Copper pipe - thermal expansion ...

[BW2]

I’ve got to do an 8 metre straight run of 22m copper for the hot water for a shower & basin, & I’m wondering what to do about thermal expansion.

One end runs up to a wall & could be anchored there, the other end has nothing to get in the way & could take all the expansion & contraction.

So queries

1) I believe I don’t need an expansion loop for this length of pipe ?

2) But what about all that clicking as the pipe heats up. I assume it’s due to the pipe sliding lengthways through the pipeclips?

3) So should I use those C-shaped open clips to allow the pipe to slide through easily, or the clip-over ones that completely encircle the pipe and grip it really hard? Put some grease on the pipe & let it slide silently through the clips?

4) And what about straight in-line soldered joints every 3 metres – don’t they get stressed with all that pushing & pulling & fail eventually?

 

[GodKnows]

Firstly, what type of boiler is attached to the copper pipe? This would determine the size of the copper pipe. Usually if the hot supply is in 22mm this denotes that it is a gravity system boiler. There is a recommended gap for clips to run horizontal and different to vertical if you want to do the job properly. The expansion on pipe is minimal, bends should be kept to a minimum to lower the overall resistance in the system...

 

[neds]

According to my calculations that piece of 8m pipe would expand about 5mm or so. This is assuming a temp rise of about 40 degrees of the hot water. Not too much to worry about really...

 

[ChrisR]

It matters not a stuff what the diameter of the pipe is, it'll expand lengthwise by the same amount.

COpper's coefficient of linear expansion leads to about 0.017 mm per metre per degree C

Soooo 8 x 0.017 x 60° gives about 8mm. Not trivial.

Avoid 90° elbows, use bends instead, unless there's a part of the pipework which can move something like this:

 

[neds]

That is incredibly hot water running through the pipes if the rise in temp is 60 degrees! Mains water will be at least 10 Degrees, hot feed a little higher. You want to make a cuppa?

 

[swbjackson]

I've never had a problem with pipes clicking where they pass through nylon clips. It's normally where they are notched too tightly through wooden joists and floorboards.

If you're worried about it go up a size in clip and use hairy felt lagging round the pipe.