Using a 3-port valve in an S-plan system

[PauloYianno]

Can I use an in situ 3-port valve as a 2-port valve where port B (hot water) is blanked off? I assume that if I simply combine the grey and white wires from the actuator to receive 230V from the CH thermostat, when the CH thermostat calls for heating, the 3-port valve opens to allow water to circulate to port A (only) and the orange wire becomes live to actuate the boiler. So the 3-port valve/actuator is acting in the manner of a 2 port valve/actuator. (I know that the more obvious thing to do is to replace the 3-port valve but it's in a very awkward location.)

Note that in the system, there is one other CH zones which is controlled by one 2-port valve/actuator. Thus, would there be any electrical conflict or running difficulties in directly electrically combining the orange wires from both valves at the boiler/pump given that there are internal switches/diodes in the 3-port actuator?

Thanks.

 

[Johntheo5]

I think it should be OK, the internal switches will still be in use but the white (&grey) will be switched live from the roomstat so SW1 will keep the valve in the CH position and SW2 will provide the boiler/pump run signal?, there will be voltage on the de magnetizing resistors with the motor powered as well with this mod but I don't think it should cause any problems

 

[Madrab]

TBH, I would recommend you take the pain just now. That 3 port motor is going to burn out at some point and will need replaced at some point.

 

[Johntheo5]

But this one will now operate exactly like a 2 port, in that it will de energize and "close" every time the CH is switched off and won't stay powered up overnight etc.

 

[Madrab]

True, as it won't ever be needed in its mid position, my thinking was though unless it's new, and it's been used as a 3 port all it's life then the motor will probably already be 'quite well used' so it will no doubt already have a reduced lifespan.

Much easier even just to remove it and site a new 2 port somewhere easier to access.

 

[Exedon]

TBH, I would recommend you take the pain just now. That 3 port motor is going to burn out at some point and will need replaced at some point.

Totally agree if 3 port of any age at all could easily be on it's last legs.
Change it now rather than a emergency job on a dark cold night in winter.

 

[PauloYianno]

Thanks guys; much appreciated.