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)?
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