Worried about frozen pipes
to an outside tap? Turn the tap on so that it is only just dripping and place a bucket underneath. The flow of water through the pipe, albeit very small, will prevent the water in the pipe from freezing.

Theoretically, you may need to experiment with the drip speed. There's also the possibility of a pretty icicle hanging from the tap.
( sandettie light vessel automatic New Twitter - @bollocksreally, Fri 17 Dec 2010, 22:58, 5 replies, latest was 15 years ago)

mmm, an interesting point. i have repaired about 40 burst pipes this winter...
'tis true that the flow will reduce the possibility of freezing, i have been advising my clients of this very point. it doesn't matter how well insulated a pipe is, if the water is static then eventually it will freeze.
if memory serves me well then the latent heat and specific heat capacity of water mean that it takes as much energy to turn solid water at zero centigrade into liquid at zero as it does to heat the same mass of water from zero to 60 degrees*. perhaps a scientist could verify.
it's definitely true that refreshing the water in the pipe will interfere with the maths but a tap dripping at a rate of two drips a second will fill a 3 gallon bucket in 12 hours.
the temperature of the mains water is a significant factor. up here in this part of the north our drinking water is surface water so is prone to large seasonal temperature variations. this morning it's 2.1c (i know this cos i've just checked). down in that there laaaaahndun the drinking water comes from artesian wells ie it's ground water so will be considerably warmer, maybe as high as 8c.
*edit: i think it might actually be 42degrees?
( blaireau69 , the Cumbrian Travis Bickle., Sun 19 Dec 2010, 9:12, Reply)

*nerdy physics student
Specific heat capacity of water is 4.2J/g/K. Latent heat is 334J/g. So, to melt a gram of ice, it takes as much energy as it does to heat the water from 0C to 80C.

The pipe runs from the rising main, up behind the wall, across under the floorboards, back out of the ceiling and down to the basin in the downstairs toilet. The pipe branches from there to the tap outside so it's covered a good 20ft inside the house.
But after that outside tap, there's another 8ft or so before it enters the shed to the washing machine feed. That froze last week and burst the pump in the washer which was annoying.
( sandettie light vessel automatic New Twitter - @bollocksreally, Sun 19 Dec 2010, 17:25, Reply)

thanks for the maths there mate! i was going off 30 year old memory...
yeah, bursts sure are a pain in the arse.
i seem to remember that the ice is at it's least dense at around -7c so if you can stop it getting quite that cold it helps.
also i've observed a real difference between old copper tube and new. the older stuff is harder (and less plastic) than new stock, the newer being more malliable and generally "softer" than the old. consequently there's quite a difference between the fractures with much more ballooning going on with new pipe and cleaner, straighter fractures in the old.
i've been pricing some pre-insulated 16mm uponor mlcp for a job, i think for exposed work it is the future.
( blaireau69 , the Cumbrian Travis Bickle., Sun 19 Dec 2010, 19:21, Reply)

Is there not
a type of compression fitting that can release pressure in the event of a freeze?

Will plastic pipe rupture if I replaced the outdoor copper? Mind you, it won't solve the problem of the washing machine breaking.
( sandettie light vessel automatic New Twitter - @bollocksreally, Mon 20 Dec 2010, 0:40, Reply)

cos of the difference in expansion co-efficients of brass and copper...
i've come across a number of compression fittings that have simply slipped off the end of the tube, leaving the circular marks where the olive was once firmly attached.
hep2o and suchlike seem more burst resistant, my personal choice is 16mm mlcp which is poly-ethylene and aluminium.
yeah, wouldn't have saved the washing machine.
anyway, duty calls...
( blaireau69 , the Cumbrian Travis Bickle., Mon 20 Dec 2010, 10:45, Reply)