Does plastic pipe need insulating?

[newman]

I am replacing some kitchen plumbing with Speedfit plastic pipe and fittings. Does the plastic pipe need insulating against frozen pipe problems which I have had in the past in this location?

Regards

[Rob Morley]

Yes.

[Christian McArdle]

Yes.

Although it will be much better behaved than the copper.

Christian.

[Andy Hall]

If the location is such that the pipes were subject to freezing before, then they still will be. Plastic pipe conducts heat less quickly than copper, so the water will cool less quickly, but the effect of insulation is to slow that down considerably further.

Personally, I would insulate this if there was a problem before.

[Set Square]

Do the pipes get pushed out of the fittings if they *do* freeze?

[Andy Hall]

I don't know, but since there will be an expansion of the water as it freezes, it is not going to help

If there is going to be a failure, I would have thought that this would be the likely area, as pipe manufacturers do say that the pipe itself won't split.

[Christian McArdle]

I thought the biggest advantage of plastic pipework, rather than the extra insulative qualities, was the fact that it can expand slightly to accomodate volume change with a lower pressure increase.

The type of joints are another matter. Most of the joints on the plastic pipework I used are actually compression joints. Only a few push fits.

However, my guess is that plastic pipework is less likely to result in a failed joint than similar joints in copper. I have no empirical evidence to back this up, though, and what I would imagine to be the best joint (soldered) is not available in plastic.

Christian.

[Pete C]

The diameter will have to go up by 0.6mm with expansion from water freezing, so I'd expect plastic pipe would be able to handle this.

After all it can be bent fairly tightly with cold forming bends which must involve some stretching of the pipe on the outside.

Anyone on here had problems with plastic pipe or fittings splitting when frozen?

cheers, Pete.

[Nick Atty]

We've got a mix of domestic style plastic pipe and hose type (just that

- potable quality flexible hose joined with 15mm pipe and jubilee clips) on our narrow boat. When we leave it for the winter we just open the taps after we've turned the water off.

The only problems we've had, even in very cold weather, has been that the plastic pipe has pushed out of one of the compression joints once or twice.

[Dave Plowman (News)]

I've seen soldered joints 'popped' by freezing. And I'd say they're likely to be worse than compression or push fit which *might* allow some movement before leaking.

[Nick Atty]

I can't remember exactly. It certainly wasn't a copper joint, it was plastic to match the tube. Which you'd think would mean push-fit. But I seem to remember it looking as though it had knurled rings on it.

[Pete C]

Thanks for the reply, were they conventional compression joints or push fit ones?

cheers, Pete.