Picking Radiators and TRVs - what's important?

[David Robinson]

Looking at Screwfix on-line, there are a lot of very similar looking radiators, and quite a few TRVs!

For a given size, with several seemingly identical double radiators with grills on top complete with brackets etc, what should I look for?

Ditto TRVs - are some more reliable (less likely to stick, give up entirely, or whistle) than others?

TIA

Cheers, David.

[spamlet]

There was a similar thread on 18/3 that gave me some handy links on this (And yes folks we did find somewhere that would put two bends in a double rad for our bay window -

for TRVs, the only experience I've had of them is having to take the tops off and hit the valve pins after each time anyone screwed the adjuster right down. IMHO much less hassle to have ordinary valves; well balanced rads; and one 'room thermostat' high up in a cool hall out of the reach of the majority of fingers. Set it so the hall is just right, then turn the other rads down to suit.

S

[BraileTrail]

In message , David Robinson writes

6 months ago I bought 14 and fitted 13 Heat Line TRVs from Screwfix. They were the cheap offer at the time. In terms of quality, one had a radiator tail with a duff thread so I had to use the tail from the spare. I had no other problems with fitting them and have had no noise problems in operation.

When the heating comes on the radiators heat up quickly and get the room to the required temperature then the TRV kicks in and shuts off the flow. They then take an age to open again and the room is almost cold before they do.

If I were to do the job again I would buy decent quality TRVs rather than the value ones I did. In the past I have had good experience with Danfoss RAS-D but this time they seemed very expensive this time at 4 times the price of the Heat Line ones, but then they work. :)

Also if you are replacing valves in an existing system I would recommend replacing the lock-shield valve at the same time.

HTH, BraileTrail

[YAPH]

There's an article on radiators on the wiki (wiki.diyfaq.org.uk) which explains their outputs and so on.

As for TRVs I fit Danfoss RAS-C2s these days. Target price under a tenner (shop around PlumbNation, Heating Controls Online etc, and Plumb Center and other real PMs may price-match). Yes you can get cheaper and more snazzy looking ones but they seem well made and Danfoss have been in the business since the year dot. A particular advantage of the RAS-C is that you can fit it - normal way up - to either end of the rad. There's an adjustment on the mechanism that lets you align the innards with the flow of water in the system so you don't get water hammer. (I don't usually bother, but it's nice to know that if I get called back to a job where it's a problem I can fix it in 5 minutes without draining down or any such faff.)

[Roger Mills]

Radiators are pretty much of a commodity - there's little to choose between them (for a given size and fin arrangement), so get some that you like the look of and are cheap.

It's worth spending a bit more on TRVs to get some good ones. You won't go far wrong with Drayton TRV4's - but get them on Ebay, not from the likes of Screwfix.

As others have said, it's worth replacing the lockshield valves at the same time - preferably with the drain-off variety, such as the Myson Matchmate.

[The one shown is 8/10mm, but you can also get a 15mm version]

[Mark]

IME cheap radiators usually have a poor paint finish so are not really suitable for damp rooms such as the kitchen or bathroom.

[TheScullster]

"Roger Mills" wrote

Drayton TRV4s seconded - but quality does cost!

Phil

[Roger Mills]

Yes it does - but shop around. I've just looked up the record, and find that I paid £115 (including carriage) for 10 TRV4's about two and a half years ago - on Ebay at the 'Buy Now' price.

[YAPH]

unless the heads snap off, as they certainly used to do on some models.

IME by the time one needs to use the drain-off facilty the rubber washers have stuck fast and won't open.

[Roger Mills]

Which models are you referring to?

> IME by the time one needs to use the drain-off facilty the rubber

That may be true with some models - but not with the ones cited in the above link. These have drain plugs in the horizontal drain outlets, which you remove completely with both valves shut, and then have to crack open the bleed screw before any water comes out, so there's no spillage.

[David]

We have had Yorkshire Mistral TRV's for over a year and there are very good, none have stuck and they react well to temperature changes.

[YAPH]

I've certainly seen it on TRV3s. I'm not sure if I've seen it on TRV4s.

I'm not sure I trust that *no* water would come out before you open the bleed valve, but from Myson's data sheet at

it seems that the drain-off valve has a metal-to-metal seal so the rubber sticking problem I complained about wouldn't apply. Sounds like a useful valve to use in installations where lower-floor rads are on drops from the upper-floor circuit, so each lower-floor rad needs its own drain valve.

However in situations where the lowest floor rads are piped from under the floor I generally try to arrange a pipe from the under-floor pipework to a drain-off outside the house. And you get triple word score if you can arrange said DOC over an outside soil gully :-)

[Roger Mills]

Well ok, but so little not to matter - and easily caught with an old towel.

Yes, my downstairs rads are individually fed from above, so that certainly applies to me. However, that partially misses the point. The *main* benefit from my point of view is that they allow individual radiators to be drained for decoration etc. with absolutely no fuss or mess.

Yes, that's fine when you need to drain the *whole* system - but (in my case, at any rate!) that's not very often compared with wanting to drain individual rads.