We live in a split-level house with a very high interior ceiling in the main foyer, and as such I get substantial variations in the temperature of various rooms when it gets extremely hot/cold outside. My existing system is about 11 years old, but the guys who do my periodic system checkups say I should get another 7-10 years out of it easily. What I think I need is a system with multiple thermostats and a way to only heat/cool certain areas based on their temperature, rather than my existing setup which has one thermostat for the whole house. I know that they make new systems that have this type of thing built in, but I'm led to believe they're quite expensive, plus since my existing one is in good shape I don't want to make that investment earlier than I need to. I know that you can zone an existing system by adding automatic dampers that cutoff certain ducts based on the temperature in that existing zone, but have no idea about cost, effectiveness, etc. Has anyone ever had this done before, who did you use, about how much was it, and are you happy with the results?
I just saw an episode of Ask This Old House on this. It looked really neat, but it cost the homeowner about $7.5k. You may to see if you can find the episode online.
Do you know if you have dampers? if the plenum is fairly easy to access, instruct the service folks to pull 1 duct and check - I believe that if they are anywhere, it would be at the takeoff / plenum. The retrofit described will be big bucks... particularly the control system. But you could be able to manually tweek the air distribution if dampers were installed. Simply adding the manual dampers might be worth a look also (comparatively cheap).
