"Christian McArdle" wrote in message
. net...
You have a heat bank with a thermostatic blending valve controlling DHW
temperature, not a combi.

Yes, but you are proposing that turning on a hot tap would produce only 6
lpm at the tap.

Where did you get that from?

Furthermore, the combi is likely
to be set to 60C output to allow dishwashing.
Therefore, even on quite moderate hot water
flow rates, you'll be in the temperature unstable range.

What are you on about? Oh, don't bother.

I'm saying that with the combi set for 60C,
the 15 lpm spec of the boiler (at 40C) equates
to around 9.5 litres per minute. Draw any more
than this and the temperature will drop,
requiring adjustment at the mixer.

If you draw large amounts of water at other taps the temp will down. Turn
all your hot taps on your heat bank suffer the same.

The 415 only has manual flow control
and auto pressure balancing. No auto
temp control to maintain a setpoint temperature,
only manual by mixing hot
and cold water to user requirements.

I don't dispute that pressure balancing is an essential feature. I would
not
buy a shower mixer without that feature. However, it is quite possible
(indeed, is normal) to buy a shower mixer both pressure balanced (for
speed
of correction) and thermostatically controlled (for temperature
pre-selection and adjusting to varying water supply temperatures).

It is not normal to buy a mixer with both functions at all. Most buy only
thermostatic mixers only.