# Mr Cool Universal 4-5 Ton Heat Pump - DIY



## Zack R (Jul 7, 2021)

Has anyone installed one of these? Our old heat pump bit the dust back in April so I've been running it on auxiliary heat (resistance heat only) to fill in the gap as the wood burning season ended.

https://mrcool.com/mrcool-universal-series-dc-inverter-heat-pump-air-conditioner-split-system/

I haven't reached out for a formal quote but the HVAC tech that visited our house last October said to replace our older 2008 system would be in the $15k range. With that in mind the idea of a $4k DIY project starts looking really good. Especially with pre charged lines that are plug and play.

I've watched a few videos and read through the brochures but any real world experience would be helpful, especially from those who live in a colder climate.  In the winter we use the wood stoves, however the shoulder seasons the heat pump comes into play.

Thanks!


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## begreen (Jul 7, 2021)

The existing system will need the refrigerant to be totally recovered. This will take some professional equipment. @Brian123 has some installation experience that he has shared in another thread.

For shoulder season heating it should work out ok. What is the size of the current system? Is it also used for cooling or just for heating?


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## EbS-P (Jul 8, 2021)

I have been on the fence about a Mr Cool mini split. I’d get a couple more quotes.  I think this is a single speed compressor.

Inquire about how much a two speed American standard unit would be.  I think it’s a good starting point from a value perspective.  You can always go cheaper single stage or more expensive variable speed.    You could always find a name brand unit online do all the physical install to specs  and find an independent installer to connect  and charge line set.  That would take a what would be a two person one day job down to a couple hours for one person. 
At the end of the day I’m still on the fence about mr cool.  Costco has the mr cool 1.5 ton mini split back in stock for 1300$. 

For the price it does looks like a good deal. Then again looks can be deceiving. 

Universal 4-5 Ton Up to 18 SEER Heat Pump Variable Speed Central System Upflow/Horizontal W/50ft Quick Connect Line Set https://www.lowes.com/pd/MRCOOL-Uni...ntal-W-50ft-Quick-Connect-Line-Set/5001230923

evan.


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## begreen (Jul 8, 2021)

EbS-P said:


> I have been on the fence about a Mr Cool mini split. I’d get a couple more quotes.  I think this is a single speed compressor.
> 
> Inquire about how much a two speed American standard unit would be.  I think it’s a good starting point from a value perspective.  You can always go cheaper single stage or more expensive variable speed.    You could always find a name brand unit online do all the physical install to specs  and find an independent installer to connect  and charge line set.  That would take a what would be a two person one day job down to a couple hours for one person.
> At the end of the day I’m still on the fence about mr cool.  Costco has the mr cool 1.5 ton mini split back in stock for 1300$.
> ...


In most cases there is a bit more work than it seems on the surface, more like a 2 person 2 day job. The new air handler probably will need a transition to connect to the existing system, same for the return, plus insulating.  Then there are systems to connect for power, thermostat, and condensate drain. And normally a resistance coil is connected for backup heat. But I don't know if you would need this in NC. On the exterior, the compressor assembly needs to be mounted above snow level and wired. Then comes the linesets.


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## ABMax24 (Jul 8, 2021)

I'd suggest you get a formal quote or two done up to replace your system before you head into DIY.

I just had a 2 ton central AC unit installed a month ago, I asked about the cost of upgrading to a heat pump/AC combo instead of the AC only Lennox ML14 unit we had installed, I was told it was only $1500-$2000 more than the $4795 we paid for the AC unit, coil and install.

I opted not to go heat pump though, natural gas is 1/5th the cost of electricity here, and is likely to stay that way for the foreseeable future as electricity prices follow natural gas prices due to most of our electricity being generated from natural gas.

Keep in mind these prices are in CAD dollars, USD should be 20% less.


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## semipro (Jul 9, 2021)

I just installed 2 of the Mr Cool 2-3 universal systems in our place as retrofits and I'm generally happy with them.   A few things to consider:

I've not been impressed with their tech support so you may want to purchase from a reseller like Ingram's who will provide better support.   Others report similar problems with Mr. Cool support.
Heed @begreen  on the issues involved with a retrofit.  One thing that can be really impactive is that the replacement units with the same/similar capacity rating may be much larger.  More efficiency generally means larger components, especially the air handler.  I really had to shoehorn our upper unit into our attic and it required some serious mods to the return and supply ducts.  The precharged lines make things super simple.  I was able to use them on one system.  I had to use a standard line set to connect with existing lines in my walls on the 2nd system.  This was not really as bad as it sounds and I used Harris Stay-Brite 8 solder and recommend it in lieu of brazing.  I've done a lot of AC work though.
The units appear to be made by Midea.
Both outside units and air handlers are very quiet, impressively so.  The highly sculpted plastic fan blade on the outer unit does a great job at moving air quietly.  The metal squirrel cage fan on the air handler is also quiet.
The compressor and outside fan are variable speed in operation.  The Air Handler fan is not really.  It will run at 2 different speeds based on 3/4 ton configuration but will not vary in operation depending upon operating conditions.   I found this disappointing as it is a variable-speed ECM motor.
The outside unit defrosts occasionally during heating operations by going into cooling mode.  This results in a short blast of cold air coming from the ductwork.  I haven't found it to be that noticeable but it might freak you out the first time it happens.
The AH drain pan is reconfigurable for all normal installation positions though the manuals don't reflect this.  You have to remove the coil to reconfigure.  I did, not a big deal.
I installed ours without emergency heat units since they operate well at low temps and we have wood heat for backup.  It's relatively easy to install the Mr. Cool resistance modules late if needed.


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## pirates712 (Sep 16, 2021)

@semipro did you happen to notice how the pre-charged linesets seal? Is it an o-ring or metal-on-metal? I've been looking at the universal 2-3 ton as a potential replacement for our 'warm climate' heat pump for better cold weather performance and it looks like the DIY route could be considerably cheaper than something like a ducted mitsubishi with hyper heat. Main concerns at this point are the no-vac linesets leaking and parts availability.


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## semipro (Sep 16, 2021)

pirates712 said:


> @semipro did you happen to notice how the pre-charged linesets seal? Is it an o-ring or metal-on-metal? I've been looking at the universal 2-3 ton as a potential replacement for our 'warm climate' heat pump for better cold weather performance and it looks like the DIY route could be considerably cheaper than something like a ducted mitsubishi with hyper heat. Main concerns at this point are the no-vac linesets leaking and parts availability.


The seal between the line and the unit is a standard metal flare.  
I'd bet that whatever seals the refrigerant within the line set before installation is a polymer o-ring seal though.  
I had no trouble sealing mine.   At least vacuum and bubble tests showed no leaks.


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## pirates712 (Sep 16, 2021)

Thanks, that's reassuring.
How did you vacuum test the pre-charged lines without vacuuming out all the refrigerant?


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## semipro (Sep 16, 2021)

pirates712 said:


> Thanks, that's reassuring.
> How did you vacuum test the pre-charged lines without vacuuming out all the refrigerant?


Sorry for the confusion.  I installed two systems.  One with the pre-charged lines and one with standard brazed connections.  
I did not vacuum test the one with the pre-charged lines, just bubble testing.


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## pirates712 (Sep 16, 2021)

That makes more sense, thanks!
Keep us updated on your experiences with the unit(s)


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## Gearhead660 (Sep 17, 2021)

I installed a Mr Cool DIY unit this spring.  Install was straight forward.  Tech support was great...once I got ahold of someone.  Haven't used for heat yet, but cooling works great.  As long as its not upper 90s for high temps I am able to run in "dry" mode and cools  just fine.  Super quiet inside and out.  Far better than the window shaker we were using.


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## pirates712 (Sep 27, 2021)

It looks to me like the universal is a rebadged gree flexx:





						FLEXX - Central AC and Heating System | GREE Comfort
					

GREE's FLEXX central HVAC system offers optimum indoor and outdoor comfort to your residential space. Find more information about FLEXX systems, or find a contractor for your residential HVAC project here.



					www.greecomfort.com
				




The service manual, available from the above page, lays out some dip switch settings that are not in the mrcool manual:

2.3.2 Set Defrost Mode
The second dip switch is selecting the defrost mode.
The second dip switch is used to change the defrost setting, factory default setting is standard defrost. Under
extremely low environment temperature, if the standard defrost cannot have the condenser defrosted completely,
please set the second dip switch to be strong defrost. Under strong defrost, the defrosting time will be longer,
which enable the condenser to be defrosted completely.

2.3.3 Set Operating Mode
The third dip switch and the fourth dip switch are selecting the operating mode. Standard mode is the
conventional mode.
By setting the strong mode dip switches of the condensing unit, the air conditioner can quickly increase the
capacity output and ensure reliable operation in a short time, so as to meet the user's demand for the indoor
temperature to quickly reach the set temperature.
Energy saving mode is achieved by setting the condensing unit operating mode to operate the air
conditioner within a small load range.

2.3.4 Set Indoor Fan Speed
Set the indoor fan speed through the eight dip switches of the indoor main control board. The higher level,
the higher speed of the indoor unit fan.
(3 fan speed levels selectable)


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## semipro (Sep 27, 2021)

pirates712 said:


> It looks to me like the universal is a rebadged gree flexx:
> 
> 
> 
> ...


Thanks very much for sharing this.  I'd seen a reference to this info elsewhere but could never find it.  
The compressor on my units is labeled "Gree" I'd assumed these were rebadged units but never thought to check Gree documentation.


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## R Alvanos (Oct 9, 2021)

semipro said:


> I just installed 2 of the Mr Cool 2-3 universal systems in our place as retrofits and I'm generally happy with them.   A few things to consider:
> 
> I've not been impressed with their tech support so you may want to purchase from a reseller like Ingram's who will provide better support.   Others report similar problems with Mr. Cool support.
> Heed @begreen  on the issues involved with a retrofit.  One thing that can be really impactive is that the replacement units with the same/similar capacity rating may be much larger.  More efficiency generally means larger components, especially the air handler.  I really had to shoehorn our upper unit into our attic and it required some serious mods to the return and supply ducts.  The precharged lines make things super simple.  I was able to use them on one system.  I had to use a standard line set to connect with existing lines in my walls on the 2nd system.  This was not really as bad as it sounds and I used Harris Stay-Brite 8 solder and recommend it in lieu of brazing.  I've done a lot of AC work though.
> ...


I know that the outdoor unit is a variable speed fan and compressor and that the indoor units fan is a fixed speed motor.
What happens when the outdoor unit slows down and the indoor fan is running at its normal speed. Does the indoor fan run for longer periods between cycling off?
I would think that the inside fan is going be ruining a lot more that a regular heat pump.
I have a lot of air noise coming out of my registers and don't know that I want the longer periods of fan noise.
Thanks for any feedback on this.
Richard


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## begreen (Oct 10, 2021)

R Alvanos said:


> I know that the outdoor unit is a variable speed fan and compressor and that the indoor units fan is a fixed speed motor.
> What happens when the outdoor unit slows down and the indoor fan is running at its normal speed. Does the indoor fan run for longer periods between cycling off?
> I would think that the inside fan is going be ruining a lot more that a regular heat pump.
> I have a lot of air noise coming out of my registers and don't know that I want the longer periods of fan noise.
> ...


Is this for a centrally ducted system with an air handler using existing ductwork and registers or for a new mini-split system?


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## R Alvanos (Oct 10, 2021)

This is to replace a existing 2 ton split system that has A/C and electric heat strip in the attic over the hall way with the compressor outside about 20' of refrigerant line. There is one return in the hall that goes into the unit and the duct work is all hard pipe. I did add some short sections of flex from the hard pipe to the registers and it did reduce the air flow noise a lot. I want to replace this with the Mr Cool universal 2/3 heatpump.


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## R Alvanos (Oct 10, 2021)

My concern is with the fan in the attic running for longer periods of time we have to deal with the noise coming out of the registers for longer periods of time that is annoying and makes it harder to hear the TV  when it is on. Maybe if I set the blower in the air handler to the slower speed on the Mr cool there want be as much noise from the ducts. 
Just looking for someone that has used the Mr cool that can shed some light for me to know before I purchase.
Thanks, Richard


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## semipro (Oct 10, 2021)

R Alvanos said:


> I know that the outdoor unit is a variable speed fan and compressor and that the indoor units fan is a fixed speed motor.
> What happens when the outdoor unit slows down and the indoor fan is running at its normal speed. Does the indoor fan run for longer periods between cycling off?
> I would think that the inside fan is going be ruining a lot more that a regular heat pump.
> I have a lot of air noise coming out of my registers and don't know that I want the longer periods of fan noise.
> ...


In short, I don't know since I can't hear the outside unit and the AH at the same time to know when each is running.
I can tell you that the AH fan does not seem to run a lot.  I have actually set ours to run a minimum of 10 min/hr. to mitigate air stratification.
I can also tell you that the noise coming through my all-metal ductwork and registers is way less with the Mr. Cool than it was with my previous system.
If you're concerned about air noise at the registers I'd suggest you try the system on its lower output mode (e.g., 2 versus 3) and see how it sounds and cools/heats.  There is a substantial difference in wind noise between settings.  The system may run a bit longer at the lower setting but max wind noise should be less.
Hope that helps.


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## EbS-P (Oct 10, 2021)

semipro said:


> e.g., 2 versus 3)


The manuals don’t have lots of details. It would be nice for this to be configured as a two stage.  But since it’s variable speed it really doesn’t matter.  The 100cfm difference is probably not really noticeable unless you hear it ramp up.


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## R Alvanos (Oct 10, 2021)

Thanks for the feedback. 
I think I am going to purchase the Mr cool.
Got a couple of quotes to replace my unit with a 14 sear heatpump and they where more than double the cost of the Mr cool. Who doesn't want to save $4000.00.


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## begreen (Oct 10, 2021)

It sounds like the current system may be unbalanced and perhaps has inadequate outlets if the air noise is so loud that listening to tv is hard. Will the Mr. Cool system completely replace everything, using their wall units? If so, this should be notably quieter.


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## R Alvanos (Oct 10, 2021)

The Mr cool universal is a split system that replaces my old system and would use the same duct work. This is not a mini split unit.


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## begreen (Oct 10, 2021)

Ah, so you are replacing both the compressor and the air handler. How does the Mr. Cool air handler spec compare with the current unit?


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## R Alvanos (Oct 11, 2021)

The air handler in the attic is at least 35 years old and has electric strip heat. The outdoor unit was replaced about 18 years ago. I don't have any specs on the unit but it is a 2 ton and the outdoor unit is very small. 
This was used in a beach house that was not rented and used only during the summer and only about 10 weekends or so each year.  In winter it was not used at all. Now I'm retired and we stay hear a lot. 
The Mr cool is a heat pump and has a seer rating of 18 which is way better for the ac and the heat is going to be much better than electric strip heat.


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## EbS-P (Oct 11, 2021)

R Alvanos said:


> Thanks for the feedback.
> I think I am going to purchase the Mr cool.
> Got a couple of quotes to replace my unit with a 14 sear heatpump and they where more than double the cost of the Mr cool. Who doesn't want to save $


So have you figured the orientation you will need?


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## semipro (Oct 11, 2021)

EbS-P said:


> The manuals don’t have lots of details. It would be nice for this to be configured as a two stage.  But since it’s variable speed it really doesn’t matter.  The 100cfm difference is probably not really noticeable unless you hear it ramp up.


The difference is quite noticable on our lower level unit. I'm not sure why. Perhaps the noise generation is not directly proportional to the airflow?


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## R Alvanos (Oct 11, 2021)

Yes. I'm going with the 2/3 ton. It will be horizontal in the attic.  The freon lines come out on the wrong side from the factory but I was told that I could unfortunately the a coil and turn it around so the lines would be on the opposite side. That way the precharged lines would not have to be routed over are under the air handler which means a 25' line set is more than enough.
I have a lot of humidity at Hilton Head island,  SC and I think by this compressor running at slower speeds for longer periods of time and the air handler moving the inside air it should be able to bring the inside humidity down better than a traditional heatpump and make the house feel cooler.


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## R Alvanos (Oct 11, 2021)

Unbolt the a coil.


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## semipro (Oct 11, 2021)

R Alvanos said:


> Yes. I'm going with the 2/3 ton. It will be horizontal in the attic.  The freon lines come out on the wrong side from the factory but I was told that I could unfortunately the a coil and turn it around so the lines would be on the opposite side. That way the precharged lines would not have to be routed over are under the air handler which means a 25' line set is more than enough.
> I have a lot of humidity at Hilton Head island,  SC and I think by this compressor running at slower speeds for longer periods of time and the air handler moving the inside air it should be able to bring the inside humidity down better than a traditional heatpump and make the house feel cooler.


The A coil is relatively easy to move to any of the three positions although the manual does not reflect that.  I have also mounted my 2nd level unit horizontally and had to move the coil.  It's also easy to remove the blower.  I removed my A coil and blower before moving the unit to it's mounting place since I was working alone.


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## R Alvanos (Oct 11, 2021)

Sounds good. Thanks for the info. I will probably do the same to make it lighter to get it into the attic. 
Everybody says hooking up the precharged lies to the outdoor unit is very tight.  Can you get 2 90 degre elbows to turn the connection lines from pointing down to the side?


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## semipro (Oct 11, 2021)

R Alvanos said:


> Sounds good. Thanks for the info. I will probably do the same to make it lighter to get it into the attic.
> Everybody says hooking up the precharged lies to the outdoor unit is very tight.  Can you get 2 90 degre elbows to turn the connection lines from pointing down to the side?


I don't know.  
I used the pre-charged lines on my lower level install and saw no need for elbows.  
I'm not sure about your situation though.


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## Highbeam (Oct 12, 2021)

Here's a guy in CO that installed one of these and wrote up a whole thing about it. He loves it. This is from a personal finance site but I think a lot of his financial related input is valuable to all of us. He's a solar nerd too and mounted the air handler sideways. 









						Our DIY Heat Pump Install – Free Heating and Cooling for Life?
					

A work of art. To most of the Internet, Mr. Money Mustache is known as the quirky early retirement financial guy, and this is a blog about Money. But really, I’m not a finance guy – someone w…




					www.mrmoneymustache.com


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