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3 mini splits VS Central Heat pump Vs. Conventional GAS furnance for Michigan new construction house 2nd story.

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My dad has spent the last several years adding an addition to an old brick house. He was originally planning to live there but now just wants to sell it. It is a 2 story house with basement and the upstairs level does not have any heating or cooling. (basement and first level is heated with forced air furnace) Location is Michigan 1/4 mile away from Lake Huron. One only "needs" AC for a few weeks in the summer IMHO, but other people will run the AC a lot more than i would. He invested a lot and if he hired realtor he'd probably loose money ,on it.

Cool Calc website said I need 25,000 BTU heat and 15,000 BTU cooling. It's just a ball park since their windows choices are avg, low or high.

the upstairs will be divided up into 3 rooms and possibly a bathroom.

Just wondering if we should go with
$2700 for 3 minisplits ($900/each),
$3000 central heatpump or
$3200 1.5 Ton 14 SEER 60k BTU 80% AFUE 2 Stage Variable Speed conventinal gas with AC unit. there is NO ducting currently and it would be run through the attic. Walls are about R25 and attic is about R60.
He bought a furnance, but an HVAC guy said the motor was not strong enough.

I am leaning towards mini splits because they are the easiest to install and least expensive. . I've never installed one, but Ive vacuumed out car AC systems and think I can braze the copper lines . Having to run duct work and registered through the attic seems like a whole lot of hassle.

Main concern is if the mini splits can evenly heat the entire rooms. Front room is 18x28 big yellow rectangle in the layout photo. two rear rooms will be about 20x20 (top white rectangle will be split in half). All the tiny rectangles are windows with U factor of 0.33 (R=3)

thanks for any thoughts on best system to use are appreciated in advance!

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You will get all kinds of advice but IMO I would never buy a house with 3 mini splits and that may cause you to lose customers. It is like having 3 window units is what some people will think. Cheap cheesy way to do the job. They are good for one off specialty jobs where no other options are available IMO. You should think about resale value.

You do not need such a elaborate furnace. A basic 1 stage furnace with basic constant velocity 4 speed motor will do just fine and all basic units come with them now. I would have a cheap Goodman furnace and AC installed in the attic.

He can sell the furnace used on Craigslist or KiJiJi
 

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Do not have ducting put in the attic unless the roof deck is insulated and the attic is a semi-conditioned space -> if you value energy efficiency, which really everyone should.

Attic also sucks for service access, so if you can spare some square footage, have the furnace or air handler in a closet.

Now, cool-calc makes a lot of assumptions, so it is important to actually input everything manually.

Assuming your results are accurate.

60 000 btu furnace is absurd for 25k btu heat loss. Putting in an 80% these days in michigan is not a good idea due to climate, though if you end up with a furnace in a cold attic, it's actually the best choice due to issues with freezing condensate.

If you want furnace:

1. If attic roof deck will be insulated:

Get a 30 000 btu lennox or armstrong 95 to 96% (A961E for single stage or A962E for 2-stage), or 30k btu goodman (ss-gm9c96) or a carrier single stage 26k btu 95%. (Carrier 26k)

30k btu gives a margin of safety, but keep in mind very few hours are spent at or below design temp.


Combine with a 1.5 ton a/c.

2. If the attic will be a uninsulated cold zone, get a 40k btu 80% single stage furnace, outputting 32k btu with 1.5 ton a/c.
2-stage with ductwork through a cold attic increases duct loss.

Either way, a furnace with a powerful 1200 cfm+ rated blower is unnecessary, 2 ton drive/800 cfm rated would do just fine.

If you want a ducted heatpump:

It should be a cold climate model that maintains full heat output as it gets colder outside and also shuts the fan during defrost cycles, would need to be sized for heating -> 2 ton. If not, it will need electric supplemental elements ("heat strips"), expect electricity consumption to be high.

Would likely be more expensive than a furnace and a/c.

What about mini-splits?:

You'll get different opinions and it depends on what is more important - looks or energy efficiency.

I would go for mini-splits if the only other choice is ductwork in a cold attic.

I would go for central with ductwork over mini-splits if the attic roof deck will be insulated.
 
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Discussion Starter · #4 ·
Thanks for the feedback. The drywall and insulation is already installed. and the roof deck is NOT insulated. So a furnance would either go un-insulated in the attic or perhaps in a closet with upflow model. While I agree about energy effciency, we just really need to sell it and move on. My dad's 75, he has otherthings he wants to do.

Didn't realize people had a negative view of minisplits? I thought they were cool new technology. I guess it just depends on where you live. I see them all the time in SE. Asia. The lineset would be on the outside so you are right it's not that pretty. Dont' think we want to rip out the drywall just to hide the linesets.
 

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I missed the part about selling.

Mini-splits are used in additions all the time and there's nothing really wrong with them - when selling, you don't have to worry about the maintenance or repair of them.
I don't mind the looks of them but opinions differ.

If not mini-splits just go single stage furnace appropriately sized -> 80% if it will be in an attic.
The load calc will have to be room by room to size the ducts.
 

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Discussion Starter · #6 ·
Thanks for the replies. If we go minisplits route they would probably be about 12K BTU each and each one would cover about 20x20' rooms about the size of an entire garage. DO I need to look at the CFM output? I assume they will blow a good 10-15 feet and it wont' be an issue.
 

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Thanks for the replies. If we go minisplits route they would probably be about 12K BTU each and each one would cover about 20x20' rooms about the size of an entire garage. DO I need to look at the CFM output? I assume they will blow a good 10-15 feet and it wont' be an issue.
Personally I don't like them as they are hard to get parts for and won't last 15-20 yrs like a conventional HVAC system unless you buy a very expensive Fujitsu and those are 3-4X the price of the no name brands. It all depends on the buyer. If you get someone whose says I ain't buying a house with 3 window shakers ( window units ) then you lose a customer 50/50 chance at least. In Asia they have no furnaces and mini splits are popular. Whole different climate and clientele.
 

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Thanks for the replies. If we go minisplits route they would probably be about 12K BTU each and each one would cover about 20x20' rooms about the size of an entire garage. DO I need to look at the CFM output? I assume they will blow a good 10-15 feet and it wont' be an issue.
You would need to look at heat output, not cfm.

For such an application, you would be looking at one outdoor unit with multiple heads.

At 12k per room, its not worth it.

Ducted systems aren't cheap either, but less than that.
 

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Minis aren't anything new, they’ve been around for decades.
The name brand units last a long time, are well supported for many years and work well at very low outdoor temperature that may be as low as -15° to -20° F. These include Mitsubishi and Samsung.
The non-name brand units, such as those available online, aren’t well supported and usually aren’t rated to low outdoor temperature.
The name brand units can be very expensive. And must be bought via an installation company.
 

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I will bet the 15k of cooling for upstairs is wrong. Heat rises and cold settles. One of the reasons I do not and will not ever own a two story house. Had a two story condo for a few years out of college bedrooms up stairs. Summer time could not cool the top. So I bought a sofa bed and slept on the first floor.

There are minis that have one compressor and several heads.
Adding more equipment to the house is a crap shoot. My recommendation is call 4 real estate agents and see what they say. They would have their finger on what the competition has when you sell.

I agree 4 compressors would make me go wander.
Being the house is in a heating climate I would get a higher efficiency furnace.
 

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Discussion Starter · #11 ·
For such an application, you would be looking at one outdoor unit with multiple heads.
At 12k per room, its not worth it.
Ducted systems aren't cheap either, but less than that.
No, we would be using 3 compressors. I like the redundancy. One goes down no big deal, the other 2 can still work.
If the multihead single compressor systems were a lot cheaper I'd consider them, seems they are not that much cheaper so why have all your eggs in one basket.
 

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No, we would be using 3 compressors. I like the redundancy. One goes down no big deal, the other 2 can still work.
If the multihead single compressor systems were a lot cheaper I'd consider them, seems they are not that much cheaper so why have all your eggs in one basket.
House is being sold - why do you want redundancy?

You have to look at installation labor too when looking at cost.
 

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I will bet the 15k of cooling for upstairs is wrong. Heat rises and cold settles. One of the reasons I do not and will not ever own a two story house. Had a two story condo for a few years out of college bedrooms up stairs. Summer time could not cool the top. So I bought a sofa bed and slept on the first floor.

There are minis that have one compressor and several heads.
Adding more equipment to the house is a crap shoot. My recommendation is call 4 real estate agents and see what they say. They would have their finger on what the competition has when you sell.

I agree 4 compressors would make me go wander.
Being the house is in a heating climate I would get a higher efficiency furnace.
There are entire houses that can cool on 15k total.

Doing a/c in north is very different from in the south - many will come out to 1 ton per 1000 to 1200 sq ft. (not that sizing by sq ft is advisable)
 

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Discussion Starter · #14 ·
I will bet the 15k of cooling for upstairs is wrong. Like I mentioned its close to Lake Huron one of the largest fresh water lakes in the USA with a cool breeze. Cooling is not what I'm worried about I want to make sure I size correctly for heatinng if my dad wants to go the mini split route. Currently with out any hvac the upstairs is around 45 degrees just from the heat rising from downstairs.
 

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can you elaborate? I'm researching this now. all the mini split info shows Cooling capacity. do i have to search for some kind of chart the manufacture has that shows heating capacity at different outdoor temperatures?
The manufacturers publish extended performance data at different outdoor temperatures.

You need enough heat output to match heat loss at design conditions.
 

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I would toss my hat in for the mulitzone split system too.
I did a couple of pioneers here, 12K BTU single units.
$1728 for a 28000 btu outdoor unit.
Pioneer® Triple Zone Outdoor Section 230V 22.5 SEER Multi Split Air Conditioner & Heat Pump

$343 each for the 9K indoor units.
Pioneer® Multi Zone 9,000 BTU 230V 24 SEER Wall Mount Indoor Section Air Cond Heat Pump

The price varies. That is for a 16' line set included.
Why I would do that over 3 units is the wiring. It is only one big power hookup at the outdoor compressor section, rather than 3. It will look quite a bit cleaner for a prospective buyer too, rather than an heat pump farm out there somewhere.
 

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Discussion Starter · #20 · (Edited)
Lexington, MI , which is about 1 hour north of Detroit, MI in the thumb area.
Not really concernd about brand as long as we can buy it online from one of the many direct to consumer minisplit sellers. We dont' have the budget to hire a pro to install. As mentioned above I think I can vacuum and braze the lineset.My dad has the tools. I was orginally thinking the Mr Cool series, but read the line sets leak and they cost hundreds of dollars more just because they are DIY. Stealth, ACiQ, Olympus, Gree are all units that meet my criteria on this website
Dual Zone Ductless Mini Split AC Units | HVACDirect.com
we'd probabaly use a two head unit and a single head unit because if we used a 3 head unit one line set would be about 65' long.

What area of Michigan, and what brands are you looking at?
 
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