Probably was me. I posted about it several years ago when I installed the valves. They are not fresh water supply or any sort of household plumbing valve, and I would not recommend using such due to questionable compatibility with the coolant chemistry, ambient and coolant temperatures, and the vibration associated with a mobile installation. The valve pictures has been problem free for several years, and I have seen them used in heavy equipment installations for much longer than that with no issues.
It was you. I remember now the reference to 'heavy equipment installations'.
Thanks, this is a brilliant idea that I doubt I'd have thought of.
Only one valve is required to stop coolant flow through the circuit, but two are necessary if you want to be able to shut the heater circuit off completely in the event of a failure.
Second option for me!