Worth replacing single radiators for double ones?

mbspuk

My gas central heating is currently hooked up to radiators with single panels. Assuming my boiler and pipes are all in good working order, how much more heat would I get from swapping my single panel radiators for double panelled ones? Also, would they be a lot more expensive to run?

Thanks

Martin

gromituk

They give off approx. twice the heat, and so in theory you will pay approx. twice as much if you replace every radiator and you have neither a room stat nor thermostatic radiator valves. If your existing radiators are cheap and nasty and you replace them with high output types you will get more than twice the heat. Taller radiators will also have higher output.

You may not be able to replace them that easily because their connections may be further from the wall, and the brackets may be in different positions.

Your boiler may not be powerful enough to support them. If your boiler runs continuously (and has been adjusted to maximum output) and your house is not warm enough, then it is the boiler, not the radiators, which are the problem. If you replace your boiler you should get a condensing one for the sake of the environment and your pocket - approx. 25% more fuel efficient. To be at their most efficient they operate at lower temperatures though, which means you need larger radiators for the same heat output!

Also for the sake of the environment, I presume you have proper roof insulation, draughtproofing, and cavity wall insulation if you have cavity walls.

Conclusion: things are probably more complicated than you think!

alanobrien

mbspuk wrote:

My gas central heating is currently hooked up to radiators with single panels. Assuming my boiler and pipes are all in good working order, how much more heat would I get from swapping my single panel radiators for double panelled ones? Also, would they be a lot more expensive to run?

Thanks
Martin

Great question but i think the "right" answer is going to be quite complex.

A quick look in a wickes leaflet will tell you that if you swap like for like single for double radiator you will nearly double the heat output of the radiator and yes it would cost more to run simply because the increased volume of water going through the boiler will take longer to heat.

But the question you need to ask yourself is can your boiler cope with the additional load ?

The experts here (and i am not one of them) will need to know a lot more detail about your system to give a meaningful answer that question.

To give you an idea;

I recently calculated the heat losses in my new place to size a new boiler and the result was very interesting.
I was about to buy a shiny new bigger one when i found out that i actually needed a smaller one than is currently fitted. OK i admit the existing one is 25 yrs old so its efficiency is low. Explanation here amongst other places;

http://www.idhe.org.uk/calculator.html

I then calculated the output of my rads only to find that
i have a heat loss of approx 14kw and a radiator output of approx 12 kw which is not good for those cold winter nights

and yes i am ignoring the heat output of 2 adults and 2 kiddies and a cat in my calcs.

Some of this is explained here;
http://www.tertullian.org/rpearse/heating/radiators.htm

But with a shiny new 22kw boiler even allowing 3kw for water heating i still would have about 7 kw of spare capacity to increase the size or number of my rads.
I hope some of this makes sense.

then again this is all is pretty meaningless if you have a combi which i believe are sized for for hot water output rather than heat loss.

gromituk

alanobrien wrote:

then again this is all is pretty meaningless if you have a combi which i believe are sized for for hot water output rather than heat loss.

Yes - combis have to be powerful in order to heat domestic hot water instantly. But they are likely to have internal adjustments to limit the output in heating mode, making them appear like a conventional boiler.

mbspuk

Wow. Proves how complicated things are when you do them properly. I hadn't thought about the boiler having to have enough power, or the fact that it would cost twice as much in fuel.

What I did think was that I'd just have to replace the radiators and that would be that.

Time to look at the bigger picture.