Work is progressing on our house and now we're actually getting to the stage where we need to think about radiators - but what size do we need to make sure the room is heated correctly? What dimensions should the radiators be or is it just their power that's important?

What is the right radiator size for a room?

Buying a radiator takes a bit of consideration. In order to calculate the radiator size you need, you need to calculate what heat output it requires to heat the room and for this you need a Radiator BTU Calculator.

Radiator outputs are quoted in watts and BTUs (British Thermal Units).

This might sound complex, but luckily the folks at Feature Radiators have helped us pull together some Radiator Sizing guidance...

Feature Radiators told us "For a fee, a heating engineer will determine the precise heat requirement of a space, based on a series of complex calculations considering a wide range of variable factors.

"In our view, the following BTU calculation, which is widely used within the industry, gives a good enough approximation. If in doubt, choose a radiator with a higher heat output than required and fit a thermostatic radiator valve to control the room temperature."

Calculating radiator BTU's

Step 1 - Find the volume of the room in cubic metres:

• Calculate length x width x height

Step 2 - Adjust according to room type:

• Lounges and dining rooms multiply by 50
  
• Bedrooms multiply by 40
  
• Common areas and kitchens multiply by 30
  
• Bathrooms multiply by 90
  

Step 3 - Allow for important variables:

• For rooms facing north add 15%
  
• For French windows add 20%
  
• For double glazing deduct 10%
  
• For very exposed sites, or very cold weather add 10%
  
• For new builds (that are much better insulated) deduct 20%

This will give you the output of any radiator in watts.

Multiply this by 3.412 to give the BTU requirement for the room.

Based on this advice we have pulled together a radiator BTU calculator:

Click to view BTU Calculator | For an editable verison contact us.

Thanks to www.featureradiators.co.uk for their radiator size advice.