Biasi boiler on/off every few seconds

[annie]

Boiler reaches temp of 62C then cuts out for approx 5 seconds then re-ignites and then cuts out approx 5 seconds later and can do this for hours!Same for HW, CH and both on. Air pressure rock steady at 1.1 bar. Was intermitant last week, now persistant. Any clues ?

 

[boilerbeasty]

Have you tried turning the thermostat down on your boiler ? Does it do that at any temperature ?

 

[annie]

Yes. Thermostat adjustment seems to make no difference.
Have now noticed that problem does not occur if only CH used when the timer comes on; as soon as HW turned on after this then problem kicks in and then affects CH as well.
Thanks for your reply.

 

[ChrisR]

That's interesting. And the answer is perfectly obvious. Something is sticking. Try posting the problem on Plumbingpages.com forum. There are one or two specialists there, on these boilers.
I wish it were obvious to me exactly what was sticking.

 

[boilerbeasty]

Is the pump running OK ? May be it is not shifting the heat fast enough. Any funny (new) noises from the boiler ? Do the radiators and HW get hot (or as hot as 'normal' ?)

I'm suprised your control board is letting the boiler cycle like that but I'm not familiar with that model so I don't know.

 

[annie]

Thanks for your replies
Doesn't seem so bad this week
Someone mentioned that high winds around the corner of the house last week may be blowing down the flue and upsetting the pilot light, or rain getting in. The flue extends about 2 feet horizontally from the building and about 15 feet up.( Upstairs maisonette.)There is no elbow on the outlet. Weather is better this week and the problem is again intermittant. Does this sound plausible?
Pump seems to work fine and all rads are normal, bled and air free.