radiator efficiency

[Dave]

What is the efficiency difference between a 1970's double radiator to today's double rads fitted with fins?

Dave

[Roger Mills]

How are you defining efficiency? In terms of heat out vs heat in, there's no difference, but if you're thinking in terms of heat output per unit area, a double radiator with double fins has an output which is roughly 60% higher than the same rad without fins at the same Delta_T (dT)[1]. A double with single fins is about 30% higher.

[1] dT is the temperature difference between the mean radiator temperature and room temperature. If you run at a low dT - as with a condensing boiler - you may well get *less* output from a finned radiator than you would have got from an unfinned jobbie running at a higher dT.

[Dave]

That is what I wanted to hear. Son has been to visit today and was pontificating on fitting more efficient rads. Quite where he fills up his bull shit tank, I don't know, but my wife takes all he says as gospel.

So the payback time will be quite long then.

Thanks

Dave

[dennis]

If you fit rads that output more heat the rooms will be warmer and it will cost more, If you want warmer rooms look at insulation not new rads.

[John Rumm]

The new rads will have a higher output for a given size. The efficiency in the true sense is the same, however if you have a condensing boiler, then higher output rads will allow you to run lower flow temperatures and yet still maintain comfort and warm up time. The will increase boiler efficiency and may make for more comfort with less temperature overshoots. With a conventional boiler there is nothing much to be gained unless you have rooms that you find difficult to get to temperature.

[Spamlet]

Ah: but the point being that you can have smaller rads. We are rather hoping that having just replaced a rad that took up a whole wall and prevented us from having a decent sized settee, with a smaller one bent to fit under the bay window, we have gained a lot of space. and, hopefully, reduced draughts at the same time as not reducing the ability to heat the room, adequately. (Draught from the window wise, it already seems to work: the winter will tell us whether the fins make enough difference to make up for the smaller size.)

S

[Andrew Gabriel]

Most heating systems nowadays have thermostatic control.

May not make any difference to the temperature of the rooms, although tends to be good for the wallet.

[Tabby]

The energy efficiency of both types is 100%.

NT

[ransley]

The efficency of a hot water system is determined by the boiler, is this a question where he thinks you will save money in your heat bill with new radiators? If you want to save money turn down the thermostat and wear a jacket or you insulate your home and put in a condensing boiler. Condensing boilers run at a lower temp, if your condensing boiler and old radiators keep you warm then you should be very happy.

[David Hansen]

On Tue, 07 Sep 2010 19:20:53 +0100 someone who may be Dave wrote this:-

The finned one will emit more of its output by convection. Depending on the room this may or may not be an advantage.

[Dave]

That is what I am going to tell my wife. Because our son has done a bit of plumbing in his bathroom, he now considers himself to be an expert on all aspects of the trade. I, on the other hand, have spent some years learning the tips and tricks from this ng.

Dave

[Dave]

Its a quite new conventional boiler fitted just as the regs were changing.

Dave

[Dave]

Thanks to all who have answered, but I have not replied to. The asnwers were what I expected. I've printed a couple out for SWTSMBO to read later.

Dave

[John Rumm]

So not much to be gained in your case unless you would like smaller rads. Next time you replace the boiler there may be some mileage in it.

[The Natural Philosopher]

Mind you, dennis is actually talking c*ck as usual. Fit TRVS to the rads, or balance them down to get optimal fuel consumption.

Small rads are never ideal.

Insulation always pays off however. The random monkey hit the right keys that time anyway.

[js.b1]

Reminds me of the nonsense marketing by the electric radiator sellers, Calortec and a whole host of others. The saving grace of Calortec was the aluminium radiator extrusions were well made, well finished, and little more than the cost of buying the actual extrusions separately and bolting them together (as in =A390 v =A3120 for example). Those priced at =A3280-480 are just a ripoff. The disadvantage of Calortec I suspect will be parts availability since Argos/Homebase have discontinued them and thus "repair" will be a case of "refund".

If you want to reduce cost, insulate the main living area, get rid of draughts.

[Dave]

Noted and printed for her to read.

Thanks

Dave

[Martin Pentreath]

Reminds me of a conversation with someone who was convinced that oil- filled electric radiators were much cheaper to run than any other form of electric heating. The reasoning was based on something to do with "oil holds the heat for longer". Logic, physics and shouting made no impact whatsoever, and I ran out f patience before I got round to brute force.

[dennis]

TNP is wrong again!

Rubbish, too small is a problem, small is not.

"Balancing them down" does not make sense. You either balance it or not, down is something TNP has made up like he usually does. Maybe someone that he hasn't kill filed could ask him to explain it? I can't be bothered with changing my nym to ask as he would just churn out cr@p as usual.

TNP would disagree with me even if I copied what he said a couple of posts before, the mans an eejit. But as he says he has randomly agreed with me.

[ARWadsworth]

Lots of people disagree with you, not just TNP.