Minisplit with different sized head units

[EricP]

I'm going to purchase a minisplit system soon but haven't found one that will work for me, yet, after numerous online searches (probably time for me to call a HVAC contractor). All the package deals I see have identical head units. I need two head units to service the following: 1) 1200 sq foot single room woodshop, say 3 tons, and 2) 360 sq foot attic room above the woodshop, less than 1 ton. Are systems such as this available? Can I buy a 4 ton unit and mix a 1 ton head with a 3 ton head?

Eric

 

[Git]

I have a 24k outdoor unit, with one 18k indoor unit and one 6k indoor unit

Go to the eComfort website (that is where I bought my Mr Slim unit). They have several ways you can look up systems - by the indoor unit size, by the ton, etc. It's a pretty good place to get an idea what is available. I don't see exactly what you want - 48k with a 36k and a 12k indoor units. You may have to go with 3 indoor units

https://www.ecomfort.com/cooling/ductless-mini-split-systems.html

 

[fitter30]

Thats a big spread in tonage you have to check with the supplier.

 

[Jackfre]

Yes you could buy a 4 ton, but sit down when you get the price. You can run up to 8 evaporators on them, but they require branch boxes, etc and they get really speedy. For the small shop I would buy the most efficient 12k btu unit I could find. That would be in the 26-33 seer unit. Then do the 1200 sq ft separately. Fujitsu makes a nice 36 ceiling suspended. It will be less expensive and better than your proposed system.

 

[EricP]

Appreciate the input and advice. Looks like I need to compare the total package price of one big unit vs. two smaller ones. Thanks.

 

[Jackfre]

Actually, Eric, there is more to its than that. Even within the same manuf lines there are vast differences in the units. As well, mini-split manuf change lines like we change socks so be steeleyed in reading your specs. That's a nice building!
Oh, and panel space will frequently drive decisions. Any 36 I ma aware of needs a 30A ciercuit but the small 12's can be either 15 or 20 amp. What, if any, constraints are there.

 

[MattT]

Appreciate the input and advice. Looks like I need to compare the total package price of one big unit vs. two smaller ones. Thanks.

Personally I'd use a seperate unit for the attic room for performance reasons, regardless of cost. That small head isn't going to modulate properly on a condenser large enough for the entire building.

You also really need to run load calcs before ordering equipment. Your current sizes are old school rule of thumb from back before houses has insulation. And be careful with sizing the attic room. If it's insulation hasn't been done right the loads will be considerably higher than the calc.

 

[jobo1004]

Just a heads up that Daikin now has a 4 ton system that supports up to five heads (5MXS48TVJU) without any BP boxes. They still have the other 4 ton system (RMXS48LVJU) that can handle up to 8 heads, but it requires BP boxes.

https://cms.daikincomfort.com/docs/...document-library/brochure/cb-mxs.pdf?sfvrsn=9

 

[brewchief]

Your total btus of your heads don't necessarily need to match the btus of the condenser, you could have a 3 ton condenser with a 30k and a 9k or 12k head. I did a 3 head system earlier this year with a 24k condenser, a 15k head and 2 9k heads, the system will satisfy based on which head was started first or you can set priority for one head to ensure that space always gets full cooling.

Sent from my SM-G965U using Tapatalk

 

[EricP]

Appreciate the additional input. It should help me have more informed questions for my HVAC contractor. One the sizing, I've used several online calculators and the results are all over the map, like 1 - 3 tons for the 1200 sq foot woodshop. Seems a bit wide of a spread. But I'll figure it out before a unit is ordered. Thanks.

Eric