I am about to purchase a York heat pump. The model I first intended to order is BP090C00S2AAA4. This model has too much electric heat (18kw) and I don't know which part of the model number to change to reduce to electric heat to 9KW. My supply will not handle the 18 but is OK for 9. I tried to get to YORK directly but no luck. Does anyone know Yorks model number meanings?