@Liriodendron, we had that problem a year or two back. Our gas engineer neighbour told us to fit the round pipe insulation around it and we haven't had the problem since.
Thanks @Lizzie27 - I think I'll give that a try. It's rare to have such low temperatures for so long in this part of Ireland, but maybe it's climate change...
Since 2019 I've lived in east Clare, in the west of Ireland.
We used to have the same problem @Liriodendron. British Gas installed the condense pipe along the roof of our car port, where it can't be accessed without climbing on corrugated pvc roofing panels, and north facing to boot. When if froze for the first time we didn't know the cause so called the BG engineer. He took one look at the location and refused point blank to sort it due to Health & Safety. When I said they had installed it there less than a year previous he just shrugged. We have since had the pipe relocated so more of it runs in the house, and the section outside I can access from ground level. It did freeze once but that was quickly sorted with a hair dryer too.
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https://www.edp24.co.uk/news/23180262.keith-skipper-looks-impact-villages-pub-closures/
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.