do this, run the boiler, turn the shut-off tap on the filter to off and let the burner die. Put an old bowl underneath the filter - there will be some spillage.

Unscrew the large ring and take this off, then gently waggle the bowl until it unsticks from the housing - watch the O-ring doesn't get lost.

Gently turn the filter to release it - it is on a loose bayonet. Then clean the filter with a paint brush.

Once you have the filter back together, try turning the oil pressure adjustment on the burner just half a turn clockwise.

Open the shut-off tap and fire the boiler - it may take 3 or 4 goes before the oil is bled through.

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OK here's what I found... not very much!

I did as you suggested, removed the filter bowl and cleaned it out; a few particles in the bottom, and a greyish fine sludge (not much) on the gauze of the filter. I wouldn't have said it was blocked based on my previous DIY experience with car carburettor filters etc.  Re-fitted it and fired up. Interestingly the filter bowl is now full to the top with fuel (it had a 1 cm space before) and the vibrating noise was considerably quieter. When I opened the viewing hole to look at the flame the noise increased. To my mind this means it's an air-related problem?? (maybe). With my usual tinkering hat on I tried adjusting the air valve thing (technical term) by a notch each way. It was set on 4; when I turned to one click to 4.25 (approx) the noise stopped! Turned it back and the noise started again. So, naturally I've left it at 4.25. Do you think I still need to get it regulated properly? It was quite expensive last time, around 100€, or is that normal?

The most recent chauffagiste recommended that I always buy Total Premier Fioul, he said it was a little dearer but made up for it with more efficient running. I've just ordered 1000L but I'm told the price is 0,663 per litre which sounds expensive compared to prices mentioned in the recent thread. Is there a difference in fuels?

I've read many of your posts Opel and must say you've been very helpful, thanks very much.

Nev

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Sounds like your noise was more "howling" than coughing then.

As long as the flame quality is still OK, I would leave the air setting at the new setting. If the flame quality is not right, try the air the other side of the original setting. Sounds like you had a resonance problem, and sometimes the settings for fuel pressure and air flow have to be shifted up or down slightly to avoid it. It often makes itself known when the electrodes are arcing at start up, and then disappears once the flame is self-sustaining.

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Do listen to Opel Fruit, he has been most helpful. After following his advice, our system is now running perfectly. We did call in a CH engineer to set up the fuel pressure and air settings but he said ' I wouldn't charge for such a small job'. I gave him a bottle of scotch for his trouble and kindness.

www.leschenauds.com
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