Thanks for the prompt and very informative reply; I'd planned to use isolation valves
However, you say the hot & cold water must be reasonably balanced ?
Currently, at my elderly Father's house, when a hot tap is opened, for a split second, the hot water is scalding; I have to keep reminding my Father to allow the water to run for a second or two before putting his hand under it, hence the TMVs.
Once the initial scalding water stops, the hot water, dispite the temperature setting, is either too hot or not hot enough, will this effect the functionality of TMVs ?