Help identify and replace this old Danfoss TRV
- Thread starter Gurj
- Start date
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The originals are obsolete and I don't know what I can replace with. I don't know the size, I'm not a plumber, I'm in other building trade. So I need as much info as I can get. I can't afford to replace the radiators in the whole house. Kids are cold in the morning. TRV is sticky in most rooms.
1. Your photograph shows what is known as a union connection between the radiator tail (the small bit that screws into the radiator) and the TRV. Most modern valves have a compression connection.
2. The connection between the valve and the pipework to the rest of the system is a compression connection, and looks like 15mm. However, it is a fairly unusual compression connection by modern standards in that the compression nut screws into a female thread in the valve. Most modern ones have a compression nut onto a male thread on the valve.
3. You can get union connection TRVs, but they tend to be quite a bit more expensive than compression ones. Also, using the existing tails with a new, union connection, TRV leaves the risk that the two sides of the union might not be compatible. I would advise you to change the radiator tails anyway, so you might as well go for the more popular compression ones. A new tail will come with the TRV anyway.
4. You might have an issue with the changing the connection on the pipework side. So far as I know no current TRVs have a female thread in the body, so you would have to change to standard male thread on TRV, compression nut on pipework. This means you would have to remove the olive and female threaded compression nut from the pipework. Various internet sources on how to do this. However, the pipework might not be long enough to reach the new valve and might need to be lengthened. Again, not difficult, but to do it well and neatly would require soldering. In turn, soldering requires the pipes to be absolutely free of water.
5. Unless you know how to "bung" the pipework, or freeze it, I'd recommend a system drain down, (you would almost certainly need this if any soldering were involved).
6. You need angled TRVs. I'd go for Danfoss, Honeywell or Pegler rather than an unknown brand. There are others (such as Tado) which seem to be well liked, but I have no experience of installing them.
7. If you drain down, then if you have a small water tank (Feed and Expansion tank), usually in the loft, clean it out before draining down or you risk running any muck in it into the system.
2. The connection between the valve and the pipework to the rest of the system is a compression connection, and looks like 15mm. However, it is a fairly unusual compression connection by modern standards in that the compression nut screws into a female thread in the valve. Most modern ones have a compression nut onto a male thread on the valve.
3. You can get union connection TRVs, but they tend to be quite a bit more expensive than compression ones. Also, using the existing tails with a new, union connection, TRV leaves the risk that the two sides of the union might not be compatible. I would advise you to change the radiator tails anyway, so you might as well go for the more popular compression ones. A new tail will come with the TRV anyway.
4. You might have an issue with the changing the connection on the pipework side. So far as I know no current TRVs have a female thread in the body, so you would have to change to standard male thread on TRV, compression nut on pipework. This means you would have to remove the olive and female threaded compression nut from the pipework. Various internet sources on how to do this. However, the pipework might not be long enough to reach the new valve and might need to be lengthened. Again, not difficult, but to do it well and neatly would require soldering. In turn, soldering requires the pipes to be absolutely free of water.
5. Unless you know how to "bung" the pipework, or freeze it, I'd recommend a system drain down, (you would almost certainly need this if any soldering were involved).
6. You need angled TRVs. I'd go for Danfoss, Honeywell or Pegler rather than an unknown brand. There are others (such as Tado) which seem to be well liked, but I have no experience of installing them.
7. If you drain down, then if you have a small water tank (Feed and Expansion tank), usually in the loft, clean it out before draining down or you risk running any muck in it into the system.
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As far as I'm aware there is no direct replacement for those trv,'s
Replacement heads are available (tho costly)
Drain down to replace I'm afraid, it's the inlet side that will give you grief especially when tight to a fitting like your picture.
Replacement heads are available (tho costly)
Drain down to replace I'm afraid, it's the inlet side that will give you grief especially when tight to a fitting like your picture.
So potentially, I could replace those with something like this ?
www.heatingcontrolsonline.co.uk
Chrome TRV with 3/4" Union Connection to Tail
www.heatingcontrolsonline.co.uk
1. That looks like a Drayton TRV4, but I suspect it is a far Eastern copy. I have had issues with recent genuine TRV4's, so would trust a knock off even less.
2. The supplier gives no manufacturer's name. I'd suggest you stick with well known makers, as post #4
2. The supplier gives no manufacturer's name. I'd suggest you stick with well known makers, as post #4
Yes your union nuts are 3/4 but that's not the problem! (tails into rad are very easy to change) your problem is the supply side its a 1/2 in female thread into valve
All new trv's have a 1/2 Male nut and olive
Any decent trv will do change the rad tail to one supplied
Take off existing nut and olive off copper pipe and replace with new nut and olive.
As a temporary fix, remove the TRV heads which are problematic, then ensure the pin in the valve underneath is free. Then just leave the head off. The pin should be able to be pushed down a couple of mm, against the spring, then it should spring back up. Up is valve open. If any are stuck in the down position, just grip them with pliers, turn, and gently ease them up/out.
Be careful pulling pins with grips or pliers.
The pins will easily pull out and then things get wet quickly. Best to tap them on the end and let them spring out themselves.
The pins will easily pull out and then things get wet quickly. Best to tap them on the end and let them spring out themselves.
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