Clever trick wanted for rad pipe stubs

[JohnD]

I am replacing some weepy old myson rad valves in my mothers house. they are about 30 years old (though boiler and controls are fairly new). My prob is that they are nearly half an inch longer than the new valves i have got (some thermostatic and some drain-off lockshields for the ground floor. Most of the ground floors are solid (poured concrete and some granolithic) so there is no play in the pipes. So I need to extend the pipes by a very small amount.

The first one I changed, I ended up taking off the rad and re-hanging the brackets, I would hope there is another way that should be easier and quicker. The remaining rads include an 8-ft double, and two long ones formed to fit in bay windows, so I don't want to have to take them off and refix.

The pipes are close to painted skirting, so it would be difficult to cut them (I would have to use a junior hacksaw), and also difficult to solder to (I am doing them singly, one per weekend, by bunging the fed and vent pipes in the loft) as they are wet.

Any clever ideas? including how to accurately measure the pipe stub required?

 

[Roddders]

Are the valves too long horizontally or vertically?

 

[JohnD]

It's the vertical axis.

If I put the new valves on the old pipe stubs, the valves are a little too low to go onto the rad tails (I'm fitting new tails at the new ones have an o-ring which I expect will make them less likely to weep than the old ones

 

[Roddders]

To accurately measure the length of pipe stub required do the following:-

1) Stick a tape measure up the inside of the valve opening where the tail pipe will fit. Just take a measurement.
2) Then hold the valve in front of the existing pipe and align it horizontally, at the base of the valve mark on the copper tail pie where the valve finishes.
3) Then measure on the pipe the distance of the line to the end of the pipe.
4) If the measurement just taken is longer than the 1st measurement you took, subtract the first from the second and that twill be the amount you need to remove.

I find that if you put the valve loosley attached to the radiator with quaret of a turn of the compression nut. Then rotate carefully and insert tail pipe into the valveas you do this ensuring the compression nut and olive has already been placed on the tail pipe.

Then just nip up both the compression nuts until they are water tight. As belt and brace wrap PTFE tape around the screw threads of the valve to ensure water tight seal

 

[JohnD]

I find that if you put the valve loosley attached to the radiator with quarter of a turn of the compression nut. Then rotate carefully and insert tail pipe into the valveas you do this ensuring the compression nut and olive has already been placed on the tail pipe.

Then just nip up both the compression nuts until they are water tight. As belt and brace wrap PTFE tape around the screw threads of the valve to ensure water tight seal

Thanks. Will it matter that the copper pipe doesn't reach the end of the socket in the valve?

 

[Roddders]

It is preferable for it to be as near as the end of the socket as possible.

 

[JohnD]

It is preferable for it to be as near as the end of the socket as possible.

yes of course, but my problem is that the pipes are placed to fit a longer valve body, and are set in concrete so I can't see how to make them reach.

 

[ricarbo]

If you're trying to extend the pipe by the smallest amount, you could get one of those tools that expands the end of the pipe, allowing you to insert another piece of pipe. It looks a bit like a slide hammer. So you could prepare one end of your new pipe, trial fit and cut to length, then solder up. Problem could be getting the olive off the old pipe. Makes the neatest joint possible.

 

[PTH]

Had the same problem myself a couple of years ago.

Try this.. Take the radiator off its brackets, then using an angle grinder with a small cutting disk, either cut a slot into the straps on the back of the rad. (the ones which engage with the wall brackets) or cut a step and new notch in the wall brackets.

That way you do not have to worry about rehanging the rad and aligning to suit your existing pipe tails, not to mention trying to drill new fixing holes just 1/2" away from existing ones!

I've used this method to make up about 3/4" difference in valve body length, and can save a lot of time and hassle especially on a long rad with three brackets.