New radiator position for a cold room

[rarara]

Hi, need some advice:

We have a large living room which is northy facing, has a large bay window and therefore is pretty cold. There is one 600x1400 rad near the door. This doesn't make the room at all warm, and even when the hall is roasting, opening the door causes a cold draught to be felt. I suspect it is the classic case of the cold air from the window area being dragged along the floor.

The only real option is to get a heat source under the window, which leads me to two questions:

1) the proposed size of radiator which will to fit neatly under thye window will be 300x1200. That is a fair bit smaller than the one near the door, but will it be sufficient to get warm air circulating properly, when its only half the size of the other??

2) I want to run the new piping behing the skirting. The main flow/return in the hall is 22mm copper, with 10mm plastic leading underfloor to each room, and the small section visible under each radiator is 15mm copper. Can I just take a T off the visible 15mm flow and return using some 10mm?? Will the existing supply be enough to feed an additional radiator??

Hope that makes sense?!

 

[JohnD]

tell us more about the bay window. Does it have curtains, or blinds? If not, why not? Is it draughty? Does it have an uninsulated little roof to the bay? Would you put a shelf over the radiator?

Presumably it is single glazed? How old is the house, and are the windows casement or sash?

(I am thinking about how to reduce heat loss. Also a rad under a window maximises heat loss. So if you put a new (smaller) radiator under the window, it will provide very little useful heat.)

Can you detect where the draught is coming from? What's the floor, and floor covering?

 

[rarara]

Hi John, thanks for your reply. Will try and aswer your questions:

The bay has pretty thick curtains down to floor level. It isn't what I'd call draughty, but you can feel the cold standing there more than any other part of the room. We got the roof insulated last year, but I have not checked to see if the bay is covered or even accessible to actually put some down. Would the roof feel colder to the touch at that bit if there was no insulation?? What to do if the area isn't accessible, and is cold!?

They are original sash, bout 120 years old, but pretty good condition. Its their size which doesn't help - each has 120x240 of glass! The room is about 4000x7000 and high ceilings unfortunately

I know that a rad at the window will lead to some of the heat escaping straight away, but I suppose my dilemma is: if i have the central heating pumping then the room rarely feels warm when its very cold outside, so it is already inefficient for not much heat. Despite some instant loss, won't a window rad help the air circulate, rather than letting the cold window air sit all across the floor, so won't use any more energy??

There isn't really much of a draught. Its simply that with the living room door closed, someone can walk past you and you can feel a cold draught on your legs, or when the door to the hall is opened it feels slightly colder straight away (even when the hall is warm). This is perhaps just accentuating what happens with the existing rad, which is next to the door. My guess is the layer of cold air is simple getting pushed about.

And the floors are all boards throughout.

Thanks

 

[dcawkwell]

I have exactly the same arrangement in my house.
If you want the room warm you need a radiator under the window.
There is no reason you can't tap off the other radiator and have two radiators in the room.
But a radiator under the window will sort it. It forms a curtain of heat against the cold window. Also check for any air leaks around the window openers and at the side and bottom of the windows. Replace seals as necessary.

 

[JohnD]

if you have long curtains, and you put the rad behind them, the heat will go straight out the window. Have a think about secondary glazing. This will not spoil the look of your old windows, and if you have nets it is virtually invisible. It will cut the heat loss and also draughts. If you want to test this at low cost before getting it, use one of the DIY clear plastic sheet kits.

You say you have boards on the floor. If they are old square-edge boards they will be very draughty and cold. If you can get underneath and insulate between the joists it will make a huge difference. I bet this is where your cold air is coming from

While you are underneath, clear away all the old rubble, especially timber scraps which promote rot, and dead wildlife. Clean away the cobwebs and dust from the airbricks so you have a good flow of air under the floor.

Also look at your fireplace to see it is not causing a draught. Disused chimneys need to be ventilated top and bottom to prevent condensation and stains, but a single airbrick will do.

You might be able to push insulation into the bay roof between the joists of the room above, but I bet draughts round the floor and window are the main problem.

 

[JohnD]

There is no reason you can't tap off the other radiator and have two radiators in the room.

yes there is, especially with his microbore pipes.

 

[rarara]

if you have long curtains, and you put the rad behind them, the heat will go straight out the window. Have a think about secondary glazing. This will not spoil the look of your old windows, and if you have nets it is virtually invisible. It will cut the heat loss and also draughts. If you want to test this at low cost before getting it, use one of the DIY clear plastic sheet kits.

You say you have boards on the floor. If they are old square-edge boards they will be very draughty and cold. If you can get underneath and insulate between the joists it will make a huge difference. I bet this is where your cold air is coming from

While you are underneath, clear away all the old rubble, especially timber scraps which promote rot, and dead wildlife. Clean away the cobwebs and dust from the airbricks so you have a good flow of air under the floor.

Also look at your fireplace to see it is not causing a draught. Disused chimneys need to be ventilated top and bottom to prevent condensation and stains, but a single airbrick will do.

You might be able to push insulation into the bay roof between the joists of the room above, but I bet draughts round the floor and window are the main problem.

hi john, the curtains would be tucked behind the radiator (or shortened to a shelf etc) for sure. secondry glazing isn't practical since it will cost a fortune for the size we are talking about, and additionally they will be a pain to store.

the boards are T&G, good condition no gaps etc. it is a flat, so no underfloor access, but there is only about an inch or so before the deadening anyway

 

[rarara]

There is no reason you can't tap off the other radiator and have two radiators in the room.

yes there is, especially with his microbore pipes.

how would it be determined if there may be an issue though, prior to fitting an additional radiator?

 

[dcawkwell]

There is no reason you can't tap off the other radiator and have two radiators in the room.

yes there is, especially with his microbore pipes.

how would it be determined if there may be an issue though, prior to fitting an additional radiator?

Sometimes you just have to go for it!
If you have TRVs fitted on other radiators in the house as the other rooms warm up the waters has to go somewhere.
I've seen whole floors driven from 15mm supply pipes working quite happily.
You'll certainly feel the difference with a radiator under the window.