Anyone installed their own thermostatic radiator valves?

nkkingston

Our radiators are pretty old, and on several of them the existing plastic knobs on the valves have become brittle and snapped off. With gas prices rising and winter approaching, I'm tempted to switch them for thermostatic valves - prices are about the same and even if it only reduces heating bills slightly it's still a little win. The question is, how plausible is it to do this ourselves? We managed to replace an electric shower last week, which took all day and more trial and error than is ideal, but works (unlike the old one!). The most we've ever done with radiators before is bleeding them, though. Do you have to drain the whole system? Are there any costly tools we'll need that we aren't likely to have in a standard home DIY kit? Are there any variations in radiator valve or pipes that might catch us out in our ignorance?

Has anyone done it themselves, and what was the experience like?

EssexExile

Yes you have to drain the system.
Yes there is plenty of variety of fittings and pipes.
You need basic plumbing tools and a box of bits, all depending on how old the installation is and how easily it all comes apart.

Farside71

I'm not a plumber, but I've regularly removed radiators for decorating, and have drained the system down a few times to give it a flush through with water etc.  Also replaced ball floats and mechanisms in thermal store water tank etc

I've accumulated a few pipe wrenches and pump pliers, spanners and stuff, that fits the different connections.  I wouldn't go near anything that involves soldering but it's not that difficult if you are competent at DIY and have the right tools.  Lots of useful YouTube stuff in plumbing.

Mine is a fairly modern installation though so I've never been too worried about old pipework.

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NSG666

If you have radiator valves with a large nut like below then you need to replace the tails (bit that screws into the radiator) which makes it a bit more difficult and to remove the existing you would need a radiator spanner. Radiator Spanner | Plumbing Keys | Screwfix.com

When using your adjustable spanner to undo the existing valves you need to support the copper pipe that they are connected to otherwise the valve can turn and damage the end of the pipe. Scrape any paint off the copper pipe to allow the nut to slide down it.

Although it's possible to replace the valves without draining the system in your case you would probably be better draining because if you get the no-drain method wrong you will end up with a mess.

If the existing valves have been put on too tight the olive might have damaged the end of the copper pipe. Also, the olive will probably be in the wrong position so you need to remove it without damaging the end of the pipe. If the end of the pipe has already been damaged then a good wrap of PTFE tape might help the new olive get a seal.

If you still fancy doing it come back for more info and post a photo of your rads and valves.

Depending on what temp you normally have your thermostat set at you might save more money by turning it lower at this stage (if you drop it mid winter you notice the difference but if you set it lower now you'll get used to it)

FreeBear

EssexExile said: Yes there is plenty of variety of fittings and pipes.

Assuming copper pipes and "standard" steel radiators, about the only fly in the ointment might be threads. Real old heating systems from the 70s & earlier will use imperial fittings & threads. You may have to replace the stubs (tails) sticking out of the radiator, but most TRVs come with these anyway. Same for the nuts & olives on the copper pipes - Getting the the tails & nuts off can be a real challenge sometimes.

While you have the system drained down and the radiators off the wall, it is worth taking them outside and flushing them out with a hose pipe - Put some blanking plugs on the tails before moving them or you'll get black gunk staining your carpets.

Don't forget to put some corrosion inhibitor in the system when you refill.

tacpot12

You might find you have imperial copper pipes if the radiators were installed in the very early 1970s, or before. if so, you might find you need these: 10x Brass Compression Olives 1/2 - Plumbing Barrel Olive Pipe Fitting Imperial 5060476070759 | eBay 

If you want a recommendation for the TRVs to go for, I've been very happy with the Honeywell VT15 TRV. Toolstation has a pack of 15 on offer for £99.97 which is a great price even if you only need 10 of them!

Have a look at the Plumberparts channel on YouTube for details of how to fit TRVs. You should also look at the video on how to use PTFE tape.  

jimi_man

Yes I did it on a bathroom radiator. Not hugely difficult but as you say, it does require draining the system. Basic plumbing tools will suffice, though I put in a new radiator so didn't have the issue of different threads. 

There are so many videos on YouTube of how to do stuff, so plenty of guidance.