Air conditioner advice

[RE2Boys]

These units are not uncommon in the US. A neighbor has a unit installed for a specific bedroom that is at the far end of the house that does not get adequate cooling from the central system.

And I know of an older church building that has 12 of these compact split systems instead of a big central AC system. Duct work would have been an architectural mess.

 

[samclem]

These units are not uncommon in the US. A neighbor has a unit installed for a specific bedroom that is at the far end of the house that does not get adequate cooling from the central system.

And I know of an older church building that has 12 of these compact split systems instead of a big central AC system. Duct work would have been an architectural mess.

In the US, the minisplit units are used in situations like this--where installing ducts would be a problem, or to provide more cooling/heating in a spot that isn't adequately serviced by the main central HVAC system. They are pricey and the commonly available ones are not of significantly better efficiency than a high-end central AC system (20-22 SEER). A conventional (i.e. with ducts) AC system can (at reasonable cost) put conditioned air in every single room, something that might be very expensive with a mini-split. But, each "register" in a mini-split (even though there are far fewer than in a typical ducted central AC system) has its own thermostat, which can allow for a lot of tailoring.

In the US, mini-splits are a niche product. If a whole house is done using mini-split systems it will have lots more motors, valves, sensors, circuit boards, etc than a central HVAC installation, and can be expected to have higher maintenance costs.

 

[pj.mask]

I just want to say you should do some cheap insulation work. Caulking cracks and adding strips to doors/windows - spend $500 on insulation will probably pay for itself in a year at your electrical prices. Also if you install this unit - consider the compressor placement. You could fix it on the outside of your balcony or build a barrier around it to limit noise.

 

[Al in Ohio]

By the way, for a free-standing portable AC make sure you buy a dual-hose unit.

The single-hose units exhaust hot air out the window by ejecting air from inside the room. This means it creates a vacuum inside the house, and that causes exterior hot air to get sucked in through cracks in the walls and around doors.

A dual-hose unit sucks in outside air via the inlet hose, heats it up with the heat extracted from the room, then exhausts that hot air via the outlet hose.

Heat is easily created with electricity, such as with an electric heater or on a stove top. Heat cannot be "destroyed", and can only be exchanged or moved from one medium to another. Hence, to cool a room you need to expel that heat, and an AC needs to have a heat exchanger to heat up the outside air while cooling the inside air.

I am an HVAC design engineer and the OP does not want to entertain this type of system. It is a temporary system for emergency spot cooling versus the ductless split AC system which is for permanent install. To the OP : I have specified and designed both Fujiitsu and Mitsubishi ductless systems on dozens of projects. You will be happy with a wall mount or ceiling mounted Mitsubishi system.

 

[Al in Ohio]

Having been renting for the past 12 years, Mrs BigNick and I have taken the plunge and bought an apartment on the Spanish island of Mallorca.



It gets hot here - 90s F and high humidity every day in summer. Plus although the winters are not very cold, the apartment has minimal insulation and currently no central heating. We plan to put oil radiators in the bedrooms.



For the main room we are looking at a split A/C unit with 3.5KW (12,000 BTU) capacity, which can also act as a heater. The installer has proposed us three models, from Fujitsu, Mitsubishi, and Midea (which is a little cheaper, being a less famous brand). I have asked him for the exact model numbers so I can compare features, but... what features should I be looking for? We Europeans tend to have very little experience with air conditioners!

The Mitsubishi is a nice system for cooling your mai room. It is offered as both a heat pump version or standard AC with several size kw electric strip heaters for heating as well as cooling the zone it serves. No ductwork and easy Retrovir install.

 

[NW-Bound]

I am an HVAC design engineer and the OP does not want to entertain this type of system...

I knew the OP wanted a mini-split, and discussed that.

Regarding the stand-alone portable units, I was replying to explanade who was talking about units that one can "roll from room to room".

Actually, it may not be so simple to relocate the exhaust hose of these "portable" ACs, and these portable units are more or less semi-permanently placed. These units do not have that good an efficiency either.

 

[Tom52]

I have a 20.5 seer 2 ton Mitsubshi mini-split in my garage in Florida. They are very energy efficient and very quiet both inside and outside. Unit will also heat the garage nicely in winter where are temps are similar to yours. For reference the condenser is model MSZ-GL24NA and the air handler is model MUZ-GL24NA. Garage walls are concrete block/stucco with no insulation, the ceiling is insulated as well as the garage doors.

 

[mountainsoft]

Good timing... We live in the Pacific Northwest and don't have any kind of AC (short of pulling out fans when it gets really hot). After suffering through a few heat waves this summer, we decided to invest in some kind of AC.

Window units were not an option. We don't like the look, the noise, blocking the window, or the difficulty installing/removing them. My brother and sister in-law had one that I helped them remove every year. What a pain. We're getting too old for that.

I really wanted to install a mini-split unit, but ironically there's only one wall in our entire house where I could place the indoor unit. Up above the cabinets in our kitchen (we have high vaulted ceilings). I wouldn't mind it there, it would mostly be out of sight, but cleaning the filters would be difficult as we get older. There would also be issues placing the outdoor unit. The only spot we really have available is between our house and garage. Unfortunately, it's only an eight foot space, and the manufacturers generally want seven feet of space in front of the unit (as well as 12" behind and the depth of the unit itself). I could shift it towards the corner of the house more, but then it would be vulnerable to getting hit by a car.

Until I started researching this, I never realized how few available wall areas we really have. Windows go almost to the ceiling, with most wall areas being under three feet wide or already in use for lighting, cabinets, etc. Interior walls would be difficult to run the line sets through, and almost every stud bay in our house is already packed with plumbing, electrical, structure, or other utilities (I photographed every wall before we insulated).

So, we are going to try a portable unit. We normally don't get that many hot days here, so it might work. I have my doubts though, as we have a fairly open floor plan and the portable units are limited to about 10K BTU (DOE rated). They look kind of hacked with a hose to a window, tend to be noisy, and aren't all that energy efficient. But, we figured it was worth a try. I ordered a Fuji portable that is supposed to arrive next week. We'll see how that goes. I'm not sure where we'll store it when we don't need it.

The only other option I can think of for a mini split is to mount the outdoor unit up on the side of the house, above the height of the garage roof. Not ideal as it would be difficult to install and a bit of an eyesore (first thing you would see driving up to the house).

 

[REWahoo]

Would a PTAC unit work below your windows? Not as quiet as a mini-split but a step above a window unit, and no remove/install issues.

PTAC:

 

[NW-Bound]

Pioneer has indoor units that are mounted recessed into the ceiling. Would this help?

They cost a bit more than regular indoor units, and look harder to install, but can solve problematic situations. I am contemplating one such unit for a 3rd mini-split.

Regarding placement of the indoor unit, it is tricky to run the condensation line to the outside. It has to slope continually down from the unit to the outside, unless you get access to a drain pipe inside the wall. This is why these usual indoor units are usually placed on an exterior wall. I was able to place two units on an interior wall, but that was possible only because these are vaulted walls, and adjacent to the attic space where I can run the drain lines outward to an exterior wall. For a new house, or if you don't mind tearing out the sheet rock, you can run the refrigerant lines as well as the drain line through the studs. Too messy for an add-on installation.

For the ceiling recessed unit, if you can run the lines in between the ceiling rafters or joists instead of through them, it saves the hassle of tearing out the sheet rock for installation.

 

[mountainsoft]

Would a PTAC unit work below your windows? Not as quiet as a mini-split but a step above a window unit, and no remove/install issues.

Nope, the standard size seems to be 16" high and we only have about 14" below our windows. Not to mention electrical outlets and whatnot already in that space.

My mom has a PTAC at her assisted living (as well as most hotels) and they are quite noisy.

I considered "through the wall" air conditioners. Basically window units with a sleeve in the wall so you don't take up a window. Those are smaller than PTAC's, have about the same output, but even at 24" wide it would be difficult to find a spot to install one.

That's the downside to designing a house where there is very little wasted space and the remaining areas already serve other functions.

 

[mountainsoft]

Pioneer has indoor units that are mounted recessed into the ceiling. Would this help?

We have vaulted ceilings, basically just the rafters, so there's no traditional attic space to get access for the line sets. Sure, it probably "could" be done, but it wouldn't be worth the trouble.

And I would still have the issue of where to place the outside unit. The only location where it wouldn't end up right outside one of our windows is the wall facing our garage. And there's only eight feet between the house and garage.

I thought about turning the outdoor unit sideways, but the width of the unit plus the distance for access on the end would put it out in the walkway. That wouldn't really work either.

Our one potential interior wall wouldn't work for the inside unit either. It would either be too close to our woodstove chimney, or too close to our ceiling fan. Because of the sloped ceiling, I couldn't raise the fan up any higher either.

It's kind of bummer. We have a nice 6'x24' attic "room" that I could stuff all kinds of pipes or wiring in, but no good location for the mini-split units indoors or out.

At the same time, it's nice to know we fully utilized every inch of space in our small home.

 

[NW-Bound]

We have vaulted ceilings, basically just the rafters, so there's no traditional attic space to get access for the line sets. Sure, it probably "could" be done, but it wouldn't be worth the trouble.

And I would still have the issue of where to place the outside unit. The only location where it wouldn't end up right outside one of our windows is the wall facing our garage. And there's only eight feet between the house and garage.

I have not read the installation of the recess unit to see if it can be mounted in a sloped ceiling. Perhaps it can, if the corner where the drain line is attached is pointed in the right direction.

Where I am thinking about mounting it, there's a 2nd story room above it, and the unit looks like it can fit in between floor joists, and the depth does not exceed the floor joist depth. The refrigerant and drain lines can run in between the floor joists and exit out the exterior load bearing wall.

About the outdoor units, my existing units are mounted on the side of the garage, with only 7' to the block fence between my lot and the neigbor's. The units are mounted on the wall of the garage, off the ground about 5' up. The exhaust hot air rises up, and has plenty of clearance to escape upwards. I measure the air surrounding the outdoor units, and see no measurable higher temperature than the ambient. I think that's what the manufacturer wants to avoid: a pocket of trapped hot air that reduces the efficiency of the system. If you have plenty of open space around the unit for ventilation, there should not be a problem.

 

[mountainsoft]

I have not read the installation of the recess unit to see if it can be mounted in a sloped ceiling.

The only flat ceiling we have in our house is in our "hall", a small 6'x8' room where a number of doors meet. Our 6'x24' attic space is above the laundry, hall, and bathroom. I'm not sure how well an AC vent in our hall would work for cooling the house. The office and back bedroom would probably be okay, and maybe the kitchen/dining. I would think the living room would be too far away. I'm more interested in cooling the living/dining/kitchen area (about 550 sq ft) than the rest of the house.

my existing units are mounted on the side of the garage, with only 7' to the block fence between my lot and the neigbor's. The units are mounted on the wall of the garage, off the ground about 5' up. The exhaust hot air rises up, and has plenty of clearance to escape upwards. I measure the air surrounding the outdoor units, and see no measurable higher temperature than the ambient. I think that's what the manufacturer wants to avoid: a pocket of trapped hot air that reduces the efficiency of the system. If you have plenty of open space around the unit for ventilation, there should not be a problem.

If the portable unit doesn't work out, I might revisit the mini-split idea. My proposed location would be right where our kitchen stove is. The indoor unit would be above the cabinets, the outdoor unit would be just outside that wall. Both sides outdoor are completely open, there's nothing above, and maybe 3' to the front corner of the garage. I doubt hot air would get trapped there.

 

[ncbill]

Nope, the standard size seems to be 16" high and we only have about 14" below our windows. Not to mention electrical outlets and whatnot already in that space.

My mom has a PTAC at her assisted living (as well as most hotels) and they are quite noisy.

I considered "through the wall" air conditioners. Basically window units with a sleeve in the wall so you don't take up a window. Those are smaller than PTAC's, have about the same output, but even at 24" wide it would be difficult to find a spot to install one.

That's the downside to designing a house where there is very little wasted space and the remaining areas already serve other functions.

What about something like:

https://smile.amazon.com/Midea-Inverter-Conditioner-Flexibility-Installation/dp/B0867GMW9X/

 

[mountainsoft]

What about something like:

https://smile.amazon.com/Midea-Inverter-Conditioner-Flexibility-Installation/dp/B0867GMW9X/

I've considered that, though there is still the issue of having to install/uninstall it each season. It would also block the view out of the window.

Soleus makes something similar, but hangs down so it wouldn't block the window. I might be more likely to one of these if I had to get a window unit.

https://www.amazon.com/Soleus-Air-Exclusive-Conditioner-Putting/dp/B08HSQC984

 

[NW-Bound]

The only flat ceiling we have in our house is in our "hall", a small 6'x8' room where a number of doors meet. Our 6'x24' attic space is above the laundry, hall, and bathroom. I'm not sure how well an AC vent in our hall would work for cooling the house. The office and back bedroom would probably be okay, and maybe the kitchen/dining. I would think the living room would be too far away. I'm more interested in cooling the living/dining/kitchen area (about 550 sq ft) than the rest of the house.

If the portable unit doesn't work out, I might revisit the mini-split idea. My proposed location would be right where our kitchen stove is. The indoor unit would be above the cabinets, the outdoor unit would be just outside that wall. Both sides outdoor are completely open, there's nothing above, and maybe 3' to the front corner of the garage. I doubt hot air would get trapped there.

Another possibility is the corner of the living room. I don't know what is right outside the living room, but if the wall between the living room and the master bedroom is a high wall, a unit can be mounted there, a couple of feet from the exterior wall.

Here's a photo of my installation, in a similar situation. The lines exit to the side of the unit, and go through the wall to enter the attic space of the garage on the other side of the wall. I cover up the lines using a short piece of square plastic gutter downspout.

This unit is fairly large, because it's a 18,000-BTU/hr unit. Mounted high above a hallway, it does not look too intrusive, compared to being in a room with a low ceiling. It is in a corner of the living room, which is open to the dining room and kitchen. It has no problem cooling the ground floor living space of my 2-story home. I have a smaller 9,000 BTU/hr to cool the master bedroom, which is also downstairs. This smaller unit is also similarly mounted high.

The lines of the indoor unit can exit to the right or left of the unit, in addition to the back of the unit. This provides additional mounting orientations.

If this works for you, I would do 2 smaller 9000-BTU/hr units, one in the living room and another in the master bed. They would be on opposite sides of the same wall, and the installation is a mirror image of each other.

Come to think of it, the two indoor units can be fed by a single multi-zone outdoor unit.

 

[ncbill]

I've considered that, though there is still the issue of having to install/uninstall it each season. It would also block the view out of the window.

Soleus makes something similar, but hangs down so it wouldn't block the window. I might be more likely to one of these if I had to get a window unit.

https://www.amazon.com/Soleus-Air-Exclusive-Conditioner-Putting/dp/B08HSQC984

Yep, but the Soleus gets terrible reviews...it seems to be going on discount some places (to get rid of stock?)

 

[W2R]

I think my approach to getting good air conditioning, is much different from what the men here normally do. So, I doubt anybody will take my approach, but here it is:

I know just about zero about air conditioning, but I know people who have lived here forever and have good air conditioning. For example, Frank. He knows who does good air conditioning work because his family has lived here forever and they all know who does good work.

So, I asked him who to call, he said "S****'s Air Conditioning", because that is who his late uncle used. I called them, they came over and looked at my house for an hour or two and told me what they recommended. I told them to do it and it has been great.

TLDR: My approach is,

1) Call an experienced air conditioning expert with a stellar reputation among honest, discerning people in your area that you know well.

2) Get his expert advice, and tell him to do what he advised. Pay him.

3) Enjoy a nice cool house.

YOU don't need to spend your time learning to be the biggest expert on HVAC in your town. A better use for your time is to spending it finding out who that expert is. Then do what he suggests.

 

[mountainsoft]

if the wall between the living room and the master bedroom is a high wall, a unit can be mounted there, a couple of feet from the exterior wall.

That wouldn't really work well in our case. The lower "flat" part of our living room wall is taken up with our entertainment center, and in-wall speakers. While there is available space up in the gable area, running the line sets would be difficult without major work or an ugly appearance.

The opposite outside wall also wouldn't work well because of our windows. While I could technically mount one above the window, I don't want to see the line sets running down the outside front wall of our house.

Also, neither location would be good for access to clean filters or whatnot. So no-go in the living room.

I don't really want a unit in our bedroom, but the wall that backs up with the living room wouldn't work anyway because we have a smoke alarm installed there. The opposite bedroom wall also has in-wall speakers. So no-go in the master bedroom.

The best location I can find is above the cabinets in the kitchen. It's on an outside wall, there's no pipes/wires in the wall up there, it would blow air towards the dining and living room, and the line set could run right down the wall to the outside unit. It would still put the outside unit in a rather visible location when we drive up, and it could potentially be vulnerable to someone backing into it with a car. I think I could shift it back far enough to minimize that, but there are minor other issues to consider.

In theory, I could install a "concealed" mini-split in our attic room with short ducts to each room. There's plenty of space in the attic room, and it's inside our conditioned air space (below the insulation). Unfortunately, that gets more complicated and expensive than I want to do. We've lived 30+ years up here without AC, so it's not a huge priority.

I'll try the portable unit when it arrives next week to see how it does. It that doesn't work out I'll reconsider the mini-split in the kitchen. Otherwise, we'll just do without like we always have. We typically only get a few days each year that are hot enough we wished for AC. This year has just been exceptionally hot and dry.

 

[mountainsoft]

1) Call an experienced air conditioning expert with a stellar reputation among honest, discerning people in your area that you know well.

2) Get his expert advice, and tell him to do what he advised. Pay him.

As you may know, I'm a big DIY person. If I can't do it myself, I'm more than likely not going to do it. Hiring someone to install an AC system would also be very expensive ($4K to 8K from what I hear). That's way out of my comfortable budget.

The only reason I'm even considering a mini-split is because I can get a DIY "Mr Cool" system for less than $2K. That's still a lot more than I want to spend, but if I could do it myself I might consider it.

The main thing I dislike about the Mr Cool units is the line sets are precharged with a fixed 25' length. They can't be cut (without paying big bucks for an HVAC pro), so the extra line set needs to be coiled up somewhere (usually behind the outdoor unit). Kind of tacky in my opinion, but I'm really picky about appearance details. Even a line set cover on the outside of the house would bug me. The fixed 25' length also means my installation locations are limited. I have to be able to get from inside to outside with 25' of line set.

Anyway, it's not an urgent need. We just got a little "spooked" by the record high heat this year. Any other year I wouldn't have even considered AC. It just made me think "what if..."

 

[mountainsoft]

Yep, but the Soleus gets terrible reviews...it seems to be going on discount some places (to get rid of stock?)

Honestly, I probably wouldn't get either unit. I like the design of the Soleus better (doesn't block the window view), but I wouldn't want to lift the units in and out of the window each season. I also wouldn't like the security issue of the window always being partially open.

 

[ERD50]

As you may know, I'm a big DIY person. If I can't do it myself, I'm more than likely not going to do it. Hiring someone to install an AC system would also be very expensive ($4K to 8K from what I hear). That's way out of my comfortable budget.

The only reason I'm even considering a mini-split is because I can get a DIY "Mr Cool" system for less than $2K. That's still a lot more than I want to spend, but if I could do it myself I might consider it.

The main thing I dislike about the Mr Cool units is the line sets are precharged with a fixed 25' length. They can't be cut (without paying big bucks for an HVAC pro), so the extra line set needs to be coiled up somewhere (usually behind the outdoor unit). Kind of tacky in my opinion, but I'm really picky about appearance details. Even a line set cover on the outside of the house would bug me. The fixed 25' length also means my installation locations are limited. I have to be able to get from inside to outside with 25' of line set.

Anyway, it's not an urgent need. We just got a little "spooked" by the record high heat this year. Any other year I wouldn't have even considered AC. It just made me think "what if..."

I wonder if they will do a special order, where you specify the length?

-ERD50

 

[mountainsoft]

I wonder if they will do a special order, where you specify the length?

Unfortunately, no. They only come with a 25' length. You can order a 16' length, but that's another $225 or so, in addition to the original package price. I "think" they have a longer line set too, but that's additional also. I saw connectors somewhere that lets you connect two precharged line sets, but again, it's all an additional cost.

At some point it just isn't worth the cost. As it is, Mr Cool charges a premium price for their precharged line sets. It's almost cheaper to buy another brand and purchase the vacuum pump and gauges to vacuum the lines yourself. Or go all out and buy the flaring tools to customize the line set to the exact length.

I love to DIY but at some point it gets excessive for a one time job. As W2R said, I don't necessarily want to be an HVAC expert.

 

[RetiredAt55.5]

Honestly, I probably wouldn't get either unit. I like the design of the Soleus better (doesn't block the window view), but I wouldn't want to lift the units in and out of the window each season. I also wouldn't like the security issue of the window always being partially open.

I also wonder whether that type of unit just kicks the problem down the road - when you need to replace it and you can't find anyone making that type anymore.