Adding a second story to our 1980s ranch house and I'm trying to figure out if we should extend the existing HVAC or go with a separate system. Our HVAC guy gave me conflicting advice, so I'm looking for what actually works best.
The real issue is that there's no single "best" answer - it depends entirely on your existing system's capacity, the square footage you're adding, and your budget, so you might need a second opinion from another HVAC contractor rather than picking between the two approaches you've heard. If your current unit is already sized tight for the original 1980s ranch, extending it usually means reduced efficiency and comfort upstairs; a separate system costs more upfront but gives you independent control and avoids overloading the old equipment. Getting actual load calculations for the addition (not guesses) from another pro will tell you whether extension is even viable or if splitting systems makes sense.
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