Mini-split installation

tvrgeek

tvrgeek
User
I thought about the slab, but it has a full VB and it has two coats of Rust Bullet over it. I have doubts on the walls as I did not do the insulation. But, the split could remove maybe a pint a day and the dehumidifier 3 gallons. I tested with buckets. Spec on the split is far more which is why I believe it is defective with the coils running so warm.

Doors and windows are pretty tight. About the biggest leak would be the louvers to an exhaust fan. Far less than the house and the house AC keeps us down below 60.
 

Billm0066

Bill
User
I installed a 110 mr cool in my sun room about 4 months ago. Did it all diy besides my electrician running the line to it. Very easy install and cools my 200 sqft room easily. I bought it from Costco’s website. If my shop was insulated I would definitely install one there.
 

jlwest

Jeff
Corporate Member
I have a Daikin mini-split and it works great. Dehumidifies as it should and even has a setting make it more dry if needed. 20 SEER. Insulation is always important. You do have to be careful about keeping the filters clean.
 

tvrgeek

tvrgeek
User
I built a large frame around my system and fitted MERV 13 filters. Building has 3 1/2 inch insulation in walls, 8 in ceiling. Ceiling is sheet rock, walls are 1/2 inch plywood. About 16 x 32 9 foot ceiling. Basic, coils at 65 are just not going to pull much water out. When it was 80%, it still only pulled about a pint a day. What I have not tried is putting the fan on low speed.
 

Brian Patterson

Bstrom
User
Given the fact that my shop is a basement shop, with a concrete floor, a significant amount of the water vapor comes up from the floor. While the AC does aid in dehumidification, when the set temperature has been satisfied and the unit cuts off, water vapor continues to diffuse into the shop, so the dehumidifier helps.
A coat of DryLoc or similar vapor sealing paint would go a long way toward slowing that infiltration process. I coated the walls and floor of my basement living space during its remodel and it has made for a comfortable space - with a dehumidifier/AC unit, of course.
 

Barry W

Co-Director of Outreach
Barry
Corporate Member
I had a Mitsubishi installed. It works very well except for humidity. The coils are just not cold enough. Tech says they are fine and running @ 65 is normal for a light load. I had to buy a dehumidifier. I think there is something wrong with the expansion valve or control there-of, but tech does not know and the OEM does not return calls. Split pulls out maybe a pint a day and the dehumidifier about 3 gallons. Where that much is coming from is a mystery. 16 x 32 pretty well sealed up. Even with the 90% we have had recently, blowing my mind. I want the shop between 50 and 55%. It had gone over 80 with just the split running.
I relayed this portion of your post to my HVAC service man and he thinks something is not right with your Mitsubishi, but, of course, would have to check it out to determine the problem. He installed one in our sun room about four years ago and we've had no problems with it, I think it cost a little less than $3,00.00. I also recall that Mitisubishi mini-splits are only sold to professional installers.
 

tvrgeek

tvrgeek
User
Mitsubishi finally contacted me. They confirmed two things. First, splits and any of the new super efficient units just don't run long enough to de-humidify. Second, they target 40 degrees. Tech came out and recharged yet again. Inside on evap it is not 49. On the pipe outside, about 42. So finally, it is working to spec. They don't put these numbers in the maintenance manual, only the pounds of 410. The tech is happy to have real numbers.

So, guess I build a shelf for a dehumidifier to sit on and drill a hole through the wall to drain. Kind of defeats the high efficiency in the summer, but I guess it still pays in the winter.

Bin or other shellac based primer is a vapor barrier. I might think about that.
 

avs5221

New User
Michael
Just want to add on to this that I have a self installed mini-split from Costco. The unit drainage backed up on me and flooded my shop, so a word of caution regarding them. Not sure if it's a common defect or not, but ruined a large dresser I had resting on the floor.
 

jlwest

Jeff
Corporate Member
Just want to add on to this that I have a self installed mini-split from Costco. The unit drainage backed up on me and flooded my shop, so a word of caution regarding them. Not sure if it's a common defect or not, but ruined a large dresser I had resting on the floor.
Self install always presents problems. Sorry it happened.
 

avs5221

New User
Michael
Insurance covered the loss, fortunately. The drain line was running fine, maybe a freak accident. But I'd go professional next time to be safe.
 

Jeff

Jeff
Corporate Member
All of us say "heck, I can install that Mini-Split and save some $$$". Then the "accidents" happen because we didn't install it correctly.
 

tri4sale

Daniel
Corporate Member
Insurance covered the loss, fortunately. The drain line was running fine, maybe a freak accident. But I'd go professional next time to be safe.
My professional installation had an issue with drain line too, took a while to track down issue. Luckily the issue was outside the shop so no damage.
 

Oka

Oka
Corporate Member
There are different add drain pans we add on moat of our inside ceiling units. Many off the shelf units do not have the emergency flood float. It is a float that if the pan fills up it shuts the unit down. But sometimes adding to a package unit is more work than it is worth, so we usually get a Titan pan to under the unit and tie both to the drain. Not that uncommon this problem
 

gmakra

George
Senior User
Room temperature doesn't have anything to do With how well your dehumidifing. Coil temp does typically a coil is 18 to 20 degrees cooler than the return air temp. And as long as your below the dew point you will dehumdify provided your not adding more moisture to the air than you can pump out.
 

Mike K

Mike
Corporate Member
I just installed a 36,000 BTU Mr Cool DIY unit in my building. Did the whole thing electrical included. It was no problem at all. The new systems are really very easy to install. Works great.
 

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