Hi Gilly
I have a spare water valve. When I look in the opening and view the Monovalve when I apply 12vdc the valve moves up about 1/8 to 3/16 of an inch. Is this enough?

If the monovalve has deteriorated and water flows through it, does that hot water go to the heater core and give you heat. ( meaning that you would get heat all the time?

If the valve is down (good monovalve) then you get no hot water which means that the AC would not be fighting the heat ?
When should it be running?

Thanks, Jack