Potterton Kingfisher MFL problem

[ArtfulBodger]

Called to a boiler breakdown today and want to avoid buying parts not required if possible. Didn't have Pottertons number and installation docs not onsite. Hopefully someone can help.

Boiler has no external controls whatsoever (!) and is installed under the stairs with adequate ventilation. Conventional fanned flue. The problem is the boiler is cycling randomly, can be out for hours at a time whilst boiler stat is calling for heat.

Fan is spinning and resistance seems OK. APS is NC but is difficult to check as only accessible with sealed case open. I found that loosening the case very slightly ensures that the boiler fires and stays on. Tightening it up, as it should be, shuts the thing down. No obvious obstructions anywhere.

Fan? APS? any ideas?

Ta

 

[corgigazza]

Had a same fault on one of these c/f fanned flue boilers it turned out to be the flue was fitted on precast flue system (should be twin wall), which is not allowed as per man instructions. Same fault happend, only got boiler to work with case slightly opened. Made safe & capped appliance gas supply as imed/dangerous boiler not fitted to man instructions. fitted new wmb in airing cupboard. hope this helps

 

[PEDANTICVINDICTIVEMAN]

Nah, it will be starved of oxygen because the air intake holes are full of fluff, remove the top of the boiler caseing and remove the flue and connecter on top of the boiler and the fan from inside, get a small boiler flue brush and a decent hoover and clean out all the fluff and muck from all the air intake holes, it is akward and fiddly, refit and should be okay.
It's definately oxygen starvation because that is why it runs with the front case slightly loose, been there, done it, got the Tshirt.

 

[ChrisR]

More details please cos I was called to one of these which HAD done as described above, though it was fine while I was there. This boiler was in a coal-bunker sort of structure outside so I wouldn't anticipate fluff, but...

The coal bunker lid was sealed against the flue so hard to remove. As far as I could work out the air intake is around the rear of the boiler by the flue, but big holes which with a mirror and torch looked clear.
Thought I'd remove the fan to have a look but it was well stuck in. M I say slide it down and out, but its white gasket was stopping it going anywhere, being adhered strongly to both surfaces. Would have needed a blade or similar to separate the fan mounting plate from the bit it sits against, held by tabs of metal apart from the gasket.
As the boiler seemed to be fine - it had only misbehaved once, needing front door removing - we decided to leave it be, until/unless it does it again. Next time I'll take a new fan gasket. It was an MF CF 70.

I don't see what the flue construction has to do with it getting enough air - can you explain corgigazza - was the problem actually found? This one was single wall modern version of asbestos cement. It did have a condensate trap.

 

[PEDANTICVINDICTIVEMAN]

Cant really give any more details in words, the air intake holes on these boilers is either side of the adjustable flue connecter on top of the boiler, you have to remove the top casing to get at them, it is fiddly, had a job to find this air intake on these boilers myself, I couldn't weigh up for quite while just where these boilers got their air from being a conventional flue and no inlets at the back.

 

[ChrisR]

Ta. I called Potty and got the lady who went off to ask someone and came back saying "round the back somewhere".

 

[ArtfulBodger]

Ta. I called Potty and got the lady who went off to ask someone and came back saying "round the back somewhere".

And that's on an 0870 number! cheers for all that, best go back and have a mooch around then!

 

[corgigazza]

Never sorted out this kingfisher (replaced with pott profile) customer said it had done this fault since it was installed, they called out brit gas who disconnected the gas supply due to boiler fitted on incorrect flue(precast). but as ped said, the incorrect flue would not stop it working, unless case left open slightly. Not had this fault again since on another kingfisher & manufatures were no use for tecnical help