Extending copper pipes for moving a rad - beginner questions

[pelago]

Hi. I want to move a radiator in my living room from its current position against a blank wall, 90degrees round a corner to under a window (please see first picture). At the moment the radiator blocks a nice wall where I could put furniture or wall-mounted TV or whatever, whereas under the window it will be out of the way. I've not worked with copper piping before, so I have a few questions about extending the pipework. I'd like to do a neat job, although keeping within my limited abilities.

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The floor is concrete, and at the moment the pipes are buried in the concrete. Looking closely at the curvature at the bottom-most visible part of the pipe, and confirmed by a pipe finder, the pipes are coming from the direction perpendicularly away from the wall - i.e. they are definitely buried in the concrete, not coming down the wall. Please see the second close-up picture.

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I guess the neatest thing to do would be to chase out the concrete and bury a new length of copper pipe in it, coming out of the floor in the correct new positions, but I think this is beyond my abilities (and tools and time). Also, this would require at least one joint to be buried, which is a bad idea.

So, I was thinking of taking the pipes along the blank wall that used to house the rad, and round the corner under the window, at about skirting-board level. I would like to hide the pipes as much as possible along the blank wall, for aesthetic reasons as well as a worry of banging the exposed pipes with furniture. I'm not worried about the pipes being visible along the wall with the window, as they will be directly under the new radiator position and so protected and not too visible.

The blank wall is an external wall and I understand that it is best to keep the pipes half an inch away from that wall to protect from frost, so I cannot really chase the pipes into the plaster or hide them in the skirting, so I am thinking of trying to box them in somehow, with the skirting board being a bit further from the wall than it would normally be.

I can think of three ways to proceed:

1, The easiest thing to do, I think, would be to leave the pipes coming out of the floor in their current position, have the skirting board in front of that and box in that way. The only problem with that is that the box will be a three and a bit inch deep 'step' at the bottom of the wall, which will be quite obtrusive.

2, Alternatively I could keep the pipes coming out of the floor in their current position, add a 90deg bend towards the wall, then run the pipe close to the wall, having the skirting board at about only an inch from the wall such that it covers the majority of the pipe run but you will see the two small pieces of pipe coming out of the floor and bending into the skirting. This too would be quite easy to do, I think, but I worry that the two bits of pipe might be obtrusive and get knocked, especially as they will be no radiator above them to help protect them.

3, So my final thought is to somehow extend the pipes within the concrete, just for the couple of inches necessary to get closer to the wall, then come out of the floor much closer to the wall and go round the perimeter. That way I can hide the pipes completely from view on that wall, and only have a skirting board an inch or so out from the wall.

Although option 3 is less work than chasing out a whole run of burying in concrete, I am still a bit concerned, as I've never done anything like this.

So my questions are:

Assuming I can chip away a suitable small trench in the concrete behind the pipes, what are my options as to how to make the pipe come out of the floor closer to the wall? Is it possible to somehow straighten out the current bend in the pipe, and make another bend further towards the wall? Or is it the case that once a pipe is bent it cannot be straightened? Or maybe you'll say that it would be risky to try and straighten or bend a pipe that is already half-embedded in concrete?

If necessary, I guess I can try digging out more of the concrete, cutting the pipe where it is still straight, and extending from there, but again that would mean a joint buried in concrete which is not ideal.

Any ideas?

 

[Softus]

I'd like to do a neat job, although keeping within my limited abilities.

You have the right approach, and an admirably clear style of posting and reasoning out the pros and cons.

Assuming I can chip away a suitable small trench in the concrete behind the pipes, what are my options as to how to make the pipe come out of the floor closer to the wall?

Tricky.

You'll need to chisel away enough of the screed around a straight section of pipework in order to make a connection onto it.

In order to solder you'll need to do lots of cleaning, and vacuum all nearby water out of the pipe (otherwise it will act as a heat sink and prevent a good joint being made).

Compression will give a good seal more easily than alternatives, but is unwise because you won't have access to the joint afterwards should it leak.

Push-fit might be a better option than compression, but you'll need the pipe surface to be in excellent condition, i.e. not pitted, scratched, dented or squashed.

Is it possible to somehow straighten out the current bend in the pipe of the pipe, and make another bend further towards the wall?

No.

Or is it the case that once a pipe is bent it cannot be straightened?

Yes. Half hard copper tubing work hardens as you bend it, and also age hardens. You don't have a hope of doing it successfully, without risking weakening the copper, which might result in a leak after you've covered it over again.

Or maybe you'll say that it would be risky to try and straighten or bend a pipe that is already half-embedded in concrete?

It's not the embeddedness, but the other factors (see above). Don't forget that copper also erodes, and corrodes, thereby becoming thinner and more prone to fracturing.

If necessary, I guess I can try digging out more of the concrete, cutting the pipe where it is still straight, and extending from there, but again that would mean a joint buried in concrete which is not ideal.

Quite so.

Any ideas?

Personally, I regard compression as the least of all evils in this scenario, subject to the copper not being so old/thin that folding or fracturing becomes too big a risk.

 

[ChrisR]

Although freezing isn't really a problem, so you can put the pipe at say plaster depth in the outside wall, I don't think you ARE going to be happy with bits of plumbing protruding out of the floor high enough for you to put an elbow on so you can get the pipe sideways towards the wall.

SO you have to dig a hole in the floor. If you buy a B&Q bargain type chipping drill, proably aout £30, or hire one for about the same figure, you'll find the floor quite easy to dig up. In places you'll need to go about 8cm deep. Drill holes and lever the stuff out, near the pipe, or you'll damage the pipe. You'll probably find you have a relatively weak screed which comes up without too much difficulty. You may well find a damp proof membrane. If you puncture it, no big deal, make a patch with silicone and suitable plastic.
You'll need a litre or so volume around where you need to cut and join the pipe. Pipeslice, water vac or blow out the water, use solder connection, I'd suggest solder ring type. Then protect the pipe - plenty pf posts here about brying pipe in screed
So you need a hole this sort of size to do anything to the pipe.

GIven that, it would only take an extra half hour to do the rest

It might sound daunting to be digging your house up , but I don't think you have any reasonable options. Including the backfilling (with a weakish general purpose mortar mix ) as long as you start off with the right stuff to hand, it'll all be done in half a day.


Grrrrrrr links not working, maybe they'll be quicker later.

 

[pelago]

I'd like to do a neat job, although keeping within my limited abilities.

You have the right approach, and an admirably clear style of posting and reasoning out the pros and cons.

Thanks, I was worried I was a bit too waffly as I have that tendency.

Thanks Softus and Chris, especially with the pics. Looks like my choices are to either box the whole lot it with a three-and-a-half inch box, or do considerable amounts of digging.

Solder connections sound the most reliable, but I've never done that either so I'll have to get a blowtorch too I guess.

Other than the two connections joining onto the existing pipes, the rest of the curves can just be done by bending the pipes I think (I know I'll need a pipe bending bar), rather than needing to solder more joints.

Any more thoughts?

 

[pelago]

Thanks for all the help. If anyone cares, or for the benefit of the archives, with the help of someone who knows much more about these things than me, I managed to dig up the floor and extend the pipes. I did most of the digging with hand tools but it took several evenings. My helper came along with an SDS drill which did the remaining bits of digging in minutes, so I would definitely use one of those in future.

I actually found a better place to join the pipes under the floor (I neglected to say that there is another rad in the room so the pipes continue across the floor) rather than extending from the current tails, and have cut off and blocked off the tails.

We used solder connections where we could successfully blow the water out, but had to use some compression connections where we couldn't. With the benefit of hindsight I wish we had gone for all compression connections as it was a hassle trying to get rid of the water.

I covered the pipes with a hairfelt insulator, and backfilled with a mix of 3 parts grit, 2 parts sand and 1 part cement.

I now have to research about sealing the screed and vinyl tiles, so may ask in the Tiling forum.

 

[Softus]

On a scale of 1 to 10, how pleased are you that you bit the bullet?

 

[pelago]

Oh I'm definitely pleased I bit the bullet and did the job properly.

 

[pelago]

Please see new question regarding covering where I've backfilled with tiles and carpet at //www.diynot.com/forums/viewtopic.php?p=1049244