Dampers are usually not installed on returns. Even if there were dampers, the conditioned air would still mix with the rest of the house. Your best option would be to close as many doors as you can to stop the flow of air.

Thank you. I tried that and it helped a tiny bit. but there is still a 1” gap under the doors and you can feel a good air current passing through. I might try weatherstripping the interior doors.

Zone systems do save money even with the way yours is operating -- it is counter productive to try to limit return air.

Why is it counter productive? by limiting or reducing return air you will increase static pressure on the system. That will raise the amps of the blower costing you more energy to run the machine. It could also increase wear and ultimately failure of the blower motor which will blow any savings you think you're getting by doing things suggested by those on the internet.

The savings? what are you comparing them to? The cost of energy has been going up across the country --- it's my opinion that it's foolish to compare based on monetary value and focus on comparing on usage. I don't know if this is what you are doing or not... you need to provide more info. That is your job, not mine to guess, guess and guess some more.

The cost of that usage billed in cents per kwh is going to fluctuate up and down. If you compare your usage before compared to now? What does that tell you?

Example: I was paying for 2000 KWH's per month before now I am paying for 1400 KWH's now.

In some situations paying for 2000 KWH's gets cheaper rates say 10-12 cent per kwh. Prices will vary from one location to another it's an example.

At 1400 KWH's your rate may go up to 14 cents per KWH.

Say you got 10 cent with a 2000 kwh rate = $200 / mo.

Rate at 1400 KWH = 14 cent = $196 / mo.

Where's the savings? I don't know if this is your situation or not because the post lacks the details needed to know... this is where you need to look --- not messing around with limiting return air causing more problems to a brand new HVAC system.

If you're in a HCOLA like California -- that is a special category all by itself.

Hi, sblauv,

Your expectations regarding energy savings from zoning may have been, well, over blown. Zoning of residential HVAC systems is first and foremost about comfort. Any energy savings is a bonus. The amount of energy savings is affected by a lot of variables: the area and specific arrangement of the rooms on each zone (e.g., large vs. small rooms, rooms with one exterior wall vs. rooms with two or three exterior sides, rooms with attic above vs. conditioned living space above,) the construction details of the home (e.g., windows, exterior doors, insulation) the heat gain/loss due to the orientation of the home (e.g., solar heat gain,) the design and leakage of the duct work system and the turndown capability of the system.

Your system has five zones. If the heating/cooling load of each zone is equal, your system would need to be capable of operating at 20% capacity. I suspect your system's minimum air flow rate won't allow operation of some zones without bleeding off excess air into another zone. Ask your installer to give you a thorough review of how to operate the system and ask about its limitations. If they didn't perform a duct blaster test before installing your system, ask them to do one. If you find the duct work system is leaky, improving the sealing will go a long way toward reducing your energy bill and improving comfort, too.

Exactly what Charles Ross said!

You are operating your system in an unintended manner.