Mr Cool Mini Split Sizing 30x40 Pole Barn in Ohio

[Brownac71]

As stated in the title I have a 30'x40' pole barn with 12' ceiling in SE Ohio (30min north of Dayton). I am in the process of insulating and am planning my heating/cooling system. I am installing R6 foam in-between the girts and sealing all the edges with expanding foam. I am framing 2x4 walls 24" OC, flush with the inside of the posts and then rolling R19 fiberglass insulation in the stud cavity and covering with 7/16 OSB. I'm installing four 3'x4' windows, with three of them under my 14' lean to on two sides. I have a 12x10 and a 9x8 overhead door, both insulated with R9.3 foam. I also have one 36" entry door and will be installing a second one. Metal ceiling will be insulated with R38 blow in fiberglass. I will also have two 56" industrial ceiling fans.

In Ohio our coldest month is January, with an average low of 20 deg F, and our hottest is July with an avg high of 85 deg F. I will be installing a Mr Cool DIY mini split to handle cooling and heating. I would like to be able to maintain 75 deg in the summer and 55 deg in the winter. I am debating between the 24k ($1614, 20 SEER, 10 HSPF) and the 36k ($1919, 16 SEER, 8.9 HSPF) size. The advantage to the 24k unit is that it is a less expensive purchase price and higher efficiency in cooling and heating. I figure either would be sufficient for cooling; it is mostly the heating I am worried about. I would rather buy a less efficient system than one that will not be able to adequately heat and cool the space. A third alternative would be a dual zone 36k unit with two 18k heads, which would be the most expensive at $2539 but the most efficient at 2.5 SEER and 11 HSPF.

Does anyone have experience with a building similar to mine with one of these systems? Any idea how long it would take to make up the price difference between the 36k single zone vs dual zone (18k+18k)? I am leaning towards the 36k single head as a balance between price and performance. I would hate to go for the 24k and find out it is not adequate. What is the recommendation of the forum on the system they would go with? Thanks for your help in advance.

 

[walrus]

As stated in the title I have a 30'x40' pole barn with 12' ceiling in SE Ohio (30min north of Dayton). I am in the process of insulating and am planning my heating/cooling system. I am installing R6 foam in-between the girts and sealing all the edges with expanding foam. I am framing 2x4 walls 24" OC, flush with the inside of the posts and then rolling R19 fiberglass insulation in the stud cavity and covering with 7/16 OSB. I'm installing four 3'x4' windows, with three of them under my 14' lean to on two sides. I have a 12x10 and a 9x8 overhead door, both insulated with R9.3 foam. I also have one 36" entry door and will be installing a second one. Metal ceiling will be insulated with R38 blow in fiberglass. I will also have two 56" industrial ceiling fans.

In Ohio our coldest month is January, with an average low of 20 deg F, and our hottest is July with an avg high of 85 deg F. I will be installing a Mr Cool DIY mini split to handle cooling and heating. I would like to be able to maintain 75 deg in the summer and 55 deg in the winter. I am debating between the 24k ($1614, 20 SEER, 10 HSPF) and the 36k ($1919, 16 SEER, 8.9 HSPF) size. The advantage to the 24k unit is that it is a less expensive purchase price and higher efficiency in cooling and heating. I figure either would be sufficient for cooling; it is mostly the heating I am worried about. I would rather buy a less efficient system than one that will not be able to adequately heat and cool the space. A third alternative would be a dual zone 36k unit with two 18k heads, which would be the most expensive at $2539 but the most efficient at 2.5 SEER and 11 HSPF.

Does anyone have experience with a building similar to mine with one of these systems? Any idea how long it would take to make up the price difference between the 36k single zone vs dual zone (18k+18k)? I am leaning towards the 36k single head as a balance between price and performance. I would hate to go for the 24k and find out it is not adequate. What is the recommendation of the forum on the system they would go with? Thanks for your help in advance.

You can't guess at this, you have to do a heat load calc. You have to look at what happens with mini splits as temps go down, generally the heat output goes down also.

 

[ericm]

Here's what purports to be a Manual J calculator: https://www.loadcalc.net/
and a Manual S to size the unit once you have the Manual J info.

Mr Cool units have a minimum heat setting of 62 degrees, and a "freeze protection" setting that's 45 degrees (I think). There's no good way to maintain 55.

How much the savings of a higher HSPF or SEER is worth depends on your electricity rates.

 

[dneiding]

I am a little more north of you (halfway between Mansfield and Sandusky). I have a 24x48 with 12' ceilings. R9 10x16 door in the front and R9 7x9 door in the back.

I bought my min-split from https://www.alpinehomeair.com/. I bought 3 outdoor condensers and 7 indoor air handlers two years ago from them and was very happy with the product and their customer service.

My barn also has a 10x16 lean to that will serve as an office. My ceiling is R30 and walls are R19. They spec'ed out a 36k BTU condenser and two 18k BTU indoor units for the shop and one 9k BTU indoor unit for the office.

Also, I installed two ceiling fans to help with circulating the conditioned air.

They seem pretty confident that I can easily keep the barn at 60 degrees in down to below 0 and in the 70s in the summer. The office will be kept to normal, comfortable, indoor temperatures.

I have yet to get them installed (my barn just got done at the end of Feb) so I don't know how they will work but can tell you they nailed the recommendations for my house so I have a lot of confidence the barn will be fine.

Hope that helps.

 

[rok_hunter]

I've got a 30x40x12 enclosed pole barn with spray foam insulation, about r16 if I remember right, and have the 36k unit. In in the FL panhandle so cooling is my main goal, but we do get temps into the teens/20's for a couple days at a time. My unit has had no problem maintaining 72-75 on the cold days, and cooling to 68-72 in our summers.

Sent from my Pixel 5 using Tapatalk

 

[Treasure]

I've got a 30x40x12 enclosed pole barn with spray foam insulation, about r16 if I remember right, and have the 36k unit. In in the FL panhandle so cooling is my main goal, but we do get temps into the teens/20's for a couple days at a time. My unit has had no problem maintaining 72-75 on the cold days, and cooling to 68-72 in our summers.

Sent from my Pixel 5 using Tapatalk

do you have the single head mini split? It does a good job evenly cooling the space?

 

[Black Oak]

AC won't be an issue , it's the heating . I think in the dead of winter a secondary heat source will be needed . Dec. thru Feb. - most mini splits will struggle . Spring and fall , you can heat w/ the mini split alone .

 

[rok_hunter]

do you have the single head mini split? It does a good job evenly cooling the space?

Mine is a single head unit, as long as the doors are kept closed I haven't had an issue with uneven cooling EXCEPT for the area within 2-4 feet of my roll-up door, which tends to be warmer or cooler depending on the outside temps - but it's also basically an uninsulated 10x10 metal panel, unfortunately on the "sun" wall of the building. I have a WEN 3417 filter unit on the opposite wall and a 20" floor fan that I'll occasionally run and combined, they all keep air moving pretty well throughout the whole building.

 

[Treasure]

Mine is a single head unit, as long as the doors are kept closed I haven't had an issue with uneven cooling EXCEPT for the area within 2-4 feet of my roll-up door, which tends to be warmer or cooler depending on the outside temps - but it's also basically an uninsulated 10x10 metal panel, unfortunately on the "sun" wall of the building. I have a WEN 3417 filter unit on the opposite wall and a 20" floor fan that I'll occasionally run and combined, they all keep air moving pretty well throughout the whole building.

Thanks for the info. Is the wall unit located on the 30' or 40' wall? Centered?

 

[NUTTSGT]

I am a little more north of you (halfway between Mansfield and Sandusky). I have a 24x48 with 12' ceilings. R9 10x16 door in the front and R9 7x9 door in the back.

I bought my min-split from https://www.alpinehomeair.com/. I bought 3 outdoor condensers and 7 indoor air handlers two years ago from them and was very happy with the product and their customer service.

My barn also has a 10x16 lean to that will serve as an office. My ceiling is R30 and walls are R19. They spec'ed out a 36k BTU condenser and two 18k BTU indoor units for the shop and one 9k BTU indoor unit for the office.

Also, I installed two ceiling fans to help with circulating the conditioned air.

They seem pretty confident that I can easily keep the barn at 60 degrees in down to below 0 and in the 70s in the summer. The office will be kept to normal, comfortable, indoor temperatures.

I have yet to get them installed (my barn just got done at the end of Feb) so I don't know how they will work but can tell you they nailed the recommendations for my house so I have a lot of confidence the barn will be fine.

Hope that helps.

We're fairly local, I'd be curious as to how well this keeps your place cool.

Heating doesn't matter as I have a wood stove for winter.

 

[BrianS]

I'm a little south of Dayton (Bellbrook) and have a 24'x32' detached garage with 14' ceilings and attic trusses. R19 in the walls, 2" closed cell foam on underside of roof sheeting and gable ends topped with R13 batts (~R30 total). 3 windows and a large 18x12 insulated overhead door on one end. I installed the MrCool 36k multizone system with a 12k unit in the attic room and 24k unit in the main area. This is the first summer and it is working great, maintaining 78* and low humidity. Have not had it over a winter yet, but I did install a 45k BTU Mr Heater hanging propane furnace for backup or if it can't keep up.

 

[GRivera]

I have a 30x40x12 pole barn with 12’ walls and scissor trusses so center ceiling height is 14’. R19 walls and R30 ceiling (all batt insulation) three 3x4’ windows and 8x18’ insulated roll up door.

I have the 36k Mr Cool Mini Split (16 seer). In winter it maintains my set temperature of 61 most of the time. Exception is when temps get into <low 30s when it struggles to do so.