How important is radiator location in a room?

[GavThePlumber]

Good thread this

I like for my missus to have optimal choosing for interior designing and furniture positioning and I don't care much for Physics, so I generally install rads straight on to the ceiling these days.

I just use Jeff Goldblum's classic line from Jurassic Park, nature finds a way, then just apply the same logic to heat, seems i am in good company with that thinking with a couple lads in this thread.

Save money too, don't need to drop pipes and at £2/m, everyone wins, we are in a recession after all.

 

[Norcon]

Onetap wrote

Would double/triple glazing stop low level draughts altogether? I've no idea.

You must have some idea. Get off the fence.
With modern glazing units with U values as low as 0.6 then in many cases the walls become the cold surfaces.
The "coanda effect" will be slithering all over the shop!

So only two reasons to fit the radiator under the window.

1 - Wall space limited else where.
2 - Mr plumber has been doing it that way for 1 x 40 years so windows it is!

 

[Onetap]

You must have some idea. Get off the fence.

Meaning I've never had to try it and don't know. I won't pontificate about something I don't know about.

With modern glazing units with U values as low as 0.6 then in many cases the walls become the cold surfaces.

You wish! Where did you get that from?

http://www.pilkington.com/~/media/Pilkington/Site Content/UK/Reference/TableofDefaultUValues.ashx

The external surfaces are always going to be coldest. I'd still fix radiators under windows.

Even in buildings with ducted air HVAC systems, it was quite common to fix radiators under the windows to offset the heat lost through the glazing. I've no idea whether that is still current practice.

 

[Onetap]

Sage reasoning there dude.

Why, thank you, kind Sir.
I shall now get wasted on White Russians to celebrate my elevation to dudedom.

 

[Dan Robinson]

I would join you but I'm driving at the moment.

 

[Norcon]

Onetap wrote

I won't pontificate about something I don't know about.

No one is asking you to pontificate.
You're professional opinion would suffice.

If the window has a lower heat loss factor than a section off outside walling and the radiator is positioned on an inner wall then where will the "coanda effect" manifest itself?

You wish! Where did you get that from?

Scandanavian design!
But have a look at Pilkingtons EnergiKare Krypton gas filled units.
Very impressive.
Government specifications always seem to lag behind whats happening in the real world.

 

[David937]

The external surfaces are always going to be coldest. I'd still fix radiators under windows.

Even in buildings with ducted air HVAC systems, it was quite common to fix radiators under the windows to offset the heat lost through the glazing. I've no idea whether that is still current practice.

It certainly is what we do at the firm I work for; a lot of the new buildings we work on have full height glazing and ducted HVAC but we usually install trench heating around the perimeter of the glazing, sometimes we use linear slot diffusers or radiators if it is not full height.

 

[Norcon]

The external surfaces are always going to be coldest. I'd still fix radiators under windows.

Even in buildings with ducted air HVAC systems, it was quite common to fix radiators under the windows to offset the heat lost through the glazing. I've no idea whether that is still current practice.

It certainly is what we do at the firm I work for; a lot of the new buildings we work on have full height glazing and ducted HVAC but we usually install trench heating around the perimeter of the glazing, sometimes we use linear slot diffusers or radiators if it is not full height.

Commercial Hydronic heating is on its way out with the advent of modern
air conditioning systems where both heating and cooling are emitted from a single emitter.

Some consultants just don't have a clue and waste clients money like it was printed from a machine.
I've seen guys on the bigs jobs (office blocks, multi storey banks, supermarkets etc) with their silly radiators under the windows while we installed ac.
Complete waste.

 

[David937]

The external surfaces are always going to be coldest. I'd still fix radiators under windows.

Even in buildings with ducted air HVAC systems, it was quite common to fix radiators under the windows to offset the heat lost through the glazing. I've no idea whether that is still current practice.

It certainly is what we do at the firm I work for; a lot of the new buildings we work on have full height glazing and ducted HVAC but we usually install trench heating around the perimeter of the glazing, sometimes we use linear slot diffusers or radiators if it is not full height.

Commercial Hydronic heating is on its way out with the advent of modern
air conditioning systems where both heating and cooling are emitted from a single emitter.

Some consultants just don't have a clue and waste clients money like it was printed from a machine.

I don't work for a consultant, I work for a contractor and we do a lot of Design & Build so we know what works and what doesn't based on our experience.

 

[Onetap]

You're professional opinion would suffice.

I'd stick the rads under the windows.

It might be cautious, but I'd be confident that I wouldn't get called back to sort out a cold draught and have to re-locate all the rads at my expense.

I'd let someone else do the innovative stuff and copy them if it turned out alright.

There's no money in innovation. Brunel died broke and broken.

If the window has a lower heat loss factor than a section off outside walling and the radiator is positioned on an inner wall then where will the "coanda effect" manifest itself?.

The Coanda effect simply accounts for the fact that the air current sticks to the adjacent surface and goes further than you might expect.

It's more relevant to AC & VAV systems, where cool supply air 'sticks' to ceilings despite the adverse convection effect. It will drop off at some stage as the VAV air flow turns down.

With a radiator on a wall opposite a window, you will easily get a cold draught flowing across the entire floor and a warm draught flowing across the entire ceiling. In the extreme case, as in the building mentioned above, it generated an impressive draught; people just didn't sit near the windows in winter.

Scandanavian design!
But have a look at Pilkingtons EnergiKare Krypton gas filled units.
Very impressive.

I did, thanks.

http://www.pilkington.com/resources/energikaretriplebrochurei8642mar2009.pdf

0.8 w/m^2 K is the lowest they quote.

It's triple glazed & probably triple expensive. Besides which, I've never seen triple-glazing in the UK, so it's probably not representative of reality.

If it had such high-performance expensive glazing, I'd go for UFH and wouldn't bother with any rads.

 

[Dan Robinson]

Have to agree on the consultant front.

Woonkers.

Big one we're doing in spring is currently being controlled by consultants.

The builder and I give them until late January before the customer realises.

 

[Norcon]

Pilkington K Glass™ S is 0.5 w/m^2 K.

0.8 w/m^2 K is the lowest they quote.

And 0.9 for double glazed units. Not too shabby eh?

 

[Onetap]

Commercial Hydronic heating is on its way out with the advent of modern
air conditioning systems where both heating and cooling are emitted from a single emitter.

Bolleaux. I've seen chilled beam installations with ventilation systems and perimeter heating under the windows.

The computer-aided thermodynamic modelling consultants advised it and I wasn't going to argue.

 

[Dan Robinson]

so it's probably not representative of reality.

This is Norcon we're dealing with .

 

[Norcon]

Commercial Hydronic heating is on its way out with the advent of modern
air conditioning systems where both heating and cooling are emitted from a single emitter.

Bolleaux. I've seen chilled beam installations with ventilation systems and perimeter heating under the windows.

The computer-aided thermodynamic modelling consultants advised it and I wasn't going to argue.

And twice as expensive as an ac system as only the refrigeration plant is required.
If I was the client I'd have been arguing.
Probably a government job where money is there for the wasting.