fitting thermostatic radiator valves.

windswept

we have just bought some trv's, unfortunately they haven't come with fitting instructions, how exactly do you fit them? when we did our bathroom a couple of years ago, we changed the radiator and I don't remember having to drain the sytem to do it, can you do it without draining and /or making a soggy mess?

bigdic

You'll need to drain the system, when you changed a radiator you turned of the valves at either side of the radiator but now you're changing the actual valves.

windswept

actually we changed the valves and I am sure my hubby had to cut the pipes down a bit to accommodate the new radiator. he can't remember draining the system either, he just can't remember what he did actually do.

thekid_2

if he didnt drain the system, then cut through the pipes a bit the answer to "he just can't remember what he did actually do." is - Got Wet!

You need to drain it down before removing the valve, or be prepared to get wet, it will take a few minutes to fit the valves if all goes well, a bit longer if they don't fit on the existing nuts...

good luck... oh and either way don't forget your corrosion inhibitor for the re-filling of the system.

btk

Avoriaz

You can buy a kit that will freeze the pipes and allow you to work without draining down.

I have never used one and personally would not take the risk.

What happens if you have a problem and can’t get the valves on before the ice melts?:eek: I suppose you add more refrigerant.

As you are doing a few radiators I suggest you use this as an opportunity to clean and drain down the entire system. Remember to add corrosion inhibitor when you refill.

And check for leaks.

TRV’s normally fit to the pipe with a compression fitting. It should be obvious when you examine them.

Happy_frank

If you block of the outlet pipe from the header tank in the loft and also seal the expansion pipe (usually hanging over the header tank) then you can cut a pipe or remove a valve without gettting wet.
You can buy a couple of rubber bungs from most plumbers merchants for this purpose. When I changed my header tank I put valves on both pipes to make it easier.
You will still get a bit of water coming out of the pipe (a small bowl full) but then the vacuum from the blocked header pipes will hold the water back.
Important : only ever cut one place or remove one valve at a time or you will loose the vaccum. Also make sure you turn of the boiler and the pump.

Mr_Warren_2

That is assuming there is a header tank in the loft (my system is directly fed from the mains as it is a combi boiler). All my rads are fitted with TRVs at home. There are 2 types. The latest design is a push fit connection....soooooooooo easy to fit. As suggested above, you need to empty your system in order to fit the new valves. As suggesetd above, one of those freezing cans is what you need. It comes with a foam sleeve that fits around the pipe you want to disconnect (arrange sleeve a good 20cm away from the area you want to work. A can should last you for 2 TRVs.There will be a need to clean the old rad pipe correctly in order for the new TRV to fit properly. The job is VERY easy but follow instructions as follows:

- Drain system or freeze said pipe below where you are going to work (remember TRVs are fitted on the in side of the radiator, the side that gets hot first...otherwise there will be a banging noise everytime the valve tries to close against the flow of central heating water).
- Remove old valve, remove old olive and make good the pipe area (that is where you might have to cut the pipe a bit as the old olive might have damaged the pipe diametre.
- Fit new valve with it's new olive (or use push-fit TRVs)
- Reconnect to radiator.
- Do all your radiators this way and after the last plug of ice has melted in the last TRV pipe, open all your TRVs and bleed system at your highest elevation radiator (you might need to add more water to your system at this stage).
PM me if needed, I will explain in more details.

Avoriaz

Even if the lock shield valve on the return side is closed, I would still expect the water to drain from the radiator itself.

It is surely necessary to drain the radiator to avoid the risk of a small flood of very dirty black water.:eek:

It is a long while since I did any DIY c/h work.

andrewmoorcroft

Some valves have to be fitted on the inlet to work properly in the upright position. Others allow them to be fitted on the oulet if they are mounted horizontally. Other are ok vertical on the oulet providing there is a small pressure difference across the valve. You can tell which is the inlet by seeing which pipe gets hot first when you switch the heating on.
Good luck!

andrewmoorcroft

windswept wrote:

actually we changed the valves and I am sure my hubby had to cut the pipes down a bit to accommodate the new radiator. he can't remember draining the system either, he just can't remember what he did actually do.

They want to change the valve NOT the radiator! He may not remember because he told you he'd been working hard all day but actually paid a plumber and went down the pub!