The Minotair and CERV2 are the only north American all-in-one residential HVAC units I know of. Given the cold climate of Vermont and the 1800 sq ft (plus a basement or including basement?) size of the house I don't think either unit will be able to provide all the heat on the coldest day of winter. The Minotair is great at dehumidification. Putting in an inexpensive back up electric resistance heater is a good idea. Your PHPP energy model will provide the minimum heating and cooling system size. Send both manufactures your plans and PHPP file and get a quote. If this is your first Passive house as your profile states then I would work with an experienced local CPHD or certifier, regardless of if you get the home certified or not. Their help and experience will be worth much more then their fee.

Frank Crawford, CPHD, P.Eng
Energy Efficiency Consultant