Your system is a 3 ton Lennox. Hard to say without the coil model and serial but the outside is a 3 ton. As far as operations are concerned there are several settings that I set on those lennox boards. It all depends on home dynamics and area of the country you are in. In Tulsa, we have a higher humidity than normal and we try to not run the indoor too long after shutting the outside unit down so we don't pull moisture off the indoor coil and re-introduce it into the home. Too know if the combo is right an HVAC specialist would need to look at relative humidity of the home, Wet bulb and dry bulb temperatures of the home and Air of the unit before, after, and during operation. Area of the country and average temperatures and Dew points of your location.

I am in south Florida

I see a S # S1615E05131

South Florida, very humid, I would say yes to your settings then. a 30 to 60 second inside shutdown is very normal and the lowest setting you normally see on a 14 seer system.

I thought my system was 16 SEER

That's what the installer told me and that's what I paid for

You have a 3 ton XC14 system. I need the complete Mdl number for your air handler but according to AHRI it appears you do have a 16 SEER rated system. See below. If you have the 036 air handler, you are short on cooling BTUs, quite typical for Lennox and one reason I don't care for the brand.

7515165 Active Systems ELITE XC14 SERIES LENNOX INDUSTRIES, INC. XC14-036-230A** CBX27UH-036-230*+TDR 1200 34200 13.00 16.00 1 RCU-A-CB All 269 Yes

7515166 Active Systems ELITE XC14 SERIES LENNOX INDUSTRIES, INC. XC14-036-230A** CBX27UH-042-230*+TDR 1200 35200 13.00 16.00 1 RCU-A-CB All 277 Yes

IMO

is it undersized for a 1668 AC SQ townhouse?

Sq. footage is not a good way to size an A/C system. I hate these rules of thumbs contractors are using. The proper way to size your system is by doing an energy audit and Heat Load calculation of your home. This involves Windows, Doors, insulation, house leak rates and then uses Residential Manual J from the ACCA/ASHRAE design standards to get you a proper sized system and duct-work. It also gives you the option to Not have to size up a unit, but seal and add insulation to get the proper tonnage and efficiency our of your home. Now Tiger dunes is right on his comment however, Lennox prefers slower CFM and FPM speeds to size their systems. 350/400 on average so a 3 ton AHU with a 3 ton outside condenser is a matched system as long as the coil is a 3.5 ton with txv to get a little more efficiency which would get your from 14 SEER to 16 SEER. Blower speed is critical here. Your area has a larger Latent Heat load. (moisture in the air dehumidification needed before a change in temperature) So slower CFM air pressure and slower velocity help you out more.

It would be beneficial to know the CFM speed setting for your system and inside humidity you currently have. If you need more humidity removal, you could adjust CFM/ton down to 350 CFMs, otherwise no higher than 400 CFMs/ ton.

IMO

tiger

and how do I slow it down?

Thanks for all the replies

Highly appreciated

I have an Ecobee 3 T stat and it says 53% humidity

53% RH is not acceptable. Dealer should come back and see what CFM setting is. If 400 CFM/ton, it should be set to 350 CFM/ton. If you are not familiar with air handler controls, then this is something for your dealer to adjust. Takes just a few minutes if tech knows what he is doing.

IMO

For a humid climate like Florida you will be hard pressed to lower humidity lower than 50%. This climate is very similar to my area (Katy, Texas -- suburb of Houston)

On occasion my area can have out door humidity of 80% or higher, this is a continually fluctuating thing... but on a single speed AC in Florida with 53% in door humidity is pretty good all things considered.

If Tiger thinks otherwise maybe he should fly out there and address the situation? --Just a thought.

The goal is to get to 40%humidity. If you can't then need to investigate why. A 3 ton condenser for a 1668 sq. foot townhouse should be good. It is better to be a little undersized than oversized in humid climates.

Keep the windows tightly closed at all times even if the temperatures are mild at night. Opening windows lets in the humid air. Air leakage around windows and doors need to be sealed.

What temperature do you set the thermostat to? How long does the AC stay on during a cycle? Have you verified the humidity readings with another hygrometer?

Mike is correct, Austin wrong. I would not accept 53% RH without trying to lower it. Of course it appears OP has a high eff Sgl speed air handler. A var speed model would have helped plus with correct thermostat dehumidify on demand could be set up. If anything, 3 ton might be undersized for Florida. But longer runtimes with a 3 ton should help on dehumidification. Is thermostat setting being maintained? What is a typical runtime?

IMO

I keep my house at around 78 degrees and it feels comfortable

right now I have my T stat set at 78 and it shows 53% humidity

the AC stays on around 15 m per cycle

at what outside temp and humidity are you getting 53% RH?...I still recommend getting your installing dealer to check your CFMs/ton setting and to lower it to 350/ton if not already there. In the meantime, I would lower your thermostat setting down to 76 for several days and see how this affects RH. Yes, this will increase your electric bill but should increase comfort by lowering RH. Keep in mind RH above 50 can create an environment for mold development, something you definitely don't want.

IMO

its been high 80 's to 92 outside here in south florida with very high humidity

so I set my Tstat down from 78 to 76 and in 20 minutes the RH went from 53% to 50%

That leads me to believe that running it at 76 for a few days ill easily bring the RH down to the mid 40's

I would run it like that for 24 hrs and periodically monitor and document the readings. Keep in mind there are 2 parts to keeping inside humidity under control...reducing infiltration and good humidity removal...also note runtimes as well...looks to me that you are sized correctly...

IMO

Austin, personal attacks are a reflection of your poor attitude and why you are contributing little if anything to this forum...

TD

Courtesy of the Department of Energy...... Enjoy.

Evaluation of Humidity Control options in Hot, Humid Climates

Austin, did you read the item you linked and understand what it is? It's not a recommendation of indoor humidity targets.

Elmer J Fudd:

I never said it was a recommendation of a target. It points to what is possible as well as what is not possible. I guess I have to spell everything out for you huh?

You can not target a specific RH set point with a single speed air conditioner controlled by temperature and expect to hit that target. RH is independent of itself. You can have 80% RH outdoors even at 70 degrees. Yet you are 'moronically' telling me you can control RH indoors with a temperature driven thermostat? LOL.

The study confirmed that supplemental dehumidification is needed to maintain space relative humidity (RH) below 60% in a hot-humid climate home.

Clearly you did not read it, right?

The OP has a single stage air conditioner. Ah, what is 'supplemental dehumidification' ?

Please Elmer, stand up at the front of the class and tell us what it is.

Anyone else care to join him?

# Tiger helping people with fiction, is not helping them.