MRCOOL DIY Mini Split, Seriously, I Think...

[alxmlr789]

I just opened my MRCOOL 24k in preparation for my installation this weekend. I have to say this is the best packaged piece of equipment I’ve ever received. They thought of everything that would break during shipping. Instructions are fairly straightforward, and all the parts and pieces are labeled nicely. It definitely feels like quality as well.

Just for kicks and giggles i called 3 AC contractors to see what they would charge for the install. 1900, 1500 and 1900. I can’t believe that, as this will probably take me an hour and a half to install.

 

[jjrbus]

I just opened my MRCOOL 24k in preparation for my installation this weekend. I have to say this is the best packaged piece of equipment I’ve ever received. They thought of everything that would break during shipping. Instructions are fairly straightforward, and all the parts and pieces are labeled nicely. It definitely feels like quality as well.

Just for kicks and giggles i called 3 AC contractors to see what they would charge for the install. 1900, 1500 and 1900. I can’t believe that, as this will probably take me an hour and a half to install.

All 1 1/2 hour jobs are just one heartbeat away from a 2 day affair with 7 trips to HD, Lowes and Harbor Freight

 

[Browneye]

Harbor Freight...LOL
About the hardest part of my install was drilling through an inch and a half of stucco - it's like concrete. HF had a carbide hole-saw kit for like $30 that had a 3-1/2" cup. Worked perfectly and sawed through that stuff like butter. Great for sheetrock as well - bonus.

The next difficulty was standing ten feet up on a ladder while holding the air handler and trying to feed the lineset through a hole in the wall. Shwew!!!!

The wallpaper top border is at 8'. LOL

 

[jjrbus]

I had to go through 8 inch concrete block and then 1 1/2 inch of stucco! I used the long carbide 1/4 inch drill from HF to line up the holes, then the HF hole saw from both sides!

 

[Browneye]

This week we got a high-pressure system over the region and unseasonably high temperatures for a couple of days - it was 94 and 98 earlier this week.
House stayed a comfy 76 with the two MrCool units kicking out tons of ice cold air. Gotta love it.

 

[dcg9381]

Just for kicks and giggles i called 3 AC contractors to see what they would charge for the install. 1900, 1500 and 1900. I can’t believe that, as this will probably take me an hour and a half to install.

Yea, 100-200% cost multiplier around here for "installed".
Course, you get a warranty that way.

I've done 3 of these. Last one I did was last weekend - even with relatively "open" walls and having all the tools/hardware, it was a good 4-6 hours worth of work.

 

[Blstr88]

Just ordered 2 of these...an 18k for my parents little lake house and a 24k for my house (really just den/kitchen area). I think the 18k would have done it for me too but I figured for the extra $200 I'd step up to 24k. Should be here early next week!

 

[h314]

I have a sizing question for you all. I am in a 20x20 room above the garage with 10 foot ceilings in a detached building from the house. I have three windows facing north and one to the west. I have no idea about the insulation of the room but there is none in the garage. The 10k BTU portable one vent A/C that I have can't keep up. When it is 90 outside like today, it can't go below 81. When it was 100 degrees, temp on the unit kept going up in the afternoon. I don't care about heating, only cooling from this mini split.

I don't mind to pay up extra to go for the 18k mini split system from mrcool but I know this seems oversized. However, with the portable 10k unable to keep up, I am concerned the 12k won't either. All opinions are welcomed for this AC newbie. Thank you!

 

[MattT]

I have a sizing question for you all. I am in a 20x20 room above the garage with 10 foot ceilings in a detached building from the house. I have three windows facing north and one to the west. I have no idea about the insulation of the room but there is none in the garage. The 10k BTU portable one vent A/C that I have can't keep up. When it is 90 outside like today, it can't go below 81. When it was 100 degrees, temp on the unit kept going up in the afternoon. I don't care about heating, only cooling from this mini split.

I don't mind to pay up extra to go for the 18k mini split system from mrcool but I know this seems oversized. However, with the portable 10k unable to keep up, I am concerned the 12k won't either. All opinions are welcomed for this AC newbie. Thank you!

If 10K can only maintain a 9* temperature differential you'll probably need more than 18K to get the room down into the 70s when it's 100* outside. Very rough guess is 24 to 30K. And yes this is way oversized because of the building.

Aside from the obvious insulation, or lack thereof, in walls and ceiling is there any insulation in the floor? I'm guessing it's pretty hot in the garage and heat rises. Also is the west window exposed to afternoon sun or is it shaded?

 

[Blstr88]

I have a sizing question for you all. I am in a 20x20 room above the garage with 10 foot ceilings in a detached building from the house. I have three windows facing north and one to the west. I have no idea about the insulation of the room but there is none in the garage. The 10k BTU portable one vent A/C that I have can't keep up. When it is 90 outside like today, it can't go below 81. When it was 100 degrees, temp on the unit kept going up in the afternoon. I don't care about heating, only cooling from this mini split.

I don't mind to pay up extra to go for the 18k mini split system from mrcool but I know this seems oversized. However, with the portable 10k unable to keep up, I am concerned the 12k won't either. All opinions are welcomed for this AC newbie. Thank you!

The 24k is only $200 more than the 18k unit. Go for the 24k. Can't see any real downside...they're both 220v units so will require same wiring for install, and a 24k might actually be cheaper to run since it won't be running the whole time to stay cool.

At least that was my line of thought when I ordered the 24k. Arriving tomorrow btw.

 

[Citation]

Do keep in mind that a single tube portable is drawing in a lot of outside air while running. So even thought it can move 10k BTUs of heat it's practical cooling is less since the air it sends out is replaced with outside air sucked into the garage.
If you look at HD's page for these units you will see the 10,000 BTU units have a Dept of Energy rating around 7,000 BTU. So figure an 18k BTU mini-split is 2.5x as much cooling capacity as you currently have vs the 1.8x the basic numbers would suggest.
https://www.homedepot.com/b/Heating...-BTU/Single-Hose/N-5yc1vZc4m4Z1z17zvgZ1z180z4

DOE talking about single hose AC units
https://homeownerfaqs.com/portable-ac-energy-labeling-rule/

 

[Fueler]

H314
1: Have you measured the temp at the walls, floor and ceiling or at least put a hand on them to make a judgement?
I'm guessing there is no insulation anywhere.
2: What will stop you from adding some insulation?

Just an opinion based on having used 3 kinds of AC.
The window shaker ACs can't hold a candle to the cheapest mini split.
OH, wait, you said portable AC. Oh, hell no.

 

[jjrbus]

The 24k is only $200 more than the 18k unit. Go for the 24k. Can't see any real downside...they're both 220v units so will require same wiring for install, and a 24k might actually be cheaper to run since it won't be running the whole time to stay cool.

At least that was my line of thought when I ordered the 24k. Arriving tomorrow btw.

Downside, Do a Google on mold in mini split blower wheels or cleaning mini blower wheels. The main cause of mold in them as near as I can tell is oversizing/humidity issues. Also minis are more efficient when they are working hard.

I am dealing with a mold issue now in a unit I am 99.5% sure is not oversized and it is no fun at all. Minis are not designed to be serviceable.

 

[Fueler]

Downside, Do a Google on mold in mini split blower wheels or cleaning mini blower wheels. The main cause of mold in them as near as I can tell is oversizing/humidity issues. Also minis are more efficient when they are working hard.

I am dealing with a mold issue now in a unit I am 99.5% sure is not oversized and it is no fun at all. Minis are not designed to be serviceable.

I find the sentence in bold contradictory.
I thought one of the advantages to an inverter mini is that it goes up and down on fan speed and temp output as needed? The load is variable in other words.

 

[Browneye]

My old house in so-cal, built in the 70's, has no insulation inthe walls. That's right, NONE!! Why did they think that was good enough? Stucco walls, about an inch thick, stud walls, and sheet rock.

So for the outside walls in the bedrooms I have removed the drywall, installed fiberglass R13 insulation, and re-dry-walled, mud and tape, texture, paint. It's not that hard, looks terrific, and oh what a difference it makes in maintaining temps, hot or cold.

I would insulate that room, at least floor and ceiling, even if you have to tear down the drywall.

And install a 18K unit. A 12K would probly do it, but 18 will be more than enough.

The mold thing surprises me, but then if the humidity is high it's understandable. When RA is above 50% mine makes condensate water in a steady stream - it will fill up a 2-gal watering can in about 2 hours. Wow!

Another way to insulate is to fir-out with strips and apply R-tech over the walls, drywall over. Just a thought, especially since it's just a room and not the whole house. 1" Rtech is rated about R4 or 5 at higher temps, but I think it helps a lot in heat transfer than the values would indicate. The stuff is pretty amazing. A 4x8 sheet is about $15. I've used it in various projects and it's been really effective.

 

[h314]

Wow, thank you to everyone that responded to me, I did not think I would get so many responses!

First of all, I purchased the portable one vent AC before the DOE BTU number came out. Looks like the 10k BTU drops to 6.5 DOE BTU, which is the reason why its terrible and not keeping up!

This space above the garage is a finished studio unit with drywall and a bath and this is how I bought the place. I would hate to rip out all of this textured dry wall to just add insulation. I only took a quick peek behind the coax box and did not see any insulation but did not do any real due diligence otherwise. However, when I come into this area to work in the morning, it is a hot box if I forget to leave the window open overnight when temps go down to the 60s. So maybe I am wrong and there is some insulation? I can say the floor under me which is the ceiling of the garage does not have insulation so its probably correct to say a lot of heat is coming up from there. I can easily add insulation there as there isn't much dry wall there but it won't be this summer as I have a lot of projects already.

The window on the west side is exposed but it is not a large window at 2x3.

I am in an area where summer temps are usually between 80-90. Now with this additional detail, do you guys think 12k BTU is enough or should I go for 18k?

 

[Browneye]

20x20? That's 400 square feet. A 12 should be able to handle that.
That's twice as much cooling as your window unit, and more efficient to boot.

My east wing of the house with the master bedroom and office/den is about the same, with some walls thrown in. The 12K btu unit seems like way overkill - it can chill like a refer unit.

That said I would hate to see you install one and then find it can't keep up with your heat gain. 12K btu is rated for up to 500 sq ft. so it should be fine. If you really think you have a severe heat-gain problem then go for the 18 - it's rated for up to 750sqft.

 

[MattT]

Do keep in mind that a single tube portable is drawing in a lot of outside air while running. So even thought it can move 10k BTUs of heat it's practical cooling is less since the air it sends out is replaced with outside air sucked into the garage.
If you look at HD's page for these units you will see the 10,000 BTU units have a Dept of Energy rating around 7,000 BTU. So figure an 18k BTU mini-split is 2.5x as much cooling capacity as you currently have vs the 1.8x the basic numbers would suggest.

Good point on the make up air And some of that make up air could be coming from the hotter than ambient garage making the de-rate even worse. That pushes my earlier guesstimate down to around 18K.

I am in an area where summer temps are usually between 80-90. Now with this additional detail, do you guys think 12k BTU is enough or should I go for 18k?

Since you mentioned 100* earlier that's what I'm basing my revised 18K guess on. 12K should be enough for 80-90 but likely won't keep up at 100*. IMO 18K is the safe bet if you want good performance now but 12K would be a better long term solution if you can live with temps climbing into the low 80*s on hotter days until you start air sealing and insulating.

And for figuring out what needs improved with the building a $20 IR thermometer would help figure out where the problems are and a thermal camera would be even better if you can afford a couple hundred.

 

[bored350]

If you have an electric coop, many will do an energy efficiency study for a low cost and credit you back if you make a certain amount of suggested improvements. Mine charged $100 for a blower door test, thermal imaging camera evaluation and manual J calculation after they did a full visual inspection of the home. I had to do $100 of suggested improvements and received the $100 credited back to me. Some weatherstripping, caulk and converting a few can lights to LED quickly covered the cost and will pay for itself in a few months.

Sent from my Moto G (5) Plus using Tapatalk

 

[jjrbus]

I find the sentence in bold contradictory.
I thought one of the advantages to an inverter mini is that it goes up and down on fan speed and temp output as needed? The load is variable in other words.

I am no HVAC guy, I can only parrot what is reported on the internet. https://www.nrel.gov/docs/fy11osti/52175.pdf

 

[Browneye]

Good point on the make up air And some of that make up air could be coming from the hotter than ambient garage making the de-rate even worse. That pushes my earlier guesstimate down to around 18K.



Since you mentioned 100* earlier that's what I'm basing my revised 18K guess on. 12K should be enough for 80-90 but likely won't keep up at 100*. IMO 18K is the safe bet if you want good performance now but 12K would be a better long term solution if you can live with temps climbing into the low 80*s on hotter days until you start air sealing and insulating.

And for figuring out what needs improved with the building a $20 IR thermometer would help figure out where the problems are and a thermal camera would be even better if you can afford a couple hundred.

^^This.
After 25 years in so-Cal we never even set AC below 75. At 70 we don sweaters. LOL
So 77-80 is our best comfort range. We don't even turn them on 'till it gets over 80. Maybe fan mode to move some air around. When it's 100+ all bets are off.

 

[jjrbus]

When sizing AC keep in mind that they modulate, change output to meet conditions. Her is what heat pump minis are rated at. They are more efficient when working harder, so smaller is better.

 

[yeldogt]

When you get into the weeds -- max efficiency is in the 75-80%. Depends on the unit and manufacturer -- they differ. So do the multi head. This is why you don't want to oversize the unit -- since the vast majority of installs have a wide temp range --- picking correctly is important. I say the same thing when people design radiant systems -- do you want it to work ... or do you want it to work most efficiently?

With a multi head unit -- the max efficiency may not be there vs a single head ... but, often it's running at a higher efficiency point vs what three separate units will be.

If you want to NOT maintain a level temp --- and get a larger unit --- understand that it's most likely not going to be running in the most efficient band. This still may be cheaper vs maintaining -- there are too many variables.

Some units can run down very low percentages -- it't rare to see any efficiencies posted.

 

[Slowbra]

For those of you who’ve been watching the prices on the DIY kits - how often does Costco do their sale on these? I’m trying to hold out for the 1299 24K they had earlier (currently at 1499).

 

[dcg9381]

I agree with weldogt - It's gonna be real hard to get "peak efficiency" and "does the job 100%" in climates where temperature changes are pretty extreme... At the upper end of the temperature range, you're going to have an efficient unit that can't quite keep up or an over-sized unit that isn't quite as efficient as it should be.

For me, dealing with this (kinda by accident) meant installing two units, but I'm not suggesting this as the "right" solution.

 

[GrantOpus]

I have another AC “sizing” question. I have a 24x40x12. I have 2” closed cell on the ceiling and 1” closed cell on the walls. Both 12x10 over head doors are insulated as well. I’m thinking the 24K MRCOOL is what I need. Will the 24K be right for me or should I bump up to the 36K? I’m in central Florida, right now the heat and humidity is killing me.


Sent from my iPhone using Tapatalk

 

[Browneye]

A new installer of one of these asked:

"It seems as if the unit constantly runs even when it hits the set temp. It doesn’t seem as if the condenser outside is always running but it appears that the fan inside is still pushing air regardless of set temp. Is this normal?"​

Here was my reply and comments on the unit design configuration and features/functions, as surely more visitors here will have the same questions:

Normal. And why there's a timer function on the remote controller to delay turn-on or off, or you can use the wifi interface.
I'm not sure why this is, but even a window air unit turns itself off when temp is reached.

All mini-splits, including the MrCool units, power down the outside condenser and slow the inside air handler to a whisper, but maintaining its power state to resume operation.

I also think you should be able to switch the numerical display on the air handler to show temp setting as well as ambient temperature. As built it shows the ambient only when set to 'fan' mode, otherwise it displays your temp setting whether heating or cooling.

I'm also dismayed that they dismantled their original wifi interface for an updated one and then required legacy users to buy another program. And when I called Ingrams to inquire they never called me back. It's beyond disappointing. But oh well, I can always fork over my $$ and get the update - I think that's just what they've decided to let users do. I've even posted my dismay on the feedback forum at MrCool to no avail.

So yeah, if you want the inside air handler to completely power off you have to shut the unit to off. But note that that small bit of air movement isn't deleterious in any way, and using so little power that it's insignificant. And the new wifi interface has a more elaborate timing programming ability by day and not just by time.

 

[Browneye]

I have another AC “sizing” question. I have a 24x40x12. I have 2” closed cell on the ceiling and 1” closed cell on the walls. Both 12x10 over head doors are insulated as well. I’m thinking the 24K MRCOOL is what I need. Will the 24K be right for me or should I bump up to the 36K? I’m in central Florida, right now the heat and humidity is killing me.

Having lived with two of these over the past year, I tend to disagree with the usual sizing and efficiency comments. These units work just as well at low fan speed setting as it does at high - the higher speed to move more cool air (or heated air). Surely a smaller unit consumes less power when running, but the difference is not that significant.

I personally prefer the extra cooling capacity for when it really is exceptionally hot out and/or you need/want a fast cool down. My 2-ton unit covers a space that is about 7-800 square feet, with walls and halls, and my 1-ton covers two bedrooms and a bathroom totaling about 300sq feet. The former has 15' ceilings and a wall of glass facing west to contend with. The latter hardly has to run - better insulation, no sun windows, low ceilings.

The bottom line is they both perform beyond satisfactorily. I would have gotten a 9K unit for the bedrooms had there been that option, but I've never been sorry or felt bad for having the larger 12K unit doing the job, considered over-size by general standards.

I would get the 36K unit for that size shop, if you really do need/want a 30-degree temp drop. If you're trying to cool from over 100 to under 80, you'll want the extra capacity. You guys have a very high RH to deal with as well, and your air handler will make a ton of condensate water. You won't be sorry.

 

[alxmlr789]

I have another AC “sizing” question. I have a 24x40x12. I have 2” closed cell on the ceiling and 1” closed cell on the walls. Both 12x10 over head doors are insulated as well. I’m thinking the 24K MRCOOL is what I need. Will the 24K be right for me or should I bump up to the 36K? I’m in central Florida, right now the heat and humidity is killing me.


Sent from my iPhone using Tapatalk

FWIW - i went with a 24k and am 35x30. 5" open cell on the ceiling and R19 batts in the walls. Insulating the doors as we speak. It cooled my building down which was 96 degrees to 78 in about 3 hours yesterday (keep in mind my doors are not yes insulated and i still have the hole drilled to the outside that i need to close up. I am in Central FL as well, if you'd like to come by to take a look.

 

[I Really Just Don't Know]

A new installer of one of these asked:

"It seems as if the unit constantly runs even when it hits the set temp. It doesn’t seem as if the condenser outside is always running but it appears that the fan inside is still pushing air regardless of set temp. Is this normal?"​

Here was my reply and comments on the unit design configuration and features/functions, as surely more visitors here will have the same questions:

Normal. And why there's a timer function on the remote controller to delay turn-on or off, or you can use the wifi interface.
I'm not sure why this is, but even a window air unit turns itself off when temp is reached.

All mini-splits, including the MrCool units, power down the outside condenser and slow the inside air handler to a whisper, but maintaining its power state to resume operation.

I also think you should be able to switch the numerical display on the air handler to show temp setting as well as ambient temperature. As built it shows the ambient only when set to 'fan' mode, otherwise it displays your temp setting whether heating or cooling.

I'm also dismayed that they dismantled their original wifi interface for an updated one and then required legacy users to buy another program. And when I called Ingrams to inquire they never called me back. It's beyond disappointing. But oh well, I can always fork over my $$ and get the update - I think that's just what they've decided to let users do. I've even posted my dismay on the feedback forum at MrCool to no avail.

So yeah, if you want the inside air handler to completely power off you have to shut the unit to off. But note that that small bit of air movement isn't deleterious in any way, and using so little power that it's insignificant. And the new wifi interface has a more elaborate timing programming ability by day and not just by time.

Is that the new SmartHVAC app? I saw that come up when I searched in the Android store for Mr. Cool. My current app is working pretty well and I'm almost afraid to switch.

 

[alxmlr789]

Is that the new SmartHVAC app? I saw that come up when I searched in the Android store for Mr. Cool. My current app is working pretty well and I'm almost afraid to switch.

Yes, the smartHVAC app is pretty neat, and integrates with Alexa if you have it. It’s not too bad at all and has good reviews (unlike the me cool app)

 

[Browneye]

Is that the new SmartHVAC app? I saw that come up when I searched in the Android store for Mr. Cool. My current app is working pretty well and I'm almost afraid to switch.

Mine quit working, so I tried to set up a new account for the phone app, and it said 'not found'. And I couldn't pair the unit no matter what I tried. Neither of them.

As I understand it the online service got revamped and the old logins quit.

But yours is still working? Hmmm...

And yeah, the new version has some more whistles and bells, so it's probly worth it. I was just a little miffed about it, having to cough up more $$ to make it work again.

 

[I Really Just Don't Know]

I'm still using this one

https://play.google.com/store/apps/details?id=com.mrcoolremote

This one asks me to connect to my Mr. Cool wifi and when I put it in AP mode, it wants a password to connect. I didn't get any further than that.

https://play.google.com/store/apps/details?id=com.smarthvac

Neither of these cost money, are you supposed to buy a new controller to get the new app working?

 

[Browneye]

I'm still using this one

https://play.google.com/store/apps/details?id=com.mrcoolremote

This one asks me to connect to my Mr. Cool wifi and when I put it in AP mode, it wants a password to connect. I didn't get any further than that.

https://play.google.com/store/apps/details?id=com.smarthvac

Neither of these cost money, are you supposed to buy a new controller to get the new app working?

Yep, new software in the dongle that plugs into the air-handler socket and connects to your wifi router. Without that their new platform won't support your connection, it just errors out.

 

[Slowbra]

I’m ordering a 36K Mr.Cool from Costco. Hope it goes on sale again soon so I can ask for some cash back.

 

[jjtrou2072]

Is there any advantage to buying straight from Ingram's vs. Costco? I'm about to pull the trigger on a 36K as well.

 

[Browneye]

Is there any advantage to buying straight from Ingram's vs. Costco? I'm about to pull the trigger on a 36K as well.

I don't think there is, perhaps a slight savings thru costco. When I bought mine they didn't offer them, but other retailers did, like Lowe's, and they had a lower price that Ingram's matched, shipping included. So it was pretty painless.

I liked the first one so well I bought a 'scratch-and-dent' one from them, and that was a huge savings and worked out pretty well - pics and story up-thread.

As near as I can tell, MrCool has designated Ingram's as their warranty provider. My hunch is they are somehow related, although the importer claims they are just 'one of their distributors'.

 

[Slowbra]

Is there any advantage to buying straight from Ingram's vs. Costco? I'm about to pull the trigger on a 36K as well.

Here are the things I like about Costco. They will stand behind their product. So if something happens down the line I know they will help me as they have before with other things. They will also adjust pricing if it changes within a certain time period.

When I spoke with Ingram’s I was told they couldn’t match Costco’s price.

 

[ItBurnsWhenIPee]

FYI - Home Depot is currently showing $1,461 for the 24k BTU DIY mini-split. That's $250-$300 off the normal price.

 

[MattT]

Is there any advantage to buying straight from Ingram's vs. Costco? I'm about to pull the trigger on a 36K as well.

Ingrams seem to have decent tech, and parts, support just based on what I've read on here.

Costco do have a very generous return policy but I'm not sure how useful that'd be for a fixed installation where repairing in place would be better than ripping the whole thing out and returning it.