Help please with radiator fittings

[Keith Dunbar]

I have posted before about the central heating system in our very old house. The radiators and pipework may well be perhaps 40 years old, although the boiler is fairly recent.

During an attempt to turn off an upstairs radiator the other day the inlet valve started leaking badly and I had to drain the system rather quickly. This has accelerated our decision to fit Drayton TRV4 valves and replace the very antiquated looking lockshields as well. My immediate problem is that the part of the new fittings that goes into the radiator has a different size nut on it (25 mm across the flats of the nut) to the one that was there already (30 mm across the flats of the nut). The trouble is that there are no flats on the pipe to aid its removal from the radiator. Restrained brute force with a plumbers wrench has shown no sign of loosening it and there is not enough room for a Stilson. Presumably it will need a gentle touch of blow lamp. Any tips please, especially as a blow lamp isn't going to do much for the radiator's paint job.

Also, I am obviously hoping that the thread on the new fitting is the same as the thread on the old fitting and it's just the end of the fitting that connects to the new valves that is different. It looks much the same - but the system seems so old that I'm a bit concerned I might be coming up against a metric vs. imperial scenario. It seems regular copper pipe and fits the new fitting OK - but the radiator is 95 cm x 60 cm! Not a standard size as far as I know!

All help and advice gratefully received.

TIA

Keith

[Heliotrope Smith]

The tool for removing the old tails from the radiator is inserted inside the tail. You would need a hex key or a slotted tool. If you get a radiator multi tool both of these (and more) will be on the same tool.

The new tails will screw into the thread in the rad. Don't for get to tape up the tails with ptfe tape prior to fitting.

[The Medway Handyman]

You need one of these

[John Rumm]

As far as I am aware the thread size on the tails has not changed. Shove the allen key on steroids up it, and it should come out, cocoon the threads on the new one ion PTFE and wind it back in. Note that some of the modern ones *do* have flats on the side for a spanner rather than the internal hex profile for the key.

Take care to make sure you don't get any of the black gunk on the carpets - it is very hard to remove the stains it leaves.

[Roger]

The message from "The Medway Handyman" contains these words:

tails from radiators.

If the OP can't find the right size Allen key then he could always take the radiator off the wall so he could address the problem with a Stilson as I did when I found my Allen key didn't fit.

[Keith Dunbar]

Ahhhhhhhh! Gentle sound of penny dropping! I think I already knew about that, but had of course forgotten, not having had many intimate moments with radiators in my time.

I even have afore-mentioned tool in my collection of plumbing bits I think.

Oops - no I don't - I've something very similar but with a square end. Now what on earth is that one for I wonder? Oh the joys of being eligible for a free bus pass!

Thanks all.

Keith

[John Rumm]

Square end is sometimes used for fitting the blanking plugs in the unused holes.

[Roger Mills]

As others have said, you need the right size of Allen key *inside* the tail to remove it.

There's little possibility of the threads in the radiator being metric - they'll be BSP of one size or another. The tails on the new valves will pretty certainly be 1/2" BSP (with the 1/2" refering to the bore, so the OD is nearer 3/4"). Some older radiators had 3/4" BSP threads (just over 1" in size) making them suitable for gravity systems as well as pumped systems. If yours *are* this size, you'll simply need to fit reducers which have a 3/4" BSP male thread on the outside and a 1/2" BSP female thread on the inside.

[John Stumbles]

I addressed the Allen key with a grinder so now it does fit :-)

[Keith Dunbar]

Have taken radiator off the wall anyway, and flushed an enormous amount of sludge out, so am planning to take them all off and flush them.

Yes, my Allen key doesn't fit - it's 13mm and the fitting I need to remove, whatever it's called is 12 mm.

And I don't have a grinder.

I'm struggling a bit finding a 12mm Allen key. Ideally I think I'd like to get a socket Allen key - I've got 10+ radiators to sort out eventually. Where should I be looking to get that sort of thing? I'd prefer to get it locally (Norwich) because of the expense of mail order for just one item. Any suggestions?

Keith

[Roger Mills]

It's distinctly possible, if it's an old radiator valve, that you actually need a 1/2" Allen key (12.7mm) rather than 12mm. If that is the case, and if you've got a vice and a decent file, it shouldn't be too difficult to file a bit off a 13mm key to suit. The hex hole in the tail probably looks smaller than it really is, 'cos it's coated with crud. File a slight taper on the end of the Allen key, and tap it in with a soft mallet.

[Heliotrope Smith]

One of these will do the job.

plumbers merchants will keep them on the shelf.

[Keith Dunbar]

Thanks for the suggestion, but it's definitely 12 mm not 1/2 inch. So back to plan A.

Keith

[Keith Dunbar]

Yes, that definitely looks like what I need - and I guess it could well be worth it with all the work I have to do on these radiators. Thanks.

Keith