Ideas for insulating outside sink waste pipe?

[Madmog]

Can anyone give me any ideas on how to insulate our outside sink waste pipe. I've looked everywhere for insulation, but none of it is wide enough to fit around the pipe.

I want to insulate it as our condensing boiler drains into it and everyone I know with a condensing boilers in the area has had theirs break down during the coldest times in winter when the water in the pipes has frozen and the boiler is unable to condense.

that the pipe runs outside the house. I'm guessing you have an older house, without an internal soil stack, and there is a gulley outside the kitchen wall?

I just had a look at some suppliers and can't see it bigger than 22mm and 28mm. A plumbers merchant may have larger sizes. You will also need some plastic cable ties to keep it in place. You want Climaflex or Armaflex which is a stiff plastic foam in a tubular sleeve that can be opened using a slit to fit round pipes. The outdoor stuff is as thick as your arm. There are some own-brands that are similar, but the black Armaflex stands up to outdoor exposure best.

A few questions:

What size is the exposed pipe? the pipe from the boiler is typically about 22mm in white plastic, and it will join the sink waste pipe that is typically 40mm grey plastic. Preferably the join is inside the house.

Does it run vertically, or at a steep angle? that is much less likely to freeze than if it runs horizontally or at a shallow angle where water flows slowly or lies in the pipe. Are there any bends, dips or traps outside?

Thanks for your reply. Have looked in every builders merchants and diy shop going and nothing fits the 40mm outdoor pipe, the length of this pipe is about 1m. There is a bend in the pipe immediately it leaves the building. The boiler pipe is 22mm and runs at an angle until it connects into the sink waste pipe internally. All pipes are on a cold north elevation (so cold even the fridge freezer in the kitchen froze up at the back the winter below last!)

Just trying to do all we can reduce the pipes from freezing in bad weather, as I know people locally who had frozen sink waste pipes a couple of years ago. One neighbour had the size of his condensate pipe increased outside to 40mm and it still froze.

I found this ad www.ebay.co.uk/sch/i.html?_sacat=0&_from=R40&_nkw=armaflex%2042mm&_sop=15

seems to be 42mm which would be for a copper pipe but should do.

wrap the pipe with bubble wrap held on with duct tape, make sure the pipe is clean and dry when you do it.

We have used bubble wrap successfully for a number of years.