storage tank and leave the output permanently 'on' (vented). As the
water expands in the heater, the excess drips from the tap. People
try to stop this dripping by turning off the tap harder, and IME the
washer is quickly destroyed and the tap really does start to leak.
Also there's a sort of 5 second delayed action when the tap is opened
or closed. This is not how people expect a tap to behave and also
causes people to turn it off harder, knackering it. I don't see how
this could be used with a mixer.

--
Andrew Gabriel

Any hints on how to change the washer on a vented tap - replacements are
£100... and I cannot see how to take the existing tap apart. Would it be
better to fit a pressure release valve, discharging outside, and then fit an
ordinary tap.

Peter