Stuck non-return valve or stopcock on way to outside taps

I’ve had a non-return valve jam closed after an episode of outside tap freezing. It would be the prime suspect in my book.

Tim

As the pipe to the outside tap freezes, the contents expand (it's why ice floats). With a non-return valve in the circuit, the pressure caused by that expansion cannot be dissipated back up the pipe and just jams the NRT. You're lucky it didn't burst the pipe. In another property, it used to blow the outside tap off the top of the standpipe.

When I isolate the outside tap in the winter I always leave the tap fully open

That's not my experience. We have at least 6 that were installed mid 80's plus others I have put in for elderly neighbours, & none of them have leaked. Not all of them get turned on or off on a regular basis but those that do don't have any problems.

I have had at lest three that leaked from the gland around the screw driver shaft. Perhaps its down to quality.

In my own house I've had problems in the past with cheap screwdriver operated isolation valves dripping slowly after they have been installed some time and then operated.

A couple of years back I help a friend living on the Welsh boarder area do some plumbing modification on some pipework that had been installed approx 10 years beforehand. There were 4 screwdriver operated isolation valves - all 4 had sieved in the open position. They couldn't be tuned even with a long screwdriver and a spanner on the he bit of the screwdriver handle to give extra leverage.

My experience also in the past but most of mine are now Pegler branded and with a small handle. They are 10x the price of the Screwfix/Toolstation cheapest.

Thanks to everyone who answered.

Later this morning I opened one of the outside taps, went inside for a minute, and when I came back it was blasting at full pressure. Both outside taps are running fine now.

I think in future I should leave the draincock and taps open during the winter and occasionally open the inside valve briefly?

Mm. Yes. But when you need an isolator to change a tap washer those get expensive and a bit ugly.

My experience is that they don't leak until you have reason to use them, when they might. I recently changed the basin and taps in the cloakroom. One of the valves started leaking when I closed it, the other started leaking when I re-opened it when the job was finished, so I finished up replacing them both. The originals had served for 20 years without issue.

Do you not cover the outside tap and any pipework with insulation? I've made boxes out of old polystyrene sheet or packaging and they work well.

If you work them back and forwards you can generally re-settle the glands

Since there is a full 360 travel its hard to tell which is the 'correct' direction

With the only kinds I've seen [1] the ball inside the valve can be turned either way as much as you want. When the screwdriver slot is parallel to the pipe(s), the valve is open; when it's perpendicular, it's closed.

I've come across both. With some there is an (external) 'stop' which prevents the valve from turning more than the 90 degrees required. The water supply to our washing machine & dishwasher are controlled by that type.>

n; when it's perpendicular,

If you take the plastic knob off the spindle can turn 360 degrees.

The only thing restricting it to 90 degrees is either a mechanical stop on the plastic knob or a stop inbuilt into the body of the valve, but again with the latter the spindle with a handle removed goes through 360 degrees

That's the norm for inline isolators. The slot/handle inline with the pipe allows flow & at 90° to the pipe stops the flow. There are odd exceptions such as where a previous owner has adapted the handle because of an obstruction.

No, because I empty the outside pipes over the winter, and because insulation just slows down the cooling of what's inside the insulation to the outside temperature (unless something else is warming up what's inside). If you put hot coffee in a thermos flask and left it outside at a freezing temperature, the coffee will freeze before winter is over.