Logic Combi 35 - constantly on regardless of thermostat settings

[geordiepaul2001]

Hi all,

Just before Christmas I had an issue with my Logic Combi 35 whereby it was constantly calling for the central heating to be on.
Even with my room thermostats set to 18 degrees, it was still heating the house to between 21 and 23 degrees.
The only way to make the heat bearable was to turn the central heating temprature down using the dial on the front of the boiler.
If I turn the boiler to hot water only the boiler still seems to be firing due to the noise and pressure increase.
Turning the boiler off using the front dial also has no effect.
The only way to stop the boiler is to turn it off at the plug but owing to the cold temperatures I don't want to do that for too long due to risk of burst pipes.

By the time I got someone out to look at it the problem had rectified itself and no problem could be found.
In this recent cold snap the exact same problem has happened again which is making me think it must be a seized valve or similar that is only happening in extreme temperatures.

Any ideas?

TIA

Paul

 

[daWilko]

Hi - I'm an Electrician (snowed in today) and my thought is the two port valve may have malfunctioned and electrically is always asking for heat. I'm sure Plumbers will have advice. Any pics?

 

[Scott_D]

Where is the boiler fitted?
Could be the frost protection

 

[geordiepaul2001]

I don't have pics at the moment but I will try when I get home.
The boiler is situated in a room that used to be a garage but has now been converted to a playroom for the kids.
As is usual it is set against the exterior wall.

 

[Harvest Fields]

Good evening. You have this post here on this already. Surely you would have had an engineer look at this since March. How is the problem still present in November. Some 8 months later. Also do you have a 30 or 35 as one post says logic 30 and one logic 35?