"Abdullah Eyles" wrote in message
om...
"BigWallop" wrote in message
...

Just take the drop spout off the ball valve and stop it from syphoning
back
out the tank. :-))


I didn't use a ball valve - electric solenoid valve from a washing
machine and water level sensor... When the mains pressure drops there
is a switch that prevents the valve from opening... Overkill but
enjoyable!

Because the house has only one circuit, the incoming main also feeds
the taps etc., hence the quick emptying...

I guess that the UK has regs to prevent this type of installation but
here... well, who knows...

So if you have a power cut, how does the tank get filled up ? I also hope
you used a floating mercury contact as the water level sensor, because any
other type when faulty might not switch the valve off properly. The mercury
float has two pins inside a float ball that contains a small amount of
mercury metal and when the float is tilted up on an arm the mercury flows
against the pins and makes the circuit to switch things on. Very simple and
doesn't need any electronic circuitry to make it work, it only relies on the
electricity flowing through metal conductors.