Condensate drain size

[Crowbar hero]

I'm wondering if the condensate drain will need to be upsized from 21.5mm when I get my boiler moved into the loft, which technically is unheated, however unlikely to freeze, as it'll be insulated between rafters as well as the loft floor.

The route of the pipework will be 3m in the loft, then down through the house to a waste pipe in the utility room, so all internal.

[TonyT]

I would upgrade it to a larger size, minimal cost and less

likely to freeze so that’s got to be good.

 

[Nickfromwales]

Insulating the condensate pipe, regardless of size, eg if there's a slight risk of freezing, is observed in most installations if it's a cold roof space. Will be a few £ and you'll be insulating all of the other water pipes too, so an extra 10 mins work at most. I'd prob leave at 21.5mm and insulate, as a risk of freezing will provoke insulating regardless and larger pipe sizes will attract more expense on insulation.