Dual Zone Mini-Split Question
 

We will be enclosing our lanai and adding a mini-split, but I am considering having them install a dual zone for our lanai as well as our garage. So that would be two inside units with one condensing unit. I am tracking that I need to insulate the lanai and garage ceiling, etc. Has anyone else here done that and if so how has it worked out and did the extra unit double the cost? Thanks
Pilgrim

You definitely need to insulate the ceiling in the lanai and the garage.

Personally, I would install two separate standalone units, one for the lanai and one for garage. I suspect that the unit in the garage will not be used very much.

OP, if you are in Sumter county, be sure to have your lanai enclosed to level 4 or 5 or you will be denied the HVAC for your lanai. The "work around" is to have a dehumidifier installed in the lanai and as far as i can determine these are ONLY the Mitsubishi units at an installed cost of $5k to $7k. The downside to level 4 or 5 may be an increase in taxes. You will need to discuss with the building department. Send me a PM if you want the gory details.

One other item specific to the dual zone mini-splits, the ones I was researching had limitations on the length of the of the coolant lines, so in my case I could not get to the garage unless these were in the attic, and for some reason I thought this was not suggested.

M&S Air Conditioning (HVAC Company Serving The Villages, FL | M&S Air Conditioning 352-310-8223) installed a dual Mitsubishi system - ceiling cassette unit in lanai and wall unit in garage with one compressor unit outside of garage next to HVAC (lanai and garage are on opposite sides of house with lanai in back and garage in front). Single cassette was $5,000-$6,000 with smaller outside unit. Both units with single, larger outside unit was around $10,000. They ran the coolant line for the Lanai ceiling cassette across the attic (not a problem) to the outside unit on the outside of the garage and the drain drops from soffit outside the lanai. Drain for garage wall unit is through wall and runs down outside wall. At this point we have not insulated above the lanai or garage, but we may in the future. Currently, both areas cool quickly and quietly. The dual zone is great as we only use the A/C when we are using that particular area and turn it off when we leave that space. M&S will give you a free quote and answer all your questions. There's also a possible tax advantage (I am not giving tax advice). Mitsubishi mini-split (heat pump) may be eligible for a 30% income tax credit. I really like Tinker and his advice and help is first-rate, but he is mistaken on upgrading lanai. M&S sets up the mini-split so it is considered a dehumidifier for Sumter County code even though it also cools.

Our experience is much like PJ SMILEY'S comments. We used Munns because they also did the attic insulation in the same contract while some companies don't, so you have to get a second contractor. We have one dual-head compressor. Everything works great and we use both our lanai and garage much more now. We are glad we did it. We can use both at the same time. Sorry I don't have the cost details at my fingertips, but the cost was not double. Something like 75% of two separate units. We got three bids. All of the estimators were knowledgeable and helpful. Go for it.

One anecdotal comment is that our garage is on the sunny side and the Lanai on the shady side. One evening we were playing poker in the garage, which was warm, and the AC would not stay on. We had the heater on in the lanai and come to find out you can't run one on AC and one on heater at the same time. Likely you would never encounter this.

Thanks so much, I will check that out. I had not considered the length of the refrigerant lines.

Thanks so much for sharing your experience as well as the details. I knew someone else had to have done this and it is great to hear your experience. I agree with you that Tinker always has great information I really appreciate his willingness to share.

The maximum lineset length is in the installation instructions. There may also be a vertical distance limit. For our Mitsubishi mini-split, the maximum lineset length was on the order of 100 feet or so, IIRC. Running it through the attic is not a problem. A reputable company will advise you on what can and cannot be done.

Several years ago, we had our lanai enclosed and air conditioned with a Mitsubishi split; approximately 15K BTU. It has saved us twice when the main AC unit died...... once for a 7-day repair. Having a second, completely independent unit was the way we chose to go. It was a lifesaving decision since both outages occurred during the depth of the summer heat waves.

Thanks so much for sharing your approach and experience. For some reason I had not considered that but it is a great advantage to having the separate units. Many Thanks,

I had my garage done and discussed a dual zone for lanai. The biggest question will be depending on your setup is the line length. I got quotes from 4 different companies and i will say they were all over the board. M&S was way higher (~8500 for just the garage) than any other quote on a lower model Mitsubishi unit. I went with the middle quote from Kalos (~6000) as I have seen the work they do on other homes as well as the people seem to respond quickly according to friends that have used them for repairs, etc. One other thing to note, Mitsubishi extends the warranty by a couple years on some of their units if you use a gold certified installation/sales company. Make sure you check that with whoever you use.

Regarding insulation of the garage and lanai ceilings, there are many companies but I've used and prefer the Solar Guys. Reason is becasue they did a very thorough job with no mess or damage to my home. Remember to get to the Lanai ceiling they have to pretty much go accross your whole homes ceiling to get there. They also "cover their tracks" on the way out of your attic so the existing insulation isn't matted down from walking in the attic. They verify the amount of insulation installed and they provide the paperwork so you can claim the IRS CREDIT, not deduction, on your income tax. What this means is you can deduct up to 30% of the total cost of the install right off the top of your income tax. Their prices are also reasonalbe and they offer discounts at various times of the year.

Agree about Kalos. They did ours last year at a very reasonable cost for 3 units (2 lanai, 1 garage). They did our garage attic and lanai insulation too. All 3 of our minisplits are on one large condenser unit. When we had a minor issue once (user error) they came out same day we called and were so helpful.

DEhumidifier……

Typo, I’m sure …..:)