Help me size new Mini Split

[TheClaw]

I'm in the finishing stages of a new shop. I'm in the Chicago area so I need a cold version of whatever I get. I wanted to validate my guess on what size to get. The whole place is insulated.

My shop is 16x36, has a lofted section halfway down the long side. The lofted ceiling is 9ft and the tall section is 16ft. Using some of the tables online and from what I've found here is I'm looking at at 15-18,000 BTU heater with a 1.5T AC. I'm inclined to err on the big side. Going to mount it in the back corner where I've indicated with the "***".

Does that sound about right to the HVAC experts on board?

Thanks,
Jeff

 

[The Metric System]

Standard disclaimers apply about doing a full load calculation and I don't know how well insulated your walls are or what's on the other side of them, but superficially what you describe sounds reasonable.

Do you care what temperature it is in the lofted area? If so, you may want some provisions to ensure good air exchange up there.

 

[Jackfre]

I have found that ease things typically exceed expectations. I think I’d go no more than the 18k. Which ever brand you choose look at the min/max in H&C in the 15, 18 & 24 sizes. I don’t care for your location of the unit. I suspect it will have a 4-way air sweep. I’d rather have it about a third of the way in toward center.

 

[TheClaw]

Do you care what temperature it is in the lofted area? If so, you may want some provisions to ensure good air exchange up there.

The loft is for storage so I'm not worried about that.

I'm more concerned about the heat. I have R-19 Bat in the walls and R-49 in the ceiling. It get pretty cold here in Chicago.

Oh, yes, I've combed thru a lot of the threads here. I'm just getting a little extra input given the configuration of the inside of the shop.

Thanks in advance,
Jeff

 

[Yankeefarmer]

36 ft seems like a long distance to throw heated air towards your overhead door with an 18 k head. I’d be more inclined to go with 24k because mini splits can turn themselves down quite well..The 18 k Mr Cool Advantage I installed in my old shop for A/C didn’t push the heated air well at 27 ft from the back wall to the OH door.

Like @Jackfre wrote, a center location allowing the air to bounce off the other side wall would probably give you more evenly distributed conditioned air. It’s just a longer lineset and condensate piping.

 

[Steve W.]

I just installed a Pioneer system (<--- click link) in my shop this past summer. It's available in 18k and 24k sizes. It hangs from the ceiling or can be mounted on a wall near the floor. I have mine on the ceiling. In your case, it could be brought forward of the location you have proposed, which would bring it closer to the center of the space. As @Yankeefarmer mentioned, just a longer lineset and drain hose necessary.

There are director vanes in the output which can direct the airflow up&down and side-to-side. I have mine mounted on the 30' side of a 30x24 area, I am comfortable everywhere in the shop.

.

 

[txvwnut]

My shop is 26' deep and I have the IDU mounted on the back wall. As others have mentioned mini-splits don't move a ton of air and you can only feel mine till about the middle of the shop. What I suggest is adding a fan or two to help with air circulation. I have three squirrel cage blowers mounted on one wall that blow across the shop and that helps a ton in keeping it comfortable in the shop.

 

[pcmeiners]

36 ft seems like a long distance to throw heated air towards your overhead door with an 18 k head.

Have a 12k Fujitsu low temp unit in a 30x36 garage which can easily send heated or cooling air 36 feet.

 

[The Metric System]

Airflow and associated thermal behaviors can be tricky and highly variable, but my 24k Costway El Cheapo minisplit has no problem warming the far end of my ~54' long garage.

 

[TheClaw]

I just installed a Pioneer system (<--- click link) in my shop this past summer. It's available in 18k and 24k sizes. It hangs from the ceiling or can be mounted on a wall near the floor. I have mine on the ceiling. In your case, it could be brought forward of the location you have proposed, which would bring it closer to the center of the space. As @Yankeefarmer mentioned, just a longer lineset and drain hose necessary.

There are director vanes in the output which can direct the airflow up&down and side-to-side. I have mine mounted on the 30' side of a 30x24 area, I am comfortable everywhere in the shop.

.

What made you decide to use this floor/ceiling configuration instead of the conventional wall mount? I like the idea that you can mount it on the ceiling.

 

[WildBill]

I would go with a 24k for faster recovery and better heating ability. An 18k (or probably less) would cool it no problem, just not do as good in the cold and take longer to recover from hot/cold vehicles and doors being opened. They ramp up and down so it's not like an old system where it's easy to cause trouble by going too large, and the difference in cost between an 18k and 24k is not a lot.

 

[TheClaw]

ok, i've started to go bug eyed trying to choose a specific unit. They all seem to be priced around the same, have some of the same specs. I didn't care to check blue tooth or alexa. I'm really just concerned about how it works. Here is a list of all the units I started tabulating.

I also didn't care about the refrigerant. I know they are moving away from R401A but I'm sure it will be supported for a long time.

The ones highlighted in yellow are the ones I'm leaning towards.

 

[Steve W.]

What made you decide to use this floor/ceiling configuration instead of the conventional wall mount? I like the idea that you can mount it on the ceiling.

There were a couple of factors in that decision.
1. Basically just a lack of wall space.
2. And a lack of ceiling height.

All of the wall-mounted systems I have seen (admittedly rather few) draw air in at the top and discharge from the bottom. With a ceiling of 8', by the time you mount it low enough for clearance to access the filter(s), it would be discharging air between 5.5' and 6' from the floor. Even if they have moving deflectors to sweep the area, that's just too low for my liking. Mounted to the ceiling, I can set the main deflector anywhere from straight out (right along the ceiling) to almost straight down. It can sweep between those extremes, but I have it locked at just below the ceiling level. I have the side-to-side deflectors moving. I have not measured them, but they seem to do at least a 90° sweep. The filter access is from below, as seen in these shots:



These shots are when it was mounted, but not yet connected:


Snap-on blaster cabinet rolls in under the mini, there is just enough room to open the lid:


.

 

[pcmeiners]

TheClaw

On all those unit the HSPF is rather low. In the Chicago area the SEER is not the number you need, it is the HSPF as your heat costs will far exceed your cooling costs. Check out the numbers on a Fujitsu low temp unit.............

https://www.goodlifehvac.ca/images/Fujitsu_LZ_Series.pdf

 

[Steve W.]

My Pioneer manual says it’s “rated to -13 degrees F. “

Have not seen a chart to see exactly what percentage of its output it still has at -13, but we typically only have a few days per year that hit zero, let alone going below.

If it does get that cold, I can still break out the kerosene torpedo that I have been using for the last 10 years.

.

 

[The Metric System]

Have not seen a chart to see exactly what percentage of its output it still has at -13, but we typically only have a few days per year that hit zero, let alone going below.

IMO for a system intended for a homeowner garage (as opposed to living space or a commercial shop) it's entirely reasonable to compromise on heating performance on the coldest days of the year.

For example, my system is rated to operate down to 15F. We might see 1-2 days each year where the outside temps fall below this number, and on those days I have several options:

• Run supplementary heat
• Wear a jacket in the shop
• Just not work in the garage

Usually when the temps are that low it happens overnight. This make it even less of an issue, because I generally don't do much in the garage at 3AM.

In the absence of a specific problem like freeze risk etc I'm definitely not going to select equipment based primarily on how well it will operate during the coldest 8-12 hours of the year.