Decisions on choosing my mini split
- Thread starter therest
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The reason I want it above the workbench is because I want to use the rest of my wall space for a lumber rack/hanging space. I don't work on the workbench as much and if I ever do, that could be easily moved. I'm not entirely against being on the side of the pegboard, so we will see.
I didn't know there was a 10' minimum, and yes I could run the refrigerant lines inside a bit. I'll have to check on that manual of the unit I get for length requirements.
I didn't know there was a 10' minimum, and yes I could run the refrigerant lines inside a bit. I'll have to check on that manual of the unit I get for length requirements.
Yes, a lot of them are not precharged - especially the more expensive brands that are not meant for DIY installation. Most of the cheaper brands are.
It's a matter of efficiency. The right way would be chop the lines as needed and re-flare the connections. Generally I do this with a cheap cutter, cheap flaring tool, and I always use nylog blue (it's like glue for lineset connections, almost cheating) and I've never had a problem.
That being said, it shouldn't make a huge difference to have excess lines as long as you don't have a lot of tight radius bends, and you keep them properly insulated. Personally I just think it looks more professional to cut the excess.
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The weight is kind of a range on these - they say "up to ** feet" uses a certain amount. I'm sure there's a most efficient value for each specific length, but you have some wiggle room.
The only accurate way I know to bleed some out is to use a recovery tank and weigh it with a refrigerant scale. At that point I generally find myself just emptying the whole thing, running a vacuum, and then refilling from scratch using a refrigerant scale and the proper refrigerant amount listed on the unit.
I was thinking the same thing. My instuctions stated if there was a leak after operating the unit, the entire system would have to be purged and refilled to the specific weight. In my opinion, the charged lines are more of a sales pitch. I can’t imagine an install not having to cut the lines to the proper length, or coil up. Your either going to have too much, or too little! Lol It sounds like you are a pro. I am fortunate to have an HVAC tech in my neighborhood. I trimmed the lines, single flared the ends and torqued to spec. My neighbor pressurized the lines, then pulled a vacuum. Do you have a ballpark what someone would charge for that service? Seems like a better option than just coiling them up and possibly kinking a line.
GLFlyer
Well-known member
For reference: I have a 20x20 (400 sqft) garage. Fairly small on the grand scale, and a wall of cabinets as well. I built the garage to house my workbench, tools, and motorcycles. I'm in suburbia so I was pretty restricted on what I could build and how big it could be... especially since it's an additional garage for the house.
Anyway... I'm in Texas as well (DFW), and I ensured that all interior & exterior walls were insulated. It has a 2nd floor room above it and I ensured that the ceiling is also insulated. I have a single 8x16 garage door on the front (facing south) and I insulated that as well.
After researching... I went with a 2 ton Daikin Mini-Split. A bit of overkill for that size, but... it doesn't run all the time, and when I do run it... it cools or heats quickly, and that was my main goal. (Powerful Mode rocks!)
Anyway... I placed it on the wall opposite of my work bench and it's pretty darn comfy... even when it's 100+ outside with high humidity.
Not posting to tell you what unit to get or how much to spend since you seem to have a good contact for that, just telling you what works for me in a similar climate and in a similar space. Had it installed this past winter. Here's a couple of pics for you:
Anyway... I'm in Texas as well (DFW), and I ensured that all interior & exterior walls were insulated. It has a 2nd floor room above it and I ensured that the ceiling is also insulated. I have a single 8x16 garage door on the front (facing south) and I insulated that as well.
After researching... I went with a 2 ton Daikin Mini-Split. A bit of overkill for that size, but... it doesn't run all the time, and when I do run it... it cools or heats quickly, and that was my main goal. (Powerful Mode rocks!)
Anyway... I placed it on the wall opposite of my work bench and it's pretty darn comfy... even when it's 100+ outside with high humidity.
Not posting to tell you what unit to get or how much to spend since you seem to have a good contact for that, just telling you what works for me in a similar climate and in a similar space. Had it installed this past winter. Here's a couple of pics for you:
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Everything I could lay my eyes on for installing these units was to not loop excess lineset in vertical loops. I even called MrCool and the said horizontal is fine, or run it along the side of your building to a more remote location. Something about creating a trap for refrigerant oil in the suction line. The DIY units have a fixed 25' lineset - no deviations.
MrCool and Pioneer appear to be the exact same unit - either that or they're buying the same installation and user manual for them from the same translator or publisher because they are IDENTICAL - I have personally viewed them both. And I mean down to the same words and diagrams and page numbers. I don't think that is coincidence.
The DIY units with precharged lines are far less common - the entire industry implores that ONLY qualified personnel may work on anything air conditioning. I guess it's kind of like being a surgeon. (J/K it's a joke son).
AC pro's are adamant about a proper vacuum of the lines, pressure testing with nitrogen to dry them out, and vac to 500microns. I still don't get what a micron gauge does, but that's what the use.
And you need power, so either diy wiring or hire an electrician.
MrCool and Pioneer appear to be the exact same unit - either that or they're buying the same installation and user manual for them from the same translator or publisher because they are IDENTICAL - I have personally viewed them both. And I mean down to the same words and diagrams and page numbers. I don't think that is coincidence.
The DIY units with precharged lines are far less common - the entire industry implores that ONLY qualified personnel may work on anything air conditioning. I guess it's kind of like being a surgeon. (J/K it's a joke son).
AC pro's are adamant about a proper vacuum of the lines, pressure testing with nitrogen to dry them out, and vac to 500microns. I still don't get what a micron gauge does, but that's what the use.
And you need power, so either diy wiring or hire an electrician.
renjaminfrankln
Member
Pressure testing with nitrogen is just to check for leaks. Nitrogen is cheap and dry, you could do it with air but you would introduce a lot of moisture into the system that you would then have to vacuum out. Not to mention contaminants like oil from your air compressor...
Vacuuming dries them out and removes contaminants. If you vac down to a certain level you are guaranteed to have removed X amount of moisture and contaminants. So you have a clean, dry pressure tested system. Then you just release the charge into the system, and you're good to go.
Of course its probably worth it to just pay a pro for 2 hours of time than buy the right tools and a vacuum pump.
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Found a quote from some guy on a popular app to just pressurize and pull a vacuum for $250, although he MIGHT not be licensed. I'm not the one to put a price on someone's work that I know very little of, but I would like to be able to find someone for less.
You can lay-off excess line set length in a serpentine fashion. If you run horizontally make sure there are no low spots. You accumulate oil there just as you would with a coiled line-set. If you can find a pro to evacuate and charge the system you will be money ahead, in my opinion. I would not install a unit that blows directly on me. In cooling the unit is designed to introduce the cool air across the ceiling where it can settle. In heat it is designed to blow down towards the floor as the heat will rise. The lower end units generally will have a horizontal air sweep. Some 12's have a four way air sweep but usually higher end units. You are talking about 400 open sq ft. The air circulation will not be a problem unless you restrict it somehow. Install the unit where it opens into the space for best air circulation. It is a modulating piece of equipment and will run for extended periods at whatever rate it decides giving a uniform temp throughout the space.
Heck, For $250 you may be able to purchase the equipment yourself. I wonder if any rental places rent a nitrogen tank?
https://www.ebay.com/itm/HVAC-A-C-R...-Vacuum-Pump/182612878442?hash=item2a8493646a
https://www.ebay.com/itm/HVAC-A-C-R...-Vacuum-Pump/182612878442?hash=item2a8493646a
Curious, but will this pump do the job as well?
https://www.harborfreight.com/25-cfm-vacuum-pump-98076.html
https://www.harborfreight.com/25-cfm-vacuum-pump-98076.html
teal95
Well-known member
I put a Mr Cool DIY unit in the in law suite above my shop. Attic trusses with 2 6' wide dormers both front and rear so around 600 sq ft. Seems to be working fine for me. I called 3 local companies for bids, 2 didn't even respond and the 3rd wanted $9k. I asked why so high since the I could get a kit for less than $2k and his response was "we use a better unit, a Mitsubishi". When I told him I could get the Mitsubishi for less than $3k and I knew it was much less than a full day job to install it he did some mumbling and hung up on me. The "industry" is really protective of their turf and I'll remember that, especially since I had to spend 4 hours helping their technician troubleshoot a failed valve in our less than a year old furnace.
softailtom
Well-known member
Specs on that pump says it will vacuum down to 75 microns? The specs on my unit said to vacuum to 500 microns. I’m not up to par on the whole micron thing. I used to work on cars for a living. Back in the day, we would vacuum an a/c system down to 29 inches of mercury. This would ensure there was no moisture in the lines. Water vaporizes under vacuum. We always looked for 29. Not really sure why. Lol I’m assuming that would be enough vacuum at any ambient temp. to vaporize the moisture.
Since when do we trust HF claimed numbers?
You only need to go under 500 microns, saw some youtube with "chinese" pump have quite a bit of problem getting down there, getting too hot, need to change oil, etc, I think he had to triple evac it to get there, but he did.
You only need to go under 500 microns, saw some youtube with "chinese" pump have quite a bit of problem getting down there, getting too hot, need to change oil, etc, I think he had to triple evac it to get there, but he did.
Exactly what I got here near Disneyland. $5K for a Mitsubishi or $4200 for a Daikin. I did find a couple of hvac pro's that would do a test-vac-turnup on offtime for cash, or I could have got the tools, but it was so easy to just receive equipment and install it and have it work. Very happy with that.
The only downside is ours have run pretty much 24-7 for a month due to a super hot summer, and we hit the next tier for power so our bill doubled - from $200 to $400. Oh well, it's nice to be comfortable. They work just fantastic - we have 3 tons with the 2 units and they cool the whole house.
justinjoyal
Well-known member
I’m sure we were. We used to have a air powered vacuum pump at the dealership. We would just let it **** down for about 30 minutes, then charge the system. I’m thinking we had few problems because of the giant reciever/dryer on those older car systems and the old R12.
I’m also questioning the claimed numbers on my cheap chinese mini split! Lol
Educate me. Are microns and inhg not the same thing? I assumed microns were just a more accurate measurement.
danb35
Well-known member
In a vague sense, yes. Inches of vacuum are a measurement of negative pressure relative to ambient atmospheric pressure--a higher number is a stronger vacuum. On a "standard" day at sea level, a perfect vacuum would be 29.92". Microns are a measurement of absolute pressure (so 0 microns would be a perfect vacuum), and are still measured on the mercury scale. One micron is 0.001 mm--or put differently, 1000 microns = 1 mm. Since this usage measures absolute pressure, a smaller number is a stronger vacuum.
On that standard day at sea level, 29" of vacuum would equate to 0.92" absolute pressure, or 23.368 mm, or 23,368 microns. To be equivalent to 500 microns, you'd need to read 29.90" of vacuum.
Good info. Would you say that pulling a continuous vacuuum at 30” would be sufficient enough to evacuate the lines then? I looked at my old gauges, and it stops at 30 on the vacuum side.
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justinjoyal
Well-known member
You need a micron gauge to properly measure the vacuum. Otherwise you cant tell if you still have moisture in there and you are just guessing.
danb35
Well-known member
Standard atmospheric pressure at sea level is 29.92", so 30" of vacuum would be impossible under those conditions--and in any event, your dial vacuum gauge doesn't have anywhere near the resolution needed to do this properly. Could you get away with it? Probably. But it isn't the right way to do it.
Very good info. Probably would not be worth investing in all the equipment including a micron gauge unless you are doing it every day. Also a good question to ask if someone hires a technician to do the final pressure check and vacuum.
danb35
Well-known member
If it does what its specs say it will do, it should work.
SALIV8
Well-known member
Never heard of mirage. Will check them out.
And I think my wife has the same purse. Lol
And I think my wife has the same purse. Lol
Some of the more obscure brands coming into the states...
AUX
Mirage
Midea
Soleus
Pioneer
Blueridge
Gree - not so obscure, but a huge manufacturer that rebrands, like for Lennox, Carrier
One can find really inexpensive product online, ebay and through direct distributors and importers. It's prudent to actually talk to them to vet them, if you intend to buy and expect any kind of support or warranty coverage. Some are simply call centers shipping cartons out of a warehouse, some are a garage operation.
MRCOOL is the only one I'm aware of the doesn't exclude owner installs in warranty coverage fine print. And Ingrams Water and Power is the primary distribution arm for them, the importer is in Miami - I've talked to them. Last year they brought 4000 units in and sold out mid-season. They initially tried to sell through conventional HVAC channels but got so much resistance they went their own way. The traditional industry only sells Mitsubishi, LG, Daikin, and Freidrich. And they charge a LOT for them.
It helps to understand that these units get installed all over the world. Local installers charge about $50 to install one in third world countries, like middle-east, poor asian countries, south american and africa. Only in the US do you find contractors wanting thousands of dollars to do the same job. The HVAC industry here is quite mature and steeped in traditional forced-air systems that are complex and expensive. The whole business model is built on that, so the profit model for cheap air simply doesn't work for them. Instead of embracing it and developing a profit model, they rail against them as ugly, cheap, poor quality, inefficient, and undependable. All of which is untrue. My favorite one is that women don't like the look of the inside air handler - sure, they don't even know what it is, and no worse looking than a floor fan. LOL
AUX
Mirage
Midea
Soleus
Pioneer
Blueridge
Gree - not so obscure, but a huge manufacturer that rebrands, like for Lennox, Carrier
One can find really inexpensive product online, ebay and through direct distributors and importers. It's prudent to actually talk to them to vet them, if you intend to buy and expect any kind of support or warranty coverage. Some are simply call centers shipping cartons out of a warehouse, some are a garage operation.
MRCOOL is the only one I'm aware of the doesn't exclude owner installs in warranty coverage fine print. And Ingrams Water and Power is the primary distribution arm for them, the importer is in Miami - I've talked to them. Last year they brought 4000 units in and sold out mid-season. They initially tried to sell through conventional HVAC channels but got so much resistance they went their own way. The traditional industry only sells Mitsubishi, LG, Daikin, and Freidrich. And they charge a LOT for them.
It helps to understand that these units get installed all over the world. Local installers charge about $50 to install one in third world countries, like middle-east, poor asian countries, south american and africa. Only in the US do you find contractors wanting thousands of dollars to do the same job. The HVAC industry here is quite mature and steeped in traditional forced-air systems that are complex and expensive. The whole business model is built on that, so the profit model for cheap air simply doesn't work for them. Instead of embracing it and developing a profit model, they rail against them as ugly, cheap, poor quality, inefficient, and undependable. All of which is untrue. My favorite one is that women don't like the look of the inside air handler - sure, they don't even know what it is, and no worse looking than a floor fan. LOL
