Yet Another Nest 3rd Gen Y Plan issue.

[jeff the gasman]

Try slapping it again!

 

[fixitflav]

If that's the case then why would heating come on when I press water.

I don't know, and I'm not familiar with Nest. But clearly either the 3-port valve is faulty, or the system isn't wired up correctly. Is it possible to isolate the Nest and wire it the traditional way, maybe on a temporary basis, to see if it works? There are wiring diagrams on the web.

 

[Tistopher]

I can put it back to how it was which is my next plan so I can have some hot water

 

[CBW]

Try slapping it again!

 

[stem]

From a wiring point of The C27 is just a box that contains two simple switches. The Heat link is identical in that it also contains two simple switches. Looking at your wiring in the photos you posted, it appears to be correct. The red wire that was in C27 terminal 4 (Heating on) should go to Heat link terminal 3 (Heating call for heat) and I assume you marked it with the black pen to identify it from the other two red wires, in which case, you have migrated the wiring across to the Heat link exactly as it was at the C27.