How much do copper pipes expand (lengthways)

[doormouse1]

About to start installing pipework from radiators to proposed new boiler location.

My house is a strange shape and the flow/return pipes will each be 16m in a straght line. It has occured to me that once the heatings on, these could expand and pull on the pipes that feed off to the radiators.

Is this the case? or is expansion so little that can forget about it?
If it may be a problem, is it worth me adding some bends to the pipes so they can flex a bit? or is there a better solution.

Paul

 

[JPC]

you are right that pipes expand length wise. i cant remember what that measurement is now without looking through the books, suffice to say don't worry about it and just go ahead and fit your pipes....the expanding pipe will make noises against unlagged joists

 

[doormouse1]

Thanks

Hate to sound stupid, but whats an unlagged joint? Do I need to add something to help the pipes slip quietly?

 

[Gasguru]

You must allow for expansion of around 1mm/meter.

I have attended several major joint failures...normally where flow/returns are run around the skirting (and the clips are close to the room corners) with soldered elbows in the corners. Give it several years and the elbows fracture.

I suggest you form expansion loops (with pulled bends). Don't clip the pipes in the joists (as many do)...just make sure all pipework is free to expand and contract.

Alternatively offset the pipework in the run..split the run into say 3 and dogleg the pipework with sufficient offset to allow movement..


Make sure the joist notches are of sufficient depth and width...lag the pipework in the joist notches with hairfelt lagging to prevent noise. All pipework in unheated areas eg under vented ground floors should be sufficiently lagged with foam insulation.

 

[doormouse1]

Many thanks for the helpful advice.

 

[gas4you]

I was always taught not to have a straight run of copper pipe greater than 6M because of expansion.

Never tested this so don't know how true it is

 

[rssteve]

16m long house, sounds very big.

 

[numpty1]

try this

http://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html

 

[Norcon]

Or this........

http://www.ukcopperboard.co.uk/literature/pdfs/Installation-Tips/Fixing-copper-tube.pdf

 

[doormouse1]

16m long house, sounds very big.

Very narrow though - only advantage is nearly all the windows face south.

 

[doormouse1]

Thanks for the links guys.

 

[baxpoti]

http://www.physics.unr.edu/181labs/Measuring the Coefficient of Linear Expansion for Copper, St.pdf


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