I lusted after underfloor heating for years. If I'd done it just 5 years ago my system would have been incompatible with 2023 current standards and very disruptive to install. I then discovered large 2-2 radiators can be sited unobtrusively and perform brilliantly!
A 10 degree drop across the boiler and across the rads was the normal design until 10 years ago. If flow temp 64 return 54 you probably have only a little condensation in the boiler but to increase efficiency you will need bigger rads. This allows a drop in flow temperature and a bigger drop...
This is a servo valve that needs high pressure to operate properly. It should be pretty simple to swap this valve for a low pressure valve from a local merchant (asking their advice). And change the pipe at the same time.
Feed in Tariff is no longer available. The Smart export guarantee payment is no longer for an estimated amount but it is metered on an export meter. And typically only 5.5p a unit, once upon a time the wholesale rate.
Can’t see that any direct cylinder with a single immersion would ever reach 60 deg throughout without a destratification pump. Must be hundreds of thousands of these out there. So risks must be very low.
To be fair the “committee” has produced HSC document L8 which recommends daily sterilisation to 60 WITH a destratification pump to make sure it’s all stirred up. This is very rare in a domestic setting and would use loads of energy. I suspect most tanks in the UK vary from room temperature at...
Heating up to 60 once a week is sufficient to prevent legionella. Without a photo your description is a bit confusing, cylinder thermostat should be attached to the cylinder.