Did you measure the voltage across the connections while it was connected to the CCU cable, I've never tried that?

I thought it saw a full 12V, but was cycled open and closed by the CCU to maintain the correct temperature, resulting an a "pulse" to the monovalve. I may be wrong. As Brian said, the CCU is magic.

As I recall, I've directly connected 12V across the monovalve contacts (unplugged) and heard a distinct click when it changed position. I would not necessarily recommend that, I'm not really sure the valve is designed for a full 12V.