Different Rad Calculators - different results

[davey76]

Hi

I've tried sizing up the radiator I need for a room.

http://radcalcer.co.uk/default.aspx gives 5,270 BTU
http://www.bestheating.com/btu-calculator gives 3,500 BTU

This seems like quite a difference - can anyone point me at a reliable site?

Ta

 

[Charnwood]

One is obviously very basic in the questions asked, the other more comprehensive.

http://www.radcalcs.com/

 

[D_Hailsham]

One is obviously very basic in the questions asked, the other more comprehensive.

http://www.radcalcs.com/

And that one uses vague factors to calculate rad sizes.

The best one I have found is this: Radiator Calculator

 

[D_Hailsham]

One is obviously very basic in the questions asked, the other more comprehensive.

http://www.radcalcs.com/

Not obvious at all!

And radcalcs uses vague factors to calculate rad sizes.

The best one I have found is this: Radiator Calculator

 

[Charnwood]

Not obvious at all!

Well it was to me.

By the way, I quite frequently confuse Quote for Edit too.

 

[D_Hailsham]

Not obvious at all!

Well it was to me.

So why do you recommend one which is no better than the OP's first choice?

Both 'radcalcs' and 'radcalcer' use a crude formula based on the volume of the room with multiplying factors to give the required BTU.

Nothing 'scientific' about either of them. Reminds me of the rad manufacturer's leaflet I obtained from a DIY shed over 20 years ago, which said: measure the volume of your room and multiply by X; that's the size rad you need.

At least 'best heating' uses U-values and actual temperatures, as does the one I recommended.