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Thread: Installed a mini-split in the workshop today.

  1. #16
    Wow, that's great info... I got estimated $4k to install a mini split around that size in a new buildout. I'm also curious too- did you need a license to get the refrigerant?

  2. #17
    Join Date
    Dec 2006
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    Mesa, Arizona
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    I installed a Mr. Cool DIY 12k BTU mini-split this past summer. It was MUCH simpler than I had feared. I had been quoted over $4k to have a unit installed (much of that was because they would need to run additional cable to power the unit). I had one slot open in the shop's subpanel, which allowed a dedicated 15amp 110 circuit for the mini-split.

    The only downside to the DIY route is I was left with a lot of extra copper line, which was coiled up next to the outside unit. When I had my A/C units serviced in the Fall, I persuaded the tech to shorten the line for me. That additional service cost less than $100. Over all, I'm very pleased.
    David Walser
    Mesa, Arizona

  3. #18
    Join Date
    Oct 2019
    Location
    Santa Barbara, CA
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    58
    I have been thinking of doing a Mini-split also. I have plenty of power but not near where I would install it, so have to run some power there. I also have been thinking of just installing a window 18k btu window unit, although my garage has no windows. I could install it in a corner of the barn doors on the back of the garage. I built those doors, 1x2 metal frame welded up and then plywood over that (that exterior grooved stuff). I know the upper door would easily handle the weight of the unit and I hardly ever use those doors anyway, they were just put in so I could get a car in the back if I ever needed to. I have a Hot Dawg gas heater so don't need the heat that a mini-spit would give me, just want the cool. I have a 50amp plug near the barn door for my TIG, hardly ever us that plug (dedicated 50amp on every wall), since I weld up front mostly now.

    Any suggestions ? mini-split or just plain old window unit ? Garage is 980sq. ft. and is very well insulated, 2x6 walls filled with insulation and I went overboard on the ceiling insulation, stays cool well into the afternoon even on the hottest days but by mid-afternoon it is quite hot. I live in S. Calif.
    Last edited by Mike Rambour; 04-19-2021 at 6:36 PM.

  4. #19
    Join Date
    Dec 2006
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    Mesa, Arizona
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    Mini-split. To install a through-the-wall (or window) unit, you'll need to create the opening in the wall. In my experience, that would be far more difficult than drilling a hole through the wall in which to run the mini-split's lines. Perhaps, it might be easier to run the electrical on the inside of the shop than the outside. I think where that is a significant issue would be rare.
    David Walser
    Mesa, Arizona

  5. #20
    Join Date
    Oct 2019
    Location
    Santa Barbara, CA
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    no I would just cut a hole in the door...that end has a barn door arrangement that I don't have even opened in over 10 years, so just cut a hole in the upper door. I welded it up 20 years ago so I can modify it easily.

  6. #21
    Join Date
    Mar 2003
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    SE PA - Central Bucks County
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    Quote Originally Posted by Bert McMahan View Post
    Wow, that's great info... I got estimated $4k to install a mini split around that size in a new buildout. I'm also curious too- did you need a license to get the refrigerant?
    Many of these units come pre-charged...the lines just need to be cleared out with the vacuum. If I'm not mistaken, some "Mr Cool" systems don't even need that. But for anyone wanting to self-install, be sure that "homework" is done beforehand to insure things go smoothly. Sometimes one can also get an HVAC "moonlighter" to do the commissioning. For the unit in my current shop, I did most of the site prep and some of the physical installation and it saved me some money because it cut the time for the professional quite a bit. (The HVAC contractor is a sorta-friend and were willing to work with me on that)
    --

    The most expensive tool is the one you buy "cheaply" and often...

  7. #22
    Join Date
    Jul 2006
    Location
    Tampa Bay Area of Florida
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    867
    I'm on my 3rd mini split here in the Tampa Bay Florida area. I live on the water and the salt air apparently gets to the outside unit as I am lucky to get 5 or 6 years out of a unit. The last replacement unit I purchased online for about $1000 and had a local HAVC guy install it for $500, this after having a local HVAC company give me a price of nearly $7,000 to install one. My shop is in a 2-car garage with NO ceiling insulation and an insulated hurricane garage door and block walls. Even with no ceiling insulation I hardly noticed a difference in my electric bill. The unit will cool to the point of too cold and keeps it toasty in our occasional cold spells. I have had NO issues with any tools or cast iron rusting for the last 15 years I have had my shop. Make sure you routinely vacuum suck the drain hose to remove any clogging as you run the risk of the unit dripping significant amounts of condensation water into your shop.

    BTW, speaking of rust, I am building a boat out back in our screened porch. I've not worked on the boat since early November. I made the mistake of leaving about 100 clamps of all types out in the porch and they all rusted, some extensively. I got a tub and poured 10 64-once bottles of Vinegar All Purpose Cleaner (at $1.10 per bottle at HDepot), let the clamps soak for a day, and all the rust was gone!! I've now put a thin coat of rust prevention on them. A real cheap but effective method of removing rust.

  8. #23
    Quote Originally Posted by Ronald Blue View Post
    So you had to vacuum the system and charge it? I'm surprised everything wasn't pre-charged. Where did you get the Freon? I'm licensed so not an issue but just curious.
    As a pro, you probably already know this but, you can buy mini-splits three ways. One is not charged at all and probably the type most used in the trade. The second is the super DIY friendly "Mr Cool" units . Their indoor and outdoor units are shipped already in vacuum. The line-set comes precharged with r410a. The upside is that all you do is just connect and go. The downside is that, since it's precharged, the line-set length is fixed. Most people just store the extra in loops behind the compressor. Lastly, there are semi-friendly units like the Pioneer I bought. With them, the outdoor compressor comes pre-charged. You have the extra steps of cutting the line-set to the correct length, forming the flare and vacuuming the line and testing for leaks before you release the r410a into the system.

  9. #24
    Join Date
    Dec 2006
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    Mesa, Arizona
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    Quote Originally Posted by Terry Wawro View Post
    ... Lastly, there are semi-friendly units like the Pioneer I bought. With them, the outdoor compressor comes pre-charged. You have the extra steps of cutting the line-set to the correct length, forming the flare and vacuuming the line and testing for leaks before you release the r410a into the system.
    Question: Doesn't the amount of refrigerant (r410a), depend, in part, on the length of the lines? That's why I went with the Mr. Cool instead of the Pioneer. I was concerned that, if my lines were too short, the pressure in the system would be too high. If my lines were too long, the pressure would be too low. That's not an issue with Mr. Cool because the amount of refrigerant is based on the length of the lines. After my unit was up an running for a couple of months, I had the service tech, who was performing the regular annual maintenance on our A/C units, shorten the lines on the Mr. Cool mini-split. He charged an additional $100 for that work -- and took any excess refrigerant with him when he was done.

    I didn't go with Pioneer (I could easily rent the gauges and other equipment for not much money) because I was afraid I'd need to vent any excess refrigerant to the atmosphere. I'm happy with the Mr. Cool mini-split. I'm genuinely asking because I'd like to know what my options are if I ever need to install another mini-split.
    David Walser
    Mesa, Arizona

  10. #25
    Quote Originally Posted by David Walser View Post
    Question: Doesn't the amount of refrigerant (r410a), depend, in part, on the length of the lines? (SNIP)
    I didn't go with Pioneer because I was afraid I'd need to vent any excess refrigerant to the atmosphere. I'm happy with the Mr. Cool mini-split. I'm genuinely asking because I'd like to know what my options are if I ever need to install another mini-split.
    The answer is yes, sort of. Mine came with a 16ft line-set. The manual said I could shorten it, but it required a minimum of 10ft to function properly. I don't remember the max but the manual had a chart that gave figures on how many lbs of refrigerant to add for x additional feet of added line-set.

  11. #26
    Join Date
    Mar 2003
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    SE PA - Central Bucks County
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    You can often order line sets in various lengths to eliminate the need to deal with excess. That's obviously brand-specific. The 10 ft minimum seems to be a common requirement if my memory serves from when I did this dance a couple of years ago.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  12. #27
    Quote Originally Posted by Mike Rambour View Post
    I have been thinking of doing a Mini-split also. (snip) I have a Hot Dawg gas heater so don't need the heat that a mini-spit would give me, just want the cool.

    Any suggestions ? mini-split or just plain old window unit ? Garage is 980sq. ft. and is very well insulated, 2x6 walls filled with insulation and I went overboard on the ceiling insulation, stays cool well into the afternoon even on the hottest days but by mid-afternoon it is quite hot. I live in S. Calif.
    Mike, I did a mini split for heat & cool comfort. I went from a window mounted ac for cooling and a 1500 watt space heater for heating. The window AC did fine, but it did take a long time to cool the shop down. The space heater in winter just never got the shop warm enough to make it enjoyable to work in.

  13. #28
    Join Date
    Sep 2016
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    Modesto, CA, USA
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    If the line set goes over 40 feet or so you have to add refrigerant. It has to be measured in by the 1/4 ounce or so. I used my car r12 ac gauge set with an adapter to the miniport used on mini splits. I only used the gauges for vac and fill. Run pressure would be too high. R12 gauges are cheap since they are no longer used.
    I insulated the lines inside the interior wall with swimming pool noddles from the dollar store and then poured in vermiculite.
    Bill D
    Bill D

  14. #29
    Quote Originally Posted by Bruce McVeety View Post
    Congratulations on the DYI. I had one sized for my garage shop, and was convinced by HVAC specialist that bigger wasn’t necessarily better and an appropriately sized unit would do a better job of keeping the humidity consistent. I moved before I installed one here in Ohio, but I’m considering whether to put one in the shop I’ll be building at my soon to be retirement home in norther Minnesota. Up North it will be mostly for heat, but also for humidity control on the big Lake shoreline.
    Where along the “big” lake will you be located.? We have a home right next to gooseberry falls. Just curious. I have a small shop and the cast iron tables on machines do get rusty

  15. #30
    Join Date
    Sep 2016
    Location
    Modesto, CA, USA
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    9,889
    FYI: you also need to clean the drain downspouts and gutters on your cars sunroof every few years. Black moldy gunk build up and can clog the drain lines. Then any water will flow into the headliner and stain it.
    Bill D.

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