I also have both a forced air AC system and a mini split system because my house has two wings, one with forced air and the other on slab so all electric. I think in a bedroom area of a house, the mini splits are ideal since bedrooms tend to not be used during the day so you can turn the system off to save energy and $ during the day and then only cool one room at night, or individual rooms being used at night.

From your setup, though, is the second floor separated from the first by a door? That would really be ideal so you can really cool and heat each area separately, as used, and save a ton of energy and $$ on your bills. Downstairs, cool/heat during the day; upstairs off; vice versa at night.

Definitely not insane, and I wouldn't agree that "usually people are doing the opposite". In fact, the mini split market in North America is growing very rapidly. I don't think your resale value in years down the road is in danger at all. In fact, higher efficiency H&C is usually a major win!

Are you looking at two single-zone mini splits (one for each bedroom) or a single 2-zone system?

Probably a single system, but not sure. What are advantages and disadvantages of doing 2 single ones vs. a single 2-zone system (besides having 2 compressors outside)?

Thank you!

The main advantage for two single zone systems would be energy efficiency. LG has dual-zone systems that top out at 22 SEER (I think maybe the best of any manufacturer), whereas there are multiple manufacturers who have single-zone systems in the 27+ SEER range (Mitsubishi, GREE, Fujitsu, Panasonic, LG, etc).

A major disadvantage of having two single-zone systems would likely be the installation costs, unless you were going to DIY. Also many people probably wouldn't like having the two outdoor condensers, as you mentioned.

Purchase price might be also be a factor, though it depends on brand. You could pick up a single zone GREE at the top of their line (Terra, 27 SEER, 9,000 BTU) for around $1,075, or you could get the aforementioned LG 2-zone system (9k, 9k) for around $2350.

Depending where you live (cold climates), the Mitsubishi Hyper Heat lineup might be a great option. They offer multi-zone options, but their single-zone MZ-FH models are really where you get the best heating capability. Those 9k systems will set you back in the $1500-range.

I am happy to see this conversation as I am in the process of having a house designed and hope to use minisplits for heating and cooling because I have read a lot of good information about them. My house will be about 1500 sq. ft with two bedrooms and a bath upstairs and kitchen/living/bedroom downstairs. I mentioned my plans to a heating/cooling repairman and he does not like them for several reasons including the problems getting parts if repairs are needed. Any comments?

Can't get parts? What place in the developed world can't you get parts overnight? It is more like an old dog can't learn new tricks. Go to the Mitsubishi, Panasonic and Toshiba web sites to find smarter contractors in your area.

Why do you want mini splits? In designing your new home, put the ducts inside the envelope (not in an unconditioned attic or crawlspace), or use mini splits. If natural gas is available and you need a lot of heat, gas is probably the less expensive fuel. (This can be done in a decentralized way as well, if you wish.) You should hire a local energy rater to help you make decisions and to set and enforce benchmarks for air sealing and other construction quality details. For more mini split information, find this study and read it:

Long-Term Monitoring of Mini-Split Ductless Heat Pumps in the Northeast

K. Ueno and H. Loomis

Building Science Corporation

November 2014

Mini splits are nearly all we do now, definitely very little downside.

This is good to know! Are certain brands preferred over others? For example, our guy quoted us Lennox units but we would prefer the Mitsubishi. Are some better than others? (Our rooms are pretty small, so we only need 9k units, one on each room).

My other question is about the bathroom between the 2 bedrooms, it currently has central A/C vent. Is there any way to cool the bathroom without installing a separate mini-split? The bathroom is pretty small.

One more question, our wall space is limited since bedrooms are in the former attic, so the walls are sloped. Also, there is no room by the windows as windows very large and whatever space was left underneath is taken by radiators (Runtals, hot water radiators, we have natural gas). So, we were looking at the units that are installed in the ceilings (ceiling cassettes?). Any advice on those? Could those be installed in the existing structure? Or are those for new construction only? How are they installed? Between the beams?

Any other ideas regarding the units placement?

Thank you all!!!

@Bongo - No, the ceiling cassettes (recessed or concealed) are not only for new construction. They can definitely be added to an existing room. There are also wall-mounted units that are designed to either be mounted on the ceiling, or down low near the floor. They're much thinner than the typical wall-mount, and were created with places like hallways or rooms with limited wall-space in mind.

Mitsubishi has the Floor Mount models - look for MFZ-KA models. GREE also has a lineup of these. Look for U-Match series. There's info on them here: greecomfort.com/our-products/u-match-inverter-heat-pump/universal-floorceiling/

The biggest downside to mini splits is the plethora of options, configurations and again you guessed it part availability. Someone mentioned the ability to over night a part... well that's a nice thought, but there's more to it than that.

The life cycle of most mini-splits is 5-7 years. Not all, but most. What ever brand / model of mini split you decide on will depend greatly on whether those parts are even available. Available? say what? If a life cycle of a unit is 5-7 years the manufacturer will move onto newer models that will use different non-interchangeable parts between another model.

If you buy the unit on your own and install it yourself you are in even worse shape because in Texas and many other areas of the country if you're not a certified dealer with an HVAC license the manufacturer warranty is VOID. (If it sounds too good to be true... you know.)

Central air systems typically have what are known as "standard" parts that are for the most part interchangeable between systems provided they are matched properly. For Mini splits the parts must be OEM and made for the specific model and manufacturer. If the life cycle of that model is up... you're not going to find parts for it.

The manufacturer wants to sell you a new unit. Happy Birthday!

I am a Texas Licensed HVAC contractor with over 20 years in HVAC. I specialize in residential systems and service Katy, Texas & Cypress Texas and some surrounding areas.

Wave at me if I just saved you from making a mistake.

I'm pretty sure our central A/C unit currently installed in vented attic will not last past the 5-7 years also. In the winter, its freezing upthere and in the summer its over 100, not to mention the money lost from the ducts in the attic, plus we can't even the insulate the attic the way they installed the A/C, also losing $$$ in the process. So financially speaking, mini-splits are still a better option for us.

@Bongo - austinairco is absolutely right about having an HVAC contractor do the installation, if you buy the system online. As far as I know, every single manufacturer has terms in their warranty that voids the warranty if you DIY. Just something to keep in mind when factoring in installation costs. :)

Absolutely, we are currently working with HVAC contractor who quoted us Lennox units. We are not that DIY savy to install something like that, so I would definately use a professional to install. i was just trying to gather as much information as possible so that I can make an informed decision before the contractor starts the install.

Thank you all!!!

I live in the Katy, Texas area and pretty much 90% of all central HVAC systems are installed in the attic. Currently I offer central HVAC systems with up to a life time compressor warranty and up to a life time heat exchanger warranty. Minimum central HVAC systems have 10 year limited warranty when properly installed with a licensed HVAC contractor and registered with the manufacturer.

If a system can withstand the Texas heat, it can pretty much withstand anything.

Isn't that the old way of doing things? It was my understanding that current recomendation based on recent research is that no equipment/ducts should be installed in unconditioned spaces. Only if the attic is made to be part of conditioned space, then the equipment could be installed there.

Yes, there are certain area of the country that are trying to change this method of installing a ducted system in the attic. But my personal opinion is that it is based on bunk science.

I live in what is typically referred to as "The AC capitol of the World". I have a ducted Zoned HVAC system at my home and most months my AC utility bill is about $30 or less. This is running the AC system 24/7 cooling the zone(s) I am occupying. I have multiple years of videos on my website showing what I pay on my electrical bill as well as discuss the operating efficiency of my system based on my own usage.

The biggest problem with ducted systems in the attic is that most companies send technicians and salesmen and there is really no way to verify that things are done properly. Money gets in the way and it's always about trying to be the cheaper option.

Most often I see these cheaper options as cheaper up front, but more costly in the long run.

Bongo, I'm well outside your area for service. I have nothing to gain... just merely my personal opinion. My advice to you is find a "working" Licensed HVAC contractor in your area and get another opinion. Good luck to you.

National average for Ducted system HVAC replacement is 15 years when done properly.

5-7 years?! My god! No wonder people call me from all over to get advice, some of you are dinosaurs. Bongo, I have hundreds of ductless install walkthrus at barrongreenteam.com on my youtube channel. Out of a hundred installs we sell 95 Daikin, 3 Lennox, 1 Fujitsu and 1 Mitsubishi. All of them are awesome and will work, but things like Daikin having a 12 year parts and labor warranty vs. 7 year parts for Mitsu/Fuji vs. 5 year parts on the Lennox tend to sway things Daikins; way considering they are all roughly the same price. Also, If you have to ask this many questions after meeting with contractor, then thats good sign you need a new one. You should be able to trust and learn from you contractor.

I would not worry about cooling the bathroom directly. If you were doing heat pumps, supplying the
bath might be a different story. If you
are concerned about drying the bathroom surfaces after showers, install a jump
duct from an adjacent room and use a timer to run it for a fixed period after
the exhaust fan is off. Some people are
having them blow directly into their showers from a downward-oriented duct in
the wall.

The last time I checked, the ceiling units were not as
efficient as the wall-mounted. Keep in
mind the placement of either type in relationship to the bed. My wife hates
having the AC blowing on her sleeping or sitting. When considering brands, look carefully at
controls. Do they allow remote (off the
property) control? Do they offer a true
set-back or only on-off ? Do they have a setting that dries them out when you
turn them off to inhibit mold growth?
Some of these things and other may be important to you and others not?

The biggest problem with outdoor ducts is duct leakage. The pressure differentials make your air
handler blower into a power vent. Indoor
ducts are better, much better than outdoor ducts. Even new duct systems leak and they go
downhill from there. With outdoor ducts,
moist, hot air gets sucked into the house at every leak. Conditioned air gets blown out
elsewhere. Don’t forget radiative heat
gain for ducts in the attic.

austinairco Austin, please point out the bunk in the
science that says that indoor ducts are no better than outdoor ducts. Are modern high efficiency (variable speed
blowers and compressors) systems still manufactured with generic, interchangeable
parts or are they specific to the model?

Shagdash25 - thank you! This is exactly what I needed to hear (i.e that you love your mini split unit). I went to a spa recently and they had a Fujitsu floor unit. I could barely hear it, and it was cooling the space beautifully. Totally made my decision!

May I ask what brand did you go with? How many BTUs? What is your experience with maintenance of the mini split vs. central air maintenance?

Thanks!

I am glad this was helpful. We have a new install so I can not speak about maintenance, but we got a Mitsubishi 12,000 btu unit for our downstairs. The brand choice was due to the contractor's alliance with Mitsubishi. The outside unit is almost silent and the inside unit is equally quiet. Today, we have rain and I have it on the dehumidify mode and its great. I was a little concerned about warm spots in the three room area that it needs to hit, but the fan motion seems to deal with it nicely.

Hi there. I'll take a stab at maintenance since we've had our Fujitsu minisplits since 2011.

Most of our problems were installation related and occurred early. The big one was the installer did not angle the drain tube through the attic properly for the condensed water. As a result the first winter it froze and cracked (unknown to us) so we had some water damage the next year. We caught it early so no mold but drywall needed replaced.

We also had the refrigerant (I think that is what you call it but there may be a different term) leak out early on. Again an installer problem. They fixed it but in a subsequent year we had a small leak between the outdoor unit and the line for the refrigerant so that had to be tightened up.

We put a ceiling cassette in our master bedroom at the foot of the bed. We ended up blocking off the vent that goes toward the bed. The other three are just fine for cooling the room and we don't have it blowing on the bed.

We have one in an upstairs bedroom that faces south and is used for an office. We have almost never used it. The main one in the vaulted ceiling blows into the room for most cases.

General maintenance is pretty easy. Every year we hose off the fins on the outdoor units if they collect the cotton from the trees. We also clean up the leaves around the unit and make sure nothing is growing toward it. We have two out door units.

Indoors we take down the filters and clean them at the beginning of every season. I don't remember if I do them during the season. I may, if we have a dust storm or something. The wall units that are accessible by normal ladder are easy to clean. One of ours is in a high vault and that one is a pain. Hasn't even been cleaned this year (even though I did the rest the first time I turned it on for the season) because my husband has to haul in the two story outdoor ladder to get to it. Since there is no duct work once you clean the filters and wipe off any visible dust in the ceiling cassette your good.

Every year I wonder why they aren't cooling like they used to. Then after a week or so I remember that I have to reset the button that uses the remote wall control unit as the temperature. For some reason it defaults to the temperature sensor on the unit over the winter. Once I do all is good again and it easily ices down the house. It is a simple button push-and-hold to reset it but I still forget to do it the first time I turn it on.

We had it off this morning with all the windows open. At about 1 p.m. the house had gotten to 80-81. 20 min. later and it was 78-79 F through out. When I shot them with my infrared heat gun. The two ceiling cassettes are blowing out 48 F and the two wall units came in at 45 and 54 F. We have tremendous thermal mass in the house because of our infloor radiant heating in gypcrete. Initially I thought I might have to run it all the time because it wouldn't be able to overcome the thermal mass. But because the cold air falls from the ceiling you feel it right away. The heat rises to be cooled and the cool air falls around you. It is fantastic at giving a cooling sensation right away.

Is a unit needed for each separate room?

There you go anno, great and important question! Mini-split interior blower units are designed to be installed on an exterior wall... while there are mini split models that allow cassette type installations you would then need access from an above attic or recessed ceiling these can and do complicated installations of mini-splits further.

Mini splits are best when adding duct is impossible otherwise there is a long list of pros and cons to consider above and beyond what I have discussed above.

The inside units can be hung on the interior of the walls also. I have mine on the interior if the living room. I only have a 1.5 ton and it diid great this last winter. It still was cranking 116 degree heat at -9 degrees. It works awesome as an ac.

I prob goin to ad a .75 ton to another room to help during the colder nights. I am defiantly glad I bought a mini ssplit over a whole house heat pump. The heating bill would be to alot and running the ac would be to cold.

In a 1550 sq.ft. 1 1/2 story new construction with a open kitchen-living area and 1 bedroom downstairs (900+') plus 2 bedrooms (500+') upstairs, how many cassettes do you estimate would be needed. I really don't want ductwork with conventional HVAC, but have to consider finances, too.

Not trying to appear I am bashing Mini splits but there are other serious things to consider with them, namely part availability. The biggest advantage a ducted system has is the ability to be repaired with standard parts. Mini split parts are brand and in many cases model of the unit specific. So when the unit breaks and it will break at some point... leaves you with a strong possibility of having to replace the unit because parts are not available.

Realize mini splits models, designs have changed frequently. If you do go the mini split route choose a well known brand name, while even that will not guarantee part availability it would be your best chance. Most of these are foreign made so if your unit does break there is good chance any part needed will have to be ordered. Manufacturers of these kinds of systems are in the business to make units... not sell parts. Your mileage may vary.

Additionally ducted HVAC systems warranties are the best in the business, especially on higher multiple speed equipment. This decision is very important... think long and hard about it.

I'm afraid I have to disagree with you, @austinairco Austin. Most major brands available within the US (Mitsubishi, LG, Fujitsu, GREE, Daikin, etc) offer at least a 5-year warranty on parts and 7-year on the compressor. Compare that to a typical Goodman central air system with a parts warranty of 10 years - clearly ductless lags behind, but it's not due to a lack of parts.

The major manufacturers all work with their distributors and installers (eg Mitsubishi's Diamond Contractors) to ensure wide parts availability.

In Austin, I know there's a Gemaire branch that would have parts. There's also a Johnson Supply branch that likely has a lot of DFS coverage as well.

For the homeower, really it's about offering them choices, and informed choices at that! I agree that the warranty coverage is not as good as with a central system...but I think being worried about parts for any of the major brands is not an issue, and certainly becoming less and less of one as ductless splits become more popular.

Everyone is entitled to their own opinion, my opinion is engrained with 20 years of running HVAC service calls. A distributor can not give you something they do not have or cannot get.

Models of mini splits change often, the parts used change with them. The warranty period is about all you're going to get in the way of any part availability. This is why the warranty period is short... the manufacturer stops making the parts for that particular model to churn new model and churn replacements.

I see it all the time.

Also to clear up this Austin confusion.. my last name is Austin... I'm in Katy, Texas a suburb of Houston.

All three of my wall units are hung on interior walls. We also have two ceiling cassettes. As a result none of the 5 units in my house are on exterior walls. The piping all comes through the attics.

I'll give my $.02 on ducted vs. mini-splits

Minisplits are good for homes like mine where there is no feasible way to add duct work.
Minisplits are good for people who are concerned about air quality and the stuff that builds up in ducts.
Minisplits are great for zoned cooling. For instance people who only use part of their house. People who want to super cool the bedrooms.
Minisplits are best for those who don't have financial concerns when obtaining the above benefits.
Minisplits are best for those who either live in an area where they are popular so there is some technical expertise or have the ability to understand and trouble shoot them themselves. Minisplit owners need patience.

Ducted air is best for those who are tight on funds.
Ducted air is best for those who need to call an expert for every technical problem.
Ducted air is best for those who want a trouble free experience. The technology is old and proven.

It is sort of like being an early adopter and getting cool features that are a little buggy. They are also similar to early adopters in that you pay a premium for them. Ours was over $16K and we didn't do two of the bedrooms we don't use so only cooled about 2000 sqr ft. A ducted system would have been less than half of that. Most of the bids for our system were $20K-$30K.

If you have money and you want what you want then minisplits can be great. If you are on a budget I think ducted is a better choice if it is an option. In our case ducted was not an option. Minisplits is the only way to cool our home.

mmmm12, I would agree with those comments whole heartedly.

Hanging a mini split from an interior wall is not impossible, but complications from such installs can be trouble some... for example: condensate draining.

In an exterior wall application the mini split drains from a tube going thru the wall to the outside of the structure... if it ever clogs up it is a bit easier to clean it out and it's less likely to clog because the condensate doesn't have to be "pushed up" via means of a condensate pump that will at some point fail.

A cassette or ceiling mount is a slightly better option in terms of condensate draining.... but by no means perfect. The more you know about these things the better you will be at picking what is right for you.

Other issues include: If you decided to change brands of mini split you may be forced to replace the line set to the indoor unit, because these machines are critically charged with refrigerant. Even off a fraction of an ounce can cause problems in performance. Most manufacturers of these systems use brand specific connectors, line sets, line set lengths etc.

The more complex any system... the more likely trouble will come.

Stay cool my friends. ;-)

Old and new technology are available in ducted systems. Many of the drawbacks cited for mini splits are similar for newer designs for ducted systems. Variable speed ducted systems are more costly, and likely have higher turnover rates wrt to design changes and parts. A better comparison might be made between mini splits and higher performing, perhaps zoned, ducted systems on the one hand, and old-school ducted systems on the other. Performance is a higher priority with the former and cost with the latter.

I have seven indoor mini split units and three outdoor. All but one indoor unit is mounted on interior walls. The one on an exterior wall is drained through the stud space similar to the other 6. They all go down to the open crawl space, no pumps. If an unfinished basement is available, drains could be done similarly there.

A couple of more subtle advantages of mini splits are the inherent redundancy of the system if at least two outdoor/compressor units are employed. You will always have part of your home cooled compared to a single system house. Another is running them well with relatively small gensets in the case of power failure. The smaller, variable speed compressors start up with no detectable genset bogging at my house on a 6800 kW portable that was running two compressors in addition to a refrigerator and a deep freezer. The refrigerator and freezer did make the genset bog down as it responded to the compressor turning on.

I don't understand the critical charging issue. Installers deal with different line lengths all the time that require adjustment. Systems are evacuated and recharged all the time for repairs with no problems.

So much of this is over my head. I wanted the mini split system because of my allergies and I hate ductwork. Thought my small 1550 sq. ft. passive solar plan would be perfect for them and not horribly expensive in my situation, but much of the discussion is discouraging. Now dramage brings up an issue with concrete pad. There is no definitive answer it seems!

@anno - This stuff certainly *can be* confusing! :) It's good you're here to ask questions. I'd also encourage you to talk to some local HVAC contractors and ask questions to them as well. (They aren't always as objective as these forums can be, however!)

With regards to your original question about how many cassettes - you mention a 900 sq ft room, and then two bedrooms at 500+ (is that combined or each?). I'll assume that's each, because otherwise you've got a couple of awesome, large bedrooms!

You can easily do a 3-zone system (so 3 indoor units) and have two 9k units in the bedrooms and an 18k - 22k unit in the living room.

###

Don't let austinairco scare you off ductless splits. There are still a lot of rural and semi-rural contractors who don't have a lot of exposure with these systems, and thus prefer to stick with the ducted systems they know.

Regardless of whether you install on an exterior wall or an interior wall, condensate drain shouldn't be an issue. Drain line is cheap and easy for your installer to add. A condensate pump would be needed for an interior wall-mount unit, but those aren't that scary. You can pick one up for about $130 - $160 online. You can install them yourself in maybe 10 minutes.

Do they eventually die? Of course... nothing mechanical lasts forever. But they're easily replaced and it's probably every 5+ years or so. Each manufacturer will have different warranties.

First off I am not trying to scare anyone off from mini splits, they serve a purpose and the configurations concerning them is enough to boggle my mind and I'm a HVAC contractor.

Who do you think is the one who goes to a house with a dead air conditioner? Have you seen a Mini split that is 15 years old and still operational? I have seen ducted ac systems as old as 26 years old just recently and still working except for Freon leaks.

In my service area the homes are built on concrete slabs, no basements and if there is a crawl space it is because it is a mobile home and the interior wall dilemma is not an issue except maybe a double wide in some cases.

If you attempt to work on your mini split yourself --- you will void the manufacture warranty. Manufacturer's of mini splits require specialized training.

Electronics reside in each part of the unit, including the both the indoor and outdoor parts of the units. The electronics are fragile and unique to each piece of equipment. The warranty on these kinds of parts can be as short as 1 year. What do you suppose could happen to the electronics in the event of a close by lightning strike?

Can you imagine having every single indoor unit go down because of a lightning strike? Could you imagine having to replace every single indoor unit because the electronics are no longer made for the unit you selected?

This doesn't mean it will happen to you... but clearly shows the kind of bad news I hand deliver on a frequent basis.

Critical charged: Mini splits don't operate like a conventional air conditioning system in that there is no liquid line that runs from the outside condenser to the indoor evaporator (wall / ceiling mount unit). They are typically sold as kits with the line set included. You don't cut the line set to fit... you coil up what ever you have left over. The lines running to and from the indoor unit are both gas lines. Special tools, techniques and methods are needed to properly install them. Adding unapproved manufacture line sets, unapproved sizing will lead to over charging or under charging the mini split. It will not work under either condition and the electronics will detect the problem and shut the system down.

PS: I'm not rural I live in the 4th largest city in the USA.

Here's a link to more information regarding mini splits. Certainly this information source would be slanted more toward conventional ac systems as this is what they specialize in, the points they make are quite accurate.

http://www.ac-heatingconnect.com/contractors/toolkit/news-and-views/july-2013/

Katy, TX, with a population of about 14,700 is pretty small. The greater metro area of Houston however is huge! :) [Great area, though. I've had a client out there in The Woodlands and enjoyed my visit.]

I 100% agree with you about homeowners doing the installation w/o a licensed contractor. Terrible idea, and absolutely will void the warranty. Adding a condensate pump, like from Aspen Pump, to the air handler will not void the warranty.

I also agree about not cutting the linesets. I see a lot of homeowners asking about this too.

Not too sure about the "using unapproved linesets" though. I've worked with the JMF linesets for a long time now, and they work GREAT across pretty much all brands (Mitsubishi, Panasonic, LG, GREE, Fujitsu, etc).

I don't see any coils of excess line in my Mitsubishi systems. The installer, who has been teaching at a local trade school for at least 30 years, must have figured out how to cut them. He must have figured out how to charge a system too since a reversing valve failed under warranty and had to be replaced.

I have no doubt that older systems may be longer-lived than newer ones, and less complex. That does not mean that the stone-hatchet stuff is better in every way. If we followed that logic, we'd all be driving the cars that they still have in Cuba. Learning new techniques can be challenging and training is expensive when you consider the time needed, but it is necessary. The down side may be that it puts small shops at a disadvantage. I don't see how one or two people can afford to stay current on everything that is out there today. It is not limited to cooling either. Right now, I've been dealing with a boiler replacement at my dad's house and trying to do it on a reasonable budget. Putting a low-mass boiler in his old hydronic system (without a lot of expensive modifications) is a challenge. Finding a local installer that is up to date in his rural area has been frustrating. (Small here is really small. Katy is huge compared to his town of 2000.)

re: http://www.ac-heatingconnect.com/contractors/toolkit/news-and-views/july-2013/

Where are they getting their numbers for installed system type? I have to be suspicious since they don't cite sources.

"What people who make this claim fail to mention is that in ducted homes which have poorly installed and leaking air ducts, the conditioned air is probably leaking out of the ductwork but it is going into the conditioned space somewhere and helping to keep the house cool. In those cases the cooling energy is really not lost to the homeowner...."

This is not true if pressure differentials are introduced. Conditioned air will be blown out through envelope leaks in some rooms and sucked in via leaks in other rooms.

Now here is a disadvantage that few can argue with. In an area with significant heating requirements and access to natural gas, heat pumps are at a significant operating cost disadvantage. When I installed my heat pump mini splits, it cost less to heat with heat pumps. Since then, gas costs have gone down considerably. Fortunately, I have very low heat demand. Gas heating equipment is also much less costly to run than heat pumps based on equipment capital costs.

I just had an issue with a 40+ year old furnace in a 1000 sq.ft. rental house. I had two firms give me estimates. The first said I needed to replace the entire heating & AC plus all new ductwork for $7400. The second checked out everything and told me the ductwork and AC were fine and just needed a new furnace and to wait to replace AC when it went out, but felt it had many more years to go. I am almost certain I had had the ductwork replied several years ago. He charged $2400 and then he told me he had cleaned off the roof of the house too, because it had lots of limbs and leaves on it. I asked how much and he said no charge. I hope I made the right decision. He came highly recommended. At some point you have to find someone you have confidence in and trust them.

Often the issue is that if you need to replace a furnace now and replace it with similar equipment, you will be limited in what cooling you can add later. Right now, you probably have a single speed blower. Better cooling equipment has variable speed blowers. If you replace the furnace now with a variable speed blower model, when the HVAC is updated, you can install a better system. Right now, however, the variable speed blower will not be useful for cooling and will cost more. Still, it sounds like the first contractor may be selling you something you don't need if your duct system is only a few years ago.

chazstevens, sorry I wasn't clearer about sizes and rooms.... the downstairs will be about 900 sq. ft. .....kitchen/living, bedroom, bath, closet, laundry. Second floor 500+ sq. ft. has 2 bedrooms, bath, closets.

I just wanted to know an idea of what I might need if I chose minisplits.

Chazstevens, Please provide a number for which I can provide people that have decided to take it upon themselves to fix their own unit. I will refer them to you.

@anno - Okay, I understand better now! With split systems, think of your home in terms of "zones". You probably have 1 zone for the living room/kitchen, and 1 zone for the downstairs bedroom. On your second floor you have 1 zone for each bedroom. But with a total space of just ~1,400 sq feet, a 4-zone system may be more than you need. I'd probably start by talking to a contractor about a 4-zone system with an indoor configuration of 6,000-9,000 BTU per zone, and a total system cooling capacity of around 36,000 (3 ton) for the outdoor condenser.

BUT - I need to stress this: only a certified contractor in your area will be able to come out and do a proper load calculation that takes into account things like sunlight exposure, how many windows in your home and how insulated they are, the insulation used in your home, etc. This estimate for a 3-ton system is based only very loosely on the ~1,400 sq feet you've given me.

With that said, part of what makes ductless splits great is their variable speed technology, which allows them to cycle up and down as needed.

I hope that helps you! :)

Yes, it does! Thank you!

Looks like the OP has done whatever he decided to do. However, I think the wrong questions were being asked to solve his problem. The original installer should have been called back to locate the air handle to a code-approved position (I believe ALL codes now require a certain minimum access around and to the unit).