DIY multizone mini-split system?

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Old 02-11-17, 09:56 AM
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DIY multizone mini-split system?

Hello, I'm looking at possibly buying a house in which most of the second floor is undeveloped. The small finished area is currently heated and cooled with a window unit, as the HVAC ductwork is only on the first floor. (I don't know if the system would be strong enough to heat and cool the second floor anyway.)

I'm contemplating doing away with the window unit and using a multi-zone (in this case probably a tri-zone) mini-split system. I see that normally self-installation voids the warranty, but there are specific DIY systems out there. Unfortunately, the only ones I've found so far are single zone. E.g. the MrCool DIY line you can get at Home Depot. Although you can that system up to 36,000 BTU, it makes no sense to me to have that output in a single zone. I think even a 30,000 BTU with a tri-zone would be a lot more efficient and comfortable over the total space.

FWIW the space involved would probably be somewhere between 1400–1600 square feet. The first floor is listed as 1968 sq ft, but the second floor would need to factor in the angle of the roof; the pitch starts right at the top of the first floor.

Anyway, my basic question is: is there a DIY heating/cooling mini-split system available that is multi-zone?
 
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Old 02-11-17, 10:22 AM
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Welcome to the forums.

I don't have an exact answer for you as I only service units but I can tell you that many of the companies require a pro installation for warranty.

The other pro's will be by. Maybe someone will have a better answer for you.
 
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Old 02-11-17, 01:04 PM
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None specifically marketed towards diy. There are a ton of off brand units available online, mostly Chinese stuff. However I would not suggest one of these as I've heard many horror stories about these units not working well if at all, minimal to non-existent technical support and very poor warranty service.
For a mini, which can be very complicated, I'd suggest Mitsubishi, Samsung, Diakin or Fugitsu in that order. None will honor a diy install. Mitsubishi goes to a length of not honoring any warranty on equipment sold online. They are very protective of their equipment and who works on it.
You need to start with a load calculation to see what your heat loss/gain is.
I'm a factory rep for Samsung and Mitsubishi. The install can be very important to what the end result will be. Purging with nitrogen while brazing, proper leak check to 600 psi. Proper evacuation to 250 microns or less. Proper calculation of end refrigerant charge. Cleanliness while running linesets to prevent contamination.
Had one guy try and soft solder the system in. The flux got into the lineset and destroyed the entire unit beyond repair. Had to rip everything out and start over on their dime.
 
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Old 02-12-17, 07:46 AM
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Thanks, guys. Given the scenario, I do want a tri-zone. I'm looking at maybe this system: https://www.alpinehomeair.com/viewpr...ctID=453069557 and probably at least get a "pro start up" to pressure test the lines, check for leaks, and release the refrigerant. They claim Blue Ridge are made by the biggest manufacturer, but of course they don't name names. But it appears to be a lot cheaper than a comparable big name system.
 
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Old 02-12-17, 08:13 AM
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Never heard of Blueridge. The largest manufacturer of HVAC equipment in the world is Daikin McQuay, and that's definitely not one of their units so their comment is a little off there.
That sizing calculator is a bit of a joke. Your going to want specific heat loss and gain numbers for sizing. Even with inverter drive.
 
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Old 02-12-17, 08:47 AM
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That unit should be plenty large enough for a second floor.
I haven't heard of Blueridge either.

The factory warranty is 1 year parts and labor with 5 years on compressor only.
You can get an extended 2 year warranty for $150.00. Might be a good investment.

But..... if you have problems.... you are still pretty much on your own. You would have to pay a servicing company if you couldn't handle the problem.

One such call could wipe out all the savings on the purchase.
 
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Old 02-27-17, 10:41 AM
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Thanks to all for your comments so far. We've been going through the official buying process. Set to close on April 3. Given what you've told me here, I will probably just get a pro to do the work.

Toward that end, though, what is generally considered best in terms of what to do with the insulation in the floor of the upstairs? Is it best to remove it and allow the downstairs central air HVAC and the upstairs unit to "share the burden," or is it best to leave it in? If I took it out, I could probably move at least some of it to the rafters and save money on insulating the roof.
 
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Old 03-21-17, 12:06 AM
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https://www.amazon.com/MRCOOL-Olympu...one+mini+split

I just found this today as I have been on the search as well. Looks like they are new arrivals.
IDK if its the same as the other Mr.cool. Im assuming so.

https://www.amazon.com/s/ref=sr_st_d...date-desc-rank
 
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