Please help, i cant figure this out

[SimonTaylor609]

Ive got a problem with my boiler/timer.

The heating and hot water work fine on their own and together but after the boiler has been on for a few hours and the timer has gone off it still runs round all systems and the only way to stop it is run hot water off.

The system is on a Y plan.

When the system is cold and you use the timer the on cont and then off it does as its meant to.

PLEASE HELP!!

 

[stardanny]

Possible a fault on 3 port valve motor head or wiring fault.

Dan.

 

[5544]

check what wires to the valve are energised that will give you the result you need. the three port valve relies on switched lives on, and a no hot water input to provide a switched live to the boiler. there are numurous flow charts on the three port valve around this forum. If the inputs do not match what is happening, and this valve has only just started doing this then its the valve.

 

[vicvapour]

The valve sometimes get stuck on these systems how old is the valve?