Just had a water softener installed and the waste pipe goes through the external wall into a drain. The pipe is about 12mm wide and I want to prevent it from freezing during winter. The boiler condensate pipe runs down the wall outside next to this and froze 2 years ago during one very cold week.

Are there any easy and inexpensive ways to do this? I was thinking about coving the pipes with some square guttering or something.

Or actual pipe insulation?

Try black neoprene insulation as used for air-conditioning pipes? Your local DIY shed might have some.

Just normal pipe insulation from any DIY store all that I would use. It’s what I have on the small bore pipework outside my home and I’ve never had any significant issue with freezing. Even if it does freeze it’s generally pretty simple to thaw out.

Will it have standing water in it to freeze? I’d have thought you either have running water during a recharge or an empty pipe.

If you’re near Leeds I have some leftover lagging that you’re welcome to.

I’m not sure how much water flows out yet. It’s a dual cylinder softener if that helps? I’m guessing it’s not a lot of waste otherwise I’d have thought the pipe would be wider.

I used normal pipe lagging on the condensate pipe before and it still froze. Although this pipe is less exposed and only about 40cm long.

It will only discharge for 15 mins or so every other day, so quite unlikely to freeze

I don’t think there is much point lagging cold water pipes outside unless you put some heat trace tape inside the lagging. Insulation only works if its covering something that is warmer than the outside air…without it, it will just freeze anyway but the difference is when the sun comes out at 11am, instead of the ice melting, the insulation will keep the ice frozen. Repeat for a few days and your waste or condensate pipe will be frozen solid.

Are you sure it is the waste pipe, it could be the overflow from the softener and the drain is routed internally. Lots of softeners discharge under pressure so unlikely to freeze if it has a decent amount of fall on it. What make of softener?

It’s a Harvey’s softener. The 12mm pipe is definitely the waste pipe. There’s a separate overflow that just pokes out the wall so not as exposed.

Repeat for a few days and your waste or condensate pipe will be frozen solid.

Beg to differ.

Our 32mm(?) condensate waste is about 4m along a north east facing wall. The first winter of new boiler I had to defrost it multiple times. Basically as soon as the pipe itself was 0*c or less, the condensate froze and backed up really quickly.

I have lagged it with thick insulation and added an access hatch at the up-slope end where it emerges from the wall and boiler. I have not had need to use the access hatch to defrost at all in 3 winters now. For example the house has been in sub-zero temps now since Friday. No issues at all.

Which reminds me of the old Scandinavian plumber joke….
“Why do the Brits always run their pipes down the outside of houses?”
“So they can access them when they freeze.”

The waste water is highly saline, freezing point will be approx -20c. Also will be coming directly from the main, through the softener, and out again, so will probably start of above approx +10c. Personally I’d not worry about it until you notice an issue.

I’d be concerned as if it does freeze then it will most likely cause the softener to break.

Beg to differ.

Thats interesting…perhaps the condensate is warm enough that the lagging allows it to leave the pipe without freezing. 32mm is also undoubtably helping as a lot of installers use 15mm pipe.

Also found that if you have your boiler set above 55 degrees it won’t enter condensing mode anyway, which presumably will avoid the condensate drain freezing as there will be almost nothing draining from the boiler.