I have a low-boy Thermopride oil furnace that is about 15 years old. Every professional that looks at it tells me that it is rock solid. I want to add a heat pump to my system to enjoy AC in the summer and some savings on heating costs in the winter because of the costs of oil. I live in Rhode Island, and have spent many hours on this board and others educating myself about what types of set-ups would be good for me. As such, I know that I am looking for a properly sized heat-pump that can be automatically controlled in conjunction with my oil furnace so that as the outside temperature drops below the efficient level for the heat pump, the oil furnace kicks in. I know that because I do not have a variable speed blower on my furnace, that I will not receive the highest possible efficiency from my heat pump, but it will cool and heat in more moderate temperatures to my desired levels.

I have seen so many quotes and so many recommendations on this board that I was fully expecting every estimator to come into my house, spend a couple of hours taking measurements, counting windows, inspecting the ductwork, determining the distance from the compressor location to the coil placement, etc.

I have had 4 estimators to my house to give me quotes on the system and none of that has happened.

2 estimators come from very large, very reputable local companies. These companies handle residential and commercial systems and participate in the local electric company rebate program that offers $150 to contractors to perform a Manual J. One of the estimators, from the largest local hvac company, told me that I would need 2 thermostats, one for the heat pump and one for the oil. His sizing calculation was taking 2 measurements of the width and length of my house. He als measured the current plenum (presumably to size a coil). The other estimator, from a large hvac company, was very knowledgeable about duel-fuel set-ups, providing me with the Lennox literature on the Fuelmaster system used to control a duel-fuel system. He spent about 20 minutes in my basement measuring ductwork. Again, his sizing was a simple measurement of the width and length of my house.

The other 2 estimators were from smaller companies. Both used only my description of the square footage of the house as the sizing calculation. When I described my desired duel-fuel set-up, one guy looked at me funny, then said, "you know what, that might just work!" like he had never heard of my idea before. The other guy suggested that I use the oil burner shut-off switch and the heat pump elecrical disconnect to control which system is being used at any given time.

I know that I will continue to get estimates. Should I be putting my desired specs in writing, inculding a Manual J calculation to ensure correct sizing?