I've been having a problem with my Central heating's 2/3 port valve when I set my heating to heating/hot water sometimes the valve moves to the heating/hot water position other times it doesn't move when it dose move after a while it will move to the water heating position on its own.
when I have to move the leaver myself its quite stiff and wants to go back to the water heating position when you let go.

What im wondering is if I change the port valve will it cure the problem?
Also how do I tell if I have a 2 or a 3 port valve?

2 port means there are two pipes coming into the valve ie __
3 port means there are three pipes coming into the valve ie T
.......so thants easy to determine.

Is it a motorised valve, if so there are two parts.....
1.The valve which is part of the plumbing pipework and will be 2/3 port.
2.The actuator is the motor which is wired up to the boiler system and turns the valve just like your hand turns on a tap but it's automated.

Probably the actuator is knackered if it works sometimes and not others. If you buy a new one and swap it over there is no wet work involved. You just unscrew the old one off the valve, screw on the new one and swap over the wiring.
The actuator might just be worn out, but a possible cause of the actuator being knackered is if the valve leaks a bit and the actuator has corroded from water being on it. In this case you will need to swap over the valve as well which involves a greter level of understanding or bigger balls to tackle as you might piss the contents of the hot water system out over the place.

Thanks for that Boost II

It is a T valve so ill take it that its a 3 port.
I'll try changing the actuator over the weekend....

Thanks again.......:)

Take the actuator off first and see if the spindle on the valve body is stiff to move because if it is then you are wasting your time replacing the actuator and will need a whole new valve.

Mog