Are all TRVs the same fitting?

drofluf

The "head" of one of my TRVs has seized. It's a Drayton TRV4. I can get a like for like replacement but will other heads fit onto the valve part? Thinking of maybe getting a smart valve as it's also not the easiest to access due to where the furniture is.

boogieman

If the valve is just seized I would try a simple fix first. Take the head off and tap the pin with a hammer. 9 times out of 10 that fixes it. 

drofluf

boogieman said:

If the valve is seized I would try a simple fix first. Take the head off and tap the pin with a hammer. 9 times out of 10 that fixes it. 

Thanks; I don't think I was clear. The valve itself is fine the thermostatic has a seized so it can't be turned, at least not without excessive effort.

boogieman

drofluf said:

boogieman said:

If the valve is seized I would try a simple fix first. Take the head off and tap the pin with a hammer. 9 times out of 10 that fixes it. 

Thanks; I don't think I was clear. The valve itself is fine the thermostatic has a seized so it can't be turned, at least not without excessive effort.

Ah ok. You could always buy a similar Drayton model and just swap the heads?

 If you really want to go down the smart route though a quick google turned up at least one system that says it replaces all the heads on the popular makes. 

exocet

I'd say that all TRVs have a common thread size but because they are calibrated differently, you need to match the manufacturer / model i.e. Drayton TRV Head to a Drayton valve body.

drofluf

exocet said:

I'd say that all TRVs have a common thread size but because they are calibrated differently, you need to match the manufacturer / model i.e. Drayton TRV Head to a Drayton valve body.

Thanks sounds like its easiest to replace like for like then

shuikit

A few years ago I bought a direct replacement from here

https://www.heatingcontrolsonline.co.uk/radiator-valves-c-28.html/replacement-trv-heads-c-28_51.html

I sent them pics of my old one to confirm that the new one would fit as my old one looked a bit different (older model I guess) and they were pretty helpful

drofluf

Thanks - Screwfix had them in stock so I used click and collect. It's fitted now

Philly_Q

Dumb question - do they actually serve much purpose?  I had a couple of radiators which stopped working, I figured out the TRVs had failed somehow so I just took them off and everything was fine.  Never bothered replacing them because I never adjusted them anyway.

ronnyb

boogieman said:

If the valve is just seized I would try a simple fix first. Take the head off and tap the pin with a hammer. 9 times out of 10 that fixes it. 

One of my trv’ has seized shut after I’ve had the rad off for decorating. From what I’ve read the pin can come out if you tap it too hard. I’ve tried the other method of hitting the side of the body of the valve but to no avail.

exocet

Philly_Q said:

Dumb question - do they actually serve much purpose?  I had a couple of radiators which stopped working, I figured out the TRVs had failed somehow so I just took them off and everything was fine.  Never bothered replacing them because I never adjusted them anyway.

You have a point there! Technically they can make a difference but in practice, they seldom do due to a number of reasons.

1. Many CH systems are run far too hot (flow temp at close to max). This causes valve to heat up and "close" way before the room reaches correct temp. End result,  everyone simply cranks them wide open to get radiator hot again.

2. Valves placed in sub optimal location I e vertically on incoming flow. The best location is horizontally on Flow & with pipes connected TOBE ie Flow at top of rad, return on bottom.

3. UK habit of turning on heating for short bursts "full blast" rather than longer time at lower temperatures. Poorly insulated homes drive this behaviour.

So you end up with all TRVs set to max, doing diddly squat.

boogieman

ronnyb said:

boogieman said:

If the valve is just seized I would try a simple fix first. Take the head off and tap the pin with a hammer. 9 times out of 10 that fixes it. 

One of my trv’ has seized shut after I’ve had the rad off for decorating. From what I’ve read the pin can come out if you tap it too hard. I’ve tried the other method of hitting the side of the body of the valve but to no avail.

I’ve done it a few times without any problems. It usually only needs a tap with a pin hammer to free it off, no need to muller it. 

Jalapeno

Timely thread as our 6mth old puppy has just eaten the platic off a couple !

Headphones

My experience with a stuck head, is that there are plenty out there to buy, once you've identified the device; and a swap is relatively straightforward.

If the valve itself sticks, or sticks and has been freed, it will leak (it's basic physics).  Perhaps not this week, but it will before long.  Plan to swap soon if this is you.  Freezing kits are your friend.

I'd also offer that they've a finite life.  Having had a leaking valve every other month this year (eighteen years from build), I'll be swapping every valve shortly (we have a kitchen refurb booked where the esystem will be drained anyway).

An early swap is a lot less hassle/costly than a slow leak you don't notice!

The observation about poor heating strategies is spot on.  I'm a Control Engineer and looking at UK domestic heating systems is, franky, offensive to any one of my profession.