My 2,900 square foot house currently has two separate AC systems (one upstairs, one downstairs). They're both very old and need to be replaced.
One of the four HVAC salesman that provided quotes suggested using a single Lennox XC21 system and claimed it can provide 2 cooling zones. They'd merge the supply ductwork and install dampers to allow one or the other or both zones to be cooled.
How well does this actually work? Is the Lennox XC21 a good unit? Based on the other info I've gotten, it seems the XC21 is spec'd out correctly as far as tonnage (5) and SEER (21) go.
On a side note, the salesman said I would NOT be able to use my Nest thermostat with the XC21 because there's some kind of humidity controller in the unit that the Nest won't be able to control. Anyone know if this is really true or if there's a workaround? I've become a bit addicted to my Nest!
Best Answer
Using a single HVAC unit with zone dampers is pretty well-established and can save the trouble of having multiple separate units. Some things to discuss with your salesman (and if s/he doesn't have detailed answers, ask for someone with detailed knowledge):
We've been in a house with three zones on one system for 13 years and it's served us quite well.
I can't comment on that specific unit or the Nest.