Anybody in or around Texas using mini-split A/C

[Bamban]

That's what you need, cool air blowing directly on you while you work. Sure, you can cool the whole space but if you're mostly standing in one place just make it comfortable where you plan to be.

BTW, I'm definitely a fan of mini-splits but for my garage in Michigan I just have a window unit over my bench. Here in Santa Cruz I just open the garage door

John

Unfortunately the only space to mount the mini split is where it is. When doing some work the 920 right in front of the unit gets too dang cold.

When I close the garage after working with it open, I run the floor fan to move and condition the air till the mini-split gets to set point, then turn it off. One picture is looking towards the door where I normally work. The other one is looking back towards the unit.



Santa Clara? I do miss Marina by the ocean weather. Lived there till my Uncle said, he wants me back in 72. Wife is from Salinas.

 

[arvidj]

^^^Arvidj^^^
I have had my mini split installed now for about a week. 18,000 BTU Friedrich. Purchased from these guys. Very good service.

As mentioned above, my shop is 36x36 with 11ft ceilings. R19 walls. I have maybe R35 or so in the ceiling, although part of it has only R-10 or because I ran out time when insulating and haven't had a chance to get back to it.
The 18k BTU unit is doing very well in this heat and humidity we are currently having up here (I live 2 hrs East of you). I would not want much less than the 18k unit though. 5000BTU wouldn't come close to keeping your place cool. Did you account for windows and doors. Most windows are about an R-3 at best.
I am curious what make and model of boiler you have. I have the tubes installed but no boiler yet.

Apologies to Investigator. I don't want to hijack his thread and am very interested in his and Fouty Niners experience.

7milesup, thanks for the feedback.

I was using the calculator found here loadcalc.net. Windows were easy ... there are none. 2 doors, one 7 x 4 insulated steel "people door" and a 7 x 9 insulated 5 panel sectional overhead. Both have an additional 4 inches of FOAMULAR glued to the inside face so at least R-20.

I had the boiler installed by a heating contractor the building slab and framing contractor recommended. The slab and framing contractor was excellent but the heating contractor ... not so much. However the boiler, installed, was about half the price but most of that decrease seemed to be labor and, sadly, that is about what they were worth.

They installed this Lars Mascot FT 80,000btu 95% efficient condensing boiler. What is interesting is that the contractor originally calculated 60,000btu as the need and a 60,000btu boiler was quoted and available. By the time I got around to the installation an 80,000btu was delivered and installed as the 60,000btu was no longer available. And now I see that 100,000btu is the smallest available.

Anyway, the 80,000btu seems to work out just fine. I have the thermostat set at 67. The slab is always warm to the touch. The initial reaction when entering the building is "not warm, but certainly acceptable" but after a few minutes of activity it becomes "comfortable" on the first level and "warm" on the 12 x 36 second floor that is 10 feet above the first level.

The modulation of the boiler is based on an outside temperature sensor and some configuration settings on the boiler controller. I was not able to discover a workable configuration setting so the boiler is binary ... 100% on or 100% off. I paid a different heating contractor to come out and inspect the work I had to redo related to the combustion air in, exhaust air out and condensate removal plumbing the original contractor had screwed up. As part of the inspection I asked about configuring the modulation settings. His response was that, in his personal experience with heated slabs, modulation is not effective. Just forget about it and leave it binary. I guess that makes sense as the outside temperature will have significant swings over a 24 hour period while the ability to quickly alter the temperature of 18 yards of concrete to follow the outside dynamics is limited.

As an example, I accidentally turned the gas valve off in early December. I didn't go into the building for a couple of days. When I finally did go back there I noticed it was cooler than expected but it had only dropped to 64 degrees. The boiler had 'faulted' 10 times based on no gas and then turned itself off. The slab was cool but not cold even after several days without heat.

One of the forthcoming challenges will be getting the boiler and the dynamics of heating the slab based on a thermostat that measures inside air temperature to work well with the heat pump that is heating the air directly. I've had bad dreams about needing a slab thermostat to make it all play well together.

 

[Forty Niner]

I need to make the same decision. Minneapolis Minnesota so hot and humid on the worst summer days and teens and twenty below on the worst winter days. Natural gas 95% efficient condensing boiler with in-slab radiant for the heat. But need to select a Mitsubishi mini-split for cooling.

Building is 24 x 36 x 18 with R-23 ... soon to be R-33 in the ceiling, R-23 in the walls and R-20 under the slab. My on-line calculations suggest 5,000 btu cooling but that sounds way too low. The contractor suggests either the 12,000 or the 15,000 will be fine for cooling with the 15,000 providing more heat than the 12,000. My calculations suggest the trade-off for heat is about 35 degrees where the btu's from natural gas are cheaper than the electricity to get the 'free' btu's from the heat pump.

So I am very interested in how your 15,000 works in a bigger building and a slightly warmer (high 80's, low 90's, 80%+ humidity here for the last few weeks) climate. Please share your experiences.

Since the installation of the Mitsuishi 15k unit, my garage has been a pleasure to be in. We've had 100 degree days and the unit keeps the place cool. I find that after the initial cool down, the unit has no problem keeping the space as cool as I want. The unit, although arguably oversized, has the ability to idle down to a whisper quiet and maintain a very comfortable temperature. It even cools when the "dehumidify" MODE is selected and you can hardly hear it. I don't run the unit all the time. I run it when I'm going to be working in the garage, and it has no problem cooling down a very hot area in less than a hour.

However, I think the climate conditions in Minnesota are quite different from central Texas. So, maybe it is best to solicit experience from people with similar climate.

 

[sru_tx]

This is perfect timing. I've been eyeing (more like lusting) the minisplits for quite a few summers. I'm getting some electrical panel work done and am making provisions to add a ductless system to my small garage.

My lathe, mill, beadroller, and other clean work is done in the garage apartment upstairs. I'm looking at the ductless system to condition the downstairs garage area where I do my "dirty" work (welding, grinding, woodworking) which makes dust. I have an overhead Jet-brand air filtration unit to circulate air and filter, but try as I might to keep dust to a minimum, there's still a lot of dust flying around.

Question:
How well would one of these systems handle the dust? Obviously keeping unit's filter clean is a must.

thanks.