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Picture of holdem
posted
I live in Orlando, FL. That is relevant, think heat and humidity.

I am considering installing a mini-split A/C system, which I know many people on this forum have mentioned having. This is something I would pay a professional to install. It would either have to be a unit installed into the roof that vents into the attic, or it would have to go through cinder block. I would also want this unit to be able to cool the garage to the mid 70's when it is 90+ degrees outside, because this would be my home office workspace. I do have an insulated garage door and tint on the small windows.

Is a mini-split capable of this type of temperature drop? Two sides are cinder block, one side is the home interior, and the other is the insulated garage door. And what type of price should I be looking for? I have no idea if this is $2-$3K job, or if this will run well over $5K?
 
Posts: 1658 | Location: Orlando | Registered: April 22, 2007Reply With QuoteReport This Post
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I could not find it right now but there is an episode of "Ask This Old House" that installs a unit very similar to your needs. In fact I believe it was also in Florida with cinder block walls in a garage.

I installed a 12k BTU unit for my in-laws and it cools an area bout 600 sqft very well and we are in Central Tx.

The unit I got was $650 and I hired HVAC company to pull vacuum and check work, everything included install of new disconnect including unit was just under $1k.
 
Posts: 2060 | Location: Central TX | Registered: February 02, 2006Reply With QuoteReport This Post
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How many square feet if the garage? I’ve installed about 8 of them for spaces from 200 sq feet up to 1500 sq ft. The mini split systems will vary in price from $800 up to 5-6k. Assuming a garage in the 450-750 sq/ft range a wall mini split will probably be $1200-2200 plus installation. A lot of it depends on manufacturer. The first 4 I installed where all LG but the last 3 have been Pioneer and they have all worked the same. Additionally all of the units I’ve installed were wall mounted or a concealed version that connects to duct work, the ones that mount in the ceiling tend to be a little more expensive and on the larger side btu wise.

Biggest issue I’ve had with them is leaking refrigerant where the compression fittings connect the line set to the indoor or outdoor unit but if your paying someone to install that will be on them. The mixture of high pressure and temp change makes the threads work their way loose enough to leak, found an engineering white paper on the issue about 5 years ago and noticed the unit I put in this spring included a paste for the threads.
 
Posts: 2447 | Location: Arkansas | Registered: July 21, 2007Reply With QuoteReport This Post
Too soon old,
Too late smart
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Figure about 6k depending on size of unit. How do you intend to drain the condensate from mini split?


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Posts: 1165 | Location: NoVa | Registered: March 14, 2009Reply With QuoteReport This Post
Ermagherd,
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You can get hi walls up to 3 tons, at least in the brands I deal with.
I would say perfect solution for what you're doing.
A new ducted system, no existing duct, will be more expensive.

If you can gravity drain down the wall that's ideal, or you will need to add a condesate pump.


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Posts: 2632 | Location: WV | Registered: September 02, 2006Reply With QuoteReport This Post
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I installed a heat/cool split (Mitsubishi) in my finished two-car garage...cost about $4000. I got a long term warranty as well on parts/labor (12 years).

Can keep up with hottest days and coldest winters...very efficient. If I open the doors, it restores humidity/temp in minutes.

I cant tell you how nice it is to work on projects now anytime during the year.


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Posts: 6079 | Location: South East, Pa | Registered: July 04, 2002Reply With QuoteReport This Post
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Picture of holdem
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quote:
Originally posted by sureshot45:
How many square feet is the garage?


Small 2 car garage, 20' deep, 19' wide, so 380 sq ft.

quote:
Originally posted by RogB:
How do you intend to drain the condensate from mini split?


No idea. That's why I plan to hire someone, that will be their issue to figure out.
 
Posts: 1658 | Location: Orlando | Registered: April 22, 2007Reply With QuoteReport This Post
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I recently added a Daikin(Goodman) mini-split system in my Shop building. Got the 3 ton compressor with 2-1.5 ton evaporators. Put one upstairs and the other down. the upstairs is about 450 sq ft and the down stairs is about 625. Works great and now my wife and I can control the temps independently. Before the vented system had the tstat down so to make it comfortable up, it was cold down. The only drawback I have noticed is that the humidity control is proportional to how hard the unit runs. Since they are variable they are not just on or off. They can run at 40%, 60% etc. They only run hard enough to keep the set temp. So the humidity will be 55% during the hot part of the day but maybe 65% at night. I tried the "dry" mode and all it does it keep the compressor on all the time. Dries it out but drops the temp between 4-5 degrees. It got really cold in that mode. I paid about 6k installed, which included the removal of the old heat pump.
 
Posts: 766 | Location: Alabama | Registered: January 05, 2005Reply With QuoteReport This Post
Too soon old,
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I assume your heat pump is outside? Personally I would want the unit placed nearby if there's room. Should be cheaper for installing the new electrical service. Also more accessible.


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Posts: 1165 | Location: NoVa | Registered: March 14, 2009Reply With QuoteReport This Post
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Condensate drains out to where the condenser sits outside. They rung the lines in a bundle.


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Posts: 6079 | Location: South East, Pa | Registered: July 04, 2002Reply With QuoteReport This Post
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Yes, my customer has a 2.5 car garage in Fort Lauderdale with ultra tall ceilings, 14-16' I'd guess, and it has one mini split and will keep it at 70F no problem.
 
Posts: 20220 | Registered: June 12, 2005Reply With QuoteReport This Post
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We have a Mitsubishi split unit we put in a couple years ago at work - multi zone that runs dual zone and its been outstanding. One of our other locations had another unit installed - an LG and since install 6 months ago no issues.

I know you mentioned you would have someone do it - so the following is more just sharing for others in case they considered it and also a point that these split units work exceptionally well and I think in FL would still work well if sized correctly. (and a humble brag cause yeah its cool I did a thing myself and saved some $) At home I put in a split unit in our garage - decided to go DIY and bought from HVACDirect.com - they actually have a unit that is pre-charged with refrigerant so no need to vacuum/fill - went with the 115 Volt 12000 BTU for our double car garage (which is well insulated including the garage door) The only caveat of the DIY ready version is the line length is 25 feet - which is way more than I needed. Just have to coil the spare line up which was no big deal but the OCD in me wants a clean line, no coil but the savings means I deal with it. Working like a champ - it actually cools off exceptionally well. We can open the regular back door to the garage to let our rescue cats onto the covered catio and leave the door open a bit and it stays within a few degrees of its 74 setting in southeast Missouri heat and humidity mid summer. All for about $1400 with supplies to install.

Drainage from the inside unit is managed through a drain hose that passes through the same opening in wall as the refrigerant, electric and control cable from the outside to inside unit - it was important to drill the hole through wall with a slight slope toward outside - mine drains exceptionally well to the outside.
 
Posts: 425 | Location: SEMO | Registered: September 13, 2012Reply With QuoteReport This Post
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quote:
Originally posted by tiwimon:
I know you mentioned you would have someone do it -

- went with the 115 Volt 12000 BTU for our double car garage


I looked at one of those on Lowes.com earlier. It was less than $1K. I even read the installation manual in PDF. I think I could do it, especially since I just have to plug it into a standard outlet. I built a deck from scratch this spring. I installed my dishwasher. I installed an under cabinet microwave when there was not one there before. So I am not worthless around the house. But man, I really do not want to be the one to drill holes into cinder block. But, if I keep getting quotes at $4k, I might change my tune.
 
Posts: 1658 | Location: Orlando | Registered: April 22, 2007Reply With QuoteReport This Post
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You didn’t mention it but the ceiling in your garage should be insulated as well if you want to condition the garage. R-30 to 38 should work.
Do not put the unit in the attic. Keep it outside where it’s designed to be.


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Posts: 4666 | Location: SML & OBX | Registered: February 19, 2013Reply With QuoteReport This Post
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quote:
Originally posted by holdem:
quote:
Originally posted by tiwimon:
I know you mentioned you would have someone do it -

- went with the 115 Volt 12000 BTU for our double car garage


I looked at one of those on Lowes.com earlier. It was less than $1K. I even read the installation manual in PDF. I think I could do it, especially since I just have to plug it into a standard outlet. I built a deck from scratch this spring. I installed my dishwasher. I installed an under cabinet microwave when there was not one there before. So I am not worthless around the house. But man, I really do not want to be the one to drill holes into cinder block. But, if I keep getting quotes at $4k, I might change my tune.


Really not hard to drill through cinderblock with the right tools - and the savings would be worth even buying what would be needed

https://www.youtube.com/watch?v=P0Pj9zzPN0s

We did our 115v as a separate circuit to the outside unit as we had space in breaker box and it was easy to run a new line from the panel to outside unit. The unit we bought only draws 9 amps at startup so even adding this to an existing regular house circuit that doesn't have an already heavy load would have been okay.

ETA - keep in mind the unit I did - the electric is run to the outside unit - the outside unit sends power to the inside unit - same with the LG and Mitsubishi we have at work
 
Posts: 425 | Location: SEMO | Registered: September 13, 2012Reply With QuoteReport This Post
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quote:
Originally posted by holdem:
quote:
Originally posted by tiwimon:
I know you mentioned you would have someone do it -

- went with the 115 Volt 12000 BTU for our double car garage


I looked at one of those on Lowes.com earlier. It was less than $1K. I even read the installation manual in PDF. I think I could do it, especially since I just have to plug it into a standard outlet. I built a deck from scratch this spring. I installed my dishwasher. I installed an under cabinet microwave when there was not one there before. So I am not worthless around the house. But man, I really do not want to be the one to drill holes into cinder block. But, if I keep getting quotes at $4k, I might change my tune.


Drilling holes through Cinder block is the easy part with the right bit and a hammer drill. The holes aren't that big and the cinder block is hollow.

A 230V unit will be a lot more efficient than 115 volt.

Check into how it effects the warranty if you do it yourself.
 
Posts: 20220 | Registered: June 12, 2005Reply With QuoteReport This Post
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I noticed that Costco sells a portable split unit, it comes all connected together and charged. This means that the entire install can be done by the homeowner. It didn't get great reviews but I'm hoping other manufacturers will follow suit. This will be an alternative for me in the future to traditional hvac systems in South Texas where the ac is used 11 months out of the year and they wear out in 20 years. With replacement costs getting over 10 grand (larger houses with multiple condensers would be even more) a self installed split unit/'s are the way around that. I'm looking at ways to be frugal when I retire and part of that involves doing repairs myself. I'd hate to retire and have my ac go out then have to come up with 20 grand to replace it.
 
Posts: 3220 | Location: Friendswood Texas | Registered: August 24, 2007Reply With QuoteReport This Post
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I may have missed anyone addressing it, but you absolutely cannot vent into attic. I'm certain a professional would talk you out of that, but in case you follow some of the diy advice, please don't install in attic.

On a normal summer day, 90 outside temp, attics can be 40-60 plus degrees warmer.

Your condenser is doing lots of things, but for your info, it is getting rid of heat that refrigerant picked up inside. Placing in attic, would make that difficult, and put even more heat in your attic which would cause other problems.

I have been working HVAC since 1997, I know that mini splits are well suited in some instances.

I know they are very popular.

I also know, it is a glorified window unit with linesets. They are made with plastic, rigid foam, and not terribly hardy. Manufacturers are pretty proud of them as well.

For your application I believe you would be better suited to use a window unit, or a PTAC unit. MUCH cheaper, and easy to replace when it dies. Would require increasing opening, or a new opening, but long term would be more reliable, and less expensive.


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Posts: 879 | Location: Virginia | Registered: October 29, 2007Reply With QuoteReport This Post
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Posts: 2060 | Location: Central TX | Registered: February 02, 2006Reply With QuoteReport This Post
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Winter home in Venice Fla. Installed Mitsubishi heat/cool split in approx. 250-300 sq ft sunroom addition. Around $3K to have installed. Works great, haven't noticed any real significant increase in utility bill. The room is regular wall on one side, 3 sides have decent windows with blinds to keep direct sun out so not highly insulated. Unit keeps room very comfortable. Actually think it has made main A/C work less as that room had been cooled via airflow through large pocket sliding door. My unit seems very efficient and economical after initial hit.
 
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