Ductless/Minisplit for a home expansion

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Ornlu
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8:36p, 5/1/22
AG
We're in the middle of getting a contract signed for a home expansion. We're going to add about 500 square feet onto the first floor of our 1.5 story home in Denton. This expansion will remove an entire exterior wall, and make the living room bigger by about 350 square feet. Meanwhile, it'll also add a new office space. These expansions will both have a northern exposure. Most importantly, removing the existing exterior wall will mean a large structural support beam across the new open area.

My AC subcontractor says he can't punch a duct through the proposed beam. I think he's right. Instead, we want to look at a minisplit system for the expansion. Maybe do two blowers (one in living room, one in office), but only 1 condenser.

I'm just starting to research this, so I've got a ton of questions. What units should I look into, or stay away from? Where can I locate the condenser? Is there a way to coordinate the living room thermostat with my other thermostat that's literally in the same room?
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jaggiemaggie
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10:11p, 5/1/22
AG
My parents had a finished attic added when they built their house 15 years ago. The room was pretty useless from May - Early November even because it was too hot. When my kids were born, they decided to turn it to a "play room" for the grand kids. They bought this unit:

https://www.pioneerminisplit.com/products/12-000-btu-ductless-dc-inverter-mini-split-air-conditioner-heat-pump-230-vac

with the 50ft kit.
My dad and I installed it over a weekend and it wasn't too bad. One of the walls had access to the attic and we just ran the line all the way to the soffit to the condenser outside.
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yayaggies
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9:20a, 5/2/22
Mini splits are great!

My understanding is that on the low end most brands are made in the same factories in China from the same parts. Unless you get into a high end Mitsubishi or something in a similar price bracket.

Might be able to integrate the different systems through home assistant.
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Ornlu
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In reply to yayaggies • 11:17a, 5/2/22
AG
Okay, I just got Mitsubishi's preferred contractor near me to schedule a bid. Thanks!
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jamesf
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11:31a, 5/2/22
AG
We installed an LG mini split system in an add-on room that was always super hot. It works well for what it is. Unfortunately, coordinating the thermostat with your main one will not work (or at least that is not an option for my system). The thermostat is one thing that I could never get to work like I wanted it to. The way we use it now is we usually keep it off unless we notice it starts getting hot in there (or cold in the winter), then we will turn it on as needed while we are in the room. In the heat of the summer we may leave it on all day, but controlled by the remote thermostat. We always shut it off at night.

Overall, I think it would be a good option for what you are describing. LG has this unit that hides the indoor unit with a picture frame. I always thought that was a cool feature. When we installed our system, there was an energy efficiency tax credit and the picture frame unit didn't qualify for whatever reason.
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yayaggies
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In reply to Ornlu • 1:24p, 5/2/22
Might also want to get a price on one of the cheap units too. They are not total crap and can sometimes be an order of magnitude less.

It sucks because I much prefer to buy quality but sometimes it really doesn't make sense.
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Ornlu
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In reply to yayaggies • 4:32p, 5/2/22
AG
Thanks. My normal AC subcontractor's going to quote a Pioneer and a Goodman.
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AgAcGuy12
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In reply to Ornlu • 9:44p, 5/2/22
AG
Ductless mini splits are great when done right.
Ducts cannot go through a beam, a truss yes, a beam no.
Mitsubishi is the brand I sell and you'd get a 12yr part warranty because I'm a Diamond Dealer.
The Pioneers, LG, Gree, Daikin, Panasonic etc are going to cool but in my experience they are going to fail sooner. But don't let me tell you that it's always worth the premium price for the Mitsubishi. Mitsubishi units are high! My cost on a Mitsubishi is higher than some of those other brands installed prices. I believe in the saying you get what you pay for but sometimes it's not worth paying.

The biggest takeaway that you as the consumer need to know is they work way different than a traditional AC and require more care and thoughtfulness during the installation and start up. A few things your contractor must do when installing:
1: keep lineset clean, no dust or dirt at all
2: no soldering, must flare the fittings
3: if you must solder you must flow nitrogen during brazing
4: you must pressure test to at least 500psi for 30 minutes
5: you must evacuate properly, triple evac is best
6: you must charge the system by weight based on total equivalent line length
7: you must have a surge protector

Those are the things that come to mind after a 12 hr day in hot attics.

The other question you had was about the thermostats and the short answer is no, you can't control the old unit and the new units from one thermostat. Each indoor of the ductless will have a remote controller likely and the original system will have it's thermostat.

Good luck!
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Absolute
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12:10p, 5/3/22
AG
I installed the diy one (Mr cool iirc) in my garage. Works great.
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tgivaughn
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5:17p, 5/3/22
AG
Ideal solution the mini-splits
They each have their own thermostat (no need to coordinate this one) and appear similar to window ACs inside (UGH for now but future holds promise)
and also must be located to drip condensate outside.
The exterior compressor can be located anywhere a 220v can be run, most efficient would be
within 40ft of ref.line, measured in all directions
out of due West sun (or shaded from ... evergreens?)

TRANE
or the original Japanese version if they have techs qualified to tune them up

I have other solutions but this is the Cadillac you'll not regret, save the most later IF you have nearby good techs.


UPDATE:
I am reminded of a lower cost, old school solution some of our remodel/addition designs employed.
You see these all the time in motels and Garage/shops, even higher end rooms in-the-day = through the wall heat pumps.
Self contained "mini-splits" quell the question where to put the outside compressor
Interior appearance no worse than today's mini-splits
Same need to drain condensate directly outside
A bit less efficient on power
Much better ability to match tonnage to SF served!
Same thermostat on each unit & ability to shut off
Servicing might be less and more disposable if a problem or $$$$ to fix, IMHO.
Washing out the filters = EZ PZ
IMHO and am sticking to it
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Ornlu
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In reply to AgAcGuy12 • 8:06p, 5/3/22
AG
Where should I put the condenser? Rooftop, on the ground, in the attic, etc.

Is there a max distance the condenser can go from the blowers? Like 20 feet to nearest blower, or 50 feet from farthest?

What type of blower is best? Wall mounted, over door, ceiling mounted, etc?

They're 240v, right? Do I need a sub panel?

How do the air filters work?
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AgAcGuy12
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In reply to Ornlu • 9:37p, 5/3/22
AG
Wall units are fine. Put them as high as you can allowing 1ft clearance from the ceiling to the top. The filters in wall units are behind the face plate and are washable. You can't put a throw away filter in them. Drain water can be pumped or gravity fed out the wall with the refrigerant line sets. The refrigerant line set will be exposed and will need to be covered with a "gutter". A gutter is a pvc cover that hides the insulated copper lines.

They also make ducted air handlers. The beauty of these is they only require power at the outdoor unit. They also make floor mounted units that look like a radiator would in a building with steam heat. They also make cassettes that mount into the ceiling but aren't a good fit for Sheetrock ceilings.

Condensers need to go outside and can be either mounted on the wall with a wall bracket or on the ground. What I always try to do is mount within 10ft of the breaker box because then I am allowed to wire it by code without the need for an electrician.

As far as the length that's specific to the size and brand you use. An M Series Mitsubishi under 12k BTU can go 65ft, 15k and up can go 100ft.

I don't know if you've got your quote back yet for Mitsubishi but I'm warning you it's going to be higher.

Best of luck.
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jaggiemaggie
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In reply to AgAcGuy12 • 9:59p, 5/3/22
AG
AgAC

What is the best way to contact you? I have a question unrelated to the thread.
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AgAcGuy12
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In reply to jaggiemaggie • 12:46p, 5/4/22
AG
Nowlivingforme at Hotmail dot com
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Leggo My Elko
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2:52p, 5/5/22
AG
My company builds sunrooms, we use the Mitsubishi 12,000 BTU Mini Splits for most of them. We've been very happy with their performance. Can't even tell you how many we've installed and I can only think of one issue we've had with one and it was minor and easily fixed.

They are more expensive, but if you are spending many many thousands of dollars on the addition, the marginal cost to go with them is not that bad relative to the entire cost of the improvement.
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jtp01
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7:13a, 5/9/22
AG
As soon as we finish moving into our new build, we will be gutting the little farmhouse we were living in. We've decided on putting in 2 mini splits instead of a central system. The old furnace is over 40 years old and is having trouble heating and with recent hail storms, the ac condenser has had all of the "fins" on the exterior bent and close off air circulation.

Insurance man will be out today to assess the roof, siding and any other damages.

We are hoping for a total loss on the roof and siding, then we can handle the ac if needed.

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GrimesCoAg95
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10:56a, 5/9/22
AG
You have a lot of great advice on the thread so far. Daikin is a good brand as is Mitsubishi. I will just say that it is worth it to move up at least one level to get to the higher SEER rated units. Also a multi-zone is more expensive and less efficient.

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