Float valve for the mains top system in my header tank

[Baz]

Pressure would be released at the first flush. I was thinking that the pump + pressure switch could be self contained, remote, and at the bottom of the well with just a time switched 12v? supply and no extra wires to worry about. I find the mechanical stop to the water more reassuring than the idea of a stuck relay and water running out of the overflow.
I had considered a float switch completely seperately one day into the home monitor to warn when the tank got down to the last 2 gallons.

[vstar]

All this talk of pressure switches etc, seems to be overengineering the system.

Let me describe my set up, designed for simplicity and low energy use. I have a 1500 litre tank outside, fed by a 3P Technik diverter.
There is 12V (Lux by Comet Pumpen, eBay less than £15) pump in the bottom of the tank, the power cable and hose pipe from the pump come out of the tank and back up the drain pipe into the loft.

In the loft there is 25 gallon header tank, which the hosepipe goes into. There is low voltage float switch mounted near the top of the tank. This is connected to the green wires ("Power Good") on a standard PC power supply (free from dead PC).
The 12V/Gnd are connected to the cable that came up from the pump. The power supply is plugged into a timeswitch, which comes on twice for 15 mins each day (duty cycle on the pump).
There is also a backup fresh water feed to the tank, with a normal float valve, but this is turned off. I don't want to use fresh water without knowing about it!

Toilets are gravity fed from the header tank. Twice a day the timer powers up the pump, the header tank fills until the float switch breaks the "Power Good" connection on the PSU, the PSU cuts out, water in the hose drains back to the outside tank (freeze protection), the timeswitch switches off the power.

The timeswitch uses around 0.5Wh, the PSU/pump use nothing while waiting.

If the float switch fails, only 15mins of pumping is wasted. There is an overflow from the header tank, that I should see as I'm eating dinner. If the pump/timeswitch fails, we would notice within 12 hours due to lack of flushing.
I keep a spare pump/PSU handy just in case.

That said, the system has been in use for 3 1/2 years and the only problem it's had was for a week during last winter the surface of the water in the outside tank froze, so I couldn't pump water.
Que me moaning about flushing with drinking water... This summer I intend, time permitting, to build a mini insulated "shed" around the outside tank to keep the cold out over the coming winter.

Lee

PS. Baz, I've been feeding my toilets using 8mm copper microbore for 3 1/2 years now, it works just fine.
Before I put filters in there was a very fine silt building slowly in the bottom of the cisterns, but now that I filter (using fish tank filter matting £5 off ebay for loads) at the gutter downpipe, at the hose into the header tank and at the tank connector out of the header tank it seems to have stopped.