We had an outdoor tap (faucet) fitted in the summer last year here in Edinburgh UK. The temperature here often dips to just below freezing over the winter. Outside, at least. The plumber suggested we should turn off the water under the kitchen sink (a screwdriver turnable valve), but also leave the tap/faucet fully open on the outside wall. That last to allow cooling water to expand up and out as it is freezing – hopefully slowly. That's exactly what we did.
Anyway, Today (March 21st), I closed up the outside tap, and under the kitchen sink opened up the wee valve. Guess what? .. super spraying burst pipe outside!! There's a copper pipe rising to the tap, from foot level, and it has burst a couple of feet up. We followed instructions to the letter 🙁
We need to get that repaired, but what to do instead for next winter? Under the kitchen floor (a crawl space for slim people) there's push-to-fit plastic piping. That goes out through a cavity wall as copper pipe, before making a 90 degree turn up the wall at foot level. Is polystyrene insulation enough for the same pipe? Do we need a mechanism to fully drain the outside section?
Outside:
Best Answer
What I would do ( have done) is replace the elbow with a "T" and add a valve to be opened in winter . Presumably the valve will be below grade and will need something like a sprinkler valve box. I have a few similar drain valves in my sprinkler system.