"Mark" wrote in message
...

Bob Mannix wrote in message

"Mark" wrote in message
i'm fitting a home style heating and water system to my motorhome, a
12
volt
eberspacher 5KW water boiler, a 20 litre twin coil calorifier (hot
water
cylinder with an extra coil to heat from the engine) 3 radiators,
digital
programmer, tank and room stats, and hopefully a 3 way valve to select
hot
water, heating or both to be heater when the boilers running.

But i just can't seem to find a 12 volt DC powered 3 way valve, the
mid
position type that's fitted to 99% of home central heating systems,

does anyone know where i can get one from?


Don't think you can get these,

I suspect you are correct. The "normal" three way valves as used in CH
systems are stalled in some positions and this is easier to achieve with
the
AC synchronous motors with which they are fitted. I think this sort of
operation would be a lot harder to achieve with a 12V DC motor, which is
probably why you can't find them. As another poster has suggested, the
use
of 2 12V solenoid valves and appropriate controls would be a better bet,
although this arrangement could fail with all shut (which a 3-way valve
can't) giving rise to potential hazards.

I *Think* on the Winnebago one valve is N/O (HW) and the other is N/C
On energising they switch state, so even with power off there is always a
water path
open.

You can get 12v valves like this too :-)

Sparks...