Adding a system to remove the moisture from the indoor air independent of the cooling system will be the best solution. Most especially when the weather is mild but wet. There is a guy here named Teddy who can get very specific for you.

The dehumidifying units / systems do cost money to run - but at least some of that gets traded-off in reduced loading of the cooling system. And because with a lower indoor RH% you will be more comfortable at higher indoor temperatures (which is also healthier) the AC thermostat in the house may well be able to be set higher - further reducing operating costs.

And your comfort is worth something anyway. If it wasn't - you wouldn't even run the AC, right? <g>

PHM
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Thanks! I really wish I had gone with a 2 stage AC unit. Is there any reasonably priced way to change it over? Convert it? trade it, etc? Sorry for the dumb questions. :cheers:

I just feel like adding a dehumidifier is a bandaid and not really solving the real problem. I also get some mild hot/cool spots at times in the house.

 

That would all depend on If it is oversized (probably is) and by how much.

There is almost NO market for used equipment so that's not an option. A whole House dehumidifier is the route to go. Less energy usage, better comfort 70 % of the year, during high cooling season it wouldn't be running anyway!

 

Thanks for the help! How is it less energy usage to run a dehumidifier? Not doubting you at all, just want to understand that part. So during the hottest part of the year (when AC runs the most) the dehumidifier isn't needed?

 

Sadly... as noted... there is not really a market for equipment that has been installed...
Used to be a tax write off to donate it... however that never was much $$$...

Where you are now... the best value would be an installed de-hum unit...
The cheap route would be a portable... however they are not economical to run and generally last 2-3-4 years before failure.
The expensive route, which will probably provide the best comfort, is a 2 stage AC...
However that requires a VS furnace to take full advantage of the potential energy savings and comfort.

IMO 2 stage AC (or HP) is the best approach for cooling in all but really dry climates (think SW desert).

We install some of the inverter systems, however they are all about comfort, they are about equal in energy usage to 2 stage units.

 

Thanks for replying!

Would the 2 stage unit help with hot/cool spots? Is the lowest SEER for a 2 stage unit SEER 17? What SEER # does the inverter systems start?

 

It appears the a/c is setup correctly because the a/c removes enough moisture during hot, humid weather.
Any a/c contractor worth his salt will tell that you a/c is oversized. A well sized a/c runs full time during peak cooling load, removing large amounts of moisture, about 3 lbs. of moisture per hour per ton of cooling. A 3 ton removes +9 lbs. per hour, +1 gallon, when running continuous.
The first 15 mins, the a/c loads the coil and pan with 2 lbs. of moisture. After loading the equipment, the moisture starts going down the drain. At the end of the cooling cycle, the 2 lbs. of moisture on the coil/pan, slowly evaporates back into the home over the next hour. Here is the important part, an a/c running 15 mins. and off for an hour will not remove much moisture.
A/c companies fixed this using a small a/c with less capacity. If half sized, less off cycles, less moisture re-evaporated back to the home.
The rub is that on a hot, humid day, the sensible cooling load peaks middle of the afternoon, while latent (moisture) remains constant or may even increase, depending on the outdoor dew point and number of moisture generating occupants.
So, less sensible cooling does really fix the indoor humidity problem during may of typically cooling loads in green grass climates.
During evenings and rainy days, small a/cs are unable to removing moisture because low/no sensible cooling loads.
The simplest solution is to add a small whole house dehumidifier sized handle the latent (moisture) load of evenings and rainy days to the a/c system. 2 stage or VS a/c will not control %RH during rainy days and evenings.
Sorry about all the detail, but I am unable to explain this condition any other way.
Interested in your understanding the problem.

Regards Teddy Bear

 

It appears the a/c is setup correctly because the a/c removes enough moisture during hot, humid weather.
Any a/c contractor worth his salt will tell that you a/c is oversized. A well sized a/c runs full time during peak cooling load, removing large amounts of moisture, about 3 lbs. of moisture per hour per ton of cooling. A 3 ton removes +9 lbs. per hour, +1 gallon, when running continuous.
The first 15 mins, the a/c loads the coil and pan with 2 lbs. of moisture. After loading the equipment, the moisture starts going down the drain. At the end of the cooling cycle, the 2 lbs. of moisture on the coil/pan, slowly evaporates back into the home over the next hour. Here is the important part, an a/c running 15 mins. and off for an hour will not remove much moisture.
A/c companies fixed this using a small a/c with less capacity. If half sized, less off cycles, less moisture re-evaporated back to the home.
The rub is that on a hot, humid day, the sensible cooling load peaks middle of the afternoon, while latent (moisture) remains constant or may even increase, depending on the outdoor dew point and number of moisture generating occupants.
So, less sensible cooling does really fix the indoor humidity problem during may of typically cooling loads in green grass climates.
During evenings and rainy days, small a/cs are unable to removing moisture because low/no sensible cooling loads.
The simplest solution is to add a small whole house dehumidifier sized handle the latent (moisture) load of evenings and rainy days to the a/c system.
Sorry about all the detail, but I am unable to explain this condition any other way.
Interested in your understanding the problem.

Regards Teddy Bear

Thanks for the info! It was easy to understand and makes tons of sense!

So on days AC isn't needed but the humidity is high the blower will kick on and only run the dehumidifier? Or another way to ask is, if the humidity is above the setpoint can the dehumidifier run by itself, with the AC, or with the gas heat depending on the time of year?