Banging from Oil-Fired boiler

Postby banquo » Mon Dec 08, 2008 2:56 pm

I've just acquired a house fitted with an Italian oil-fired back boiler (kerosene).
There was a problem with the motor front bearing seizing, so I had a new motor fitted, and the system seemed to be working fine last winter.
When starting is up this winter, there was a problem with air in the system, and I traced this to corroded auto-vents, which I replaced, and all radiators now heat OK.
Problem I have is with loud banging noises from the boiler. Initially I though this might be water boiling inside, as the noises don't occur when it first switches on; only after it's been on for a few minutes. There are two copper capillary bulbs for the thermostat, and these are correctly fitted in pockets on top of the boiler. The boiler does cycle, so something is working with the thermostat, but I'm wondering if one bulb is meant to be the temperature control, and the second is an overheat safety bulb, which is maybe doing the control due to some fault in the primary one..? I've turned the boiler-stat setting to a low value, but no change. :?
The noises are quite loud, and sound more like mini-explosions in the boiler cavity. No sign of smoke from the flue, and I can't hear anything from the flue, which suggests to me that they're not really explosions in the combusion area, otherwise I'd hear the bangs outside as well. If the water is circulating freely, is it still possible to actually have water boil, and is this likely to result in loud bangs? My previous gas boiler used to overheat now and then, but the boiling was more of a gurgling noise - certainly not a bang....
As you'll understand, I'm not very happy using the boiler until this is resolved, so any comments would be welcome!
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Joined: Mon Dec 08, 2008 2:40 pm


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