Radiator measurements

[al]

I want to replace some of my rads but am confused about the measurements. The units I have are quite small and old. The one in my hallway for example is 600mm wide across the actual body, but 700mm across from the extremity of each tap/joint/whatever you call it just before where it meets the T-junction for the house pipes.

Looking on Screwfix, the widths available are 300mm, 500mm and 600mm. It also seems like those radiators are the same width body as the place where the pipe would join, unless there's something you screw in that makes up the distance ..?

I'm confused - what should I be measuring? Also, does anyone have a good recommendation for a web-guide to replacing rads? I'm going to get help from a mate putting a new one in where the pipes need cutting, but was hoping to do straightforward direct replacement myself before going as far as draining the system.

a

[adder1969]

measurements.

extremity of

The bits that screw in the radiator are part of the valve rather than being part of the rad so the width you want in your case is 600. When you put new valves on really make sure they've sealed properly!

Close off the valve at each end, drain the rad in whatever way, disconnect the valve from the rad at the obvious joint, carefully remove rad. Now either remove the other part of the rad valve from the old rad or get a new one and put it in the new rad. Refitting is the reverse of removal etc.

[al]

I took out the radiator today. The only thing "in" the radiator that looks like I can remove it is about 1cm worth of pipe going into the side of if (with the locknut around it). Looks like it would probably only extend into the radiator about another 1-2cm, which is a pretty small amount. Makes me think a 600mm new one would be too narrow ... however there doesn't appear to be a 700mm or 650mm standard size.

I've uploaded a couple of (bad!) pics below:

about the exposure ... a lot of bright white surfaces taken with a flash on a cheap camera! The conical parts going into the main radiator body are fixed parts of it, not removable. Will a 600mm rad really fit with just those little other bits in it?

a

[basil]

On Fri, 25 Mar 2005 01:27:47 GMT, "al" wrote: however there doesn't appear

if the pipes wont flex enough to fit you can use extenders like:

'd replace the valves aswell, it looks like the old ones have been painted over some.

[al]

Are those extenders horizontal pieces that fit directly into the radiator at one end and the screw-fit face of the vertical heating pipe at the other (sorry about the nomenclature, no idea what to call these bits!)?

The valves (and pipes) are quite nasty. However I'd have to drain the system to do that wouldn't I? Think I'll just sand down and re-paint.

a

[basil]

The ones from Wickes are! The nut on the valve (I think its called 3/4 inch BSP ) which holds the current tail is passed over the new tail which is then screwed directly to the radiator with some ptfe tape on the thread. You then screw the nut back to the valve and thats it. Looking at your pictures I think you probably have the right size nuts on your valves.

Looking at the screwfix ones I cant make out how they attach.

the one at the bottom of this page looks like the Wickes ones I have;

>The valves (and pipes) are quite nasty. However I'd have to drain the

[al]

Speaking of which, I want to get Thermostatic Valves for the upstairs bedrooms, as they get hot a lot quicker than the ambient temperature downstairs where the main thermostat is. Any recommendations on good, reliable makes? I've heard a few stories about some of them getting stuck on/off and doing buggar all after a while ...

a

[basil]

I've heard they last 10 years or so. I replaced the old ones here with this tpe:

work, and no noise like with some.

Of course it means a drain down and you may have to replace the old olive. I think very old valves have an imperial thread even. While your doing this you could re-plumb the new rad so you dont need extenders.

Basil

[Andy Hall]

I've always used Invensys/Drayton TRV4s and had good results. In general, I think that you could expect good behaviour from any of the branded products like Honeywell or Pegler.

It's generally reckoned that the heads have a life of about 7 years. I've never had less than about 12 from a TRV4 so am pretty happy with them.

It is important in any case to have a clean system, so while you are doing replacements, it is worth giving the system a thorough flushing and filling with corrosion inhibitor.

[al]

they work, and no noise like with some.

Unfortunately, the original rad in question wasn't one of the ones I was thinking of putting a TRV on! Those ones you've pointed out sure do look nice, but cost a bit! Most of the ones I've seen on Screwfix, etc. seem to be in the £5-10 range. Is the extra money for style or function?

a

[al]

And when they fail ...?

a

[Andy Hall]

If you mean the radiators, then it was probably because inhibitor wasn't used.

If you mean the TRVs, then making sure that the system is and remains clean means that the plungers in the valve bases are less likely to stick. Thus, when the heads do eventually go, it may well be possible to just replace those.

I've found that the failure mode of the heads is generally that they become hard on or off with no control in between.

[Ed Sirett]

IME this is one of the few products which goes against the usual wisdom of you pay for what you get. I have found that the cheap TRVs seem to last longer and go on operating longer. Whilst the ACL Drayton units seem to be the priciest and shortest lived. Furthermore I have found them to be more flow direction sensitive (whilst claiming bi-direction).

However this is not reason to set aside you-pay-for-what-you-get just yet, except in this matter.

-- Ed Sirett - Property maintainer and registered gas fitter. The FAQ for uk.diy is at

Gas fitting FAQ CH FAQ

[nick smith]

Well Ed, I found the opposite !

In a sample of 5 cheap TRVs from B and Q, costing about £5 each, 3 failed within a couple of months - I took them back with the receipt to get them replaced and they had stopped selling them - "too many returns" the resident plumber bloke said....

So I had to get some more expensive ones at about £9 each - problem was they were a different size and the plumbing was well bedded in to the wall, so I had to dig out the wall to modify, then make good the wall. The replacements are still going well after two years.

I vowed to myself that I would only buy the better ones (not cheapest) from now on.

Nick

[al]

That's still about £6 cheaper than the TRV4's though. Suppose it depends on how many I go for. In one bedroom, there are two small double rads. Might put a TRV on one and not the other. Usually I only use one rad unless it's exceptionally cold so that should work. Might put one in the hall, but not anywhere else downstairs as the thermostat is in the sitting room/lounge.

a