Radiators and BTUs

[Alfie25]

I need to replace a few radiators and am looking to see if my boiler will cope ok with bigger sizes (replacing singles with doubles)

As I understand it, the boiler has a limit in the number of BTUs it can provide. What I can't understand is why the BTU rating is different for a double panel double convector and a double panel single convector. Surely all that matters is the size of the panel (i.e. the volume of water the boiler has to heat?), and this volume will be the same for thes 2 radiators. Why does a radiator with more fins take more of the boilers output when the volume of water requiring heating is the same?

 

[Agile]

Boiler and rad outs are now specified in kilowatts. ( kW )

The more metal and surface area the more heat is dissipated.

Its virtually certain your boiler has ample output for higher output rads.

You can calculate the whole house heat loss and compare it with the boiler output power.

Tony

 

[Alfie25]

Cheers. The boiler is a conventional worcester 12kw, which is pretty puny in my opinion but was in the house I've just moved into and it's not very old so I'm loathe to change it.

So it's too simplistic for me to look at volume of water being heated? Are you saying as there's double the fins in the double/double it draws more power from the boiler?

 

[ALEC1]

To find out ehat size the boiler should be, sizi it correctly at www.idhee.org

 

[dcawkwell]

Although small it is big enough to handle the heat loss of most houses.

If you have thermostatic valves on the radiators as rooms get to temperature the water will be diverted to other radiators.

Ensure you have full loft insulation and double glazing.

 

[Dan Robinson]

The fins increase the surface area of the rad significant;y. this increases the heat loss of the rad to the room (to make you warm and toasty).

The boiler is burning gas to create heat to replace that which is lost from the water as it leaves the rad.

You would be surprised at how little a house really needs. I have a 4 bed detached, not huge, not small. 12kW is more than enough. If I sorted a few draughts, sorted the cavity insulation and upped my loft insulation I am pretty sure 8kW would still cope.

My hot water requirements are a different kettle of fish though.

 

[D_Hailsham]

The technical name for a "radiator" is "emitter". That's because them majority of heat is not produced by radiation but by convection of air over the surface of the radiator. Hold your hand a foot away from a 1kW radiator and you will hardly feel a thing; do the same with a 1kW electric fire and you will definitely feel the heat being radiated.

The fins on the back of a "radiator" increase the output of the radiator by channelling air close to the hot surface, so improving the convection effect.