We must replace our old oil furnace with a new, 90%+, hot-air gas furnace.
We have four widely different proposals. They vary from a 115K Goodman to twinned 80K Carrier Infinity Series. Prices go from about $5,500 for a Bryant 3 stage 355CAV060120, to nearly $7,000 for 2 Rheems RGRL 07EMEAS furnaces, to $7,400 for the Goodman 2 stage 115K, up to about $10,000 for the 2 Carrier 58MVC 80K units. These include filter cabinets, piping, duct work, removal of large old furnace and of two 275 gallon oil tanks.
Guesses about the size of the furnace vary from a bit over 100K to 160K. The wide range worries me.
Part of the difficulty in estimating the proper size of the furnace is the house. It was built in 1815 with 16" limestone walls and mostly original windows. Despite a lot of recent work, there are still plenty of air leaks. And the building is big, 40' by 50'.
Another difficulty in estimating how much furnace we need is that we live n the 2nd floor and the 1st is used for storing antiques and books for a part-time business. We cut the dampers to the 1st floor almost completely off and send the heat to the 2nd.
We are in our 70s and will have to relinquish the property within the next decade or so. We want what we do to be useful to the next owners. They are likely to be commercial--this will be encouraged by the village planning. The village we live in is a bit outside Lancaster, PA.
Finally, the offer that seems the best value--the 2 Rheems furnaces--is by a one-man shop, operating out of his house. He is a Ruud distributor, involved in HAVC for many years, and has good references for his recent work, but he has been on his own only since 2007 or 2008. And can one man properly service the installation? If a Rheem distributor has to take over, will they be resentful we didn't buy from them?