DIY Doctor

Main navigation

Flowrate Balancing for new Mixer Tap Shower

Postby Heptagon7 » Sat Nov 11, 2017 4:00 pm

I want to fit a bath/shower mixer tap unit to replace
an electric shower.I have a combi fed with around 1.5bar.My concerns after measuring flowrates and some calculations is that there is a significant (but normal) pressure drop across the boiler during HW flow and also the pipe tails under the bath are quite narrow bore.Such that the bath tap HW and CW pressures are likely to be quite unbalanced during mixing which will make
temperature control difficult in that a small change in the CW tap position
will cause a large drop in temperature and increase in flowrate. In this case a thermostatic valve option would also be unlikely to function properly I believe given the balancing requirement specs I have seen.

I believe a solution would be to choke back the existing service valve in the CW line to the bath taps so as to match the HW & CW flowrates on fully open.

Is this a reasonable or standard solution? Are service valves designed to be used as chokes/flow restrictors? Are installers supposed to balance flowrates as good practice (my current H&C flowrates are ~7 and 13 l/min into the bath)?
Rank: Labourer
Progress to next rank:
Posts: 2
Joined: Sat Nov 11, 2017 3:36 pm


Simply Build It

  • DIY How to Project Guides
  • DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!

  • Related Topics