Insulating outside copper pipe

[llykstw]

I've got a short (1 foot) run of 15mm copper water pipe outside, along an external wall. It goes between a spur from the outside tap into the conservatory, where it feeds the washing machine. At the moment, it's uninsulated, but I want to protect it before the bad frosts arrive. Do I need special insulation for external pipework, or will the normal grey spongey stuff from B&Q etc. work ok?

 

[spacethegas]

personally i would fit a full bore 1/4 turn valve inside. shut it down & leave outside tap open.

 

[roberta1000]

I assume that you want to keep the water flow to the washing machine otherwise as the previous poster suggests just turn it off and drain as best you can. If you want to keep it live the best thing is to replace it with plastic which will stand freezing better. Whatever you insulate it with it will still freeze if the temperature is below zero for a few hours. The grey foam from B&Q will work OK within its limits but no amount of insulation will stop an outside cold water pipe freezing eventually.

 

[simond]

You should use a closed cell insulation like Armaflex. This gives better protection outside than the foamy stuff you describe.

 

[doitall]

As Simond but you will need to insulate the pipe through the wall as well.

 

[ChrisR]

Even the "B&Q foamy stuff" is closed cell. Armaflex (which is also sold by B&Q) is just a make. What matters is its insulating properties and whether it's UV stable, if it's to be exposed.
It needs be about 75mm outside diameter insulation for a 15mm pipe, because thin pipes lose heat quickly.
I would suggest it would be worth getting the pipe rerouted, or if not, using the insulation, then constructing a box around it. that would hold more insulation, and protect it from UV and damage.

 

[TicklyT]

It might help to insulate the outside tap at the same time, to stop it acting as a heatsink and chilling the pipework you want to protect.

Insulation alone will not protect against a prolonged frost.

Long pipe runs are often heated with an electric heater tape wrapped around the pipe.

Years ago, the old outdoor thunderbox used to have an old Davey lamp hanging from an 'S' hook on the supply pipe to the cistern. That provided just enough heat to stop it freezing.

Re-routing the pipework indoors is the best solution.

 

[lagunaglen]

As Chris R said then box it in and use plenty of insulation,use pipe insulation then posssibly fill box with loft insulation which you can find in your loft.