15 into 22

[Vass]

I've noticed the boiler uses 15mm for the HW

I have a small amount of 22 running to the bath (about 2.5 mtrs) the rest of the house is 15mm for the HW

will it be a problem for the new system running 15mm from the boiler then about 2 mtrs away a 22m branches off to the bath tap, while the 15mm carries on the rest of the house?

TIA

[Roger Chapman]

Larger bore pipe is used to reduce resistance to flow. It sounds as though you have a combi where hot water flow rate depends very much on the power of the boiler. Mains water pressure should be more than enough to maintain that flow. The downside of the section of 22mm is that you will have to run off a bit more cold water before you get any hot.

I would have thought that running two hot taps off a combi at the same time is a chancy business but all the 22mm branch will do is give a marginally better flow to the bath compared to the other tap.

[Vass]

yep new combi, thanks Roger