what size pipework for bath hot water

[jon3674]

In the process of moving my existing bath, current pipe work 22mm hot water, 15mm cold water. Having my boiler and c/h system upgraded in the next few months and was wondering if bath hot water needs to be 22mm or could it be changed to 15mm. The new boiler being installed is a viessmann vitodens 24kw on a sealed system, it is going to have a grundfos 15-60 pump and myson 3 port making it fully pumped(which means nothing to me) as i am moving the bath before the work is carried out, thought i would install the correct size pipework before the heating engineer starts, incidentally the bath is being moved approx 5 metres further than it's original position.

Thanks for any help given

 

[gas4you]

Are you having an un-vented mains pressure cylinder fitted? If so bath hot can be 15mm. if you are keeping with open vent gravity cylinder it will need to stay at 22mm.

 

[jon3674]

according to quote, they are installing a new 36 x 16 indirect high recovery cylinder with base immersion

 

[gas4you]

Sounds like a standard open vent cylinder, so stick with the 22mm then.

At least your installers are on the ball enough to install a new fast recovery cylinder. Good on them

 

[jon3674]

One thing he did tell me was that i will be losing the tank in the loft which feeds the rads but keeping the larger tank, which i presume feeds the cylinder

 

[gas4you]

Yes thats correct, the system boiler has its own expansion vessel built in.