Copper pipes under concrete floor

[Grumps]

Hi What sort of tape do you need to use over copper pipes under a concrete floor? Can you buy pipe which is already coated with an appropriate covering?

[John Rumm]

Denso tape or one of the equivilents.

You can get plastic coated pipe. See

and look at the copper pipe section.

Or if you are *not* carrying gas, you could use plastic pipe instead.

[Grumps]

It's just for water to central heating radiators.

[Weatherlawyer]

Actually anything to seal the copper from the calcium will do. Or you could make a box out of batton and ply to let you get at it should it ever leak. You won't need to insulate it then.

[The Natural Philosopher]

I would definitely use plastic then, and wrap in foam to prevent heat loss and or localised cracking.

Its dead easy to join to copper at each end.

[Michael Chare]

I made the mistake of using some gooy tape on a vertical run. The problem was the hot water melted the goo!

[Grumps]

Any idea of the cost for a plumber to hang two rads, route one set of pipes from the first rad, through a wall and on to the second rad. Tee off horizontally from the centre of this run, and join up to the existing pipework some 3m away. I estimate about 8 3m pipes, two TRVs, and other bits. Location: Berkshire.

[Kate]

Round here they have spent three months digging up the old gas main and laying plastic replacement, right up the meter.

It was absolute chaos as the plans were wrong and they had to dig up everyone's garage hardstanding to find where things went. Parking was a nightmare.....

[Grumps]

Maybe a stupid question, but how much would a 3m length of copper pipe expand when increased in temperture by 50 degrees? If it is embedded in a 3" concrete floor, will it be compressed and buckle?

[jhewitt]

Place a plastic sleeve [ pipe ] in the concrete, make it way oversize for the copper tube. When the slab has set, run the copper line thru' it. Believe me, one day your gonna be very glad you did.

John Hewitt, Malaga, Spain

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[Bob Mannix]

About 2.5mm along its length (coeff. of linear expansion 1.7E-5 /K)

If it is embedded in a 3" concrete floor, will it be compressed and buckle?

Probably not.

[Chris Bacon]

2 1/2 mm approx.

Maybe - depends on what shape the run is.

[Grumps]

Why? Is this better than using pre-coated copper pipe?

[Grumps]

The longest run could be 4-5m. So, take the max of 5m, the pipe will expand by over 4mm. I'm not sure how to cope with this.

[Chris Bacon]

What shape is the run going to be? How's your ASCII art?

[Grumps]

Dead straight, 4.5m (I just measured it).

Poor.

[Andy Hall]

You can use normal copper pipe wrapped in Denso tape or plastic coated copper pipe.

However, I think that a better solution would be to use plastic barrier pipe and run it in corrugated plastic sleeve intended for the purpose. That way, if there is ever a need to replace, it can be done without excavating the floor.

[Chris Bacon]

But what's at each end?

[Grumps]

The radiators. The feed (and return) will be tee'd into the middle of this run. (Please don't tell me you need to see my ASCII art)

[Chris Bacon]

You said "hang two rads, route one set of pipes from the first rad, through a wall and on to the second rad. Tee off horizontally from the centre of this run, and join up to the existing pipework some

3m away.

So you want:

wall rad @@ rad ############## @@ ############# ############## @@ ############# ############## @@ ############# ############## @@ ############# | | @@ | | |_________ | _______________________| | |_________________\________________| 4.5m pipe run -> @@ \ \ \ \ \ \ Tee'd off to existing \ \ 3m away

Is that something like? All in concrete?