school me on a/c mini-splits please

[newbury]

I need some schooling on mini-splits so I'm not dumb when dealing with my son.

SWMBO has a 12x26 "Craftroom" that requires cooling to 74 degrees. It's in Mississippi, in full sun and last month the temps were hitting 100 degrees plus. The room is located above a garage that was transformed into a library. The room has 3 large windows. It has one small duct from our central a/c that looks like it was added as an afterthought and has all the cooling capacity to prevent water boiling.

I've initially put in an 8K BTU window unit (which I had from another house) which labors to keep the room temp down to 76 (not enough says SWMBO).

A downside to that is the noise and it blocks half a window. It looks like a 10K BTU window rattler would cost about $250 plus.

Amazon lists a 9K BTU mini-split kit for $600 so it seems prices are getting pretty close.

And my ace in the hole is that we've a son who is a licensed a/c tech and could finish the install with the proper tools.

So what I'm wondering is:
Would a 12K 110V 15 SEER system for $650 do?
How much savings (ballpark) would I see stepping up to a 12K 220v 22.5 SEER system ($1200)? The unit will probably run all summer.
What other brands should I look at?
The ceiling is a gambrel roof, about 2' high at the sides and 8' in the center. Can the inside unit be mounted at an angle or is it better vertical?
Is running a 220V (actually 240) line worth it? I've a relatively easy 50' to 70' shot from the breaker box, w/ plenty of spare breaker room to put in a new 240V line. I suspect I'd have to run a 20A line if I went with 110V (actually 120).
I've a concrete driveway just outside the former garage to base the outside unit on, and would run the wire through the wall adjoining the driveway.

The attached pic shows where I thought I could run the power line easily and 2 potential site for the compressor/coolant lines.

Advice? Pointers? I"m pretty sure we can get our son to help (he's 3 hours away in Memphis) but I like to do the research myself also. Besides, Hurricane Harvey rains are shutting off outside work and the noise level in my workshops is up around 72 decibels at times.

 

[RNeumann]

Your a/c tech son should be a good resource. Also try to Google HVAC sizing by zip code for a general idea of how to size a unit. It has to do with location/climate, aspect, insulation, windows etc. Beyond that and folks are guessing.

 

[Old Red]

So sizing a mini split inverter HVAC unit is not as "mission critical" as sizing up a traditional HVAC. The inverter mini split can run from its max BTUs down to a minimum amount of BTUs. It is variable in the load that it provides based upon what the demand is. For most traditional HVAC units when your T-stat calls for air, boom...you get the entire BTUs of the system...with the mini split you get what you need. Part of the reason for the efficiency of the inverter mini splits is the variable BTU output along without having duct work.

How's that for a school lesson?

PS. I have the Pioneer mini split 1.5 ton unit. The same that you see on Amazon. 2 years this august...great unit.

 

[timswi]

I had a Trane split-mini heat pump put on the 2nd floor when I built my daughters bedroom--Can't recommend these things highly enough. Great units.

 

[newbury]

Your a/c tech son should be a good resource. Also try to Google HVAC sizing by zip code for a general idea of how to size a unit. It has to do with location/climate, aspect, insulation, windows etc. Beyond that and folks are guessing.

I'm not too concerned about the size, 8K has proven just a little to small, I figure 9 or 10K would be on the border so I'm pretty sure 12K is in the right ballpark.

So sizing a mini split inverter HVAC unit is not as "mission critical" as sizing up a traditional HVAC. The inverter mini split can run from its max BTUs down to a minimum amount of BTUs. It is variable in the load that it provides based upon what the demand is. For most traditional HVAC units when your T-stat calls for air, boom...you get the entire BTUs of the system...with the mini split you get what you need. Part of the reason for the efficiency of the inverter mini splits is the variable BTU output along without having duct work.

How's that for a school lesson?

PS. I have the Pioneer mini split 1.5 ton unit. The same that you see on Amazon. 2 years this august...great unit.

Ah, thanks! That is a lesson.

 

[robstaples]

I have several Fujitsu units in the seer 30 range. They work great. The 240v units take the main feed at the outside unit and a 4 wire connector to the inside unit ( fed with the copper freon lines)

 

[astrohip]

I've been thinking about a mini-split for my new workshop. Great timing!

/subscribe/

 

[forgeblast]

We put a Fujitsu system in, split between three rooms. Amazing product we added the heat pump and used it all winter. I recommend them highly. We have the halycon series.

 

[GLyford]

We have a Mitsubishi unit with two heads, I don't remember but I think both are 12 (unit cools the whole 1st floor, about 900sf).

Plumber who also does HVAC put it in so not as cheap as some of the deals you guys are pointing at.

Power is 240v to a disconnect at the unit, was easy since it is about a dozen feet from the panel.

No issues at all with operation, works very well to keep the temp and humidity down and I am very glad we did it. It basically keeps us from living in the one bedroom with a window unit all summer.

 

[lennyzx11]

I just finished mine this weekend. Here's my thoughts.

I bought the Pioneer 12000 BTU 208 volt from Amazon Prime at 708 bucks. I later found the same unit shipping from HighSeer in Miami Florida for around 100 bucks cheaper. Came from same place. The Rule of thumb was 12K for 500 sq ft.

I bought the snap together trim pieces from Amazon. Everything was included in kit.

I bought the Yellow jacket 60278 Flaring tool in order to cut my line down from the original 16 ft length. This could have been coiled up but the tool made it a one shot cutoff and reflare. It was pricey at 100+ bucks though. The Ebay listing showed being able to order the unit from HighSeer with assorted different lengths like 10,16,20 ft etc. Amazon didn't show that.

I used a 2 1/2" milwaukee hole saw to cut the hole in the wall.

My buddy has a Harbor Freight vacumn pump (80 bucks) and I bought a special adaptor that was needed for the Minisplit port (about 16 bucks, I think)

All in. it took me 4 hours to install. And that was with two or three beers "thinking bout it".

How's it work? My two car garage is insulated and 20X24 with 8 ft ceiling. Concrete floor. In Oklahoma it has hovered in the low to mid 90s. My wife makes glass jewelry in her "shop" there with two small kilns running frequently but not all day. It has maintained the temperature she wanted non stop. (I think 75). I set it at 60 just to see first night and it was able to make it. I measured the output coils temperature with my temp gun and it stays a steady 43-50 degrees. It does not make noise.

I have two of the Mr SLim units professionally installed in my seceond floor home and bought this based on the performance of those.
I will buy another for my shop and yet one more for the little guest cabin I'm beginning on now.

I've watched the electric meter and had her not turn the AC off so I can get a baseline though she does turn the temp up to 80 because it get's too "cold" in there sometimes from working directly in front of the output breeze. I can't see any difference in electricity being used than normal.

I'm a believer and won't buy anything different ever again.

Lenny

I need some schooling on mini-splits so I'm not dumb when dealing with my son.

SWMBO has a 12x26 "Craftroom" that requires cooling to 74 degrees. It's in Mississippi, in full sun and last month the temps were hitting 100 degrees plus. The room is located above a garage that was transformed into a library. The room has 3 large windows. It has one small duct from our central a/c that looks like it was added as an afterthought and has all the cooling capacity to prevent water boiling.

I've initially put in an 8K BTU window unit (which I had from another house) which labors to keep the room temp down to 76 (not enough says SWMBO).

A downside to that is the noise and it blocks half a window. It looks like a 10K BTU window rattler would cost about $250 plus.

Amazon lists a 9K BTU mini-split kit for $600 so it seems prices are getting pretty close.

And my ace in the hole is that we've a son who is a licensed a/c tech and could finish the install with the proper tools.

So what I'm wondering is:
Would a 12K 110V 15 SEER system for $650 do?
How much savings (ballpark) would I see stepping up to a 12K 220v 22.5 SEER system ($1200)? The unit will probably run all summer.
What other brands should I look at?
The ceiling is a gambrel roof, about 2' high at the sides and 8' in the center. Can the inside unit be mounted at an angle or is it better vertical?
Is running a 220V (actually 240) line worth it? I've a relatively easy 50' to 70' shot from the breaker box, w/ plenty of spare breaker room to put in a new 240V line. I suspect I'd have to run a 20A line if I went with 110V (actually 120).
I've a concrete driveway just outside the former garage to base the outside unit on, and would run the wire through the wall adjoining the driveway.

The attached pic shows where I thought I could run the power line easily and 2 potential site for the compressor/coolant lines.

Advice? Pointers? I"m pretty sure we can get our son to help (he's 3 hours away in Memphis) but I like to do the research myself also. Besides, Hurricane Harvey rains are shutting off outside work and the noise level in my workshops is up around 72 decibels at times.

 

[CincyFlyer]

And another note: "It's not the heat, it's the humidity", as they used to say in the muggy midwest. A dehumidifier can be installed cheaply (one drain line, one wall plug) and can remove all kinds of water. Get that humidity low, and the temperature becomes much less critical.
That being said, we're probably gonna install a two-headed mini in our house, which was greatly expanded 15 years ago. The HVAC zones overlap ... never the best situation, as you cannot close off unused areas.

 

[3Ts]

I have an LG mini-split 18K BTU. The A/C shop wanted about 2K to install it so I installed it myself. I bought a vacuum pump and a digital vacuum gauge. The digital vacuum gauge is important, the analog ones will not show you how low the pressure is accurately enough and they really need to be down around 300-500 microns. It's important to get all the moisture out of the lines. If you don't the oil will react with the moisture to form an acid which will be circulated through out your closed A/C system and corrode the coil, compressor, and lines from the inside, meaning the unit will not last long. To determine the BTUs you need, you will have to do a heat load calculation. If you don't you'll probably be either over or under what you need. Under means it won't provide the heating or cooling you need. Over is not good either because it won't remove the humidity from the air and consumes more power. (However, Over is better than under since you can add a separate dehumidifier.) And as mentioned earlier, with its inverter it will adjust down to what is needed for cooling fairly efficiently but "right sized" is best and most efficient. "Rule of Thumb" is not a good plan for this, but you don't need "Manual J" calcs either, you can find heat load calcs on the i-net. I used a small pump and let it run most of the day to get down to 300 microns, then released the freon. It's been running 2.5 years now and only needed the filters cleaned and the coils cleaned.

My unit came precharged for 25' lines. I needed 22' so I put an S curve in to take up excess length so I would not have to adjust the freon charge. The most difficult part of the installation is holding the 35# inside unit up in the air while trying to get the 2 freon lines, 1 drain line, and electric cable thru a 2.5" hole in the wall - 2 senior citizens were doing this. I recommend 2 younger folks or assistance from a 3rd senior citizen. Otherwise, 1 person can install one of these units.

 

[GLyford]

Almost forgot...I got reversible units that also work as heat pumps on cool days.

 

[newbury]

And another note: "It's not the heat, it's the humidity", as they used to say in the muggy midwest. A dehumidifier can be installed cheaply (one drain line, one wall plug) and can remove all kinds of water. Get that humidity low, and the temperature becomes much less critical.
That being said, we're probably gonna install a two-headed mini in our house, which was greatly expanded 15 years ago. The HVAC zones overlap ... never the best situation, as you cannot close off unused areas.

Due to central air in the rest of the house humidity is pretty well controlled, as much as one can in muggy Mississippi.

I just finished mine this weekend. Here's my thoughts.

I bought the Pioneer 12000 BTU 208 volt from Amazon Prime at 708 bucks. I later found the same unit shipping from HighSeer in Miami Florida for around 100 bucks cheaper. Came from same place. The Rule of thumb was 12K for 500 sq ft.

I bought the snap together trim pieces from Amazon. Everything was included in kit.

I bought the Yellow jacket 60278 Flaring tool in order to cut my line down from the original 16 ft length. This could have been coiled up but the tool made it a one shot cutoff and reflare. It was pricey at 100+ bucks though. The Ebay listing showed being able to order the unit from HighSeer with assorted different lengths like 10,16,20 ft etc. Amazon didn't show that.

I used a 2 1/2" milwaukee hole saw to cut the hole in the wall.

My buddy has a Harbor Freight vacumn pump (80 bucks) and I bought a special adaptor that was needed for the Minisplit port (about 16 bucks, I think)

All in. it took me 4 hours to install. And that was with two or three beers "thinking bout it".

How's it work? My two car garage is insulated and 20X24 with 8 ft ceiling. Concrete floor. In Oklahoma it has hovered in the low to mid 90s. My wife makes glass jewelry in her "shop" there with two small kilns running frequently but not all day. It has maintained the temperature she wanted non stop. (I think 75). I set it at 60 just to see first night and it was able to make it. I measured the output coils temperature with my temp gun and it stays a steady 43-50 degrees. It does not make noise.

I have two of the Mr SLim units professionally installed in my seceond floor home and bought this based on the performance of those.
I will buy another for my shop and yet one more for the little guest cabin I'm beginning on now.

I've watched the electric meter and had her not turn the AC off so I can get a baseline though she does turn the temp up to 80 because it get's too "cold" in there sometimes from working directly in front of the output breeze. I can't see any difference in electricity being used than normal.

I'm a believer and won't buy anything different ever again.

Lenny

Thanks for the pointers, I had forgotten to add in a beer overhead charge for our son.

I have an LG mini-split 18K BTU. The A/C shop wanted about 2K to install it so I installed it myself. I bought a vacuum pump and a digital vacuum gauge. The digital vacuum gauge is important, the analog ones will not show you how low the pressure is accurately enough and they really need to be down around 300-500 microns. It's important to get all the moisture out of the lines. If you don't the oil will react with the moisture to form an acid which will be circulated through out your closed A/C system and corrode the coil, compressor, and lines from the inside, meaning the unit will not last long. To determine the BTUs you need, you will have to do a heat load calculation. If you don't you'll probably be either over or under what you need. Under means it won't provide the heating or cooling you need. Over is not good either because it won't remove the humidity from the air and consumes more power. (However, Over is better than under since you can add a separate dehumidifier.) And as mentioned earlier, with its inverter it will adjust down to what is needed for cooling fairly efficiently but "right sized" is best and most efficient. "Rule of Thumb" is not a good plan for this, but you don't need "Manual J" calcs either, you can find heat load calcs on the i-net. I used a small pump and let it run most of the day to get down to 300 microns, then released the freon. It's been running 2.5 years now and only needed the filters cleaned and the coils cleaned.

My unit came precharged for 25' lines. I needed 22' so I put an S curve in to take up excess length so I would not have to adjust the freon charge. The most difficult part of the installation is holding the 35# inside unit up in the air while trying to get the 2 freon lines, 1 drain line, and electric cable thru a 2.5" hole in the wall - 2 senior citizens were doing this. I recommend 2 younger folks or assistance from a 3rd senior citizen. Otherwise, 1 person can install one of these units.

Thanks, I guess we'll call it 1 senior citizen (me) and 1 younger folk (our son) for the labor force. But thankfully he has ALL the tools and materials. He did an a/c valve replacement on our Jetta TDI and saved us hundreds.

And like I wrote, real life experience shows 8k is just a little small so I'll probably go for 10 to 12K.