I've got an HVAC system consisting of a single stage heat pump and an air handler with 4 electric heating elements grouped into 2 stages(HE1+HE2 and HE3+HE4). (5KW each for a total of 20KW)
The original setup had W1 and W2 tied together in the air handler so the heating elements were acting as a single stage(HE1+HE2+HE3+HE4). When replacing the original tstat with the Nest, I separated them and configured the Nest software to treat it as 2 stage electric heat(I had a spare tstat wire so I could run a separate W1 and W2).
My question is whether the Nest keeps W1 energized when switching to Alt. Heat Stage 2?
If the Nest only energizes one at a time, then all I'm doing is switching from HE1+HE2(10KW) to HE3+HE4(10KW) and I'm never running all four elements(20KW) at the same time.
A second question is whether this wiring config is any better or worse than the traditional setup of Aux/Emergency that is normally used with a heat pump?
My heat pump does not have an external ambient temp cutoff sensor, so I use the Nest for that. I'm currently testing an ambient temp cutoff of between 10-15F as my heat pump is a regular one and not a cold-climate heat pump with inverter.
I don't think the Nest can do both aux heat(heat pump + electric) and 2-stage electric heat at the same time. So I don't know if I'm better off wiring it as aux heat or as 2-stage electric.
