TRV at top of radiator?

[plumbermitch]

Question from a non-plumber!
Photo from Amazon appears to show the TRV head attached straight in to the top entry of the radiator without a valve or a pipe in to it! Is this really possible?
I ask because I would really like to have the stat where I can reach it but without altering a lot of pipework.

 

[Wayners]

Pipes are behind radiator out of sight

 

[cross thread]

no but you can have the valve fitted in the top ,with pipe work or a remote thermostat connected by a fine wire .

 

[denso13]

That's a made up photo. It's just a TRV head with no pipework. Fake.

 

[ChrisJP]

For a TRV to work, it has to have the water flow into the radiator passing through it so it can regulate the flow according to the temperature of the room.
If you could somehow get a TRV which didn't have any feed pipe connection (which your picture apparently shows) how could it work?

 

[endecotp]

Here's a photo of a radiator with the TRV at the top that's not fabricated:

Post in thread 'Radiator Sludge'

14 Jan 2026

That’s the actual radiator.

Most (4 in total) of the others are the same, lock shield bottom left , TRV top right.

One has it diagonally swapped, lock shield bottom right , TRV top left. That’s the one in kitchen, physically closes to boiler, also doesn’t work good at all

One has both at bottom, lock shield left, TRV right. That’s the radiator that works best.

This was all setup when central heating system was setup approx 20-25 years ago, which included installing all the piping to all the radiators.

Sorry if I appear slow/stupid, but I’m not understanding “looks...

• RainTown

It's from another thread on this forum. Note the pipe comes out of the floor and up the side of the radiator to the TRV. I don't suggest reading the whole thread, it will just make you depressed; just be aware that if you connect the TRV to the top of the radiator in this way, it must be on the flow (input) side.

 

[ericmark]

There are TRV heads which can be remotely controlled, the Kasa for example can be controlled with sensors on the opposite wall, and so can Drayton Wiser. I fitted Energenie TRV heads, which monitor both water and air temperature so it can compensate for the direct heating from the radiator, but the anti hysteresis software was rather OTT, so set it to heat room at 7 am to 20°C, and it was 11 am before it got there. So would set at 22°C at 7 am and 20°C at 8 am.

I also found if on the return, setting the lock shield valve so no over shoot, resulted in it taking longer to reach a new temperature than having the TRV on the feed, how much depends on radiator size, and we are looking at circulation so return air is what we want to measure, so just to one side at the bottom is idea placement for most TRV heads, unless using a remote sensor.

The idea is, having a radiator on an outside wall, means the sensor is also against the outside wall, so can turn on the radiator premature, hence option to sense on the opposite wall, but once the circulation is established it does not really matter.

Remember, unless linked, the TRV can't turn the boiler on. So if a wall thermostat lets the boiler turn off, then the TRV will not heat the radiator, and will motor to fully open position, which when the boiler does turn on, can cause over shooting as it takes around 4 minutes to close, with a mechancial head, a lot longer. A few days ago with a hunt, I found one can still buy electronic heads as a group at under £15 each, but these have no bluetooth or any other wireless linking, by time you pay £45 they are all singing dancing, linked through a hub to the boiler.

It is likely one needs multi-sensors to turn the boiler on, but not one on every radiator, I have three devices that can turn on the boiler. But once using a programmable TRV head, the need to reach the head is rather diminished, mine in my living room, auto turn up in morning, then further up in the evening, and then down over night, so I have no need in the main to touch them.

 

[plumbermitch]

Loads more photos like this ! are they all fake!!?? My feeling is that the head should indeed be on a valve but then I keep finding this sort of thing to confuse me even further!

 

[plumbermitch]

Found loads more photos like this which is what I would like but I do think it needs to be on a valve or pipe. But are all these photos fake to boggle my mind!!?? Keep hoping somebody has done one like this!!

 

[plumbermitch]

Sorry, IT is not my strong point! Thought first attempt had failed!

 

[endecotp]

In that photo, I believe the TRV head is simply being held against the radiator's unused top port.

Where are you finding these images? If you are searching for "TRV at top of radiator with no pipe", because that's what you're hoping to have, then you're going to get images of TRVs at the top of a radiator with no pipes - real or not.

 

[denso13]

But are all these photos fake to boggle my mind!!?? Keep hoping somebody has done one like this!!

Those are special radiators with internal pipework, not seen any for a long time, you can't do that with normal rads.

You can just about make out the vertical pipe in this pic,

 

[plumbermitch]

Many thanks Denso 13--that picture and video are just what I needed to convince me that there does indeed have to be a valve! Wish I had one of those radiators! All the good ideas seem to bite the dust!

 

[Deluks]

It's still a thing on the continent. A friend showed me a picture of a newly fitted rad in a house in Germany. Trv at the top, I was initiated confused!
Not unknown for a foreign tradesman to bring in materials from their own country and install using 'their way of doing it'

 

[denso13]

It's still a thing on the continent.

It's very much still a thing here, get's the best heat output from radiators.