Re: HVAC problems (2 zone system 1 unit)

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Jun 24, 2022, 7:41:57 AM6/24/22
Martisha Zale wrote:
> On Sunday, June 19, 2022 at 8:10:53 PM UTC-4, Martisha Zale wrote:
>> Hello,
>> I moved into my house back in 2013. The outdoor 3 ton unit was put in back in 2012. I have a 1,558 sqft house, and 2 thermostats (one upstairs and one downstairs). Since we have moved in I have always noticed that the cooling and heating just is never up to par. When it's 100+ degrees out (we live in the south) it can barley cool the house to 79 degrees. Even when the t-stat shows 79, it runs and runs and runs. One day it was around 95, I set it to 76, we got home, it read 76, but it was a hot and stuffy 76. The airflow is subpar as well. The registers upstairs (air handler is in the attic upstairs) blow pretty well, the downstairs for example, not so much. There are two in my living room, about 10 ft apart, one is pretty good, the other, is rather weak. I have 4 return air vents, but one is a joke, it's on a vaulted ceiling and looks like a regular supply vent, but it is not cause I traced it and when I put a piece of paper up to it, it suctions the paper inward, like a return vent. The air handler has a barometric bypass damper, and there are 2 ducts that have aprilaire zone dampers with a stop screw. I have messed with them in the past, opening and closing, but it has made no difference. When I call for heating or cooling on either thermostat, the airflow is the same upstairs and downstairs. The air blows cold, and the outdoor unit is clean, fan spins, new capacitor was installed a bit ago (DIY), but overall, my house is just really uncomfortable from 2 pm to 7pm on summer days. When I go in other peoples homes it feels wonderful and it's nice and cool, and they got it on 75 or 70. I had to put a window unit upstairs just so I could work from home cause during the summer it reaches 85, even with the air on, and the air is blowing cold out of the vents. Could it be an undersized unit? Bad duct work (I checked the ducts in the attic the best I could and notice no signs of tearing). All of the duct work is upstairs, and has to make a long way to the other rooms, which I know can be a problem, but damn, it's just miserable. I cannot afford to get a new unit right now, and I am just looking for what might be the problem, and if it could be fixed or should I just get another unit and cut the zones out altogether? I would have to save a lot of money and struggle, but I already did it for 9 years and figured my air conditioner was just a piece of crap, but I think there is more to the story than the outdoor unit.
>> Any information would be helpful, I am just trying to determine what the problem is before I make any decisions or maybe get a ballpark estimate or kind of an "idea" of what is wrong. I know it's hard to make a call like that over the internet, but please, anything is better than nothing.
>> More info:
>> Upstairs has 5 floor vents
>> Downstairs has 9 vents on the ceiling
>> When closing any vents upstairs or downstairs
>> it makes 0 difference in the airflow, maybe a little bit, but not enough to notice.
>> Unit is a tempstar 3 ton
>> Zone controller is: aprilaire 6303
>> Thanks
> Also, I have replaced the thermostats and it made no difference. Air filters are clean, outdoor coils are clean, fan blows hot air from the unit outside. The "cool" line is cold, but it never sweats or gets much condensation, and the thin copper line is hot. When the thermostat downstairs reads 75 and it gets to 75 it still runs and runs and eventually turns off, but I think that is only because the weather gets cooler at night. During the night, I can set it to 73 or so, and it runs and when I wake up, it's off, so it appears to be doing it's job, but still, at night it can be 60-70 degrees, so it's not really a big deal and it might just be getting "help" cause the house is cooling down. Insulation appears to be fine. I am at the point where I might consider ductless systems, if I can ever afford them.

Have you had the unit checked for proper Freon charge? Feeling the
lines is not exactly a good way to know if the unit is running as well
as it should.

I have a Tri-level home and it has two units, one for upstairs and one
for down. Seldom have I heard of one unit working well for a
multi-level home. Your comment regarding air flow being weak in some
areas seem to support the theory that a single unit may not be enough.

One other thing: My air handlers are also in the attic and the
temperature during the summer up there can be very high. I added power
vent fans to keep the temperature reasonable in the attic. Otherwise
the air handlers are operating in an oven-like environment.
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