I would like to explain a problem I am currently experiencing since I carried out some modifications to my heating / hot > water system. When I ask for Hot water only via my programmer the three port valve moves to position "W" and the flow is via port B which is ok, when I ask for Central heating only the lever on the valve moves to "H" > and flows through port A again working satisfactorily the same applies to requesting both, whereby the valve moves to mid-position and hot water flows down both ports A & B. However what I have noticed is that when the temperature on my cylinder stat reaches the required set temperature the hot water cuts off satisfied, but it is also cutting off the central heating which remains off until the cylinder stat cuts back in again. I would assume this is not correct and although it is not causing me a major problem I would like it to work correctly. I think the answer may be solved by the addition of an additional core from the programmer to the junction box ?
Appreciate any advice