On Dec 12, 12:20 pm, wrote:
In our house it's much harder to heat the kitchen than the other rooms
mainly becaus it is in a separate single story section at the back
with 3 exterior walls and poor insulation in the roof.
To heat the kitchen properly we need to have the boiler on quite high
which makes the other rooms too hot.
I tell my missus we should keep the boiler on high and turn the
thermostatic valves down in the other rooms but she thinks this will
use a lot more energy than turning the boiler down and having the
thermostatic valves fully open in the other rooms and put up with the
chill in the kitchen.
How can I explain to her that she is wrong?

I don't think you can, because I believe she is right.

If you don't heat the kitchen (much), you will use less energy than if
you do.

One thing you may find helpful to explain to your wife is that (to a
first approximation), changing the setting on a TRV does /not/ change
how fast the room heats up when it is too cold.

Thus, even when you have the boiler turned down, you can turn down the
TRVs, and it won't make any difference (until you set them too low of
course). You can then turn the boiler up a bit, and the extra heat
will go into the kitchen (because the TRVs will switch off).