Humidity: The air conditioner as a dehumidifier 

I always watch at 2x 😁😁😁

0.5x speed is much more entertaining!

I appreciate the advice

+Ollie Good thoughts. GFM

Sounds like another video. GFM

A de humidifier will add heat due to its compressor heat. Humidifiers actually remove some heat to evaporate the water unless it has a heating element. In that case, heat is neither added or removed to the sensible heat of the air. Hope this helps. GFM

You can try lowering the fan speed. The additional temperature split across the evap coil will remove more moisture. GFM

+mef1975 Assuming a relative humidity of 50%, lower the temp, the air molecules get closer together which increases the relative humidity, perhaps 70%. It will only condense if the temperature reaches the dew point (100%). As for your problem, I am assuming you are cooling. Some mini splits have fan adjustments that will increase the moisture removal. Hope this helps. GFM

A simple fix is to increase the fan speed if it is not already at the highest speed. Also, be sure the filter is clean and not reducing air flow excessively. GFM

@@grayfurnaceman Thank you for your advice sir I'll be sure to try this. Keep adding value through these videos to those who need it👍

Generally, the larger system will remove more water than a smaller one. GFM

One of the things you might try is decreasing the fan speed. It is one of the simplest methods and may help. GFM

Thank you, I had heard that but I wanted your opinion. I will try it.

@@dudemup69 You should do 350 CFM per ton if you're in a humid area and have humidity issues inside.

Closed. GFM

grayfurnaceman thankyou

In high humidity, it is too high for dehumidification. 1600 may still be too high. GFM

@@grayfurnaceman OK thank you. Yes Gulf coast, which is high humidity. We will try either 1600 or the next level below that, which I think is 1400.

The air conditioner is a dehumidifier in addition to being a cooler. The cold temp of the evap coil reduces the air temp to the dew point, so the water condenses out of the air. GFM

If you raise the indoor fan speed, that will reduce the moisture removal. It is best done by a service tech, as he will understand the implications of any change. GFM

In most cases, the air temp is lowered to or below the dew point. The dew point is 100% humidity. GFM

Warm air passing thru the evap has its temp dropped below the dew point. At that point, moisture condenses out of the air. That means the air supplied to the structure is 100% humidity. It then mixes with the ambient air in the structure and the humidity decreases. Each time the structure air passes thru the evap, more moisture is removed. The result is reduced humidity the structure. GFM

@@grayfurnaceman Thanks for the information, I have been watching videos on enthalpy and it make more sense to me now. I always worked with compressed air systems under a pressure anywhere from 100 to 150 psi. not HVAC. I always knew that when checking dewpoint on a desiccant dryer we would use a sample cell to monitor the dewpoint of the air leaving the dryer outlet. There was a valve on the inlet that was always wide open and a valve and a "pig tail' (copper tube wound in a coil) on the bottom of the sample port. The bottom valve would always be just barely cracked open. This allowed the air to expand out and give you a correct dewpoint. If you took that reading at line pressure it would not be accurate. On refrigerated air dryers we never checked the dewpoint with a hygrometer. We knew that as long as the evaporator temperature was between 38 and 42 degrees there would be no water downstream in the compressed air system (we had a per cooler /reheater in the refrigerated air dryers that would warm up the discharge air to almost the same temperature it was as it came into the dryer), (prevents the compressed air piping from sweating). Our desiccant air dryers were sold to maintain a dewpoint between -40 F or -100 F depending on the model purchased. When air expands out it will lower the humidity of the air stream, one day I will get a temperature meter that can read the wet bulb and the dry bulb temp then use a psychrometric calculator to get a enthalpy number on my home HVAC system. I guess we are never too old to learn 😀. Looks like air flow across the coil will also determine the humidity in the discharge air. Now that I am retired I have more time to study and learn things that I always wondered about but always had an answer that would work in most situations. I knew that you could change the air flow across the evaporator coil but I never understood why. Thanks

What you are up against is residential A/C units are designed to cool to 70F. If you want it lower, the system may not be capable of doing it without freezing up. There are methods to allow it to reduce that temp but they require changing components in your system. Now, if the unit will not bring the temp down to 70F, you have a system that is too small. GFM

75° temp with 75% humidity is certainly uncomfortable. How long is the run cycle time with your unit? Is it not running long enough to remove moisture from the home?

@@TJ-22 how can i make it run longer? Move the thermostat?

@@jamescarnes2466 Well I was just curious how long the AC unit runs, when it kicks on. Does it run for approximately 15-20 minutes? Does it run for only 5-10 minutes? You might not be able to get an accurate test until the weather outside is hot again.

​@@grayfurnaceman Almost identical problem as James'. First summer in my new home, I was happy and comfortable. First winter and I was freezing because the blower/air circulation was powerful. Builder sent a technician to adjust it and I've had miserable summers ever since. It's hot and super humid (60% on average). What did the technician change and how can I get it back? I'd rather freeze in the winter than suffer in the summer. 😭🥵

An air conditioner cannot increase humidity. However, it may not reduce humidity as much as an older A/C. Reducing the indoor fan speed may increase the moisture removal. Best done by a professional. GFM

@@grayfurnaceman I had the ac guys out here yesterday and the plenum that all the ducts connect too lost its seal and was mixing with hot humid air in the attic.

@@FlydreamMedia OK GFM

My air conditioner adds humidity too. Upstairs air conditioner broke and used fans pulling downstairs cool air up and humidity went down to 45%. When air conditioner upstairs working the humidity is70% and I have to use 4 floor dehumidifiers when it is on.

The coil cools the air to the dew point (100% humidity). Then the water condenses on to the coil. Not all the water in the air condenses out. Just enough to make it 100% humidity as it leaves the coil. Hope this helps. GFM

cooler temperature, the less moisture that air temp. can hold, so it would be a higher percentage RH? i might be barking up the wrong tree..not an expert here, just curoius. ....

bababooey7576 Think of the air as a container. Lets say its a 1 gallon container with 1 quart of water in it. 25% full. With a lower temp, the container becomes smaller, such as 1 quart. Then it is 100% full. Hope this helps. GFM

yeah, more or less what i was trying to stammer out in answer to the person's question... coincidentally I had an hvac guy over servicing mine and my parents' furnaces...theirs was red tagged due to being oversized and some other issues...we were discussing AC and how the one in my place is 31 years old and still going strong etc etc, we were talking about dehumidification and h e was saying how he'd put a 1.5 ton condenser outside with a two ton evaporator to increase dehumidification (in a general sense he was say ing, not geared specifically to me). he seemed to be a stickler with sizing and numbers and clearances etc., does his theory make any sense re 2 ton evap? i'm in canada btw..only a few months of cooling required, but lots of dehumidification in that time, too.. And, your thots on electronic air cleaners? my parents have one and u nless my dad is down there every 3 weeks washing them (which he isnt, it's usually me), the amount of particulate that blows by is enough to have clogged the drain in the A coil twice and there's always fine bits of particulate in the furnace blower housing...are these filters better than a regular decent quality media filter if kept clean? (i do like the way it eats up odours and the house smells clean, when the filters are clean) Their old furnace is being replaced next week and the EAC may go with it depending on the answers/info i can find out before then. Thanks

bababooey7576 The dehumidification actually increases with a smaller coil, not a larger one. The smaller coil has a higher temp difference that removes more water from the air. The EAC filters are not perfect but most of the pleated filters have quite a lot of pressure drop the EAC does not. Hope this helps. GFM

The lower the temp of the evap, the more moisture will be removed from the air. Air flow increase will increase evap temp, lowering moisture removal. GFM

The A/C unit can be used as a dehumidifier, and is far better at it than a room dehumidifier. Air flow adjustments can fine tune the amount of dehumidification. GFM

Cut my teeth on them. GFM