Mini split for shop

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The welding related angle to this thread is I weld in my shop. I plan to install a 24,000 btu mini split in my 1,000 sf shop. I have 2 questions. I was told I only need a 20 amp circuit with disconnect. Do I need a neutral and a ground or just 2 hots and a ground? Thinking the wall unit may use 110v. I’m thinking a ceiling mount near center of shop would work better than a wall unit but they are considerably more expensive. I want the best coverage and that would save valuable wall space. Attic access is fine with pull down stairs. Heavy insulation is already in place. Anybody used one or the other? What do you recommend? Issues cleaning filter?Thank you for your help!Burt _____________________Miller Syncrowave 250Millermatic 211Miller 375 Plasma Cutter Hobart Handler 12010FtDrillBit.com
Reply:

Originally Posted by wb4rt

The welding related angle to this thread is I weld in my shop. I plan to install a 24,000 btu mini split in my 1,000 sf shop. I have 2 questions. I was told I only need a 20 amp circuit with disconnect. Do I need a neutral and a ground or just 2 hots and a ground? Thinking the wall unit may use 110v. I’m thinking a ceiling mount near center of shop would work better than a wall unit but they are considerably more expensive. I want the best coverage and that would save valuable wall space. Attic access is fine with pull down stairs. Heavy insulation is already in place. Anybody used one or the other? What do you recommend? Issues cleaning filter?Thank you for your help!
Reply:They have blowers, so wall mount is probably near as efficient as ceiling. You want a circular air movement pattern. Usually they mount high on the wall where space is less at a premium.An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.
Reply:ceiling mounted cassette types work fine if ceiling is at least +9ft. below that go with a wall mount but you will still have concentrated a/c air flow . or you can use the remote mount blower units that will use ducting like traditional a/c.if unit is 230v then all you need is 2 hots and a ground to the outside unit. the inside will get it's power from the outside unit. they cool very well as outlet temps are much lower than traditional central air.Last edited by filetobeef; 03-26-2021 at 09:49 PM.
Reply:

Originally Posted by filetobeef

ceiling mounted cassette types work fine if ceiling is at least +9ft. below that go with a wall mount but you will still have concentrated a/c air flow . or you can use the remote mount blower units that will use ducting like traditional a/c.if unit is 230v then all you need is 2 hots and a ground to the outside unit. the inside will get it's power from the outside unit. they cool very well as outlet temps are much lower than traditional central air.
Reply:I currently have two mini-splits operating here on the farm.  One is a Mitsubishi unit with a ceiling cassette in a 750 sq, ft well insulated building, and the other is a Pioneer wall mount unit in a 250 sq. ft log cabin.  Both are heat pumps that provide both heating and cooling.The Mitsubishi is a top of the line unit.  They cost more than other mini-splits, but have the best reputation in the industry.  We used to use them on in-building cellular sites when traditional HVAC equipment was not an option, and their durability is superb.The Pioneer unit has been ok.  A power surge wiped out a control board in it (not it's fault), and the replacement part was covered by warranty (but not the labor).  It was about 40% of the cost of the Mitsubishi unit ($1,000 for the basic package versus $2,800 for the Mitsubishi package)Their efficiency is excellent (20+ seer ratings), but they don't recover quite as fast as a traditional split unit if you have the doors open a lot.  The Pioneer unit does not work as well sub-freezing as the Mitsubishi unit does, but that's probably a case of you get what you pay for.A 20 amp circuit is all that's required for a 240VAC system.  I don't think that either of mine required a neutral, but I ran one anyway so that I could install a 120VAC receptacle next to the condenser for maintenance needs.Miller Trailblazer Pro 350DMiller Suitcase MIGMiller Spectrum 2050Miller Syncrowave 250DXLincoln 210MP
Reply:

Originally Posted by scsmith42

I currently have two mini-splits operating here on the farm.  One is a Mitsubishi unit with a ceiling cassette in a 750 sq, ft well insulated building, and the other is a Pioneer wall mount unit in a 250 sq. ft log cabin.  Both are heat pumps that provide both heating and cooling.The Mitsubishi is a top of the line unit.  They cost more than other mini-splits, but have the best reputation in the industry.  We used to use them on in-building cellular sites when traditional HVAC equipment was not an option, and their durability is superb.The Pioneer unit has been ok.  A power surge wiped out a control board in it (not it's fault), and the replacement part was covered by warranty (but not the labor).  It was about 40% of the cost of the Mitsubishi unit ($1,000 for the basic package versus $2,800 for the Mitsubishi package)Their efficiency is excellent (20+ seer ratings), but they don't recover quite as fast as a traditional split unit if you have the doors open a lot.  The Pioneer unit does not work as well sub-freezing as the Mitsubishi unit does, but that's probably a case of you get what you pay for.A 20 amp circuit is all that's required for a 240VAC system.  I don't think that either of mine required a neutral, but I ran one anyway so that I could install a 120VAC receptacle next to the condenser for maintenance needs.
Reply:

Originally Posted by wb4rt

Thinking the wall unit may use 110v.
Reply:Met with my friend who is a HVAC guy. He thinks a wall mount is better and has less parts than a ceiling mount. I’ll run power to a disconnect box and he will do the rest. I’ll post pictures and give a review in a week or so.Burt _____________________Miller Syncrowave 250Millermatic 211Miller 375 Plasma Cutter Hobart Handler 12010FtDrillBit.com
Reply:

Originally Posted by Willie B

They have blowers, so wall mount is probably near as efficient as ceiling. You want a circular air movement pattern. Usually they mount high on the wall where space is less at a premium.
Reply:

Originally Posted by Capt B

I would love to know how you like the system you go with.  I have been planning on adding one to my garage at home but haven't had the time to do much research yet. I was hoping to get it done before this summer but not sure if I'll get to it by then.
Reply:Another vote for Mitsubishi....I have a Mr. Slim for my shop that's 30K AC and heat pump.  It's a wall-mount and my ceilings are a bit over 13' so I put it up as hight as possible.  It easily cools my shop that's 1,000 square feet, and the heat is only used in part of the year....I have a radiant floor heat setup for when it gets really cold and part of why I went with mounting the unit up high to work best for cooling.You almost can't hear the thing run, and they really don't use much electricity at all.  I would buy another in a heartbeat!Check out my bench vise website:  http://mivise.comMiller Syncrowave 250DXMillermatic 350P with XR AlumaProMiller Regency 200 with 22A feeder and Spoolmatic 3Hobart Champion EliteEverlast PowerTig 210EXT
Reply:Got the unit connected yesterday. Man, is it quiet. It only pulls 6-7 amps on high AC, so it should be cheap to run. Inside unit:

Outside unit:

Burt _____________________Miller Syncrowave 250Millermatic 211Miller 375 Plasma Cutter Hobart Handler 12010FtDrillBit.com
Reply:

Originally Posted by wb4rt

Got the unit connected yesterday. Man, is it quiet. It only pulls 6-7 amps on high AC, so it should be cheap to run.
Reply:Great topic, good info to know. Thanks!
Reply:cover the lines with the split line cover kits so the foam lasts and helps with efficiency.
Reply:

Originally Posted by filetobeef

cover the lines with the split line cover kits so the foam lasts and helps with efficiency.
Reply:Throw some more straps on the PVC conduit or it will sag, one of the things I dislike about exposed horizontal runs of PVC conduit is it's propensity to sag.
Reply:

Originally Posted by Norcal01

Throw some more straps on the PVC conduit or it will sag, one of the things I dislike about exposed horizontal runs of PVC conduit is it's propensity to sag.
Reply:That should work out well for you.  Mine is so quiet that you don't even know when it's running.Good clean installation too.Miller Trailblazer Pro 350DMiller Suitcase MIGMiller Spectrum 2050Miller Syncrowave 250DXLincoln 210MP
Reply:Looks Great! I plan on doing the same hopefully soon.Lincoln 350MPMillermatic 350PSyncrowave 2501969 SA200HTP Invertig 221
Reply:Just curious did the unit come precharged with refrigerant? I was reading that some do.Lincoln 350MPMillermatic 350PSyncrowave 2501969 SA200HTP Invertig 221
Reply:

Originally Posted by Capt B

Just curious did the unit come precharged with refrigerant? I was reading that some do.
Reply:

Originally Posted by wb4rt

Yes, comes with Freon for up to 16’ (I think) line set but you need a tech to vacuum the lines after connecting. That’s why I had to have  HVAC guy finish the connections. I hung the inside and outside units, cut the wall port for lines and wiring, and ran circuit to disconnect box. Only requires 15 amp, 220v circuit. So far I’m well pleased with it. BTW, I covered the outside line sets and added clips on the conduit as suggested above.