Relative efficiency of finned vs unfinned rads.

[Malcolmkeith]

I want to replace some old single and double steel radiators. These rads have no fins and I would like to know what is the relative efficiency of modern finned single and double rads. In other words how much smaller would a finned radiator have to be compared to an unfinned one for the same heat output.

 

[Bahco]

You should not be worrying about what you are worrying about

Measure your room, ceiling height, etc and take them to a plumbers merchants who will work out the correct Kw of each rad for each room.
Finned rads increase the surface area to get more heat out of each rad and are the norm these days.

 

[Diyisfun]

If you go to a plumbers merchant they will sell you what they stock. If you look on the manufactures web sites they will give you the BTU's of radiators, what you need is to calculate your heat requirement, and thee are sites for that.

 

[PEDANTICVINDICTIVEMAN]

Just swop em for the same size and fit TRV's and a room stat, it aint gonna make enough difference to warrant fitting smaller rads and then having to alter our pipe centers.

 

[Slugbabydotcom]

To answer your question I reckon on a rad about 2/3 the size of the un finned.
Suggest you follow the sage advice already given

 

[Agile]

The answer to the original question is that ALL radiators are 100% efficient!

All the heat output is used to heat the room with no loss.

Of course what the original poster meant is what is the relative heat output increase from adding fins. The answer is about 30-40%.

However that is irrelevant. The correct procedure is to fit the same size finned rad with a TRV and it will give faster warm up and better temperature control. Just as stated above!

Tony Glazier

 

[ChrisR]

Have checked a few makes in the past, and found the convector fins add 30 to 33% to the output.

 

[traineegasman]

Do you mean, without going all around the world... you are considering changing you`re old radiators, & how do I choose new ones? & will they be as hot?.....is that the general idea???

 

[PEDANTICVINDICTIVEMAN]

Makes you wonder if it's all a conspiracy, we fit finned rads in place of standard hence more output which is gonna make your condenser condense longer and we paid for it all in the price of the rad plus the extra vat, looks like the goverment has managed to rake in more revenue or am I just paranoid.
Just because your paranoid doesnt mean their not out to get you.

 

[Malcolmkeith]

Just swop em for the same size and fit TRV's and a room stat, it aint gonna make enough difference to warrant fitting smaller rads and then having to alter our pipe centers.

Actually this is exactly what I had planned to do until I was told you can't fit TRVs to rads on a one pipe system which is what I have, although I still don't understand why this is so. Perhaps someone can enlighten me.

 

[nstreet]

Just swop em for the same size and fit TRV's and a room stat, it aint gonna make enough difference to warrant fitting smaller rads and then having to alter our pipe centers.

Actually this is exactly what I had planned to do until I was told you can't fit TRVs to rads on a one pipe system which is what I have, although I still don't understand why this is so. Perhaps someone can enlighten me.

Think of it as a long hose pipe, if you put a kink in it, will water come out of the end? Same with a single pipe system fitted with a trv.
The trv is the kink.

 

[bripl]

hello if a one pipe sys is installed correctly YOU CAN FIT TRV so what is the problem/reason for not fitting them

 

[Diyisfun]

bripl
hello if a one pipe sys is installed correctly YOU CAN FIT TRV so what is the problem/reason for not fitting them

Im not a plumber ..but 1 pipe is '1 PIPE' as has been said its like a hose with a kink & trv is the kink...SO HOW WILL IT WORK?

 

[bripl]

if you install a one pipe sys and turn off the first rad HOW DOES THE REST WORK now think before you answer.also how do you balance the sys

 

[kevplumb]

like this

i have been told you can get trv's for a one pipe systen never seen them tho