Prevent Outside Tap Feed Freezing

[Traveller 47]

I had an outside tap fitted by a professional plumber last autumn. During the recent cold weather the feed pipe under the kitchen sink froze and the compression joint where the pipe enters an isolation valve now leaks. The outside tap was covered for the winter by an insulating blanket.

I believe the problem is that the feed pipe from the T joint with the cold water riser ((up to the cold water tap in the sink) travels horizontally for about 12 inches before turning vertically upwards for a further 12 inches and then bending 90 degrees to pass through the outside wall to the garden tap. This arrangement means that the “L”-shaped pipe (two 12-inch sections) cannot be drained despite the outside tap being opened and the isolator under the sink being turned off.

Is this an acceptable way to fit an outside tap? Also, should I solve the problem by inserting a drainage tap adjacent to the isolator? If so, what is the best 15mm drainage fitting?

Comments appreciated.

 

[ShaunCorbs]

Any pictures of the pipework ?

 

[SimonG]

Should have an isolation valve and an internal double check valve. Isolate I side, open tap outside, removes most of water and prevents the ice pushing off compression joints.

 

[Lou]

If you can post us some photos that will help our members diagnose!

 

[Traveller 47]

Not the easiest to photograph, However, this shows the pipe concerned, the lowest pipe in the pic Ts off the rising cold water pipe. Disappears briefly behind a waste pipe, then rises vertically to rod left where it passes through the outer wall.

 

[ShaunCorbs]

Did you leave the outside tap open ?

 

[Traveller 47]

Did you leave the outside tap open ?

I opened it to drain any water - just a trickle came out, then closed it for winter.

 

[SimonG]

Need to leave outside tap open. It's all about the physics.

 

[SimonG]

No internal double check valve either. Doesn't look very plumbery.

 

[Traveller 47]

No internal double check valve either. Doesn't look very plumbery.

Don’t see why there is a need to leave the tap open. Air is compressible and water is not. A double check valve isn’ listed as necessary for an ou5side tap although I suppose there would be no disadvantage.

However, to get back to my question, what should I do to prevent this happening next winter?