Bolier Fires when programme off

[Boggy]

My boiler fires up even though the programmed time has finished. The radiators do not get hot at this time. This normally happens late at night approx. 11pm. The timer for the hot water and heating finishes at 9:30pm The red ON light is not lit on my programmer so the programme is not at an ON cycle.

I have a Potterton Prima F boiler and an ACL programmer

Any thoughts?

 

[croydoncorgi]

Frost thermostat?

 

[breezer]

in built frost stat?

 

[ollski]

I am guessing it's an s plan system?, ie 2 x 2 port motorized valves.

 

[wilhelm]

yep, ill agree with that one,
err although i have had the odd faulty (old) froststat.
mmmmm ......let me review my message, ah yes ive covered all the options without actually commiting myself. excellent.

 

[wilhelm]

aaahhhhhhhh is the boiler outside? this information was not in original question....!!
which means......... we need to know

 

[kevplumb]

i see big hole looming mate

 

[wilhelm]

that is nothing unusual
but lets have a laugh on the way down

 

[kevplumb]