older/newer GCH radiator efficiency?

Post when you've got something to say that's not based on you making silly things up.

come back when you've got a fact to offer us.

Feel free to tell us where the inefficiency is in an oil filled radiator. (I think we can assume it doesn't get so hot as to glow.)

NT

we have

the meaning of efficiency in physics & engineering is well established. The failure of some to know it does not make it not so.

We could probably all agree that what is relevant is something other than radiator efficiency. Deciding that that something else /is/ radiator efficiency is a factual error.

snip

yes it has been discussed here

System efficiency is probably most relevant to the OP, and radiator choice can sometimes affect it.

NT

If an engineer isn't able to design a silent fan they had better stay out of that business.

NT

All hot water radiators output their power almost entirely by convection.

NT

Its typically about 80%/20% at a 70 degree flow rate.

Also worth considering is the effects of the adjacent wall. A radiator will heat that by radiation, and you will get a boost to the rate of convection from the "hot" wall.

(also counter intuitively, its common to place reflectors on outside walls to reduce transmission through the wall - however in doing so, you lose the convection boost you get from local heating of the wall surface. It might save energy, but make the room actually feel less warm).

I'd prefer to save the energy. There is CWI but the heat gets through to the cavity eventually and there'll be a bit of convection through the rock wool. The reflector will reduce the rate of radiation from the rad as it's sending some heat back into the rad - nett IR. There could be, I suppose, some increase in convection due to the rad /not/ being cooled quite so much.

My new rad calls for at least 15 cm clearance from the floor so that convection isn't impeded; I wonder how convection is affected by gap from wall to rad.

Have it your own way. Some things are exactly 100% efficient. I take it you work in advertising?

Would that be 100% silent? ;-)

If you have the ability and tools to drain down the whole system, you could remove them, take them outside (if you have a garden) and 'power flush' them with a hosepipe.

A black&decker workmate is ideal. Clamp the rad vertically in the jaws and connect the hoepipe to an inlet then rock the whole lot, workmate and rad back and forth until the water runs clear.

In this weather leave in the sun to dry then gently bang them onto the ground, impacting one of the corners where a connection is to see if any flakes of rust or grey powdery stuff comes out.

If a lot of stuff still comes out, try filling with cheap vinegar and leaving for couple of days then hose them out again.

My house (1976) had single panel rads upstairs. In the two largest bedrooms, the one where the class 2 flue blocks were (for the baxi bermuda non-pumped back boiler) had a rad 2/3rds the size of the room without this benefit.

The wall where the flue blocks were got so hot the rad was only needed during extreme weather.

If mounted on an external uninsulated wall, then there must be additional conduction losses via the section of wall immediately behind the rad.

Isn't that why putting insulated foil-stuff behind the rad was one of the 'energy saving' tricks that people used to do in the late 70's and 80's ?.

If it is placed close to an external uninsulated wall, then you have a warm radiator and a cold radiator back-to-back, with an air gap between them. The warmer you make the inner surface of that external wall, the more heat will flow to the outer, cooler surface.

But would a man from BG with a powerflush machine get all that gunge out ?. No easy way of telling..

PS Beware of doing this with single panel rads. When I did the one from the small bedroom, it blew out some sort of rubbery bung from inside the rad, so that I could see right through from one connector to the other. I suspect this was a baffle to force the water to flow through the rad and not take the path of least resistance.

That's a bit extreme for Scotland isn't it ?. Even in Sussex I would feel cold at 17C.

They must be mythical, since I have never heard a silent fan! :-)

A silent fan that can be heard would be noisesome.

The fact is some of us have moved with the times and accept new or a change of meaning to a word.

It's another fact others are in denial, suffering from senility.