Removing radiators with trv

Alanp

Hello, 
this may seem a really stupid question, but I’ve just removed two radiators at my sons house, both had trv,s fitted, I set both valves to 0, and removed rads, should I have capped the radiator connection at the trv?, I have visions of the trv opening and causing a flood, the heating is on but the house is only semi occupied atm…

FreeBear

One would usually replace the TRV with a decorator's cap (a small cap that screws on and holds the pin down). It would be worthwhile popping a blanking plug over the open end of both valves just in case they leak.

Alanp

FreeBear said:

One would usually replace the TRV with a decorator's cap (a small cap that screws on and holds the pin down). It would be worthwhile popping a blanking plug over the open end of both valves just in case they leak.

Yes, I thought so, just for peace of mind

ThisIsWeird

Well, I did the same a couple of years ago and - yes - the darned things opened up overnight and dumped all over my floor... And it wasn't anywhere near freezing. And, at '0',  they shouldn't even have opened with a frost.

It should be ok - it should remain fully off - but they are not the most precise devices, so there's a genuine risk. The simplest method is to remove the TRV heads (too late now without releasing water ) and replace them with the screw-down caps usually supplied with the TRV valves, but I bet you don't have these? (Nor do I).

Reviews suggest these are the correct size: https://www.screwfix.com/p/flomasta-blank-nut-1-2-x/51939 and you may wish to add a roll of PTFE tape to your order . Only the TRV sides need doing as the other ends - the lockshields - should be fully shutoffable.

Did you remember to note how many turns open the lockshields were as you closed them? Really, they should be returned to their original positions or else the radiators won't be 'balanced' - ie they are unlikely to be received the correct amount of flow commensurate with their size and distance from the boiler.

FreeBear

ThisIsWeird said: Reviews suggest these are the correct size: https://www.screwfix.com/p/flomasta-blank-nut-1-2-x/51939 and you may wish to add a roll of PTFE tape to your order

These are more likely to fit - https://www.screwfix.com/p/flomasta-compression-blanking-nut-15mm/55441

You shouldn't need PTFE tape on a compression fitting.

Alanp

I didn’t count the turns as they were fully open, I think they are going to move one rad and replace the other with a slimmer one, but the plumber is doing that, 

FreeBear

None of my lockshields are fully open...

Those radiators are going to need balancing once the plumber has done his bit. Worth investing in a couple of cheap digital thermometers...

ThisIsWeird

FreeBear said:

ThisIsWeird said: Reviews suggest these are the correct size: https://www.screwfix.com/p/flomasta-blank-nut-1-2-x/51939 and you may wish to add a roll of PTFE tape to your order

These are more likely to fit - https://www.screwfix.com/p/flomasta-compression-blanking-nut-15mm/55441

You shouldn't need PTFE tape on a compression fitting.

I'm hoping the ones I linked to were 1/2" BSP. These will be physically larger than an actual 1/2", but is hopefully the correct size to fit on the exposed (rad) end of the TRV valve - a review suggested it was anyhoo.

ThisIsWeird

Alanp said:

I didn’t count the turns as they were fully open, I think they are going to move one rad and replace the other with a slimmer one, but the plumber is doing that, 

Worth asking them to balance the system for best performance, then. If the LSs are fully open, then the boiler is likely to be getting too-warm water returning to it, which means less efficiency. It'll also likely mean that your rads won't heat up evenly - the furthest away or larger rads will take longer. That shouldn't be the case.

As it's a very time-consuming task, you may wish to do as FreeBear suggests and to buy a rad thermometer - an instant IR type is good - and do this yourself. Lots of vids out there

(And a magnetic filter if not already fitted. And fresh system inhibitor...)

Alanp

Well,I went to b&q and bought the appropriate fittings, trv,s capped off, all good, thanks for all the suggestions everyone 

Gavin83

ThisIsWeird said:

Reviews suggest these are the correct size: https://www.screwfix.com/p/flomasta-blank-nut-1-2-x/51939 and you may wish to add a roll of PTFE tape to your order .

I know the OP has sorted it now but for future reference most (all?) radiator tails are 1/2” BSP and therefore this is the correct cap to buy.

However you don’t need PTFE tape. These caps will come with a washer which will prevent the flow of water.