How much cooling power can I expect from a mini split ac unit?

dstig1 · Jun 27, 2019

If you are fine with the temps, then why not just get a dehumidifier? I put one in my shop a couple years back. It is very well insulated and I keep the doors closed as much as possible when the humidity is up. This is just a 120 pint frigidaire portable unit, made for a house. It make a HUGE difference in there. Shop is 32x80x13 high. I have to empty tanks as I don't have a drain, but if you had a drain,l you could run it straight into that and never have to do much other than clean the filter from time to time. I have found that I don't even notice how how it gets with the humidity down. It can easily be mid 70s in there and it feels cool even.

4570Man · Jun 27, 2019

The dehumidifier makes too much heat and I ceased operating it. And I don’t like the temperature it would just be a lot better without the humidity.

Milo · Jun 27, 2019

4570Man said:
The dehumidifier makes too much heat and I ceased operating it. And I don’t like the temperature it would just be a lot better without the humidity.

The nice thing about a mini split in "dehumidify mode" is it makes adds cool inside, the heat is outside.

dstig1 · Jun 28, 2019

4570Man said:
The dehumidifier makes too much heat and I ceased operating it. And I don’t like the temperature it would just be a lot better without the humidity.

Yeah I wondered about that as you are in a much warmer spot than I am. It seems to do the trick for me up here at least...

Milo · Jun 29, 2019

If you don't need heat, only dehumidify and cool, what about putting a sleeve in an outside wall (or window) and slide in a window AC? Inexpensive yet surprisingly effective. My previous home had a small shop consisting of a 24 x 24, and a 12 x 24 room. The shop was brick, built in 1990, pretty well insulated, and had it's own small high efficiency gas furnace but no AC. Because it was well insulated it never got terribly hot inside maybe up to 80 on a hot day but that and the humidity made it pretty uncomfortable in Summer. I decided to set an AC in one of only 2 small casement windows in the shop which happened to be in the larger room. The only AC I could find that'd fit was a really small unit I forget how many BTU but not a lot, it was made in China and cheap but what the **** I removed the little casement pane and put it in. After reading about all the settings I put it at 75, Auto, Economy mode, and it made a huge improvement. 75 and low humidity is worlds better than 78 and high humidity.
After temp would drop to 75 it would shut down but even if the temp stayed at 75 about every 30 minutes the fan would start and run for 10 minutes to circulate air then either shut off again or if called for the compressor would come on and it'd cool it back to 75. I just left it set at that all Summer and if there was a bump in the electric bill it wasn't even noticeable.

Tractor Seabee · Jun 30, 2019

Back to the OPs original question! They will produce the amount of cooling indicated by the units tonnage rating, BTU rating, or Horsepower. Basically 1 HP = 1 Ton of heat extraction or 12,000 BTUs. As stated earlier; to determine if a specific unit will do the job, you need a space heat gain calculation, or if calculating for heating, the heat loss at expected ambient temps. If using for both heating and cooling with no other heat input to the space you need to base unit size on the heating load. Your local utility can usually answer some questions short of doing the calculations.

Ron

4570Man · Jun 30, 2019

I don’t need heat because I already have a natural gas heater.

Barnbuilder · Jul 8, 2019

We put one in a man cave I built about 8 years ago. 36x40, I think the ceiling was maybe 20'. It was 3 units. 2 ran off one pump.

3Ts · Jul 8, 2019

The thing I don't like about the mini-splits is access to the filter. It's in the top of the head unit which is mounted about 8' up (10' wall) and I have to climb on the washer and dryer to get to it. Otherwise they are really nice units and relatively easy to install.

As for reducing humidity, an AC can only do so much and a dehumidifier is the real answer (yes they do seem to make it warmer). I would use a ducted dehumidifer with a filter at the intake and the exhaust plumbed to the opposite corner so you get an air flow. Then use the AC to cool the shop.

The mini-split I have is 18,000 BTU and is used in a 24 x 36 x 10' shop with 5.5" spray foam in the walls. It's more than enough, if I ever have to replace it, I'll probably go smaller. Keep in mind that the AC is not dehumidifing if it's not running. I also have a dehumidifier in there that's always on.

Smokeydog · Jul 10, 2019

Mini split is the way to go. I put a filter on top the indoor unit to help with the big dirt and hair.

We have a 26x45 two story old log cabin. Heated with wood and cooled with window acs. Upgraded to a Mitsubishi best minisplit heat pump, heat/cool. One ton unit the biggest I could fit in the stairwell to heat/cool both levels. Was planning to install two. This thing is amazing. Don’t use window acs anymore. Needed one fire last winter. Better at dehumidification. Much quieter. Avg <$100/mo electric on all electric home. Paid for itself many times in eight years. 26seer.
Only con is it is hard to clean inside coils and fan once a year when switching from cooling to heat.
With a lot of company and cooking could use a second unit for cooling.