What size core drill to select

by **rdo1104** » Wed Jun 06, 2007 11:32 am

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 :?

by **htg engineer** » Thu Jun 07, 2007 7:04 am

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.

by **rdo1104** » Thu Jun 07, 2007 8:46 am

Thanks for that. Much appreciated