Fitting a radiator that's too short

[rwb196884]

TL;DR: Office workers should not be allowed spanners.

Just bought a house and found the living room wasn't getting much above 15 degrees. It had a type 11 1400x600 radiator that seem to be about 3,500BTU but online room BTU calculators come out at about 8,000 to 11,000. Bought what I thought was a type 22 1400x700 thinking it would be a straightforward swap but it turned out to be only 1200 wide.

The first problem was that it wouldn't hang on the existing brackets, but I've now got it on the wall -- and it's been there for a week so I'm starting to get a confidence factor that I've got that bit correct.

To bridge the gaps between the radiator and the valves I had got extension valve tails, but the wider radiator sits further away from the wall and therefore they don't line up to the valves.

So: Plan Z is to use compression fittings and a piece of barrier pipe to bridge the gaps. Plausible? (I'm expecting the pipe to not be flexible enough.)

How much PTFE tape to use? How many winds round? For the compression fitting I'm anticipating some round the pipe to go underneath the olive, and then some more over the olive. And some around the threads that go into the radiator.

If that doesn't work then it'll be time to get a grown-up to do it for me.

Out of curiosity: what is the correct solution? (Even if I had got a radiator that was the correct size it would not have lined up to the valves.)

Also: WTF is going on with the mixture of metric and imperial fitting sizes? It's insane.

 

[steadyon]

1. The best way to do it is to lift the carpet, lift two floor boards, or more as necessary, adjust the pipework under the floor to bring the pipes up to meet the valves at the correct centre distance and the correct distance from the wall. Lose the pipe under the radiator to under the floor.
2. If you are happy to have that under radiator pipe still there, then you could trim that one to match the radiator, but this might mean moving the radiator to the left. You could get away with a compression elbow, and there is almost certainly enough play in that pipe to match the wall - pipe centre distance required. The other end, where the pipe comes out through the floor will need some adjustment. You could add some pipework to the left hand ("fixed") end to get it to match the radiator position, then trim the right hand end by that much less.
3. Barrier pipe looks awful on show, but you could get a piece of 15 mm copper bent to take up gap on the left hand side. I doubt barrier pipe would have sufficient bendability to do the same.
4. If those radiator extenders are the sliding adjustable type, be aware they have a reputation for leaking.
5. Don't be tempted to use flexi pipes - they almost certainly won't be rated for constant central heating temperatures.

If you want it done well, copper is the way to go, and I'd suggest you get someone with the tools and experience.

 

[Darren Jackson]

@steadyon , Could not have said it any better myself. Good advice.
Only thing to add is no PTFE on compression fittings! done correctly hand tight and 1/2 turn more with a spanner should suffice maybe another 1/4 - 1/2 turn if there is a slight weep. Important to not over tighten your compression fitting and crush the olive. Then it will leak and PTFE might work if your lucky and not have to cut it out and try again.

 

[JCplumb]

Those pipes come out of the skirting board, not up from the floor. If the pipework was under the floor the original installer would have brought the pipes up so my bet is that it's all in the stud wall. Possibly a solid floor
You would have to break into the wall to redo them. You could sweat the elbow off and extend from there but for a neat job you'd want the pipes coming out into the valves.

 

[king of pipes]

Save yourself alot of grief get a professional to do it . Kop

 

[moonlight]

Fit the radiator to the left hand valve and shorten the one on the right, looks like it come out of the skirting board and stretches under the old rad. If you don't solder at least then you can put a compression straight to join the pipe.
Alternately get yourself a professional.

 

[Ric2013]

Regarding our fitting sizes, UK conventions are rarely insane once you understand the historical basis. This contrasts with Italian conventions which genuinely are insane. UK Plumbing threads are generally British Standard Pipe thread. This is sized in inches, even in Europe. Hence a 1/2" x 15mm fitting is clearly a fitting which has a BSP thread on one end and a compression, soldered, or push-fit fitting on the other end.

To switch to an existing metric thread would not necessarily be better from an engineering point of view (BSP was designed for the purpose of sealing on the thread and works well) so you'd need to design a new pipe thread to metric sizes - this would only make life harder as you'd still need the imperial fittings to connect to existing installations.

Uk copper pipe sizing is weird. As we usually used to use 1/2", 3/4", and 1" bore copper, we switched to metric sizes of 15/22/28mm external dimensions which are sometimes (but not always) compatible, which is why plumbers often have adapters to hand. In Europe, the standard seems to be even number sizes of metric pipe, but the UK switched to metric without actually adopting the standard used in other countries - I'm not, frankly, sure why we bothered going to metric at all.

 

[WC1]

the UK switched to metric without actually adopting the standard used in other countries -

Because it was overseen by people who work in offices.

 

[fronty]

Haha welcome to the wonderful world of radiator replacements! Even if you replaced that type 11 with another type 11, chances are the existing brackets wouldn't fit, and the new ones would mean the offset is different anyway. I've been going round replacing all the crusty old radiators in my house and what I would do is measure the offset from the wall to the centre of the tail, then check all the spec sheets for various different radiators and pick the one that had the same offset (or nearest). It means I have all sorts of different brands in my house but it reduces the amount of plumbing and fiddle-arsing about required.

When I have switched from a single panel to double panel, the offset is always going to be different as you have found out, the best solution therefore is to replumb the radiator - your right hand tail is easy, you can just cut that to size and solder on a new bit of pipe, the left hand one looks a bit more tricky, tbh I'd probably get a pro to do that one, and whilst they're at it do the one on the right too. Sometimes it's best to know your limits.

** GAH, I just noticed this is actually an old post from last year, and now can't seem to delete my post DOH **