where to place radiator in extension and what size?

aoleks

I was wondering if someone can give me some advice on where a new radiator should be placed in a new extension and what size it should be. the image below shows the house and the extension. in the lounge, the blue radiator on the wall separating the lounge and the living room is existing and will likely stay in place.



the blue lines in the extension are the only options I have:

- on the wall return, next to the bifold
- on the side wall
- on the wall between extension and utility room

is there some sort of a rule as to where to place the radiator and what size to get for maximum efficiency? the space will be mainly an entertainment space, but also the space where we spend most of our time. the kitchen will go on the left wall, so nothing can be done there, but the heat from the hob/over should compensate.

any articles on how to decide where to place it would be helpful.

thanks

FreeBear

Personally, I'd go for a plinth heater or two - They sit under the base units and blow a steady stream of warm air out floor level.

An alternative would be underfloor heating -Certainly worth considering in light of the fact that we may all need to install heat pumps in the not too distant future. UFH is a good match for heat pumps.

aoleks

UFH is unfortunately not an option due to the problems we had with the previous builder, leaving us tens of thousands in the "minus". there's no budget for it and no way to integrate UFH in the extension (easy) with UFH in the lounge (solid floor, thin, no insulation, too expensive to retrofit). I'm also not convinced heat pumps are the future in the UK, where the property stock is quite... rudimentary, to put it mildly.

so going back to radiators, what's the best option and how is this calculated/decided?

Bendy_House

Size? Output to be chosen to provide the required amount of heating for that size of room, when supplied by water at ~45oC...

So, roughly a half-sized larger than what you would normally put in there.

This extension will be to current insulation standards, so that really helps. The skylights should provide a surprising amount of solar gain too. On bright days, even in cold weather, and after a chilly start in the morning, the room should largely look after itself. If the bifolds face anywhere close to South, that should help a huge amount more.

We've just had a 6x6m extension built - large bifolds like yours, and two sky lanterns. It is heated by just two vertical column rads, around 500mm wide x 1800mm high - and this works fine except in the very coldest outside temps. BUT, it is running from ~65-70oC gas boiler supply, as the rest of the house needs this. If I had to lower the boiler/new-fangled energy unit down to ~45oC, it wouldn't be nearly enough.

The thing is, tho', they look great, and fit in with the room perfectly. And that's kinda important!

So, I think what I would do - after doing some calculations to ensure they'll be powerful enough - is to fit tall column rads to both sides of the bifolds, so they match. Make them white or wall-colour to 'disappear', or anthracite (as we did) as a statement - ie our window and door frames are also anthra. 

Then ideally (just for aesthetics) the same style on the utility room wall - you clearly have a lot more space there, so use this as the main heat generator - or, if you are concerned that there won't be enough heat from a column style rad, go conventional, and as many panels/fins as needed!

This amazing room looks as tho' it could become your main living area? Especially if so, do your damnedest to get it warmed enough on a cool boiler output - that should save you £££'s. If you need to occasionally turn the boiler temp up, so be it, but as soon as it ain't freezing outside, turn it down again!  

And, any room you are not using, turn these rads right down - to 'frost' if you can.

FreeBear

aoleks said: so going back to radiators, what's the best option and how is this calculated/decided?

Plenty of online calculators that you can use to determine the minimum size required. If the space is reasonably well insulated and draught free, hang the radiator(s) on which ever wall suits you best (on the back wall by the utility room ?). Look at the plumbing of the existing system, and extend at a convenient point. Keep pipe runs to a minimum, and with 15mm pipes, limit it to three radiators per 15mm leg (usual pipe size is 22mm or even 28mm, with 15mm branching off for the radiators).

But as per earlier post, if you are limited for wall space and/or don't like the look of radiators, have a look at plinth heaters.

BUFF

If you are building to modern building standards (as you will be) the coolest part of the fabric/room will be by the bifolds (also furthest from the lounge rad).
If you had not mentioned the kitchen on the left wall my inclination would have been to suggest a vertical rad on either side of the opening. With that, I would go with top right hand corner ( possibly with addition of FreeBear's suggestion of a hydronic plinth fan convector under the kitchen cabinets).

There are calculations regarding output sizing according to room size, construction & outside walls, openings & outside temp (this may vary according to where you are in the UK but generally used to be designed for -2C). From that you can then do radiator sizing according to design & flow temp. (delta T). You can do it yourself but normally your heating engineer would.

TerminalChimp

We've got a similar layout and didn't want underfloor. We've got a big vertical radiator on one side of the room and on the opposite is a plinth heater in a kitchen unit, this was suggested by our heating engineer, particularly having them at opposite sides of the room to ensure that there was never a 'cold' or 'warm' side to the room as it was quite big. The plinth heater is rarely needed to be honest, but it is brilliant if it is a cold day as it heats the hallway too. 

Personally, I agree with Bendy, two vertiical rads opposite to each other. Regarding sizing them, you can do this yourself, but we trusted it with the engineer as we didn't want to get this wrong. If this isn't built and you're interested in money saving, consider sliding doors, we actually prefer them to bifolds and they are much cheaper. 

DRP

+1 for 1 or 2 tall radiators (you might only need 1).

I would avoid putting rads on the long wall - think about furniture positioning