I have a large swamp cooler for the shop, it's on a cart so I just open an entry door and it sets in the opening. With all the rain this spring the humidity starts off around 55 % and drops as the day gets hotter. This isn't helping at all with the shop temps,
Sorry about that but in your area, you have to suck it up for the next several months. I never thought the swamp coolers would do much in a shop. They can do pretty well in smaller places but as with everything, there are limits. Just think of us. 62 degrees for the high today! Yes, we love it.
55% and dropping? Ha! That's better than what's been happening here. Starting off at 65-70 in the AM with RH at 70% or better. As the day heats up to the 80s, the RH may fall a few point but we typically get afternoon t-storm rolling in and the humity rises until it storms and by then it's cooling off so fast that the RH stays high through the night. Air conditioners are working hard to make it tolerable indoors.
Air conditioners do two things. first they cool the air. But, more importantly it removes the moisture from the air. Over sizing the unit sounds good in theory, but is not as good in a lot of cases. The longer the unit runs, the more moisture it removes. Getting the higher efficiency units (seer rating) will make up the difference.
I understand, sorry for you! I had swamp coolers for 30 years now, worked great most of the time. Once it got above 30-40% humidity, they did not work that great. In a jam I have used the squirrel cage only, atleast for a breeze. You mentioned you opened the door, maybe try an exit for the air on the other side of the shop might help.
I had a shop back in the 70's with a swamp cooler ( huge one fixed ) it poured water pumped from the river over the pipes to cool the air - it did absolutely nothing for removing humidity from inside as it was an open unit, you could watch the water flowing over the air pipes. looking back that unit was reversed from what one would expect. Place was a rental, and that thing ate a lot of juice for a marginal return.
My weather station is currently showing a temp of 60. Coincidentally, the current dew point is also 60. It's been really humid here so far this year. Most days in the morning the dew point is 1 degree below the actual temp. Ugh. I've ran the central ac much more than normal, just trying to get the moisture out of the air. My 70 pt dehumidifier runs constantly in the basement just to keep it at 60%. I'm glad we don't have the Texas heat here, but the humidity is killing me.
I have a high window that stays open and the other entry door opened, swamp cooler only adds humidity, I can usually knock 5 degrees off the shop temp but not while the sun is up now.
Had that kind of weather last year - you could hang a towel out side in the morning and it would still be pretty damp in the evening. Have a DH running constant in basement - it does cycle the compressor off and on holding 50%. Only run the AC twice so far and then just for a couple hours - more to move humidity out than temp. have a HD upstairs as well only run it twice also this season. July- Aug and sometimes Sept are the warmest months .