Hi there, Looking to install a thermostatic mixer shower in a flat with night rate unvented cylinder. It's an almost like-for like replacement for a thermostatic bath fill/shower diverter which has a broken thermostatic cartridge. During the day, hot water temperatures can fall to 45°C, or perhaps the thermostat is set too low, but the customer seems to like it like that and seems to have paid plumbers to set the temperature so I don't want to interfere, not that I want to touch anything unvented anyway. In any case, my grandmother used to keep her water at this temperature and she never caught anything from it so I'm not especially worried. It concerns me that most thermostatic shower manufacturers seem to insist on water temperature being 10°C higher than the blended water temperature. A non-thermostatic mixer would be ideal, but I suspect the customer has a touch of dementia so I'm not giving him that option. I find manufacturer's instructions can sometimes be taken with a pinch of salt and I'm hoping the unit would still work, even if it doesn't work perfectly outside its comfort zone. So what will happen? If the water temperature drops to 45°C, can he still get a 42°C shower, or is that not an option? Cheers for any experience on this.