Heating my extension

Blue76

I recently moved into a 3 bedroom detached property which has had a single story extension added and made into a fourth master bedroom with en suite. My problem is that this room is absolutely freezing! I have a combi boiler with a room thermostat in the living room. My timeclock is set to be on all day between 6.00am and 10.00pm with the tempreture being controlled via the thermostat in the living room.

My bedroom has a single radiator in it which has its own TRV which is always set at 5. However the room temp is normally always between 12C-15C despite the living room being heated to a higher temp - normally 18C-21C. I have plenty of insulation in the roof and have been told that the walls are unsuitable for cavity wall insulation.

I have currently resorted to a plug in heater to heat the room so any advice regarding insulation / heating would be welcomed

Cardew

Assuming the radiator in your room is not faulty(filled with sludge or air) and/or your TRV is not faulty, it is simply a case of your radiator being too small.

You can test the TRV by taking it off and then it will be full on. Ensure that all the radiator is getting hot.

Obviously a double or triple panel radiator will give out more heat(a simple solution) or you may need to run an extra radiator. For both solutions you need to ensure that your boiler is up to the job - not that it will do it any harm if it is a bit small.

Have you tried dry-lining the room? This entails fixing battens to the wall with plasterboard on top, and sheets of insulation between the plaster board and wall - a form of double glazing. I had it done to an old cottage I have and it is quite effective.