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Low a/c airflow on first floor

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  • Low a/c airflow on first floor

    Hey everyone,
    Hopefully you can help me out. I recent moved into a newly built two story house. The air conditioning system is a dual zone system, with the first floor being one zone, and the second floor being the other zone. Each zone has its own thermostat, and they work independently of each other. Well I recently noticed the first floor cools much slower than the second floor. The other day, the first floor cooled at a pace of about 1-2 degrees an hour, and it wasn't even that hot outside (not even 90 degrees). When I put my hand up to each of the registers on the second floor, I feel a nice strong cool air current. When I put my hand up to the registers on the first floor, I feel a very weak air current, amost more like a cool draft moreso than an actual current. (It is maybe like only 10-20% of the air current that the second floor is getting, so thats at least a 80% decrease) Does anyone have ideas what might be causing the problem? All the registers are completely open. I can understand that maybe the current loses a little bit of strength making its way down to the first floor registers all the way from the attic, but this seems like a bit much. I am hoping to talk to the site foreman on Monday morning, if I can find him. I was hoping you guys might have some ideas before then. Thank you so much. Keith

  • #2
    Re: Low a/c airflow on first floor

    If the temp coming out of the supply vents is cold enough, I would start with the filter, it could be clogged.


    • #3
      Re: Low a/c airflow on first floor

      There is far less cooling load on the first floor, so by design there would be less air volume serving the first floor. What you observe could be normal.

      First there are all of the obvious things that need to be checked, i.e. air filters, blower and evaporator cleanliness, separated ductwork, closed balancing dampers, etc...

      If the furnace or air handler is located in the second floor attic, it is not uncommon to see performance problems on the first floor, since ductwork is often "stuffed" between floor joist, cracks and crevices. This is by bar the most difficult problem to solve.

      If you have a single HVAC system with two thermostats, then you probably have a zoning system, which probably utilizes a bypass damper. If the bypass damper is not working properly, then total air volume serving the home could be diminished.

      Consider hiring an HVAC contractor who is ,or employs ,NATE certified technicians. They should be able to tell you what the problem is and how to fix it. Which might be pretty handy when dealing with the builder warranty (assuming there is one).

      Until lions have their own storytellers, stories of the hunt shall always glorify the hunter


      • #4
        Re: Low a/c airflow on first floor

        Thank you everyone for the responses. I checked the filter right after I discovered the weak air flow. It was still very clean, however it was installed backwards by the builder. I purchased a new filter, and made sure it was put in correctly. There was still very weak airflow. I spoke with the site foreman earlier today, and he said it sounds like it could be a damper problem. The customer care department is supposed to be contacting me shortly to set up an appointment for the HVAC company to come out and check things out. Ill keep everyone updated. Keith


        • #5
          Re: Low a/c airflow on first floor

          check the fan speed it may be to low

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          • #6
            Re: Low a/c airflow on first floor

            Hey guys,
            I just wanted to post an update about my a/c problem. The HVAC guy came out and discovered a defective damper feeding the first floor a/c ducts. It wasn't opening very much when turning on the first floor a/c, so I was getting increased air flow on the second floor, and decreased on the first. They are ordering a new damper, and will be replacing the defective one. Ill let everyone know how the finished product works. Keith