Help me understand AC diagnosis, please?
In December 2023, I had the AC replaced for the upstairs of our house. Installed was a "Bryant Preferred 2 Ton" 227TAN02400A and the corresponding Fan Coil FV4CNF002L00.
Two weeks ago, when the heat came (I'm in NE Florida), I noticed that our upstairs was not able to keep up. We keep it set to 73 both up and downstairs and the upstairs unit was just continually running from 11AM-7PM and never getting below 76-77.
A tech came out and let me know that, based on the pressures he was seeing, the expansion valve and coil needed to be replaced. It was under warranty, so I said sure, go for it. The install was scheduled for Monday, a week ago.
That tech showed up last Monday and replaced both parts. When he left, he said that we should be good to go and everything was looking great. Last week was a milder week for temperatures (mid to high eighties), but I did notice the humidity was still quite high in the upstairs (in the 70's and low 80's).
Things still didn't seem right by the end of last week, so I called again and they scheduled someone to come out today.
When the guy showed up today, he checked the pressures and said I was on the low side of the manufacturer's specs. He topped it off a bit and brought me to the high side of the manufacturer's specs.
Of bigger concern he said that my drain pan was cracked. He said this had been identified by the very first tech and the part had been on order since then. He said they installed the coil and valve to get things cooling better even though they didn't have the drain pan in yet.
Today was the first I heard anything about the drain pan. Anyway, they are trying to get that as soon as possible and will have to install it when it comes in.
So, now that the background is done, here's my question. Would this cracked drain pan cause my cooling issues? Right now (4PM) it is 97 outside. My downstairs unit has no problem getting me to 73 and 50% humidity (and shutting off). The upstairs unit is running non-stop and is at 76 (set to 73) and 83% humidity.
I understand that the crack in drain pan is making it "all wet" inside the air handler. I understand that can cause the humidity to be high, but would that also be the cause for cooling issues?
I have to run on some assumptions as I am not at your house, and there are like 2 dozen variables to sizing an AC.
But the biggest one that you need to understand is that ACs in the SE US are rated for 92 degrees, anything above that and you can only expect around a 20 degree drop over the ambient outdoor. If it's 92 degrees, your system will literally run all day. This is assuming it is sized correctly.
Your downstairs system will not have this issue. Heat rises, and that means upstairs systems have to run longer.
I do not know if your system is sized correctly. I'm in ATL, we have a lot of two story homes we service, and most of them are around the same size. Generally we'll do 2T up and down, 2.5T up if it's a bigger home.
I do not know if they are referencing the evaporator drain pan, in which case that coil shouldn't have even been installed (though won't affect cooling), or the drain pan under your entire unit, in which case that will not affect anything, until you get a clogged drainline, and then you have a massive water problem.
Here are some red flags:
He identified the coil needed to be replaced based on pressures? What? Why? How? That doesn't make any sense. That's literal nonsense. Thermal expansion valves do not require new coils. You can just replace the valve. Unless he identified a leak in the coil, he made shit up. Or he was too lazy to bother with an actual diagnosis and just shotgun approached it.
You were on the low side of manufacturer specs after they just installed a new coil? He either made that up, and
just overcharged your systemI'm realizing now that he literally admitted to overcharging the system (companies like to do that with expansion valves, just dump refrigerant and have the valve sort it out) or the guy they did send to put it in didn't do his job. Either reality is bad news.Your absolute best bet is getting a second opinion. Avoid large businesses that use bill boards. Avoid one man shows. Find a midsize company with decent reviews. Keep in mind that a second company will not honor the first company's labor warranty obviously, only the parts warranties from the manufacturer.
EDIT: Other thoughts I'm having, I am editing this as I think of stuff:
Is this a heatpump or a gas furnace w/ AC? Are the blower speeds set correctly?How's the insulation in your, what I'm assuming is, an attic? How's the duct work look?
What is the temperature drop of your system? You have a temperature probe of some kind? Measure the temperature of the air going into a return and coming out of your supply registers. See if it's around 20 degrees. Is it less? Try it at the unit itself, measure the return plenum and supply plenum temperatures and see what the difference is, how much it's cooling.
If you have a second company come out, have them do a static pressure test. Find out what static pressure your system is rated for.
That's a two state heat pump. Is it actually running in second stage?
The thing I'm having a hard time with is that my previous unit (same tonnage) was able to keep up.
They are saying it is the evaporator drain pan that is cracked. They are saying that because of this crack, the water isn't leaving the unit correctly. They are saying two things are happening. First, water is pooling in the cracked drain pan due to the crack causing part of it to be level now instead of sloped. Second, water is going through the crack and wetting down the unit, including the blower box (the unit is in a horizontal position).
What was explained to me was that he could tell is was most likely a thermal expansion valve based on the pressures, but there was a chance it could be debris in stuck in the coils.
I haven't personally looked at it, but the previous unit was keeping the upstairs cool and this new unit is not.
I have seen the Nest thermostat say it is in the second stage.
It is harder to cool humid air, so that could certainly explain it. If its waranteed, get anybody and everybody who can inspect that thing and fix it for free while you can. :)
I don't know anything about your home, but my home needs about 4T cooling and I've got a 2000 sqft rancher in New Jersey. Second floors often require even more cooling simply because heat rises....2T may not be enough oomph.
In my childhood home we actually had through-floor fan vents pulling air up from the lower levels for that exact reason. We also had a whole-home fan which we'd open windows at the lowest level on sundown, run it for a few minutes to pull the coldest air to the upper levels and cool the attic. I have no idea if that's more efficient, but we didn't have zone heating/cooling and it was definitely more comfortable.
No. The drain pan leaking is not good for the bones of your home (you really don't want moisture buildup inside the building envelope, mold + rot are serious problems) but short term it's not a cooling issue.
Did you replace tonnage with equivalent tonnage? Here in California (no humidity problem, but it is currently 106 in the shade) I need a 4-ton unit on each of my home's floors, ~2,700sq/ft total. When we had a two-ton unit upstairs, it couldn't keep up, much in the manner you describe.
Assuming your system is working as intended, try to keep your home at a lower temperature at night to get ahead of the day's heat. If your home is well insulated, starting at a lower temperature will make keeping it at a low temperature much easier.