I purchased a home in 2015 and in 2016 got a price on a 2.5 tonne split HVAC system. Because of a lack of money I wasn’t able to move ahead with replacement. Just recently I had the same firm come out and re-quote the system.
We found the email from 2016 where they quoted a 2.5 tonne Amana system and they suggested that I go with the Goodman brand since it’s essentially the same, but would be less expensive bring the quote in very near the 2016 level.
Later in the day the guy calls back and says, “Hey we took a photo of the plate on the outside unit and it’s a 3.5 tonne not a 2.5 tonne. If you want to downsize to a 3.0 that would probably be okay, but we don’t think a 2.5 tonne is sufficient. Especially on the heating unit they are recommending that I stay with the current sized unit as the ductwork is sized for the bigger blower motor of a 3.5.” The ductwork in the garage and at the returns is ductboard. I am not sure what it is under the house.
Now…more detail. The home is a two story with only a single thermostat downstairs. We also want to install a second thermostat upstairs and put in some dampers to give us somewhat of a zoned system.
The house is about 1800 sq ft with more sq footage on the 2nd floor as there is a room over the garage.
Currently during the summer we shut quite a few of the downstairs vents to get better cooling upstairs. If we have a dampered system (BTW redoing all the ductwork just isn’nt the budget) then in the summer when we need more cooling upstairs it seems logical to me that a 3.5 or 3 tonne unit would just be way the heck too much for a an upstairs that is maybe 1000 sq ft.
Finally, the current system cycles way too often. I’ve gotten used to it, and it’s not summer right now, but from memory I think it cycles on and off multiple times within a single hour during the summer.
My thought is that the advice is going to be have someone do a manual J, but I’m wondering if I can find someone who will do a manual J in Knoxville, TN. The firm I am using is the firm that did the HVAC for some experimental homes for the lab in Oak Ridge (course the engineers in Oak Ridge probably specified what they wanted to see in the system).
This firm in the past (at a house I built back in 2009) did do a manual J, but the owner (who I am pretty sure is the one who did it) is now deceased.
I know I spoke with the owner back in 2016 about the sizing, but I don’t remember details. Anyway…I don’t even know what I’m asking. Does it sound like a 2.5 tonne unit is enough? Answer…manual J
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