DIY Doctor UK DIY Forums

Hi

This is my first time so apologies if this is posted to the wrong area!!

I am getting a new boiler installed and also have several other pipes to get through the walls. I'm unsure what core drill sizes to select for the following pipes:

100mm boiler flue
40mm washer waste
25mm boiler waste (condensing)

There seem to be a lot to choose from of similar sizes but I would like to know what clearance is needed for each. Many thanks :?

condensing boiler flues has to rise away from the boiler so this hole has to be larger than the flue 120 - 140mm i would say. The condensate and the washing machine pipe will not require any clearance, as they are plastic and will not corrode if in contact with bricks and mortar.

Thanks for that. Much appreciated