Cold temperatures in 15 year old cavity wall extension!

[Harry Bloomfield]

To be honest, what you've said is unfortunately the conclusion I've been slowly coming to given there seem to be no obvious issues with insulation, etc. However, is 13.5 degrees at around 8am really not that unusual in a 15 year old extension in October (with no heating on)? I think my main confusion is that it is 3 degrees colder than the 140 year old solid walls in the rest of the house - my uneducated brain just tells me something must be wrong!

Where is the room thermostat located, can it be moved so it uses the temperature in the extension?

Are TRV's fitted on any/ all/ some of your radiators?

 

[HaroldFinch]

Did anyone have any thoughts about the gaps above and below the outside of the windows in the photos I linked to? Adding them to this message for reference. Could they cause draughts that go through the walls somehow? What would be the best thing to fill the larger holes with? Expanding foam?

 

[HaroldFinch]

Where is the room thermostat located, can it be moved so it uses the temperature in the extension?

Funnily enough the thermostat is in the lounge extension! It's a Hive system that was installed by the previous owner. Given the room gets down to 13 degrees, I set the thermostat to 19 degrees as it wouldn't reach anything higher by the time it goes off.

 

[^woody^]

Yep the heating is definitely sufficient for the space. It definitely heats up quite quickly, but I still need to check if it retains the heat well or not.
I did think about this myself to be honest, regarding the cost of the work vs just having the heating on earlier in the year and potentially for longer each day. If there were one thing that had been earmarked as an issue by the insulation surveyors that I know fixing it would increase the temperature in the extension, then I'd do it. But yeah if it's going to cost a few grand and won't guarantee a result, then the option to heat for longer is probably the wise decision!

I guess my main curiosity comes from the rest of the house (140 years old!) being 3 degrees warmer at all times!

Whether the heat emitter is sized correctly is more about working out if it can replace the heat escaping, rather than it heating up quickly. There are various calculators online.

The other issues are whether its a perception of coldness due to draughts or air currents (radiator positions drawing air across a room) or whether the room is better served by more than one radiator suitably sited to heat the room evenly

If the rest of the house is warm, then that normally indicates an issue with the heating of the room, not the room structure