Rad sizes and regs

[motorbiking]

In which case - its not the end of the world to shell out for some beefier rads here and there.

 

[bernardgreen]

Can you explain how? That would seem to be 0.5kw of free energy.

When the room temperature is 0°C the water leaving the radiator is cooler than it would be if the room temperature was 20°C.
The water will give up more heat energy to the room at 0°C than it will to the room at 20°C

 

[dilalio]

In which case - its not the end of the world to shell out for some beefier rads here and there.

Agreed.

 

[^woody^]

There is no specific building regulation requirement, other than a tenuous link to Part L in that the system should be efficient so as not to use more energy than necessary to heat the property.

If the build was done under the NHBC, then section 8.1 will apply and this specifies performance requirements of the system, and this will link with
BS EN 12828:2003 for the system design and performance standards - and this would be the reference point for an independant claim under the purchase contract.

As an aside, when I added a highly insulated extension a few years back, I was surprised on just how small the radiator was compared to the large radiators in the smaller existing rooms, and yet the room is the warmest despite the radiator calling for heat the least.

 

[D_Hailsham]

Can you explain how? That would seem to be 0.5kw of free energy. Or are you saying its able to radiate 1.5kw of energy against a rating of 1kw, rather than turn 1kw in to 1.5kw.

Your second suggestion is correct: it's radiating 1.5kw against a 1kW rating;it's not "free" energy. The extra 0.5kW comes from the water, so the boiler has to produce an extra 500W -if that is possible. Thats why rads have to be tested under specified conditions: it ensures a level playing field. Some unscrupulous retailers were, until recently, quoting rad outputs using the pre-1997 Standard as it gave the impression that their radiators gave out more heat.

I should point out that this is a theoretical calculation of the output a "one kilowatt" radiator would produce at a constant room temperature of 0C.

As I said earlier, a radiator is not like an electric fire which gives off a constant amount of heat. The heat output of a radiator is determined by three temperatures: flow, return and air.