Pipe Bending Question

[TheScullster]

Hi all

I am looking to replace a rad or at least re-valve it. As it is close to the hall stat, I believe it should have fixed valves not thermostatic. I like to fit Pegler Terriers as they seem reasonable quality - these have a length (from rad connection to centre of tail pipe of 48mm)

To fit these will mean increasing the distance between the tail pipes by

15mm. This rad is ground floor and the floor is concrete. I tried to remove the rad at the weekend, but found that (a) one of the valves was passing significantly and (b) the rad must have been crow barred in between the valves (I couldn't move the valves far enough to get the rad out)

So I need a plan of action. I can drain the whole system to allow removal of the rad complete with valves and re-valve rad OK. But how do I generate the 15mm extra distance between tail pipe centres? I do not like the "street elbow straight into the valve" approach. Is it possible to put a "set" or "crank" (not sure of the correct terminology) in a pipe to give a 15mm offset in 75mm length using bending spring?

Any other options?

TIA

Phil

[Dave Plowman (News)]

Remember the valve fits into a taper on the rad tail, so if the pipes are firmly fixed as in concrete they will need springing apart. Slackening the pipe ends of the valves would have allowed enough movement. But not of course without draining down.

I would think this impossible - you'd not get enough purchase, and you need a straight end for the valve compression fitting. And of course when you bend something in that way the top of the pipe will move downwards so may not reach into the valve correctly.

But I'd get some tube and anneal it. Then see if you can form the required offset with a spring. You could then fit that to the existing pipe with a end feed straight coupler at floor level which shouldn't be that noticeable - and neater than using elbows.

[John Stumbles]

If the pipes are set directly in the concrete they are likely to be corroding. This will in due course be a bigger problem than just replacing the rad valves, but if you strain the pipes trying to change the valves you may cause them to leak which will turn it into an immediate problem. Still, at least you're doing this in the summer :-)

Longer valve tails (from BES & other good plumbers' merchants) or DIY with chromed 1/2" BSP M * 15mm compression + length of chromed 15mm pipe + chromed compression nut & olive onto the rad valve

[TheScullster]

"Dave Plowman (News)" wrote

Thanks Dave

Yes I should have made it clear, intend to cut back existing upstand of pipe and pre-form the necessary off-set. Then couple to the shorter stub at ground level. Not sure whether this amount of bend is achievable in this length of pipe - that was the real question.

Phil

[TheScullster]

"John Stumbles" wrote

1970s build - all ground floor mains wrapped in "material" laid in sand filled channels and covered with concrete capping. All rad tails simply concreted in place. Gas pipes installed similarly.

Phil

[Dave Liquorice]

I doubt very much with that length of pipe, by hand, using a spring. You can probably do it with a new, longer, length of pipe and a proper bender no trouble, it might even be possible with by hand and a spring.

The snag is you need two bends one to start the widening and another to stop it and get the pipe end vertical again to fit the valve.

[Dave Plowman (News)]

A proper bender works to a fixed radius, and it's definitely possible to get tighter than this with a spring and soft pipe, although not as tight as two 45 degree elbows back to back. Or at least I couldn't. ;-)

Yes, but the idea is to make a new section and fit that to where the original emerges from the floor.

[John Stumbles]

Nasty. When I've come across corroding copper pipes in concrete it seems to be the bits nearest the surface that corrode worst.

[John Rumm]

Easy enough with a pipe bender on a new stub of pipe, you may be able to do it with a spring, but tricky...

Could you not use a couple of end feed 45 degree bends? That ought to give you a pipe widths offset nicely.

[TheScullster]

"John Rumm" wrote

John, you might have solved it with that one! Being an amateur, I have always tended to use solder-ring fittings. So my measurement of the throw of a 45 degree elbow is based on those. Will check this out next time I'm in B&Q.

Thanks

Phil

[Dave Plowman (News)]

You can also trim the ends of end feed elbows to get an exact fit. Obviously not by much, though. And if you make up the 'tail' off the job you could make sure the joint is invisible by using excess solder then sanding, etc.

[John Rumm]

You may be able to get one "street" 45 deg elbow - that would fit directly into the next ordinary one. That may get the offset closer still and eliminate the need for the small stub of pipe between them.

If you are used to making solder ring joints you wont have any difficulty making an end feed.