Potterton boiler makes roaring noise; what might be wrong?

[rockdoctor]

I've got a Potterton boiler that came with my house and I haven't had it serviced in 3 years. It has started making a roaring noise sometimes, as if a strong wind is blowing down the flue (except there's little wind outside) and a bit of yellow appears in the blue flame at the same time. The worst it gets is when the boiler starts to vibrate and gets quite noisy (I can hear it outside its cupboard). The boiler still works fine (ie water and radiators get hot!), and makes no noise most of the time.

Is this a case of me taking the cover off and hoovering everything in sight? Or is it a "call out CORGI guy who tells me the boiler is dying and I need a new one" job?

Or is it the intermediate case of a £200 bill for a major hi-tech servicing that can't be done by a good DIYer with ordinary tools?

Obviously you can only guess, but an educated guess would be very useful - I'm happy to try hoovering if there's a reasonable chance it will cure the problem.

Otherwise I'll pay for a service and let the CORGI guy do the hoovering!

[Ed Sirett]

The model name and number would be helpful. May be we are talking about a Kingfisher (CFnn) or a Flamingo.

It is quite possible that the boiler has developed a potentially harmful fault - so don't use it until you are sure it's safe. One of the possible causes of a roaring noise is the flame jumping back to the injector (this will also make a lot of soot and toxic carbon monoxide).

The fact that this may well be an open-flued appliance and that it has not been maintained are causes for concern.

Ordinarily servicing the boiler might well be within the scope of an experienced DIYer (it depends on the model amongst other things). However given that there are now problems you would be well advised to get in some help.

[rockdoctor]

I'll find out the model. There is a carbon monoxide alarm in the same cupboard that has never gone off. When the system was changed to Megaflo in 2003 (part of loft conversion work) the plumbers told me the CO detector was unnecessary because the boiler was isolated from the inside of the house - so I guess it's not open flue?

[Ed Sirett]

OK it's some sort of Room Sealed appliance, so my concerns for safety are reduced slightly. However unless you know what's wrong don't use it until it's been checked.

[Dave Plowman (News)]

It needs a good clean - for a start. But there's more to it than just removing the cover. You'll need to remove the inspection plate and the burners. And use a proper flue brush as well as a vacuum. The idea is to clean the heat exchanger properly. And check the terminal is clean too, and the firebox linings are in good condition. Then all the seals before replacement. It's not that difficult, but just take time to make a good job. I'd replace all the seals as a matter of course. A decent PM will have them. Give the burners a good wash in the sink - like you'd do with a heavily used frying pan, and inspect them carefully afterwards. Even use a magnifying glass to check they are clear. Also make sure the pilot jet is clean and clear. But don't use anything brutal to do these. ;-)

It mainly just needs common sense, really.

[rockdoctor]

I checked; the boiler is a Potterton Prima 80e Profile.

It does sound like it would be worth paying the callout to get someone to service the thing.

What I was afraid of is paying for a CORGI guy to come out, only to watch him do something incredibly easy that I could have done myself (as I have with various other items).

Since it sounds like there is a fair degree of knowledge & skill required for the task, I'd be happy to pay (or at least, not UNhappy!).