We have recently had a new shower fitted, non-electric just standard hot and cold pipes feeding into a mixer. The water is quite hot however when you turn the mixer completely to cold it stays warm. I’ve mentioned this to the plumber and he muttered something about the heat exchange valve in the boiler.

This doesn’t ring true to me. The hot feed comes from the boiler and the cold feed from, well the cold feed. In my mind, turning the mixer completely to cold should isolate the hot feed completely and facilitate a cold shower.

Any advice before I unload both barrels at him?

Is it thermostatic?

If it’s a thermostatic shower, it might be as simple as changing the limit settings on the cartridge/lever. What’s the make/model?

Turn off the hot supply. If you can get a cold shower then, it’s the mixer.

Thanks. Pretty sure it’s a thermostatic. However if I turn it completely to cold then it should isolate the hot feed completely and facilitate much icy goodness. Is that not the case or am I missing something?

If it’s working properly, yes. If it’s either been set wrongly or it’s goosed, then it could be that.

If it’s thermostatic then it can be adjusted, although I agree with you, I would expect it to shut off the the hot water completely when turned to cold.

Have a look in the manual at how to adjust the settings, it should be accessible on the outside.

What are you up to, needing cold showers, eh ? 8)

Thanks. Pretty sure it’s a thermostatic. However if I turn it completely to cold then it should isolate the hot feed completely and facilitate much icy goodness.

Ours is thermostatic and you get 100% cold feed water on the cold setting….

the cold feed from, well the cold feed

Cold’s coming from a mains pressure feed like the hot, not a tank?

Yup, cold feed from mains pressure feed.