Author Topic: Mini-split AC for owner-occupied 100-yo duplex?  (Read 922 times)

lilactree

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Mini-split AC for owner-occupied 100-yo duplex?
« on: June 24, 2020, 09:37:07 AM »
We have a 3-story home with our apartment on the first floor, a tenant in apartment 2 on the second floor, and a large unfinished and poorly insulated attic on the third floor. There is also a basement which has the boilers for heating both apartments with radiators. Each apartment has two bedrooms and is about 870 square feet (see attachment). Currently the "window" AC unit that was installed in the wall in the kitchen without a sleeve, is not working; it broke down late last summer and is old and noisy. I think it's 12,000 BTU, and with the ceiling fan in front of it was good enough for the whole apartment; we did not attempt to cool the front porch which is enclosed. We do happen to have a very noisy secondhand portable AC that we made do with when our AC broke down last summer (and we were all mostly at work or daycare during the day). Tenant upstairs has a window AC.  

We are in an HCOL suburban area in USA, hard hit by COVID-19, not far from New York City which means 4 seasons, hot humid summers, cold winters. DH is working from home and it's getting hot. He was using the attic, but at this point it's getting unbearable up there. He's used our front porch, but that is also getting uncomfortable. He's now outdoors on the back porch and may use the basement next. I'm not working at the moment due to disability but likely to work at least partly from home at some point. We also have a young kid recently back in preschool (private for now due to pandemic), but might be home again all day if things start shutting down again. Basically it's worth investing in keeping the place comfortable enough to be productive here. Neither of us has previous experience with central AC or mini-splits, mainly just clunky old window units, and we are not very handy. 

I've been emailing back and forth with an "elite" installer for one of the well-known, more expensive mini-split brands. He seems super busy and like he doesn't have time to hold my hand and pore over my every thought and question with me. He is giving me a quote based on photos and emails. Originally he was going to suggest a lot of units but I asked for something much more pared down, like one unit for each floor. The quote is over $10,000, with a 12-year warranty, for a 3 ton condensing unit, one 9000 BTU head unit on the first floor, one 9000 BTU head unit on the second floor, and one 12,000 BTU cassette unit in the attic. The condensing unit appears to have both heating and cooling; I had mentioned the idea of being able to heat the attic, but I consider this aspect optional. 

Some thoughts I had: 

1. This is more than we'd like to spend at the moment. We could make do with just cooling the first floor for now. We don't even use the second floor, frankly, and the rent is way below market. It would be nice to cool the attic, but not a necessity at this time. Also, what I end up not liking mini-spits for some reason?

2. I asked if it makes sense to do this in phases, like one floor for now and add the others later, but he said not really because later the equipment could be incompatible.

3. I had been thinking one condensing unit could be enough and the quote reflects this thought, but now I'm thinking that since it's a multifamily, maybe the first and second floor systems, at least, should ultimately be separate. That way it could be set up so each household's usage is reflected in their own energy bill -- yes? Also tax-deductibility would be simpler. Not sure how to handle the attic, which we currently use for storage but may eventually do something else with. 

4. If each apartment should have a separate system anyway, we could just do the first floor for now. Ideally we would cool the enclosed front porch, which can be used as a workspace.

5. If we just do the first floor, would we just have one condensing unit with cooling only, and just one head in the kitchen wall where our defunct "window" unit currently is? If so is 9,000 BTU enough? What if we attempt to also cool the enclosed front porch (by opening the hallway door, or just the window between living room and porch, and maybe moving the air with a fan)? Remember, I'm not familiar with mini-splits, so not sure if I think about them the right way. 

6. Noise level and clean air are very important considerations for us, affecting productivity and disability. I thought mini-splits would be best, am I right? And, I know this isn't "proven", but I am not convinced that there is no such thing as health effects from EMFs, so I like the idea of the condensing unit not being really close to where anyone sleeps or works. My experience being mostly with window units, I'm used to turning on ACs only when needed and using windows and fans more. How different is having a mini-split? What if I don't want to run it 24/7 because of noise, desire for fresh breezes, or even EMF stuff. (Please let's not spend too much of this thread on discussing the lack of evidence that EMFs are harmful.)

Uhhhh thanks for reading, please share your knowledge, and please help me think about this :) 

 

bacchi

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Re: Mini-split AC for owner-occupied 100-yo duplex?
« Reply #1 on: June 24, 2020, 10:13:19 AM »
Do the first floor with a single-head outdoor condensing unit.

It'll be more expensive to put in 2 or 3 separately, and it'll take up more outdoor space (though mini-split condensing units are small), but if you don't want to spend $10k right now, it's the best choice. Also, as you wrote, it makes a lot more sense with the owner/renter separation.

Whether 9000 BTU is enough depends on how well insulated your place is. As a comparison, it's plenty for our 600 ft2 place, which is a two story loft with very high ceilings, but it's also very well insulated with new windows.

There's no problem with turning it on and off. We run ours in dehumidify mode at night to get rid of moisture and so that it's not constantly running the fan.

mozar

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Re: Mini-split AC for owner-occupied 100-yo duplex?
« Reply #2 on: June 24, 2020, 11:13:51 AM »
Since you are only trying to cool the one floor, I think it's fine to just replace the kitchen AC with something high quality and efficient.
If you want to go the mini split route there is a brand called MRCOOL that sells DIY units for 2k to 4k. You just need to drill a whole in the wall and you can hire an electrician to wire it if you don't feel comfortable.

rothwem

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Re: Mini-split AC for owner-occupied 100-yo duplex?
« Reply #3 on: June 24, 2020, 03:05:26 PM »
Two big questions:
-Are the utilities seperate?
-How long to do you plan to keep the place?

I went with mini splits to replace the window units in my duplex because the utilities were separated and if I were to do a full up A/C system on each side, it would be way too much capacity for the 720 square foot units.  It ended up being about $12,000 to do both sides, but I did a ducted setup instead of a ductless setup because of some weird stuff on my 1950s building, basically there wasn't enough wall room to hang the wall units because the windows were so huge.  Also adding to the cost was the electrical service upgrade, I only had 60 amps running to each side and the units needed a 40 amp circuit. 

I think that if you're planning on keeping the place, I'd go ahead and upgrade the A/C on both units, so that you can get market rent.  If the utilities are not separate, I'd do a normal heat pump type system instead of dealing with two mini split systems. 

FatFI2025

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Re: Mini-split AC for owner-occupied 100-yo duplex?
« Reply #4 on: June 24, 2020, 07:31:09 PM »
I would just do the first floor now and do the second floor when your tenant turns over, you have the cash, and you want to up the rent. I'm against paying for tenant electricity because many people would drive that bill through the roof. No way I'd install an interconnected system if the two units were separately metered.

alsoknownasDean

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Re: Mini-split AC for owner-occupied 100-yo duplex?
« Reply #5 on: June 24, 2020, 10:58:32 PM »
I would just do the first floor now and do the second floor when your tenant turns over, you have the cash, and you want to up the rent. I'm against paying for tenant electricity because many people would drive that bill through the roof. No way I'd install an interconnected system if the two units were separately metered.

Agreed with this. It's worth keeping the billing separate if you are renting the place out. Is there room outside for additional condenser units if you decide to do the second and third floor down the track?

FWIW I've just had a multi split system installed with a 7.1kW compressor, and a 5kW, a 2.5kW and a 2kW head. It was well under $10K (in fact it was under $US5K), even with the fancy Wi-Fi modules and the more efficient head units (the smaller two have a COP of over 5). Maybe get three quotes? The first installer could be giving you a 'go away' price.
« Last Edit: June 24, 2020, 11:04:45 PM by alsoknownasDean »

lilactree

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Re: Mini-split AC for owner-occupied 100-yo duplex?
« Reply #6 on: June 25, 2020, 08:58:40 AM »
Thank you @bacchi , @mozar , @rothwem , @FatFI2025 , @alsoknownasDean . (Did I do this correctly with the "@"s? The names did show in a menu but now it doesn't look right to me.)

Most likely we'll keep the place a long time, whether or not we live here the whole time, rent the whole place out, or rent out both apartments but still somehow utilize the attic, large yard and shed.

Gas & electric are already billed separately to the two apartments. We all use the same laundry machines in the basement, and I assume that usage is billed to the first floor but I'm not sure; same with the shed, but that is used minimally so far. If we end up cooling the attic in the future, I'm not sure how we should anticipate doing that, i.e. which apartment the electric usage should be associated with vs. whether there's a reasonable way to keep it separate in case we move out in the future and rent out both units (or even move into the upstairs someday and have two floors to ourselves). Or if it can be set up to be easily switched between accounts.

MrCool seems like a good idea, but we couldn't do any of it ourselves at this time. We would still need to hire someone for installation + electrician, but I would think there are more options of whom we could hire, especially if we get the "DIY" products. Does anyone have tips on how to find someone for this? We do have a Costco membership, Costco being a seller of MrCool.

Also, I forgot to mention we have plaster walls, this being an old house. Not sure if that makes things easier or harder.

Another potentially complicating factor is that I'd like to have the old "window" AC removed; it is in the wall above a window, without a sleeve. Not the same shape as a mini-split head. I feel like it's harder to ask about these details over email with the installer. Also to @alsoknownasDean's point, this may be a "go away" situation. And suppose he came here ready to install, but then we couldn't agree on where to put it, or he won't patch up the wall if he takes out the old AC and I have to find someone else, or I'm confused about what placement options there are for the outdoor condenser. If he installs in a different spot, I could later deal with having someone remove the old one and put something in it's place (a challenge for another day).

At the same time there is the pressure of the pandemic. Our cases are still relatively low right now, but who knows for how long? I'm afraid of introducing more delays, but at the same time I'm being slow. (In my defense, I'm concurrently handling my medical/disability situation which takes a lot of brainpower, too :) )  Also, it might not be a "go away" quote, given the pandemic and this being HCOL and a hard-hit area; everything is a little crazy right now.

Papa bear

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Re: Mini-split AC for owner-occupied 100-yo duplex?
« Reply #7 on: June 25, 2020, 09:32:04 AM »
I have multiple 100+ year old 2 unit rentals that I have recently added AC to.  Iíve been through this a couple of times.

You mention a boiler system. Iím going to assume that you do not have existing ductwork for a forced air system.

You need to keep your units separately metered.  You do not want to have your tenants sharing any of the utilities on this.  If, down the line, you rent both units, you will continue to have problems.  Keep your systems separate.

Your options basically are:

Adding a forced air system, ductwork, air handler, condenser, returns, etc.  this will work phenomenally, but can be invasive and expensive.  However, if your basement is unfinished and you do not plan on finishing your attic, you can run ductwork fairly easily.  Youíre probably looking at 8-20k of work for this.  I had existing forced air systems, but with no supply ducts to attics and the returns were gravity fed.  I added central air and the necessary ducts (also included a furnace replacement) for $12,500 for the 2 units.  In another with only return ducting necessary for a top/bottom double, Iím having new furnaces, air handlers, coils, and condensers installed for under $9k.  For both of these jobs, I had minisplits priced out.  For the first, side by side, the quote was the same, 12,500.  For the 2nd place, the minisplit options was 10k per unit.  All of the hvac contractors Iíve used (multiple geographical regions) have made their cases against minisplits.  One group told me they are problematic in rentals as tenants are notoriously dirty and will ruin the units.  the other said the air flow will be poor and the bedrooms would not be cooled very well.

Running minisplits - I still love this idea. It works well in your situation if you have no existing ducts.  But the drawbacks are what I mentioned above.  A single head unit will cool your living space, but not the bedrooms well.  For the upstairs unit, you can look at a ducted minisplit system.  They will install a small air handler in the attic and duct the air to each room.   This would be an effective, but expensive option.

Window units - cheap, easy, inefficient, ugly, temporary.  Itís what weíve provided to tenants when there is no AC. You do not typically need to run new wiring.

In wall AC - inexpensive, permanent, ugly.  I had one on a unit that was installed before I owned it. It worked well for 700sft living space.  I know they will work well in bedrooms, and each room can have its own temperature.  You may not need to run any new wiring.

Anyway, thereís no good perfect option.  For the tenants, I would be providing window AC units. At a few hundred $$ a piece, buy 2 cheap units. Then when they move out, look at different options.

For your place? I would price out a traditional central air system and see what it would cost.  You might be surprised at the price.  In the meantime time, but a few window units to be comfortable during the heat of summer.  Itís a cheap solution while you figure out how youíre going to drop 10k +.


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rothwem

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Re: Mini-split AC for owner-occupied 100-yo duplex?
« Reply #8 on: June 26, 2020, 06:03:48 AM »

For your place? I would price out a traditional central air system and see what it would cost.  You might be surprised at the price.  In the meantime time, but a few window units to be comfortable during the heat of summer.  Itís a cheap solution while you figure out how youíre going to drop 10k +.


The issue that I had with my 720 square foot units was that there was literally nothing made that had low enough capacity for such a small place.  That's how I ended up with the ducted mini-split setup that I paid $12,000 for. 

Also, OP, as I mentioned in my post, you should make sure that your electrical system can handle an actual A/C unit.  Mine couldn't.  I had to pay the power company $1000 to run new lines to my house, and an electrician another $2000 to put a new box in and run the lines for the new circuits. 

Papa bear

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Re: Mini-split AC for owner-occupied 100-yo duplex?
« Reply #9 on: June 26, 2020, 06:53:12 AM »

For your place? I would price out a traditional central air system and see what it would cost.  You might be surprised at the price.  In the meantime time, but a few window units to be comfortable during the heat of summer.  Itís a cheap solution while you figure out how youíre going to drop 10k +.


The issue that I had with my 720 square foot units was that there was literally nothing made that had low enough capacity for such a small place.  That's how I ended up with the ducted mini-split setup that I paid $12,000 for. 

Also, OP, as I mentioned in my post, you should make sure that your electrical system can handle an actual A/C unit.  Mine couldn't.  I had to pay the power company $1000 to run new lines to my house, and an electrician another $2000 to put a new box in and run the lines for the new circuits.
There are 1-ton central air condensing units available, which is 12,000 btu.  Iíve seen mini splits down to 9000 btu at the low end. So there shouldnít be a problem getting a unit sized appropriately.

Agreed with the electrical service.  If you have 60amp service and another large draw, such as a drier, h20 tank, or range, you may not have enough power.  If you have no other major appliance on electric, youíre probably just fine, but may need physical room in your panel.  You can look at tandem (cheater) breakers, a sub panel, or pay to replace your panel to something larger.  You should be looking for under 1500 for an install, this is less than a days work for an electrician + materials. Labor costs in my areas are usually around 60-80/hour for an electrician to replace one. The panel is under 200, and if you go with arc fault breakers, you may have an additional 200-300$ just in breakers.


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Papa bear

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Re: Mini-split AC for owner-occupied 100-yo duplex?
« Reply #10 on: June 26, 2020, 06:56:41 AM »

For your place? I would price out a traditional central air system and see what it would cost.  You might be surprised at the price.  In the meantime time, but a few window units to be comfortable during the heat of summer.  Itís a cheap solution while you figure out how youíre going to drop 10k +.


The issue that I had with my 720 square foot units was that there was literally nothing made that had low enough capacity for such a small place.  That's how I ended up with the ducted mini-split setup that I paid $12,000 for. 

Also, OP, as I mentioned in my post, you should make sure that your electrical system can handle an actual A/C unit.  Mine couldn't.  I had to pay the power company $1000 to run new lines to my house, and an electrician another $2000 to put a new box in and run the lines for the new circuits.
12k for 2 ducted minisplits units is a good price. I would have seriously considered going that route if I could have found that. My quotes were always away more, and it included me running all the electrical. 


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rothwem

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Re: Mini-split AC for owner-occupied 100-yo duplex?
« Reply #11 on: June 26, 2020, 07:44:54 AM »

For your place? I would price out a traditional central air system and see what it would cost.  You might be surprised at the price.  In the meantime time, but a few window units to be comfortable during the heat of summer.  Itís a cheap solution while you figure out how youíre going to drop 10k +.


The issue that I had with my 720 square foot units was that there was literally nothing made that had low enough capacity for such a small place.  That's how I ended up with the ducted mini-split setup that I paid $12,000 for. 

Also, OP, as I mentioned in my post, you should make sure that your electrical system can handle an actual A/C unit.  Mine couldn't.  I had to pay the power company $1000 to run new lines to my house, and an electrician another $2000 to put a new box in and run the lines for the new circuits.
There are 1-ton central air condensing units available, which is 12,000 btu.  Iíve seen mini splits down to 9000 btu at the low end. So there shouldnít be a problem getting a unit sized appropriately.

Hmm. I couldnít find a single one when I was looking, though this was 5 years ago so things mightíve changed. A quick google shows a 1.5 ton Goodman unit, but I think that would probably short cycle still.

Anyways, Iím fairly happy with what I got. It was a pretty good deal, theyíre Fujitsu units instead of no-name generics, and theyíre so quiet you can barely tell theyíre on.

lilactree

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Re: Mini-split AC for owner-occupied 100-yo duplex?
« Reply #12 on: July 03, 2020, 02:00:51 PM »
Thanks again, everyone. We might hold off for a little while, while some income uncertainties get sorted out.

I've just posted a related but different question, if anyone's interested :-D  :

https://forum.mrmoneymustache.com/ask-a-mustachian/inexpensivetemporary-home-office-in-unfinished-attic/

blingwrx

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Re: Mini-split AC for owner-occupied 100-yo duplex?
« Reply #13 on: July 03, 2020, 09:45:33 PM »
10k for 3 units doesnít sound like a good deal. Iíd check around for sure. It would actually be cheaper to go to some local AC/applicants stores rather than a big name installer, theyíre all licensed and they have some level of negotiation on the price if youíre buying a lot of units. There is also some rebates you can get from the electric company like around $250 per unit. Of course without the elite installer you probably wonít get the same level of warranty but youíll save a ton up front. Definitely get more quotes. It is busy season as weather is hot now and everyone wants these installer ASAP if you could bear through another summer maybe try doing this install in the winter installers will be a lot more reasonable on the price then.

I donít think a 9k bpu for an entire floor will do it. The way I set it up is I have a separate unit in each room. My home is 600sqft 2 bedroom. I have a 12k bpu for common area, 9k each bed room. The 9k in the bedrooms feels a bit overkill but they donít sell anything smaller. I do save electric as I donít run all the units at once. I have the common area one on during the day and the bed room ones on at night for when we sleep. These cost me about 1k-1.3k each unit including install. but Iím also using a low end brand so add a bit more for better brands but yeah probably could end up costing 10k if you want 9 units on 3 floors.

Sealing the hole for the old AC is another issue that could set you back $4-500 and you may need to find a different contractor to do it. The ac installer may not want to deal with that.



The electricity I wouldnít worry about they sell these units as 110v and they use about half the energy of an old window unit. The old wall unit you have probably needs 220v power and runs 3-4x more power. Iíd definitely wore these up per apartment. The installer will take care of it for you.