Psychrometrics, Humidity & IAQ

Every piece of air conditioning equipment can move a certain amount of heat BTUs (British Thermal Units) at set conditions. In most cases, during the cooling mode, a portion of those BTUs will go toward changing the temperature of the air, and a part will go toward changing vapor water in the air into water […]

Humidifiers are a big part of HVAC systems in dry locations, especially in the winter. I have no experience with them personally because they aren’t prevalent at all in Florida. I asked some of the HVAC School contributors to weigh in with some of their top humidifier tips. Thanks to Nathan Perney, Steve Domansky, and […]

This article is written by tech and business owner Genry Garcia from South Florida. I met Genry at a Solderweld demonstration, and he later offered to write this excellent article. Thanks, Genry! Though dehumidifiers have increased in popularity, thanks in part to the implementation of new building codes, they have become a kind of red-haired […]

Does heating the air cause the humidity in the air to decrease? Yes and no. Heating air causes the RELATIVE humidity percentage to decrease, but it does not change the overall moisture content in grains of moisture per lb of air. Many old-timers will swear a blue blaze that oversizing a furnace will directly result […]

I was listening to someone talk about air relative humidity the other day while looking at a psychrometric chart, and he commented that the chart ends down at freezing (32°F) because “all the water freezes out of the air at that point.” I think I made this Jed Clampett face: The psychrometric chart is designed […]

If you don’t do a lot of commercial work, you may see a system like the one above and wonder what the heck it is. It is a 100% fresh air unit or a makeup air unit. You will see them more and more as codes start to reflect that balanced ventilation and conditioned outdoor […]

A quick note about UV lights: they work like sunlight in that they prevent and kill many types of bacteria and fungi when exposed to the light on surfaces. They do not generally do a great job of killing spores suspended in the air stream. UV lights are great at killing yucky stuff on surfaces […]