US 5-wire (O/B) setup


#1

Apologies as this question may be a bit off topic:

Unlike the 4-wire setups that use Y for cooling, my system uses Y for the heat pump compressor and the additional O/B wire to move the reversing valve to cooling when it is energized.

Since the relays only have 4 positions I need to short the compressor wire (Y) to cooling (O/B) when I want cooling and manually move Y to heating (W) when I need heat.

I feel that jumping Y to both and using something like an inline diode would solve my issue but didn’t know if there was a more elegant solution?


#2

My last post contained some misinformation so let me correct and sort of answer myself. After inspecting the unit more and doing a little research I found that my wiring is actually exactly like this unit: https://www.youtube.com/watch?v=qiAOvJhq8_s
Screenshot%20from%202019-04-12%2013-51-45

Since W is actually emergency heat not primary heat then I believe only Y needs to be powered for heat. So the wiring for that would look like this:

This wiring configuration seems to be common in my area, specifically hvacs with 1-stage Lennox heat pumps.

I haven’t gotten my HestiaPi unit in yet but I will report back with my findings in case it helps anyone else out reading this in the future.