Sure. Somethings not going to operate, but what the hay!
Can You wire a low voltage side of a Heat Pump( Single Stage) with only 3 wire?
Sure. Somethings not going to operate, but what the hay!
Training is important!
Practical Training is a must!
You can wire a heat pump with 3 wires to either heat or cool, but not at the same time. If you wired it to cool in the summer you would have to rewire it in the winter to make it heat. With only 3 wires you would not have a defrost in the winter time nor any monitoring controls.
Why would you want to? There are remedies for situations like that.
There is nothing more frightful than ignorance in action....Mark Twain
Using relays,you could make it work with only 3 wires (cool,heat),but your e-heat would either be on all the time or off all the time if the 3rd wire is common.
If everything was always done "by the book"....the book would never change.
OK, "IF" your heat pump has a defrost board that does require being energized all the time, you can get away with wiring just the contactor hot lead, the reversing valve hot lead and the common.
With that configuration, only "IF" a continuous hot lead is "NOT" required by the defrost control, your heat pump will operate both heating and cooling but will not energize the aux. heaters during defrost.
Now..."IF" your heat pump happens to be a Rheem/Ruud product that requires constant energizing of the defrost board, you can also jumper the reversing valve control lead to the "hot" lead on the defrost board and it will still operate.
Training is important!
Practical Training is a must!