Alterntive / best way to heat room radiator selection

[ETAF]

We have a utility room made from Airated blocks, insulated warm flat roof - installed a few years ago
the extension room may have been built in the 80's

Width 2.5m , Height 2.1m , length 5.8 m
Putting an insulated suspended floor - 40mm celitec and 22mm floor boarding on a concrete floor

Room BTU calc on bestheating = 5600 btu
400x600 = 2333 btu
800x600 = 4666 btu

But I could instead of the 800x600 add in a 1000x600 (cheap price as well £60+ screwfix = 5832btu = and not have the 400x600 at all - makes things so much easier and less hassel connecting up to the new heating

most likely going to do this now .... - i was concerned if 1 was enough for the space - BUT it will have to be i think , the alterantives are just too expensive and hassle

i was going to install a 400 wide type 22 radiator one end of room (size restriction ) But this maynot be possible now and a 800 wide rad at the other end
I have a picture below - all worked out
BUT Now , i have looked at where the pipework was going up the old soffits into the roof space - as already hot/cold pipework there - BUT i have the old house cavity wall and so its proving a bit difficult as to what to do and to get the pipework upto the valves - as its such a small width 52cm (i was happy for the valve to come over the door architrave

will a radiator at one end of the room, heat it up enough ??? then i will just put a 1000x600 at one end, as i have now worked out the space available which is 1300 - so 1000 + connectors and a therm valve would fit perfect

or maybe electric - but thats a lot of power

the boiler is NEW and will support the additional radiators

I will come back and edit - and make a better drawing later
EDIT - Now thinking of just 1 rad at the other end of the room

1000 x 600 type 22 = 5832 BTU

 

[Wayners]

Modern rads have way more surface area and give out loads of heat, and im surprised at how small radiators need to be for the size of room.
I also prefer a k21 rad. The k22 are just too wide for my liking...

I'd say. Work out the btu required. Then buy a radiator that's around that size give or take. If in the middle of winter its on a bit more to get room warm who cares.

I've always just guessed size based on location space and what I can pick up at sensible money. The trv cuts heat anyway.

If you were estimating for houses you would do calculations but it's just a guide. You don't have to stick to it

 

[ETAF]

Thanks a lot for that

yep, i fitted a couple of type 21 in lounge - mainly because of the existing microbore

how much it sicks out down the corner will not be a problem as have plenty of room and have to leave the space free for a door -

i calc roughly room needs 5600BTU and the rad 1000x600 is type 22 = 5832 / 6007 (screwfix v toolstation) type 21 = 4560 / 4545

i'll probably go for this as it makes the plumbing so much easier - and will be able to box the vertical pipes in easier and other pipes will be under the floor anyway now

thanks again for the reply and info - very helpful