Plumbing

38kw combi boiler supplying a shower. 22mm or 15mm pipework?

Anonymous user 23/02/2024 - 3.34 PM

I am refurbishing a 1st floor bathroom and installing a shower to replace a bath and have a 22mm/15mm pipe quandary. There is currently a newish Worcester Greenstar 38CDi Classic combination boiler and my question is should I redo historic mixed diameter pipework. The boiler has 15mm mains-in and DHW out connections. At some point in the past there was a cold water tank in the attic and presumably a hot water tank somewhere. There is a half meter of 15mm pipe coming from the DHW boiler output which becomes 22mm supplying the bathroom bath and sink 3m away. The 15mm mains water pipework comes up from the ground floor into the boiler cupboard and also is connected to an historic 22mm pipe to supply the bathroom. This looks an easy route that the previous installer took. I was considering replacing all the 22mm pipework with 15mm as that seems to be the general internet consensus from what I can gather but I want to make sure I am not going to throttle the supply to my shower as the aim is to have a GREAT shower. Any advice gratefully received.

PDunn

Rating: 5 out of 5

5/5205 reviews

Holloway, London

What yove explained is clear. Pipe feeding cold in and hot 🔥 out is 15mm. If you have exposed access to any of pipework - yes you may change it to 15mm - but then the energy (hot water) in the pipeworks is much much easier to dissipate (lose) heat for obvious reasons - pipe is smaller? Would recommend - put in place descaler to the 15mm cold water inlet to prevent scale build ups - if you are taking that route - as the water flow and heat up time through 15mm will be faster to oulets. Remember WRAP - LAG as much exposed pipework as possible to keep the heat inside pipe for longer.. Hope this helps Pd

Answered2 September 2020

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