It seems high but you would have to get comparable quotes to know. Our system was quoted between $14K-$30K. We paid $16K. It has two ceiling cassettes, three wall units and 2 outdoor units. We got it installed some time ago. Maybe 10 yrs, I'm too lazy to look right now.

Try asking for a wall unit. Those are alot simpler to install than the ceiling cassettes or the units that look like regular duct vents. It all depends on your attic access. They may have never installed a ceiling unit so they gave you a quote they knew no one would ever take. Also they may have to upgrade your electrical panel.

Ductless minisplits are more expensive than central air.

Consider buying a 6000-8000 BTU window unit for about $200. That would be sufficient to keep the bedroom at 75 degrees while you set back the temperature in the rest of the house.

There are pros and cons for whatever it is you decide to do. If this home is located in an HOA deed enforced neighborhood you may not be able to use a window unit. The HOA *may* at some point fine you. The other problem with a window unit is noise. Certainly the longer you operate it you will become accustomed to this noise... even still it's a nuisance.

The mini split is an option but as you've found out the cost to install it is likely no where near as cheap as you thought it might be. Obviously aesthetics are important to you or you wouldn't be looking at a cassette type indoor head, that is likely what has driven the price up.

You obviously know about zoning as you asked about it in your initial post. The biggest problem with zoning is finding some one to do it right. When it comes to resale value of the home I think the zoning option is the better play... it's out of sight out of mind and a part of the regular HVAC system and as long as the zoning is done properly there is little to no additional cost to maintain the zone system.

If your HVAC equipment is single speed this probably won't save on utilities as much as you might hope for. The sum of the parts that make up your AC system typically decide how efficient or inefficient the system may be... especially when considering zoning options.

However, HVAC systems are also about achieving comfort. That was the whole reason this market exists was that people wanted to sleep, eat and play in their homes and be comfortable. A zone system tends to make areas of the home more comfortable than they would otherwise be without a zone system. In addition to that the zone system tends to minimize operating costs as well as maintain the aesthetics of the home. All good resale points.

Google the unit, and see what they sell for unit only.

I am not certain whether the OP is considering a ceiling cassette or a minimially-ducted model. Anything other than high wall mounted models are more costly and less efficient. Given that the installation is in an upstairs room, if the door to the bedroom is left open, it may keep the entire home pretty cool and dry overnight. I have seven high wall models and one or two of them running overnight work well in my single-story, not open floor plan home. Given that the compressors throttle back to 6-8,000 btu, they probably cycle some in driving 6 or 9,000 btu indoor units. From a comfort standpoint, it seems to me that this could be a winner. That is especially for humidity control.

Depending on the home layout. the bedroom mini split alone might cool the house sufficiently by itself for large parts of the day and large parts of the year when loads are not near peak. Energy costs might go way down, but may never pay back the investment.

I don't understand how this can possibly be true, especially for a single-speed system:

Even if you shut down the central A/C overnight, you'll lose some of that savings when it has to work extra hard in the morning to bring the temp & humidity down (and if you are in a humid climate, I wouldn't recommend shutting it off at night).

Thank you all for the responses and information. I agree that I should get another estimate or two - not sure why I didn't think of that before posting. :)

I'm also going to ask about the price difference between the ceiling cartridge and a basic wall unit. As was mentioned in one of the comments, aesthetics are very important to me, but I could live with a wall unit if it's a huge $$$ savings.

I'm also now seriously considering looking into a zoned system. Our existing central AC is probably the original one from when the house was built in 1990 (not sure - we bought the house in 2011). It wouldn't upset me too much to replace it with a variable speed unit.

Just to clarify a few things that were brought up:

I'm not sure what my HOA's policy on window ACs is, but that's out of the question anyway. I'm a light sleeper and a window AC is pretty much guaranteed to keep me awake all night because of the noise.

I'm mostly interested in getting a separate system (or zoned system) to save energy and to make my bedroom more comfortable. Making back my investment over the long term would be great, but this is not my primary motivation.

Thanks again!

with the age of your existing AC, it would seem that you should consider just replacing everything and having your bedroom zoned rather than spend all that money on a minisplit. Just another option to consider.

good luck!

I don't understand how this can possibly be true, especially for a single-speed system:

Even if you shut down the central A/C overnight, you'll lose some of that savings when it has to work extra hard in the morning to bring the temp & humidity down (and if you are in a humid climate, I wouldn't recommend shutting it off at night).

Single speed, 2 speed or variable speed (any AC system really) works less hard outside the heat of the day. (3-6pm in most cases)

If OAT is lower, the system runs at slightly higher capacities than it otherwise would under the heat of the day type load. You gain efficiencies when you run the system outside of the 'heat of the day' time period.

If you have a zoned system and running a smaller zone (humid climate), it's best for efficiency of the system so that the unit will run longer when cooling a smaller zone. The return air is still drawn from hotter areas of the home, but because the system is running in lower speed it is more or less dehumidifying the home when in a lower speed. Even better if the compressor is variable speed, because it will run at much lower speed than a 2 speed system will... thus increasing runtime without 'over cooling'. Because over cooling will increase cycling of the system.

With that said, you can still zone a single speed system... but it will cycle much more frequently when only running small zones within the structure. The efficiency of doing so is quite a bit less I think.

If you lower humidity in the main part of the home, the higher temperature due to not running those zones is of no great concern because less humid is more comfortable even at a slightly higher temp (typically 10 degrees from a cooled zone outside the heat of the day time period in most cases). A well thought out zone system can pull down those areas quite quickly especially if you aren't using other areas of the home at that time and close those zones off.

The other key area(s) to making a zone system work well (above that of 2 speed / variable speed condenser) is to have a well designed air return and make sure the attic is properly ventilated as well as insulated well. (no thermal breaks, good natural attic ventilation.)

Austin, Is your intent to show that setbacks do not save energy? It looks that way, but I combed through you post looking for logic or data that indicates that set-backs will not save electricity, but I come up pretty short. Recovery from an over night temp increase indoors is at a relatively cool part of the day if not the coolest. Setbacks lower energy consumption in these simple situations.

If switching the discussion from single speed blowers and compressors to variable speed, you have to get into some math to show that a set-back is useful. With a well-insulated house and a closely-matched system capacity, set-back is less useful because the system runs at lower efficiency when running flat out. I wish the manufacturers would get on the stick and give us recovery modes that are more in the efficiency sweet spot. The situation is reminiscent of early heat pump installations where the resistance heat kicked in every time the thermostat was nudged up.

Austin, Is your intent to show that setbacks do not save energy? It looks that way, but I combed through you post looking for logic or data that indicates that set-backs will not save electricity, but I come up pretty short. Recovery from an over night temp increase indoors is at a relatively cool part of the day if not the coolest. Setbacks lower energy consumption in these simple situations.

No not at all... but setbacks are not comfortable to the user. So this is more complicated than just merely setting back your thermostat. How more likely is the user going to set back, if they are more comfortable in the areas they are actually using?

You see with what I propose is that you are comfortable in the room(s) you are using as opposed to a room(s) that are not occupied. The idea isn't only to cut costs, the idea is also to be comfortable in the area of structure in which you are using. This goes far beyond the terminology of just merely 'setting back' a thermostat.

If switching the discussion from single speed blowers and compressors to variable speed, you have to get into some math to show that a set-back is useful. With a well-insulated house and a closely-matched system capacity, set-back is less useful because the system runs at lower efficiency when running flat out. I wish the manufacturers would get on the stick and give us recovery modes that are more in the efficiency sweet spot. The situation is reminiscent of early heat pump installations where the resistance heat kicked in every time the thermostat was nudged up.

I wasn't trying to change the subject, I believe I was answering questions to a very complicated subject and the OP brought up the subject of zoning in the original post.

As an example: I rarely use the west side of my home and so most of the time I have this zoned to off. So you could classify this as a 'set back' as you say. I have the ability to cool these areas if I so desire. In the heat of the day these areas (far west zone) has the potential to hit 90 in the afternoon, early evening sun. As the load changes over night the temp typically drops to 80-85 in this unused shut off zone.

So just because it hits 90, doesn't mean it stays at 90 all day long. Which is my point I mentioned previously about attempting to drop attic temp another 10 degrees from a different post I made when we entered this discussion before.

With that said... it's not like the structure is without any air conditioning at all. Realize the far east side of my home I keep 76 during the day and 74 at night. Very comfortable considering the west side (currently) can hit 90 on days of 95 degrees plus so far.

This all comes from loads being placed on the structure, not to mention a good amount of thermal envelope breaks as well as attic ventilation problems.

So to sum this up:

Set backs can save you money, but at the expense of being less comfortable. My goal is to show you that it possible to not only have your cake, but also get to eat it... in the form of COMFORT.

That is the purpose.

I just check the stat on the west side it's at 82 this morning... but it's supposed to be really hot here coming up, so we'll see what happens.

While this doesn't seem to be answering the OPs original question I will throw in my $.02 on how we actually use our ductless minisplit for those who are researching this issue. We have a full house system, 5 indoor units and 2 outdoor units. Of the 5 indoor units 2 are ceiling cassettes and 3 are wall units. We use the 2 ceiling cassettes and 2 of the wall units regularly. One wall unit, in a south facing office isn't used very often.

We do turn off all the air conditioning in the house most nights. Sometimes if it is really hot out we will leave the master bedroom on set to a higher temperature like 76 because I do not like the air blowing on me at night. We have a ceiling cassette in the master bedroom but have blocked off the vent that goes over the bed to help with this issue.

If there is no rain/high wind in the forecast I will often open the upper floor windows and some of the main floor (that are inaccessible to someone outside the house due to how high up they are) to cool the house over night. If I can't do that I will often open them all in the morning to cool before the day heats up.

When we have had remodeling done and I needed to air out the house I would leave the AC off and just air condition the master bedroom and bath. The dogs and I hang out in their a few days to let fumes bake out of the remodeled areas.

If for some reason I haven't had the air going and need to move into that area of the house the ductless minisplit will make it feel cool within minutes of turning it on. This is because the cool air is falling from the ceiling. So even if we have been out of town and come home to a 98 degree home, within 5 min. of turning the system on we can feel the cool air. It will take a while the actually cool the rooms and structure because the walls/furniture/floors are at 98 but the humans in the room will feel cooler almost immediately. Conversely if you are indoors on a very hot day and have been running the ductless minisplit all day then it is easy to feel a chill because of the cool air running by your skin all the time. I often keep a long sleeve lightweight fleece handy to throw on. It helps to turn the temperature up but because whenever it is running the cool air is blowing on you on very hot days it is blowing often so it can get a bit chilly.

what mmmm12 posted is an illustration to another reason zoning (no matter how you do it) has a place because I like to sleep at 74 and mmmm12 likes 76.

No two of you are exactly alike. With zoning you can find your sweet spot and sleep in absolute bliss as well as other people in your family. How many families out there fight over the thermostat setting? zoning can solve those issues.

However, the zoning I am talking about isn't using mini splits to accomplish it. I am using a regular ducted system to accomplish this goal. This method of design keep the number of pieces of equipment lower... which over time will be the more cost effective solution.

Speed to cool down a zone with my system is similar as to what mmmm12 posted. I actually tested it and posted this info in that other thread... took about 30 minutes to pull down the zone I was using. With that said you feel the cool long before the setting is accomplished.

In comparison to a single zone AC you would probably be looking at a minimum of 4 hours maybe longer depending on OAT as well as other loads on the 'whole' structure. In the heat of the day it may take over 4 hours. If you're not at least feeling it within 4 hours for a single zone AC... your AC isn't what she used to be.

That 4 hours is a lot of run time... making that utility meter spin like a top. I can't make it any more clear than that.

Set backs don't make me uncomfortable because I am not there to notice. On the odd day that I make a trip home in the middle of the day might be the only occasion.

Because utility rates continue to go up has people looking into other options. If set backs work for you there is nothing wrong with that, you just lack the control for anything more than that.

Zoning gives you better control, it can reduce operating costs as well as making occupants much more comfortable with varying tastes in comfort for people who like different temperature settings.

Set backs for air conditioning basically work by you setting (or programming) into your single stat a time and temperature arrangement. The higher the setting you select the longer the recovery period will be, depending on heat of the day among other factors that effect the load of the building. Depending on your setting it could take 4 hours recovery or more.

As an example: you leave for work the setting on your one thermostat is set to 85. If you set it to 80 your savings via the set back are diminished. If the thermostat breaches 85 and initiates cooling at that temp it will also take much longer to pull down by the time you come home.

In other words lets say the temp hits 85 in the home your setting is 78 for when you come home. (I am only guessing, because you haven't told me what your setting is.)

If you come home by 6pm your unit will likely kick on and stay on from 2pm to 6pm to reach your set point by the time you come home. 4 hours of run time.

zone system: you have anywhere from 2 to 4 thermostats (typically) each stat can be programmed to that area's desires in temperature or simply turned off.

The zone system reduces costly run time, the better the more efficient the equipment the more cost effective this is.

Because utility rates are poised to only go up, has people thinking about ways to reduce and lower those bills with the ability to be more comfortable than without the option. Realize there isn't a wrong way. As I have said many times before HVAC isn't a one size fits all market. Certain housing designs sometimes make HVAC zoning impractical.

All true, Austin. My first objection was to the post that appeared to say that you lose any setback gains when you are in the recovery mode. You post appeared to accept that and I found it hard to believe that you do given what you have written in the past. That is a really annoying urban legend that I believe can be traced to early heat pump installations with very simple controls that could not recover from any really heating setback without hitting the backup, electrical resistance heat strips. That was fixed, obviously with better thermostats.

Things they are a'changin, however. One important point is that with variable speed systems, maximum output puts you in relatively inefficient operation. That has led some writers to advise homeowners similarly, don't do setbacks. In fact, that is too simple. If the setback is deep enough and of long enough duration, the building characteristics lead to high loss, and you are not too close to the outdoor design temperature, setbacks can still be useful. The trouble is that most homeowners are not able to make the judgement. Many HVAC pros probably can't do it either. The fact is, to determine what will work best requires the kind of calculations that HVAC engineers are used to making and some good starting data.

That is why the cooling equipment makers of the HVAC industry needs to get on the stick and catch up with the boiler makers (and probably furnace makers) who have relatively elegant controls allowing efficient setback recovery at partial output. They make it work, so can the cooling equipment gurus. Eventually, we should be able to get to the point where someone can look at their thermostat, or home computer, and see a message from the system telling us that it has decided that due to the weather forecast, it is not doing a setback today because it won't be able to return to your comfort level (conditions too close to outdoor design temperature).

Those heating systems (mod cons) can take advantage of require considerable set-up and tweaking although I think that they are getting better at self-learning. Some are so adaptive that not much or any learning is needed to operate pretty efficiently. If anyone is not familiar, here is an example. I am making up the concrete numbers, but they are probably not too bad: The boiler starts up to recover from a setback at 60% output. The controls know the outdoor temp and the target temp and have already determined what time to start the recovery to have the floors warm by the time pop usually gets up (before the kids and wife) to get to work. Uh oh, the temperature rise is not as expected after 30 minutes so it bumps output up to 80%. After another half hour, still not good. It is a little too late for dad since he is leaving a little earlier than usual today, but it bumps output up to 95% and makes it time for mom's feet to hit a warm floor. (OK, efficiency has dropped from 97% to 92% for that last 30 minutes, but no biggie.) Cooling systems have the ability to look at outdoor temp and determine start-up time, but the modulation, on the fly or not, is not there for residential systems as far as I have seen. I'll be optimistic and believe that we will get there soon.

There was never a post which said that you lose 'any' setback gains when in recovery mode. I wrote that post and it says "some" of that savings. Meaning, that it's not as simple as "I saved a ton b/c my AC was setback 10 degrees overnight for 8 hours", because your AC then works harder to get back to a comfortable temperature. And of course there are tons of variables which alter the equation for each particular situation. It was just part of my overall point that spending $7k for the mini-split in OPs situation is a poor economic decision. However it could be a great decision from a comfort standpoint.

freeoscar, what you wrote is, at best, too simple to be useful and misleading. At worst, simply incorrect If you define a setback as a temporary lowering or raising of the thermostat or even a temporary shut off of a system allowing the temperature/humidity to float towards ambient outdoor temperature. If you define setback as a permanent raising or lowering of the thermostat or a permanent shutdown, It is correct:

"Even if you shut down the central A/C overnight, you'll lose some of that savings when it has to work extra hard in the morning to bring the temp & humidity down (and if you are in a humid climate, I wouldn't recommend shutting it off at night)."

In the olden days, with entirely single-speed, bang-bang, systems, the correct guidance was, simply, "setbacks save energy/money". Today, with variable speed systems, it gets complicated. If they system relies on a simple single-speed system, however, the advice has not changed and is still simple.

Yes, we agree that setbacks may save money, and the magnitude depends on the particular situation. For whatever reason you are looking for a disagreement.

I am not looking for a disagreement. My problem is that several people might read what you wrote and conclude that setbacks are not productive. Each of those will tell a hand-full of impressionable folks and get them to believe it and so on. That is how urban legends are born.

You see this theme of setbacks are stupid all over the web and I've heard it from many mouths, including my sister's. The way I am often successful in explaining it way is to go to a limiting example, turn the heat off and leave your house for a year. Come back and turn it back on. Do you really think you use more energy than leaving it on? Sure, daily setbacks are somewhat different, quantitatively different, but not qualitatively. The question of whether it is worth spending money on an expensive thermostat is requires calculation especially since some of them are expensive and when it breaks, the savings will be eaten up by that cost. Can the old round Honeywells break if not abused?

On the other hand:

Do setback thermostats meet potential in the hands of average people?

Adding to some of the comments and data there, if people feel very righteous about their setbacks, it might well lead to wasteful "cranking" of the thermostat instead of putting on a sweater in the winter when engaged in couch potato behavior.

My first objection was to the post that appeared to say that you lose any setback gains when you are in the recovery mode. You post appeared to accept that and I found it hard to believe that you do given what you have written in the past.

It really depends on the system in question. The efficiency of not only the equipment but the duct system, the ventilation system within the attic, the insulated envelope of the structure. You can't say a blanket statement and have it come true each and every time. There are too many variables that will likely make the statement inaccurate. If you're talking to a salesmen how often do the statements they say wind up being true when their motivation is to sell you something? (about as plain as I can say it.)

The point being is that you don't make a system efficient by merely 'setting it back'.

If the system is inefficient from the get go, it will be inefficient regardless of what you do in setting it. Certainly setting it back could increase the efficiency (run cost) of it under certain scenarios... under heavy heat loads? I doubt it. Under heavy heat every flaw in that system will come out, these flaws make the equipment run longer and perform less.

"Even if you shut down the central A/C overnight, you'll lose some of that savings when it has to work extra hard in the morning to bring the temp & humidity down (and if you are in a humid climate, I wouldn't recommend shutting it off at night)."

Zone 4 in my house is shut off. Far west side of house. (sun is hottest as it sets in the west, there is no bigger load than the sun.) Zone 4 hit 91 degrees yesterday early evening. This morning it is 83. Realize this zone is OFF.

Please explain to me how my zone 4 would have to work extra hard in the morning to bring down the temp of 83, when the temperature in this zone has fallen 8 degrees on it's own being shut off?

Temperatures in a structure can change merely due to outdoor ambient temperature and air exchanges thru the structure envelope.

You are comparing apples and oranges. I'm talking about an area of the house you actually use, and would never let get to 91 degrees in the middle of the day. No need to be daft.

comparing apples and oranges... yep, we've both done that. But this is what you do when considering HVAC options.

31 flavors... the world can't agree on one flavor of Ice Cream either.

As far as letting an area get to 91 degrees... I do it for a couple of purposes... for demonstration of before and after is one. You can subscribe to my YouTube Channel here.

You can view there several years worth of utility bills from my previous home and make up your own mind how silly I am. Then subscribe to the channel so you find out what my utilities eventually come out to be on this house.

I am in the process of 'painting a picture'.

Reason and data are good. Name-calling is not good.

Over paying the utility company isn't good either.

Unless you own their stock. (but that power bill comes every month... $50 to $100 a month less adds up to a small fortune in short order. > free country - you choose.)

My flavor = better control, more comfort, low operating cost. Additional benefits: quieter equipment, better warranty coverage.

There are 30 other flavors to choose from... have fun.