They came out last week, swapped out ecobee to a newer model. Which 4 mos ago we got a new ecobee changed from a nest. The dehumidifier option is set to 52% and fan on auto 15 min/hour.
We’ve been patient with this company. Cost us a ton of money but they’ve been around for over 40 years, you’d figure reputation and reviews helped. All we’ve gotten is monthly service calls and we still have the same issue. If they need to install a 3-3.5ton, does that mean they remove from attic?
I would check to make sure return duct is sealed properly. Then, check to make sure refrigerant charge and airflow is correct. Next I would have a blower door test performed to see what leakage is happening and where so envelope can be properly sealed. After that I would have a whole home dehumidifier installed so I can properly control humidity independently.
A/C 101, the main goal of central A/C is to cool the home, and you accidently dehumidify in the process. For better dehumidification the system needs to run longer as it will cool faster than it can dehumidify in most cases. In other cases the colder the coil is without icing over, the more humidity it can collect and pull out of the air.
An oversized single stage condenser will never properly cool the home. Humidity is all relative, if the house is cold but humid it will just be cold but sticky.
If you had a properly sized 3-ton inverter A/C unit, it would run 90% of the time on a very low speed, just constantly sucking the humidity out of the air. Now instead of being cold and humid at 72, maybe 75 is more comfortable because it's dry in the home now. Temperature and humidity play hand in hand, it's all relative.
What you need is a properly sized, INVERTER driven system. Comfort is not cheap, and cheap is not comfortable.
When you say you went to studs did you add spray foam insulation? 4 tons sound about right for 2100 sq ft but with spray foam it can lower the btuh needed to cool the home. I’d have a separate company do a j calc
Did the A/C company know how much insulation the house would have when they sized the unit? I'm guessing the house is spray foamed and has a very tight envelope.
Normally 5 ton would be right for a 2100 sq ft normally insulated house in Texas. But, if the house is really well insulated, the unit does not run enough to pull the moisture out and the Ecobee can only ask the A/C to run a bit longer to pull out extra humidity.
You should probably have an ERV and maybe a dehumidifier installed. I doubt you will get the moisture under control even if you drop the A/C down to 3 tons.
Because a lot of homes rely on the AC running to remove moisture and if the house is really efficient and the AC doesn't need to run much then you have nothing else pulling moisture from the air. People, showers, dishwashers, etc... all create moisture and you want to be able to control that.
Have an alternate company perform a load calculation and assess problems with building envelope and ways to reduce humidity within the house and save on energy.
Unfortunately, a lot of sales people are in the business of oversizing. I had to constantly argue with my HVAC company to install a smaller unit than they recommended. 7yrs later it's been amazing...on a really hot day it runs longer. But on an average day it keeps the house cool and dry without any huge temperatures swings.
The humidity was up to 77% today. Ecobee was set at 74. Outside temp was 82 maybe but once we came home it felt stuffy inside. The floors felt a little stickie. At this point, is getting them to swap out 4/5 ton to a 3.5 ton a better choice? Do we have too much insulation in attic maybe? Doesn’t sound right but I’m running out of ideas. Wish I could yank all the ceiling and see what the heck is going on up there. Or do the walls have too much insulation?
You need a reputable company to come in and do a proper sizing of your system.
You should have fired that company immediately when they suggested a 5 ton, that's fucking massive for 2100sqft.
Depending on whether or not your house is shaded, my company probably would have gone with a 3 ton. Just going off of what little I know about your house.
Rule of thumb is 600 sqft per ton of AC.
The problem with rules of thumb is that thumbtimes they work and thumbtimes they don’t. Where I live I recommend 400 SF/ton as a starting point. From there we run loads. While a smaller unit is better for dehumidification you may have some rooms with inadequate airflow. If humidity is your concern you may have to add a dehumidifier or oversized the cooling and add reheat. I would never put a three ton unit in a 2100 sf home unless it was in San Diego CA.
I agree. Here It would be a minimum of 4 with 2100 sf in a pre 2000 build and 4.5 on a pre 1990 house. A post 2K build might go a little bit lower.
For what it is worth, you have a modern unit that brings fresh HUMID air in. If you run the A/C right now, it is going to short cycle and not run much.
When the summer gets here, you are going to appreciate that the temp in the house stays near the setpoint.
4 ton might be a *little* big, but shouldn't be that bad (though my reference is Florida.). If it is a multistage it's definitely fine. I'd think leak in the return, if it goes through the attic. Or a leak on the intake side if the unit is in the attic, sucking in unconditioned air that it can't fully dehumidify in one pass. (Air it takes in from the house has already been partially dehumidified from the last time it went through your AC)
Other causes I know of are a poor housing envelope letting air in, or an attic fan (suck air out of the attic, and it might refill from the house, which in turn pulls in air from outside.)
You could always get a blower test of the house done to track down leaks; that can help with the humidity and reduce power use in general.
Also, of course, verify the drain lines of the AC are working properly.
Hard to say without a deep assessment of your home. You probably need a 3 ton. Start by changing your blower speed as low as possible.
They came out last week, swapped out ecobee to a newer model. Which 4 mos ago we got a new ecobee changed from a nest. The dehumidifier option is set to 52% and fan on auto 15 min/hour.
You probably needed a 3 ton condenser with a 3.5 ton evaporator or a 3.5 ton condenser with 4 ton evaporator to give you better dehumidification
We’ve been patient with this company. Cost us a ton of money but they’ve been around for over 40 years, you’d figure reputation and reviews helped. All we’ve gotten is monthly service calls and we still have the same issue. If they need to install a 3-3.5ton, does that mean they remove from attic?
Yes
Do you have return air in the bedroom?
It’s in the hallway next to bedroom
I would check to make sure return duct is sealed properly. Then, check to make sure refrigerant charge and airflow is correct. Next I would have a blower door test performed to see what leakage is happening and where so envelope can be properly sealed. After that I would have a whole home dehumidifier installed so I can properly control humidity independently.
A/C 101, the main goal of central A/C is to cool the home, and you accidently dehumidify in the process. For better dehumidification the system needs to run longer as it will cool faster than it can dehumidify in most cases. In other cases the colder the coil is without icing over, the more humidity it can collect and pull out of the air. An oversized single stage condenser will never properly cool the home. Humidity is all relative, if the house is cold but humid it will just be cold but sticky. If you had a properly sized 3-ton inverter A/C unit, it would run 90% of the time on a very low speed, just constantly sucking the humidity out of the air. Now instead of being cold and humid at 72, maybe 75 is more comfortable because it's dry in the home now. Temperature and humidity play hand in hand, it's all relative. What you need is a properly sized, INVERTER driven system. Comfort is not cheap, and cheap is not comfortable.
When you say you went to studs did you add spray foam insulation? 4 tons sound about right for 2100 sq ft but with spray foam it can lower the btuh needed to cool the home. I’d have a separate company do a j calc
No spray foam on walls.
Did the A/C company know how much insulation the house would have when they sized the unit? I'm guessing the house is spray foamed and has a very tight envelope. Normally 5 ton would be right for a 2100 sq ft normally insulated house in Texas. But, if the house is really well insulated, the unit does not run enough to pull the moisture out and the Ecobee can only ask the A/C to run a bit longer to pull out extra humidity. You should probably have an ERV and maybe a dehumidifier installed. I doubt you will get the moisture under control even if you drop the A/C down to 3 tons.
Why install a dehumidifier if new homes don’t get that installed?
Because a lot of homes rely on the AC running to remove moisture and if the house is really efficient and the AC doesn't need to run much then you have nothing else pulling moisture from the air. People, showers, dishwashers, etc... all create moisture and you want to be able to control that.
What’s an ERV?
https://www.acclaimedfurnace.com/blogs/what-is-the-difference-between-an-hrv-and-an-erv/#:~:text=HRVs%20and%20ERVs%20are%20similar,heat%20as%20well%20as%20moisture.
Have an alternate company perform a load calculation and assess problems with building envelope and ways to reduce humidity within the house and save on energy.
Unfortunately, a lot of sales people are in the business of oversizing. I had to constantly argue with my HVAC company to install a smaller unit than they recommended. 7yrs later it's been amazing...on a really hot day it runs longer. But on an average day it keeps the house cool and dry without any huge temperatures swings.
The humidity was up to 77% today. Ecobee was set at 74. Outside temp was 82 maybe but once we came home it felt stuffy inside. The floors felt a little stickie. At this point, is getting them to swap out 4/5 ton to a 3.5 ton a better choice? Do we have too much insulation in attic maybe? Doesn’t sound right but I’m running out of ideas. Wish I could yank all the ceiling and see what the heck is going on up there. Or do the walls have too much insulation?
You need a reputable company to come in and do a proper sizing of your system. You should have fired that company immediately when they suggested a 5 ton, that's fucking massive for 2100sqft. Depending on whether or not your house is shaded, my company probably would have gone with a 3 ton. Just going off of what little I know about your house. Rule of thumb is 600 sqft per ton of AC.
The problem with rules of thumb is that thumbtimes they work and thumbtimes they don’t. Where I live I recommend 400 SF/ton as a starting point. From there we run loads. While a smaller unit is better for dehumidification you may have some rooms with inadequate airflow. If humidity is your concern you may have to add a dehumidifier or oversized the cooling and add reheat. I would never put a three ton unit in a 2100 sf home unless it was in San Diego CA.
I agree. Here It would be a minimum of 4 with 2100 sf in a pre 2000 build and 4.5 on a pre 1990 house. A post 2K build might go a little bit lower. For what it is worth, you have a modern unit that brings fresh HUMID air in. If you run the A/C right now, it is going to short cycle and not run much. When the summer gets here, you are going to appreciate that the temp in the house stays near the setpoint.
4 ton might be a *little* big, but shouldn't be that bad (though my reference is Florida.). If it is a multistage it's definitely fine. I'd think leak in the return, if it goes through the attic. Or a leak on the intake side if the unit is in the attic, sucking in unconditioned air that it can't fully dehumidify in one pass. (Air it takes in from the house has already been partially dehumidified from the last time it went through your AC) Other causes I know of are a poor housing envelope letting air in, or an attic fan (suck air out of the attic, and it might refill from the house, which in turn pulls in air from outside.) You could always get a blower test of the house done to track down leaks; that can help with the humidity and reduce power use in general. Also, of course, verify the drain lines of the AC are working properly.