Is this a dumb idea?

plumb1_2

A manufacturer won’t inform you how to adjust their product over a safe limit. They would be open to be sued if someone got scalded.

Thermostat valves are there for a reason 

casper_gutman

I wouldn't personally want to use a non-thermostatic mixer shower with a combi boiler. The temperature control would be *very* erratic and you'd likely get big fluctuations e.g., freezing cold if someone switched on a hot tap near the boiler, or hotter (potentially dangerously so, subject to the boiler's DHW set temperature) if others turned on cold taps fully.

ThisIsWeird

casper_gutman said:

I wouldn't personally want to use a non-thermostatic mixer shower with a combi boiler. The temperature control would be *very* erratic and you'd likely get big fluctuations e.g., freezing cold if someone switched on a hot tap near the boiler, or hotter (potentially dangerously so, subject to the boiler's DHW set temperature) if others turned on cold taps fully.

I totally agree.

Even with a thermostatic mixer there's a part-second 'ouch' or 'brrr' when another tap is used and the thermostat responds. If B-F is already running the flow at approaching 50oC, then the result will almost certainly be very unpleasant, possibly very dangerous, and it WILL happen at some point. Most likely repeatedly.

I would only tentatively suggest it as a solution if you can get to the plumbing behind the mixer, and supply the hot via a blending thermostat. That way the hot can theoretically be set to a max or just over 50oC, and the cold should remain unaffected.

Still not a very good solution, tho'.

How many different shower cartridges are actually out there?! I bet that two different types will cover - fit - the vast majority of shower mixers, with only a few other more esoteric showers having their own bespoke valves. I bet there's a fractional difference between them, but how to find...