Mini Split sizing help please!

[DENALIAKITAS]

I have a 30x40x12 pole shed. It will be fully spray foamed with closed cell foam r13 walls r24 roof and gables. The floor is 6" concrete with 2" dow board under it and a vapor barrier. The 16' wide by 11' tall overhead door is a clopay premium and rated at r18. I am located in Kansas and the summers get quite hot here. I am needing suggestions on size for a mini slit and/or possible going with 2 smaller higher seer mini splits vs a single one. Please let me know your thoughts thanks.

 

[pseudorealityx]

What indoor space temperature are you trying to achieve?

 

[DENALIAKITAS]

What indoor space temperature are you trying to achieve?

Frigid 70 would be ideal.

 

[pseudorealityx]

You going to keep it there, or only turn on the HVAC from time to time?

 

[Jackfre]

You will do better with two evaporators vs one large unit. The two operating together in an open space will give better air circulation and more even temps. Be aware that if you buy a multi unit, meaning one condenser and two, three or four interior evaps that the efficiency is lower on the multis than on the singles. Run the numbers for single high efficiency units vs multis. Pay attention to the amount of copper needed to run a multi as line-set costs are significant and need to considered as well.

There is no substitute for a real heat loss/gain when asking a sizing question.

 

[DENALIAKITAS]

You going to keep it there, or only turn on the HVAC from time to time?

Probably mon-fri 9-6 and raise the temp overnight and off on weekends

 

[DENALIAKITAS]

You will do better with two evaporators vs one large unit. The two operating together in an open space will give better air circulation and more even temps. Be aware that if you buy a multi unit, meaning one condenser and two, three or four interior evaps that the efficiency is lower on the multis than on the singles. Run the numbers for single high efficiency units vs multis. Pay attention to the amount of copper needed to run a multi as line-set costs are significant and need to considered as well.

There is no substitute for a real heat loss/gain when asking a sizing question.

I was thinking maybe 2 15,000 individual units rather than a two evap single condensor unit.

 

[Jackfre]

Ok, be aware that both Fujitsu and Mitsubishi are making units that will heat down to -15f. As well, other models will go down to 5f. Make sure you get what you want for your application. I think you should be safe with two fifteens, but I heard somewhere that you cannot do this reliably without a full heat loss/gain being run. I think I'd put them opposite each other on the long walls. 1/3 of the way up one wall and the other 1/3 on the opposite wall from the opposite direction. The 15's should have a 4-way air sweep. You want that.

 

[DENALIAKITAS]

Ok, be aware that both Fujitsu and Mitsubishi are making units that will heat down to -15f. As well, other models will go down to 5f. Make sure you get what you want for your application. I think you should be safe with two fifteens, but I heard somewhere that you cannot do this reliably without a full heat loss/gain being run. I think I'd put them opposite each other on the long walls. 1/3 of the way up one wall and the other 1/3 on the opposite wall from the opposite direction. The 15's should have a 4-way air sweep. You want that.

I am thinking the same thing for size. I dont need a unit with heat as i have LP heat currently and will also be adding a passive solar setup later. There shouldnt be any dead spots for air movement as i have a 14' "Big *** Fan" ceiling fan to go in the shop.

 

[JakeKohl]

I'm heating a 24x36 with one 18kbtu unit and it's over-kill. Turning it on at 38 degrees only takes about 15 minutes to get the interior space to 60+. I think your larger space would really benefit from two different 15kbtu units to get better airflow. Mine barely moves enough air around to heat the whole space.

 

[Jackfre]

I am thinking the same thing for size. I dont need a unit with heat as i have LP heat currently and will also be adding a passive solar setup later. There shouldnt be any dead spots for air movement as i have a 14' "Big *** Fan" ceiling fan to go in the shop.

Buy a heat pump unit. You will be happy that you did. The most efficient units are heat pumps and the major brands are doing very few cooling only units. As well, you will be happy having the option of the heat pump at times when LP prices may go nuts.