Mr Cool DIY Mini Split AC/Heat Pump

[Lineman North Florida]

One major difference between MrCool and others like Mitsubishi is the ability to drive a number of heads/registers. If you only need heat/cooling in one place, well, it is not an issue. If you want to heat and cool several rooms or zones, it is a big difference. One mitsubishi "outside" unit can drive several "inside" units. The MrCool cannot do that.

I wondered how that would work as I do have a bedroom and bathroom walled up and I wondered how one head or zone would do keeping them cooled and heated, the bulk of my layout is open but those two rooms are walled up. Maybe someone who has a similar situation will chime in and let me know how their experience has been.

 

[prichard]

I wondered how that would work as I do have a bedroom and bathroom walled up and I wondered how one head or zone would do keeping them cooled and heated, the bulk of my layout is open but those two rooms are walled up. Maybe someone who has a similar situation will chime in and let me know how their experience has been.

This is the main reason we are likely to go with central unit instead of mini-split. We were going to do mini in each bedroom and one or 2 for great room/kitchen (open space). But then I thought of the bathrooms. I can't stand a cold bathroom.

Since there is no return or vent in rooms that do not have units there will be little air movement so little transfer of heat.

 

[jrepp44]

I have three Mr. Cool DIY units, a 12K, 18K and 36K. They were not too difficult to install and they are all performing satisfactorily.

 

[cqaigy2]

Can those units heat too?

 

[LouNY]

This is the main reason we are likely to go with central unit instead of mini-split. We were going to do mini in each bedroom and one or 2 for great room/kitchen (open space). But then I thought of the bathrooms. I can't stand a cold bathroom.

Since there is no return or vent in rooms that do not have units there will be little air movement so little transfer of heat.

I have two Mitsubishi 36,000 units with one feeding 3 heads and the other 4 heads, the system works well and I only run the units in occupied rooms.
As far as the bathrooms are concerned if I run the exhaust fans they do quite a bit otherwise not much but it wasn't worth it to me to cool them.
It was an expensive system to have installed but the "professionals" wanted to put the system in a hot attic and use flex duct and no zoneing.

 

[GLyford]

Can those units heat too?

Heating is an extra cost option. It requires a set of electrically controlled valves to swap the coolant direction, so the cheapest units don't have them and can only run AC.

I spent the extra to get that on a mitsubishi with two heads, but honestly, we have only used that a handful of times in the two years we have had the units. It works okay, we just rarely remember to use it. We have friends who have a bonus room where it is the main source of heat, so it can work well even here in the chilly NE.

But if you don't need the heat, the units are cheaper and have fewer moving parts (so in theory more reliable?) without it.

 

[Lineman North Florida]

Can those units heat too?

The Mr Cool unit that I am looking at does heat and cool.

 

[buckeyefarmer]

Heating is an extra cost option. It requires a set of electrically controlled valves to swap the coolant direction, so the cheapest units don't have them and can only run AC.

I spent the extra to get that on a mitsubishi with two heads, but honestly, we have only used that a handful of times in the two years we have had the units. It works okay, we just rarely remember to use it. We have friends who have a bonus room where it is the main source of heat, so it can work well even here in the chilly NE.

But if you don't need the heat, the units are cheaper and have fewer moving parts (so in theory more reliable?) without it.

Mrcool web site indicates it also heats. Where did you find that it was an option?

 

[swnoel]

I am looking at options to heat and cool, actually mostly cool my 800 sq ft hunting camp that I am building and with some of the prices that I am seeing from AC company's it makes this DIY mini split system look pretty appealing, an 18k btu or ton and a half comes pre-charged with everything you need so you don't have to pull a vacuum and then charge the system therefore you wouldn't need an AC company for that, the unit run's about $1,500.00 and has a 7 year compressor warranty and 5 year part's warranty, so does anyone have any experience with this brand or another DIY mini split system? Thanks, Charlie.

Never heard of them. I've installed well over a hundred units mostly Fujitsu and Mitsubishi . They're great units and do as they promise. Over time you will need to get it serviced and cleaned, usually about in 3-4 years, mold and debris will build up on the evaporator fan requiring it to be flushed. $1500 is cheap money for both heat and cooling.

 

[GLyford]

I meant in general, I do not know any specifics about the Mr. Cool units. If they come with heat that makes it sound like an even better deal.

 

[3Ts]

I have an LG mini-split 18K BTU does both heating and cooling. I installed it myself.

The local HVAC guys wanted ~$4k to install one. I bought one on-line with the vacuum pump and meter for a little under $2k. The hardest part on the install was holding the 35# indoor unit up in the air while my wife tried to guide the pipes thru a 3" hole.

We have about 900 sqft it's 24x36 with an enclosed bath at one end and a room divider (no door) for a 12x12 area at the other end. we have no problems with heat/cool in the bath.

The biggest problem for us is maintenance. As was mentioned, the coils have to be cleaned periodically. Ours is mounted 8' up on a 10' wall over the washer & dryer so we have to move those out of the way to get the ladder in for the tech to work on it. The tech won't move the appliances and we're getting old enough where it's getting to be difficult to do. We've had it up 3 years now and have had the tech in once to clean the coils and check it out. I also vacuum the drain line from the outside periodically to make sure it stays clear, otherwise you'll have water running down your wall. That's all it gets for maintenance.

 

[jhasafety1]

I installed a DIY Mr. Cool 24,000 BTU mini split in my shop a little over a month ago. Works great keeps a 30x40 shop with 10' ceiling exceptionally cool. I have it set to 73 degrees and it has not had any trouble keeping the space very cool. The indoor head unit runs very quiet, the only way I know it is running is seeing the vent is open, the outside unit is very quiet. My wife has expressed her frustration that this unit is way quieter than our home central air system. Installation was not as difficult as I thought it would be. Best money I have spent on this shop.

 

[strantor]

I installed a DIY Mr. Cool 24,000 BTU mini split in my shop a little over a month ago. Works great keeps a 30x40 shop with 10' ceiling exceptionally cool. I have it set to 73 degrees and it has not had any trouble keeping the space very cool. The indoor head unit runs very quiet, the only way I know it is running is seeing the vent is open, the outside unit is very quiet. My wife has expressed her frustration that this unit is way quieter than our home central air system. Installation was not as difficult as I thought it would be. Best money I have spent on this shop.

Does your shop have windows? Roll-up doors? Blow-in insulation? How hot is your outside?

I'm considering getting one of these units for my 30x30 shop. My shop is a typical industrial-type metal building built from structural I-beam with metal siding. There is the white-backed fiberglass insulation. It has no windows. 11ft eaves, 15ft peak. One 10ftx10ft "Insulated" (looks like it has a radiant barrier taped to the inside) rollup door and a single man door. The building is color "polar white" which is supposed to reflect light/heat even better than regular white. I can see daylight around the rollup door. Probably need to do something about that before I expect any AC to perform well. I'm in Texas by the coast; the ambient temperature and humidity stays right at about Satan's ******* for most of the year, and because I only have a single rollup door, I can't even get a breeze through there.

Here's my concern: AC manufacturers probably spec their "good for _X_ sq ft" numbers on house-type spaces with reasonable insulation, attic space, etc.; not a structure built like a convection oven and with an extra 4 cubic ft of air per every square foot of floor space. I don't know the R-rating of my insulation but it's probably half what a house has, at best. So without any math or science at my side, I'm taking a stab in the dark and estimating that I need at least double the BTU as whatever a given AC MFG says I need. So I'm looking at the Mr. Cool 36k BTU for my shop. But then I keep running across examples (like yours) of people with bigger shops than I have, cooling it with smaller units, and having no issues. I don't want to over-spend, but I dang sure don't want to buy an A.C. that's too small and have to eat it and buy a bigger one the second time around.

What size would be recommended for my shop?

Also, I am having trouble wrapping my head around how a small unit mounted far away on one wall of the shop, which intakes and discharges air from the same spot, can cool all the hot air on the other side of the shop. Seems to me, most of the air it would be taking in, is the same air it just cooled. I don't understand how I or anyone could get away with anything but a ducted solution, where air is drawn in from one side of the room, cooled, and discharges somewhere else in the room. Do these things really provide cooling for the whole shop or would I need fans mounted all around to distribute/mix the air?

 

[vvanders]

Our minisplit pulls air from the top of the ceiling and vents it out the bottom so you're cycling the hottest air into the coolest which will settle lower and is pretty efficient. Probably not as great for heat but works great as an AC.

 

[thepumpguysc]

Strantor, I'm in the same boat as you.. Metal bldg., hi roof, little insul.. For some reason, mine stays reasonably cool in the middle of the day, prob. because its tucked in the corner of the wood line.?? but in the winter, you can see your breath & cant feel your fingers..
Granted, it could always be cooler..
I've been following this thread also.. I recently ran across a listing on my local Craigslist from an a/c seller & installer.. selling guaranteed reman units. 1.5-2 &3 ton units for &1500. 1800.00-$2,000. INSTALLED w/ warranty..
& even an offer to come out to your shop/building & "spec out" what you need. size of unit, electr. needs & so-on..so you don't buy something unnecessary..
I just thought I'd throw that out there, incase you haven't thought about looking "there"..
That's prob. the way I'm leaning towards because like you, those "small" wall mount units are nice but scare the heck outa me.. as far as not putting out the air I want vs the money I spent.

 

[strantor]

Strantor, I'm in the same boat as you.. Metal bldg., hi roof, little insul.. For some reason, mine stays reasonably cool in the middle of the day, prob. because its tucked in the corner of the wood line.?? but in the winter, you can see your breath & cant feel your fingers..
Granted, it could always be cooler..
I've been following this thread also.. I recently ran across a listing on my local Craigslist from an a/c seller & installer.. selling guaranteed reman units. 1.5-2 &3 ton units for &1500. 1800.00-$2,000. INSTALLED w/ warranty..
& even an offer to come out to your shop/building & "spec out" what you need. size of unit, electr. needs & so-on..so you don't buy something unnecessary..
I just thought I'd throw that out there, incase you haven't thought about looking "there"..
That's prob. the way I'm leaning towards because like you, those "small" wall mount units are nice but scare the heck outa me.. as far as not putting out the air I want vs the money I spent.

Thanks I hadn't considered that. I'll look into it.

 

[Lineman North Florida]

Well I ordered a Mr Cool 18k from Costco today, it will be a little while before I'm ready to install it but the price was right and hopefully I will have good luck with it, thanks, for all the replies. Charlie.

 

[Tough Luck]

Mine came yesterday. This thread has sold two Mr. Cool 18k BTU units. My line set cover and wall mount are all I need to get started. They should be here this weekend from Amazon. I also still need to get a 3 1/2" hole saw bit.

 

[pmsmechanic]

I'm going to follow this. The 8000 btu unit we have in a window in the house would easily cool my shop and a new mini split would be awesome in the house!

 

[buckeyefarmer]

I got one room upstairs on southwest (sunny side) that stays warmer. Thinking about a small one for it. I already have power disconnect outside that used to feed an outdoor unit before i put in geo.