I'm looking for some help regarding my HVAC system's sizing. I own a new home that's 1,871 finished square feet across two floors, built in 2024 in Kansas City. It has three levels, including an unfinished basement, and features 9-foot ceilings. The insulation includes R-13 walls and R-49 in the attic. There are a total of 19 windows and two exterior doors with varying orientations.
The HVAC setup is single-zone, consisting of a 2.5-ton Goodman AC unit, a 3-ton Goodman evaporator coil, and an 80,000 BTU Goodman gas furnace, all installed in 2024. We are under contract to sell our house, but the buyer's inspector claims the HVAC system is undersized and needs replacing, which seems odd given that it's new and we've had no issues with temperature or energy bills. Our builder insists it has enough power for the space, and we're expecting the original Manual J report soon. I'm unsure if the inspector's claims warrant concern or if it's an overreaction. Any insights would be appreciated!
4 Answers
I’m no HVAC expert, but I have a similar setup in my own house of the same size, and I’ve never had any problems with it. Sounds like the buyer might be making a mountain out of a molehill. Honestly, if the market is slow where you are, I’d suggest telling them to find another buyer if they’re going to make such a big deal over it. Who wants to shell out an extra $15-20k on a new system when there hasn't been any real issue?
If they’re asking for a replacement or a price drop, I’d tell them to walk away. Their concerns might be more about the brand than the actual sizing. Just remember, if the system is oversized, it can actually lead to worse humidity control, so you might be fine as is.
I have a similarly sized home built back in the 50s, and they sized mine at 3 tons due to the age of the house and its leakage. A well-sealed, modern home like yours would only need the 2.5 tons, so you should be good to go!
It's not undersized at all. To really figure out what's going on, you’d want proof, like a Manual J load calculation. Factors such as duct work, sealing, and insulation all affect system size. Just know, if the issue is really just about the 2.5-ton condenser, you might not need a full system replacement—just that part could be enough.
R13 isn't outrageous, especially with 2x4 construction. You typically max out at R15 unless you're using closed foam insulation, which could be costly for new builds.