sizing a radiator for a loft

[Mgrant]

Hi can anyone help give the correct size radiator/s or btu output require for a loft space 4.7 meters long, 5.2 meters wide, and 2.7 meters at the highest point, is a pitched roof. Thanks for any help.

 

[lame plumber]

i asked this recently but why are you heating an attic space?

 

[Ermintrude]

A massive one but don't connect pipework as your heating bills will be immense. If you have no vapour control and poor insulation start saving to replace the roof. Wet rot will eat roof in 18 months

 

[Mgrant]

The attics been converted to a bedroom a long time ago so the roof is insulated

 

[lame plumber]

fm experience of attic convertions, if the insulation is done to b regs orders, youll not need anything bigger than a matchbox to heat it! do an online search for rad sizing calcs and off you go

 

[village idiot]

A minimum of 7500BTU.
But that is just a guess as it will take a lot of heating.

 

[PlumbBobBob]

well it's not an attic then it is a bedroom in the loft. different kettle of fish. how long ago was the conversion done and did it pass building control.

 

[Mgrant]

air vents if fitting a rad in bedroom in the loft? haven't heard of this before.

 

[Mgrant]

Some online calculations are coming up with about 5000btu's sounds small to me

 

[Mgrant]

Was thinking two 600 x 600 doubles giving 7600 btu's

 

[Mgrant]

Sound about right to people?

 

[AWheating]

honestly its gunna be a guess if you dont know the heat losses.

 

[Mgrant]

the roof is insulated then plaster boarded

 

[mountainman]

Big radiators with tv's will cover every eventuallity.

 

[Centralheatking]

If I have not missed something u dont say which system - combi or system/conventional
cause you might have probs with the latter regarding 'head' on the 'F & E' against the top of the
radiator/s - LET US ALL HAVE A DIAGRAM then we can see the rabbit Centralheatking

 

[village idiot]

it may be a conventional system, but if sealed, then no need to worry about head

 

[Mgrant]

Its a sealed system off a combi boiler. Does two 600 doubles sound ok. Was struggling to work it out do to the ceiling high being pitched.

 

[Best]

You need the actual cubic metres worked out.
This shouldn't be too hard to do with a pitched roof. Work out the volume of "triangular" part(s) of the upper part of room by multiplying the length, & height o & divide by 2. Then multiply by width of room for volume of that area.
As someone has said, plenty of heat & a Trv will keep it okay. If the roof & stud Walls are done with 100mm insulation board, any cavity walls insulated & double glazed windows, you won't need much heat.