Radiator for a 3x5m living room?

[rednaxela]

Hello All,

I have decided against underfloor heating for my new lounge/hall, and will be going for radiators.
i've worked out using various websites that for the lounge, I need 5200-6250 BTU.
Screwfix do one at 7083 BTU.

My questions are;

Will one radiator be ok to cover a room of this size 3x5m or do I need two smaller ones spread out

In a room with double glazing and cavity wall insulation, is it best to over spec and then control the radiator with a valve, or should I stick to a mid BTU value radiator

any opinions would be great.

thanks, Alex.

 

[Agile]

You should fit a TRV which will control the temperature.

A longer rad will distribute the heat better. Avoid double panel rads. This is less relevant when the insulation is good.

A higher heat output is no problem and will work better at a lower temp which can increase efficiency with a condensing boiler.

The rad should ideally be placed on an external wall and below windows. This is much less important with cavity insulation.

I prefer to work in kilowatts and dont understand why rad makers still quote outputs in BTU. That sounds like the old days of coal and steam.

Tony

 

[gas4you]

Most new rads will be quoting their outputs at 50C now so should not need to oversize for condensing boilers!

 

[rednaxela]

Thanks guys.
Yes, it will be placed under a window. To get the output I need in the space available I will need a double radiator.
I have cavity wall insulation + I will fit a sheet of reflector material to the wall.

Alex.

 

[ChrisR]

Since you've done the rounds, which online calculator worked best for you Alex?

 

[rednaxela]

They were all similar, however this one had an output range.

http://www.theradiatorcompany.com/heatoutput


B&Q also do one.

http://www.diy.com/diy/jsp/bq/templates/content_lookup.jsp? content=/bq_advice/planning_tools/btu_calculator.jsp

+

http://www.heatershop.com/btu_calculator.htm