# Mini split recommendations



## DonTee (Jul 3, 2022)

I’ve been thinking about getting a mini split for my house. I have some questions about what’s the best unit, and if what I want to do will even work. I’ll tell you about the house first, and then what I want to do. 

House is about ten years old. It’s wood frame construction with 2x6 walls, decent insulation, and decent windows. The house is pretty tight. Around 1500 sq ft. 
It’s located in upstate NY. Right now the only heat source is a wood stove. 

First of all I need to get home owners insurance on the house. I used to have it years ago, but let it lapse. I’ve been telling my wife I’ll get it again before wood burning season. The insurance I had before was more of a construction insurance. 

I need to have some other primary heat source besides the woodstove. Not that I would actually use it as a primary heat source, but for insurance purposes. Would the mini split work for this? 

Second, there are times when I have to leave the house on short notice. Usually not in the dead middle of winter, but I can’t rule that out as something that will never happen. I know the heat pump will not work below a certain temp. Of maybe it’s just super inefficient IDK. I’m not sure if some mini splits have heat strips in them as well. Anyways, I need something that could keep the house above freezing for short periods of time during the winter. 

3rd. On hot summer nights my kids would like it if I could cool down the house a little. It doesn’t have to be an icebox, just cooler and less humid. 

And last, during shoulder season it would be nice to not have to fire up the woodstove on days when it will warm up shortly. 

Basically my house is almost a square. It’s 24x30 and two story. When heating with the woodstove in the winter all rooms are very close to the same temp. I can keep downstairs 75ish and upstairs 77ish. The plan is to put the mini split blower unit in the middle of the house. I think maybe in the stairs between the floors. 

Can you guys recommend a brand(s) and size unit? Thanks.


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## DonTee (Jul 3, 2022)

Reading this thread it does look like the mini split would heat down to the low temps here. The lowest is usually around -15. 
In that thread the OP said his mini is rated down to -22. 






						Mini Split Heating at -8F
					

Mini Split Heating at -8F  In another recent thread, the subject of mini splits and heat pumps came up tangentially in a heating context. I have been heating for two seasons at my new house with a mini split, and this may be one of the last times I can report on cold weather performance with the...




					www.hearth.com


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## Highbeam (Jul 3, 2022)

It’s super cheap and almost universally accepted as a primary heat source to pop in a few cadet wall heaters. Straight electric. Zero maintenance, last forever, thermostat controlled. Electric cost is based on local rates, very common here in the pnw.


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## DBoon (Jul 4, 2022)

Yes, a mini-split will work in your home and your climate, but I would suggest that you not to try to have it do everything, i.e. don't size it to be too large and don't try to make it heat when it is the coldest day of your year. 

Mini-splits that heat down to 5 degrees F are pretty common and have higher coefficients of performance (COP) when it is warmer than mini-splits that heat down to -17 degrees F or so. If you just need emergency backup below 5 degrees, consider also electric resistance heat as a fail-safe should the house temperature drop below 40 degrees and you are not there. Mini-splits don't have backup electric heating elements. I would recommend the mini-splits that provide heat to 5 degrees F - their efficiency gains during the majority of the heating seasons compared to the -17 degree F units will make up for the few times a season you might have to run electric resistance heat when you are not there to run the woodstove. 

A central location will work well for a single mini-split. Heat rises - for heating it will be best on the first floor and for cooling best on the second floor. If you are only going to get one and you don't really need the AC, then it should located on the first floor. 

I've owned both Fujitsu and Mitsubishi mini-splits. They both work very well and they both make units that operate in very cold (-17 degree F) weather, if that is what you really want. I think these are the two premium brands (with premium prices). Others have used other brands (LG and Daikin come to mind) and seem satisfied with them.


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## EbS-P (Jul 4, 2022)

What’s your budget?  Given your use case spending extra for efficiency might not payoff like it does for someone who will use for 100% of those heating and cooling needs.  There are DIY units the come with evacuated lines and quick connect fittings (look up MR cool) but they aren’t as high quality as a Mitsubishi with hyper heat.  MR cool do not  turndown as low as the Mitsubishi and Fujitsu units. But Costco is selling a 12k btu (120v) unit shipped for 1100$.  Saw an add for the 4th gen mr cool units but haven’t looked at specs.  

I probably would not go bigger than 18-24 k btu.  And as long as the units lowest output doesn’t run you out of the first floor bigger is ok (to a point).  And sizing for heat is probably more important.  A smaller top tier cold climate heatpump would be better suited for you but you could buy 2 or 3 mr cool 12k units.   

Just my thoughts


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## DonTee (Jul 4, 2022)

Thanks for all the good input.  I was hoping to spend 2 grand or less. A unit I could install myself without calling out an HVAC guy is a bonus. 

Like I said, this would be a backup system in case I have to leave the house in the winter for some reason. If I have to leave for longer than the woodstove will last. 

Having a smaller wall unit is a big plus for WAF. I just need something that will keep the house above freezing if need be (50-55 degrees?). 
And the AC part would probably be used like a dozen times a year. 

Unit efficiency is a plus, but with the amount will use it, it’s not necessary to have a super efficient unit. Especially if it will add substantially to the cost.


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## EbS-P (Jul 4, 2022)

I’m not sure you can get any name brand unit for 2k.  Install would likely be another 1000$ just guessing. I have a quote for a 15k Mitsubishi that was 5600$.  6000$ if I wanted the cold weather hyper heat model.  

Mr cool 18k btu might do it.   Not sure if it’s the right size.  Look at the lowest output  between the 18 and 24 Kbtu  units.    Both are 240v units.  

I use this site to look specs up.  Looks like they have dual head single compressor units now available in the DIY line.  Not that it matters.  To you but it might. 

https://ashp.neep.org/#!/


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## DonTee (Jul 4, 2022)

Besides buying the unit itself what else would I need?I know I’d need a new breaker in the power panel and wiring to the unit. I have some stuff left over from when I wired my house I can use. 

I assume the Mini split comes with the hose/wiring that connects the inside unit to the outside unit? Anything I’m forgetting?


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## begreen (Jul 4, 2022)

For peace of mind, I would include a  second circuit for a resistance-style baseboard or built-in wall heater. That will be the equivalent of a strip heater in a ducted system. It can be connected to a low temp thermostat set at say 45º to prevent pipe freeze-up in the event that you are away.

Moved to the DIY forum where there are many other mini-split install threads here for more tips. Search on mini-split, title only, in this forum.


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## EbS-P (Jul 4, 2022)

DonTee said:


> Besides buying the unit itself what else would I need?I know I’d need a new breaker in the power panel and wiring to the unit. I have some stuff left over from when I wired my house I can use.
> 
> I assume the Mini split comes with the hose/wiring that connects the inside unit to the outside unit? Anything I’m forgetting?


Bracket to mount the compressor unit.  Exterior disconnect.  Hole saw to cut the right sized hole.  If I did it it would be an excuse to buy torque wrench for the fittings.


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## gthomas785 (Jul 4, 2022)

I have a Pioneer mini split that I got mostly for backup heat, but I gotta say we have ended up using it a lot more than we thought we would. It's just so efficient and convenient. Especially found using the dry mode in the humid months of August and September to be life changing. And it added a whole $20 to my electric bill.

For heat, it works great but I did notice the output drops off when it's below ~15f out. It says it will heat down to -5, which it will, just that there's less heat coming out right at the moment when you wanted more heat.

Keep in mind that the system will actually dehumidify better if it's slightly undersized, and will remove less moisture the more oversized it is (per btu of sensible cooling). So in cold climate where you sized the system for heating it will most likely be oversized for cooling and not dehumidify as well. Somewhere in here is an argument for having 2 small systems as opposed to 1 larger one. Or just get a smaller one and accept that it won't keep up when it's -17 degrees out.

Anyway, if you want 100% reliable backup heat, get electric baseboards. They cost very little to install and give you peace of mind, and there's no question whether your insurance will accept them. Set them to off unless you leave the house. I'd get a couple of those in addition to the mini split.


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## DonTee (Jul 4, 2022)

I hadn’t thought about the dehumidifier aspect of it, but yes that’s a good point. 

Like I said, part of what I want to do is to satisfy the insurance company, but the other part is to have a system that’s reliable if I have to leave the house for some reason. The reason why I’m leaning towards the mini split instead of just baseboard heat etc is because it’s useful in many more ways. 

Basically the selling point of this system to my wife is that it only takes up the one space on the wall. I might have to buy the mini split and test it out this winter to see what it can do. Then if it’s not enough I could add some baseboard heaters also.


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## DonTee (Jul 4, 2022)

So we’re thinking 24k btu is the size I should look for?


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## EbS-P (Jul 4, 2022)

DonTee said:


> So we’re thinking 24k btu is the size I should look for?


If looking at the mr cool diy the output at 5F is probably 15k btu.  That works out to about 3 pounds of firewood an hour (at 20 % MC burned at about 65% efficiency).   So if you burn 70 pounds of wood or less on a really cold day it would keep up.  It appears  to me the minimum heat output is only different by 1000btus between the the 18 and 24.  So Id with the the 24.  

I get the whole don’t over size for cooling but these units the turn down is low enough and the fact you can run a programable thermostat where you can set it colder for a couple hours  and knock the humidity down.  And theoretically they have the humidity control mode that runs the cool below the indoor dew point problem is it just doesn’t move enough air to keep the humidity low.  If it did the house would might get too cold.  Bummer a cold dry house on the hottest most humid summer days.  

18k btu runs on #12 wire I think.  The 24 probably needs #10 but I didn’t read close enough to be sure.  I have not looked at the price of wire in a while.  

I can easily burn 70# of wood a day in my 1.6 cu ft stove and I have a 36k btu heatpump that does 22k at 32 dF.  My point is if it’s pipe freezing cold and you are not there have another plan like heat wrap, or a baseboard heater.  

Just some thoughts. I  haven’t  actually bought a mr cool unit.  Have been close a couple times.  Got a second wood stove last year instead.  Could never justify the extra cost of a name brand or the install since I have heatpump that does ok already.


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## gthomas785 (Jul 5, 2022)

DonTee said:


> So we’re thinking 24k btu is the size I should look for?


Do a manual J on your house to figure out heating and cooling loads. Don't guess.
www.loadcalc.net


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## DonTee (Jul 5, 2022)

Ok thanks. I’ll check it out.


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## EbS-P (Jul 6, 2022)

I’ve never actually completed a manual j though I have started it at least 5 times.  It’s a good idea but I’m guessing at some of values I’m putting in. 

Any way.  Learn from others mistakes.  Don’t snap off the line set.


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## gthomas785 (Jul 6, 2022)

For the manual J I usually recommend people look at the spreadsheet, then make a list of all the measurements you need to do and then walk around with your tape measure. It's definitely not a project you can finish in 10 mins. Each window and door gets a number to make things clearer.

There's a ton of good refrigeration / HVAC content on YouTube, however look for the professional channels not the diy guy doing it for his first time. There's lots of misinformation/bad advice out there as well.


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## DonTee (Jul 6, 2022)

Yeah I glanced at it and it’s a little confusing. If I could find a guide on how to fill it out that would be nice. Or I could look at a completed sheet like you said. 
I have 18 windows in my house, but they’re all one of two sizes.


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## EbS-P (Jul 6, 2022)

Quick search finds this.  






						Downloads - Public Files - ACCA
					






					www.acca.org


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## EbS-P (Jul 6, 2022)

EbS-P said:


> Quick search finds this.
> 
> 
> 
> ...


The issue you have is a nonstandard Indoor temp.   Say 55dF.  I’m not sure I’d that is allowed in the manual j sheet I just posted.  Hence my how much wood do you burn estimate.


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## DonTee (Jul 6, 2022)

Ah gotcha. I don’t have good numbers for that. I haven’t consistently stayed in this house all winter since we built it. Last winter was the first, and we were only here for part of the winter. It’s been seasonal until this point.
And, I’ve changed woodstoves. I started out with an old Timberline stove until last year. Then I had a VC encore for most of the winter. And this year I’ll have a BK Princess.

Last winter I burned almost 4 cords. But that was with the house under insulated. This winter it will be fully insulated, with a vapor barrier, drywall, and the BK stove.


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## coaly (Jul 6, 2022)

I installed my first mini-split in a rental home last year. Used as the primary heat with a propane stove back up that has not been needed.

Not difficult, but I was a propane appliance and heat tech (no heat pump or mini splits back then) for many years with my own service business. The only thing different was torquing copper flare fittings and using Nylog  Blue lubricant/sealer on fittings that are normally done dry.
Many like mine are 220 volt that have a DC inverter to run very efficient DC motors. 12-2 wiring in most cases uses 220v breaker, and both conductors were 110v hot, with no neutral needed. Disconnect at outside unit, connecting harness from outside to inside unit supplied.

Like many, my outside unit was precharged for diy installation. You will need a vacuum pump with gauges to vacuum the system, confirm it holds vacuum and slowly open valves on outside unit allowing the precharged refrigerant into system. Once you do it following installation instructions, it’s not that difficult.

I had a professional precision flaring tool, so I could cut and flare tubing. If you don’t have a good one, you need to use the factory flares making sure they are perfect. The line set connects at both inside and outside units with flare fittings.

So special tools required would be a vacuum pump and gauge set, means of torquing fittings, precision flare tool if you need to shorten line set.  And Nylog Blue Gasket and Thread Sealant. Practice on many flares if you are not well versed in copper tubing flaring. You will also need line set covers for outside to run lines through before connecting. I’ve had very good experiences with Pioneer brand as well.


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## Highbeam (Jul 6, 2022)

If you go over on lineset length then you’ll need a pro to add refrigerant. I’m finding most come charged with only enough for 25’. 

The mr cool diy kits allow you to add more length without adding refrigerant.


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## DonTee (Jul 7, 2022)

Thanks for the detailed write up coaly. I either have or can borrow the tools I need. I’ll need to get some of the thread sealant. 

I haven’t decided (my wife hasn’t told me. Lol) where the mini split is going. It would be nice to keep the run from inside to outside at 25’ or under. I imagine she would want the outside unit on the back of the house. But maybe it could go on the side by the electric panel. That would be easy since my outside panel has spaces for breakers as well. 
I know I have some 30 amp 220 breakers left. Maybe I have a 20 amp as well. I know when I was wiring the house I had issues finding some breaker sizes. Seems the Eaton BR series are hard to find because of the covid shortages.


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## peakbagger (Jul 7, 2022)

DonTee said:


> Thanks for the detailed write up coaly. I either have or can borrow the tools I need. I’ll need to get some of the thread sealant.
> 
> I haven’t decided (my wife hasn’t told me. Lol) where the mini split is going. It would be nice to keep the run from inside to outside at 25’ or under. I imagine she would want the outside unit on the back of the house. But maybe it could go on the side by the electric panel. That would be easy since my outside panel has spaces for breakers as well.
> I know I have some 30 amp 220 breakers left. Maybe I have a 20 amp as well. I know when I was wiring the house I had issues finding some breaker sizes. Seems the Eaton BR series are hard to find because of the covid shortages.


Be very careful on where you locate the outdoor unit, its a big cause of failures in snow zones. Yes some units have electric pan heaters but its no substitute for location. Ideally put it well up off the ground in any area not subject to drifting and ideally out of the prevailing wind. Ideally you want it in place where the wind scours the snow, usually on the downwind side of the building. There are shutters that can be installed to make a big location a bit better but its far better to do it right. No matter what consider what its going to look like with slanted roof over it as in many cases one is going to be needed. I have seen them installed directly under drainage points from the roof so when it rains they are constantly under steady stream of water. The other thing is the keep in mind wintertime snow banks. My install is near a driveway and I was always careful to do post plowing clean up so that the plow guy did not inadvertently push the banks back and wreck the unit.  

BTW the pan heaters are usually in the 40 watts range, they take a long time to melt out a unit full of snow.


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## EbS-P (Jul 7, 2022)

DonTee said:


> Thanks for the detailed write up coaly. I either have or can borrow the tools I need. I’ll need to get some of the thread sealant.
> 
> I haven’t decided (my wife hasn’t told me. Lol) where the mini split is going. It would be nice to keep the run from inside to outside at 25’ or under. I imagine she would want the outside unit on the back of the house. But maybe it could go on the side by the electric panel. That would be easy since my outside panel has spaces for breakers as well.
> I know I have some 30 amp 220 breakers left. Maybe I have a 20 amp as well. I know when I was wiring the house I had issues finding some breaker sizes. Seems the Eaton BR series are hard to find because of the covid shortages.


Rember you will have to slope a condensate drain line.  Mr cool units don’t need flare tools or vacuum pumps.  But if you step up to the other units that require those you have many more choices.  But I’m not sure you can save any money.


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## DonTee (Jul 7, 2022)

I think behind the house would be the best area as far as protection from the wind and snow. I’ll have to push for that spot. 

Otherwise it would be on the side with the roof possibly unloading on it. In that case I’d have to build a little roof over the unit.


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## peakbagger (Jul 7, 2022)

Mine is on a gable end of the house so no snow dumps. It you have the chance of snow slides off a roof make sure you avoid placing one there or make sure the roof can take the force of snow slide.


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## Highbeam (Jul 7, 2022)

EbS-P said:


> Rember you will have to slope a condensate drain line.  Mr cool units don’t need flare tools or vacuum pumps.  But if you step up to the other units that require those you have many more choices.  But I’m not sure you can save any money.



I believe I’m moving away from the mrcool diy line. The price jump is very high and those extra tools are really cheap and look easy to use. You dont need to cut and flare if you do what you would have done with the extra lineset from a diy kit. You do need a 140$ pump that comes with the gauge set. A fancy 200$ torque wrench that can maybe be rented,  and some folks like to nitrogen purge their systems too. It all looks very easy. The flaring tool is only about 40$ and looks foolproof. The money favors the standard units, plus bigger profit if you’re doing more than one. 

The warranty on the diy units does not require a pro so there’s that. The diy units are identical to all the other Chinese mini splits so you’re not getting a better unit. 

Then the tough part is sizing them. Easy to get enough heat in the dead of winter with units that are oversized the other 95% of the time.


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## begreen (Jul 9, 2022)

Suggestion, for DIY. Flare joints are a typical failure point, even for some pros. Get a good quality tool and practice on a few scrap pieces of tubing first. And as noted, make sure you are not voiding the warranty with a DIY install.


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## peakbagger (Jul 9, 2022)

The two techs who pumped down both my systems did not like flare fittings and cut them off at the indoor unit and brazed them. They did use them on the outdoor unit but cut of the factory supplied flares on the line set I had pulled.


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## DonTee (Jul 9, 2022)

My dad is wanting to put in a mini split system as well. It might be worth it for the two of us to split the cost of the tools, and get the regular system instead of the DIY. 

Am I understanding correctly that you lose the warranty with the regular system unless a pro installs it?


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## DonTee (Jul 9, 2022)

Also what kind of torque wrench are we talking about here? I have the regular automotive type torque wrenches in 1/4”, 3/8”, 1/2”, and 3/4” drive. Could you use one of those with a crows foot to tighten the flares? 

I would imagine the torque is probably in inch pounds. No 3/4” drive torque wrench for this job. Lol.


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## coaly (Jul 10, 2022)

DonTee said:


> Also what kind of torque wrench are we talking about here? I have the regular automotive type torque wrenches in 1/4”, 3/8”, 1/2”, and 3/4” drive. Could you use one of those with a crows foot to tighten the flares?
> 
> I would imagine the torque is probably in inch pounds. No 3/4” drive torque wrench for this job. Lol.


Torque varies with tubing size given in foot pounds.


			http://www.ampcomp.com/assets/PS-138B.pdf
		


A crows foot works. I didn’t have one, but have a nice brass fish scale. I calculate the length of a combination wrench, or adjustable wrench with hole in the end.  Snug the fitting. Put a backup wrench on fitting and let it hang. Put the open end wrench on the nut, hook the fish scale which is graduated in pounds on the end of wrench through hole or closed end of wrench. As you pull on the scale holding the backup wrench, pull to the poundage required. As an example, a 12 inch wrench from center of tubing to where scale attaches, pulled to 1 lb. on the scale is 1 foot pound torque. Pulling on the wrench with the scale shows the foot pounds torque when wrench stops moving at desired foot poundage. I torque axle nuts that are above my 1/2 drive torque wrench range with my weight on a pipe with a breaker bar the same way. Calculate your weight at how many feet away from axle center you need to apply the correct weight for foot pounds of torque required. I put the pipe all the way down the wrench, make a mark on the pipe at correct distance away from center of axle for torque needed with my weight, place my foot directly over mark on pipe and let my weight tighten it until it no longer moves. Did the same with locomotives and steam engines not having torque wrenches that go that high. Old timers in the shops didn’t have fancy torque wrenches. Fish scales and length of leverage calculation.


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## coaly (Jul 10, 2022)

peakbagger said:


> The two techs who pumped down both my systems did not like flare fittings and cut them off at the indoor unit and brazed them. They did use them on the outdoor unit but cut of the factory supplied flares on the line set I had pulled.


Most HVAC guys will cut off the factory flares not trusting them. I do too, having a precision flaring tool that the dies come together exactly, has a depth gauge that inserts tubing the correct amount, and the mandrel has bumps that work the flare into shape without thinning the wall, and polish the inside when loosening mandrel to remove tool. My precision flaring tool also angles the flare a few degrees off, so the flare nut angles the flare to match the seat perfectly when torqued. Wear in dies and mandrel on factory machines may not be as accurate as the tool you’re used to. It takes practice to get it perfect every time. A good flare tool allows cutting lines to exact length, and I made one coil at compressor for vibration. Copper hardens with time and looses flexibility.


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## Highbeam (Jul 10, 2022)

DonTee said:


> My dad is wanting to put in a mini split system as well. It might be worth it for the two of us to split the cost of the tools, and get the regular system instead of the DIY.
> 
> Am I understanding correctly that you lose the warranty with the regular system unless a pro installs it?



I just ordered the slightly more expensive diy mr cool set for the warranty reason. It’s the only mini split I could find that can be amateur installed and warrantied. What if the non DIY mini is dead on arrival? You got nuthin. 

The biggest drawback other than cost for the DIY is that you can’t cut the lineset so you have to coil the extra somewhere and the directions want you to lay this coil horizontally so that oil can’t pool. Not sure if I’ll follow that rule. 

For torque wrenches no, you can’t use a crows foot on a regular automotive torque wrench. The settings are high enough like 20 foot lbs but you need an “hvac” torque wrench. These are like 200$. I don’t know why but the professionals are quite consistent that you need an hvac wrench.  

Vacuum pump, gauge set, torque wrench, flare tool, pipe cutter. Optional is micron gauge, nitrogen tank, nitrogen regulator.


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## Highbeam (Jul 11, 2022)

One more thing. I’m running the 10 gauge 30 amp circuit right now and wire costs 50% more at big box stores than at Amazon. Just order it! The 100’ roll of 10/2 was 230$ at Home Depot!


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## coaly (Jul 11, 2022)

Highbeam said:


> I just ordered the slightly more expensive diy mr cool set for the warranty reason. It’s the only mini split I could find that can be amateur installed and warrantied. What if the non DIY mini is dead on arrival? You got nuthin.
> 
> The biggest drawback other than cost for the DIY is that you can’t cut the lineset so you have to coil the extra somewhere and the directions want you to lay this coil horizontally so that oil can’t pool. Not sure if I’ll follow that rule.
> 
> ...


As long as you use the the crows foot on a 90* angle to wrench handle the torque is accurate. If you extend the open end of crows foot forward, away from handle this lengthens wrench from center of square drive to center of flare nut. The wrench will be under torquing since you are lengthing the lever.


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## Highbeam (Jul 11, 2022)

coaly said:


> As long as you use the the crows foot on a 90* angle to wrench handle the torque is accurate. If you extend the open end of crows foot forward, away from handle this lengthens wrench from center of square drive to center of flare nut. The wrench will be under torquing since you are lengthing the lever.


The install manual for the mr coil unit actually disallows socket style torque wrenches and requires the hvac torque wrench. 

From a physics perspective, I don’t think it matters which way you put the crows foot on the square drive. It’s just a torque measurement. Both applied and received acting about a central axis.


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## DonTee (Jul 11, 2022)

I was looking at the HVAC torque wrenches online. Kind of a weird combination of tools. Something imprecise like an adjustable wrench (all sixteenths. Lol) and something precise like a torque wrench. Kind of funny looking.


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## gthomas785 (Jul 11, 2022)

You guys are really getting into the weeds here with the torque specs. Yes it's a good idea to use a torque wrench, and usually required by the install manual, but the type won't make a difference as long as it's in the right range.

If the warranty wants you to use HVAC wrenches, challenge them to prove that you didn't.


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## begreen (Jul 11, 2022)

Highbeam said:


> I just ordered the slightly more expensive diy mr cool set for the warranty reason. It’s the only mini split I could find that can be amateur installed and warrantied. What if the non DIY mini is dead on arrival? You got nuthin.


Is this for the house or shop?


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## Highbeam (Jul 11, 2022)

begreen said:


> Is this for the house or shop?


For the house! I’ve been wanting to do this for years. 24k btu but wife doesn’t want the ugly inside unit in the living room so it’s in a less ideal place but fingers crossed.


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## coaly (Jul 12, 2022)

Highbeam said:


> The install manual for the mr coil unit actually disallows socket style torque wrenches and requires the hvac torque wrench.
> 
> From a physics perspective, I don’t think it matters which way you put the crows foot on the square drive. It’s just a torque measurement. Both applied and received acting about a central axis.


I guess they wouldn’t approve of my fish scale.  A pound of force on the end of a lever is the same no matter what you use, as long as the measuring device is accurate, and length of lever is calculated.


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## Highbeam (Jul 12, 2022)

For reference, the torque specs we're talking about here are in the range  of 20-30 ft-lbs. Nothing super tiny or tight.


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## begreen (Jul 12, 2022)

Highbeam said:


> For the house! I’ve been wanting to do this for years. 24k btu but wife doesn’t want the ugly inside unit in the living room so it’s in a less ideal place but fingers crossed.


Congratulations. I hear you. My wife is a stickler about this stuff too, but we have traveled enough that she has seen mini-splits for a long time and is more used to them. Hopefully, your wife will get used to it quickly, after all, she let the Princess in.


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## hockeypuck (Jul 22, 2022)

begreen said:


> Congratulations. I hear you. My wife is a stickler about this stuff too, but we have traveled enough that she has seen mini-splits for a long time and is more used to them. Hopefully, your wife will get used to it quickly, after all, she let the Princess in.


After a while, you really do not notice them.  My wife was the same way but convinced her that the benefits would far outway the "box" on the wall.  My wife will not even let me tear off the wood clapboards and change to vinyl siding.  She put her foot down on that one. It has and we love our unit.  DIY Mr. Cool 24k.   I love to take a walk outside and stare at the drain tube pissing out water.  Always puts a smile on my face.  I was done dealing with window units.  I have posted on other threads we use it more days for heat than cooling on the shoulder season to get us to firewood season.  Going to put one up at the winterized cabin next year. We have no heat but a wood stove up there.


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## RustyShackleford (Jul 27, 2022)

DonTee said:


> A unit I could install myself without calling out an HVAC guy is a bonus.


I have had little difficulty finding an HVAC guy who is willing to come and do the freon work once I've done the rest of the install.  He'll charge $60-80/hour for perhaps 2 hours, plus the cost of refrigerant.   Maybe $200.


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## RustyShackleford (Jul 27, 2022)

EbS-P said:


> I’m not sure you can get any name brand unit for 2k.











						Mitsubishi MZ-HM24NA - 24k BTU Cooling + Heating - HM-Series Wall Mounted Air Conditioning System - 18.0 SEER
					

Buy Mitsubishi MZ-HM24NA Today. Free Shipping. Check the Mitsubishi - 24k BTU Cooling + Heating - HM-Series Wall Mounted Air Conditioning System - 18.0 SEER ratings before checking out.




					www.ecomfort.com
				



THE top brand, two-ton, for right at $2K.  Of course, this doesn't include the line-set and other installation parts.


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## RustyShackleford (Jul 27, 2022)

gthomas785 said:


> Do a manual J on your house to figure out heating and cooling loads. Don't guess.
> www.loadcalc.net


This tool is, I think, a bit easier to use: hvac.betterbuiltnw.com

I actually used both, for my application, and they were re-assuringly close.


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## RustyShackleford (Jul 27, 2022)

coaly said:


> I had a professional precision flaring tool, so I could cut and flare tubing. If you don’t have a good one, you need to use the factory flares making sure they are perfect. The line set connects at both inside and outside units with flare fittings.


There are actually now available connectors for refrigerant lines that are "push to connect" like SharkBite plumbing fittings.



			https://www.supplyhouse.com/PRO-Fit-Quick-Connect-HVAC-Fittings-30580000
		


A local friend, who does HVAC work, swears by them.   He uses the ones called "sockets" that connect to the factory flares on one end and are push-to-connect on the other end.  Installs them on the two lines on the inside and outside unit first.  Then cuts the line-set to fit, cleans up the ends real well (like you would for a SharkBite) and pushes in to conenct.

I believe he uses a different brand though, only sold at HVAC supply houses (that typically won't sell to DIYers).


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## EbS-P (Jul 27, 2022)

Mr cool 24k is now 1900$.  

It’s a hot one here today.  Ac came on at 3 and has not shut off. Temp is 2 degrees above set point.  If I keep putting  my mini split off  and we get some record temps my Maine born wife won’t be happy.


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## RustyShackleford (Jul 27, 2022)

EbS-P said:


> Mr cool 24k is now 1900$.


Yep, and the Mitsubishi I linked above is $2088.   Hence my dilemma.   Do I pay virtually the same, for what by all accounts is a far superior unit (both in reliability AND in performance), at the cost of having no warranty because of my DIY install ?   I'm leaning towards "yes".


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## peakbagger (Jul 27, 2022)

RustyShackleford said:


> Mitsubishi MZ-HM24NA - 24k BTU Cooling + Heating - HM-Series Wall Mounted Air Conditioning System - 18.0 SEER
> 
> 
> Buy Mitsubishi MZ-HM24NA Today. Free Shipping. Check the Mitsubishi - 24k BTU Cooling + Heating - HM-Series Wall Mounted Air Conditioning System - 18.0 SEER ratings before checking out.
> ...



I assume you have done your homework between the two models with respect to annual efficiencies? The up front cost savings is rapidly eaten up by long term operating expenses. I would do it myself but its PITA to find the spec sheets for specific units as every manufacturer had many models.


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## coaly (Jul 27, 2022)

RustyShackleford said:


> There are actually now available connectors for refrigerant lines that are "push to connect" like SharkBite plumbing fittings.
> 
> 
> 
> ...


Cool, everything in this world is made to make me obsolete.


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## RustyShackleford (Jul 27, 2022)

peakbagger said:


> I assume you have done your homework between the two models with respect to annual efficiencies? The up front cost savings is rapidly eaten up ... I would do it myself but


Well, the costs of the units is similar.   


> its PITA to find the spec sheets for specific units as every manufacturer had many models.


Actually, there's a great site that does this for you.






						ASHP
					






					ashp.neep.org
				




They should have the MrCool too.   Can do a search at the site, or type in model numbers from a vendor's site.   Not sure if this is the specific $1900 one that people are discussing here ...






						ASHP
					






					ashp.neep.org


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## EbS-P (Jul 27, 2022)

Biggest difference I noticed in general was the the mr cool diy lowest output was much greater than the Mitsubishi units I was comparing.  Not a big deal but I wanted constant dehumidification without much cooling.  18 vs 20 SEER,  I personally wouldn’t see much benifit in the higher rating.   

I vote Mitsubishi.


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## RustyShackleford (Jul 27, 2022)

EbS-P said:


> I vote Mitsubishi.


Mitsu over MrCool, for sure.   But I'm actually voting Fujitsu.   Look at this sucker ...






						ASHP
					






					ashp.neep.org
				




... It keeps doing 18Kbtu/hr even at 5 degrees, but at 47 degrees it turns down to 2800btu/hr.   That's less than a freakin' hair dryer !


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## gthomas785 (Jul 28, 2022)

You should be aware that Mitsubishi units are currently very difficult to get, a lot of orders are backed 6+ months out. The online retailers may be hesitant to let you know about that, because they still want your money.

According to what I've been able to find online,  pretty much all of the non-Japanese mini splits are made by one of two major manufacturers, either Midea or Gree. Other brands (like MrCool) buy them wholesale and slap their name on. I think even the off brands have a pretty good reputation as far as performance and reliability, but 90% of that is dependent on the quality of the installation.

I have heard horror stories about the MrCool quick connects leaking from the factory. Maybe they've improved over the past few years, but I still don't trust them.

We were really impressed by the performance and price point of our Pioneer system, so at my wife's request, I just bought and installed a second one last weekend. This time it's a 2-zone,  9k+9k btu to take care of the upstairs of our old Colonial.

I had zero issues with the install, other than the insane location we chose for the outdoor unit (up high on a wall, above a 1st story roof) to keep it out of sight from the nosey historic district people. But we managed to hoist it up there without dropping it. Used all the tools I had still on hand from the first install, rented a small tank of nitrogen from Airgas,  took my time and had it done in 2 days.


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## RustyShackleford (Jul 28, 2022)

gthomas785 said:


> You should be aware that Mitsubishi units are currently very difficult to get, a lot of orders are backed 6+ months out. The online retailers may be hesitant to let you know about that, because they still want your money.


I don't have any direct experience with the vendor I plan to use, as yet (ecomfort-DOT-com) but their website appears to be honest about lead-times, saying some items (particularly Mitsu) are backordered, other 3-4 weeks, others in-stock.


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## gthomas785 (Jul 29, 2022)

RustyShackleford said:


> I don't have any direct experience with the vendor I plan to use, as yet (ecomfort-DOT-com) but their website appears to be honest about lead-times, saying some items (particularly Mitsu) are backordered, other 3-4 weeks, others in-stock.


Just saying, my buddy ordered one earlier this year that said 3-4 weeks, time came and went, they gave him the run around for 2 months until they finally admitted it would be another 6+ months but no guarantee so he ended up canceling it. I believe this was from HVAC Direct.

That was one reason I chose to go with pioneer again. At least they don't seem to be having any supply chain issues at the moment.


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## Highbeam (Jul 30, 2022)

@RustyShackleford  I just yesterday fired up a self installed 1900$ 24k mr cool at my house. Happy to answer any questions. It’s all about warranty. Self installed mr cools get a warranty. This thing is great. I’ve never had AC before. Keeping my 1963 1700sf as cold as I want it from a central location in the mid 90s ambient with no shade. 

Install was easy.


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## peakbagger (Aug 12, 2022)

No details but the inflation reduction bill reportedly has a $8000 tax credit for minisplits for low income home owners and $2000 credit for anyone to install one. I think the price of minisplits is going up. The old R410 units are being cleaned out of inventory while the new refrigerant units will be coming out soon.


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## mcdougy (Sep 7, 2022)

peakbagger said:


> No details but the inflation reduction bill reportedly has a $8000 tax credit for minisplits for low income home owners and $2000 credit for anyone to install one. I think the price of minisplits is going up. The old R410 units are being cleaned out of inventory while the new refrigerant units will be coming out soon.


Sorry if you have already answered this on another thread, but is there an advantage to waiting  for the new units with new refrigerant? Does it improve the efficiency or maintaince of the units?


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## peakbagger (Sep 7, 2022)

I do not know technically the impact. My guess is higher refrigerant pressure means new HVAC gear?


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## gthomas785 (Sep 7, 2022)

mcdougy said:


> Sorry if you have already answered this on another thread, but is there an advantage to waiting  for the new units with new refrigerant? Does it improve the efficiency or maintaince of the units?


From a equipment performance perspective I don't think R32 or R454b have any advantages over R410A. They are more environmentally friendly, that's it.


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## EbS-P (Sep 7, 2022)

gthomas785 said:


> From a equipment performance perspective I don't think R32 or R454b have any advantages over R410A. They are more environmentally friendly, that's it.


And flammable.  

I don’t see any reason to wait and I really don’t want to own the first generation of new equipment so there is a reason to get a 410a unit.


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## peakbagger (Sep 8, 2022)

The biggest issue is in order to get a future rebate, the unit needs to be certified to certain performance standard and listed. When I checked a couple of weeks ago the listing agency had no listings yet. Therefore claiming a rebate on current unlisted model could be problem.

I think the rational on the potential flammability of the replacements is that its small volume of gas that would rapidly get diluted if there was a leak.


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## gthomas785 (Sep 8, 2022)

Yeah, I don't really see too many people proactively preparing for the phaseout. No units certified or for sale with the new refrigerant yet. I suppose manufacturers must have the new system designs up their sleeves but they seem to be mainly focused on cranking out 410a units while they still can.

I also think the hazard of flammable refrigerant is overblown. Many smaller commercial refrigeration systems have been using R290 (propane) for decades without major incidents. Most of the risk arises from improper servicing by untrained technicians.


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## EbS-P (Sep 8, 2022)

I don’t see how a 20+ seer 410a shouldn’t qualify but…. Stranger/stupider  things have happened.


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## Tegbert (Sep 8, 2022)

I installed a 3 zone Mr. Cool DIY system a year and a half ago and am happy with its performance. Wife wasn't too thrilled with the heads on the wall but after having it through some pretty hot days for the PNW she is absolutely glad they are there and forgets that they are there now until someone asks about them. So much better than portable and window units. We have a poorly insulated house and when we had over 100-degree days last year for a few days the thing never skipped a beat and kept the house at 74 except for an outlier next to a sun facing wall was 78. In the wintertime it is nice to be able to leave the house for a long period of time and not have to use the baseboard heaters and just keep the house at 64 ish till we get home and fire the wood stoves back up.

I had to buy multiple extensions and connectors to get the inside units where I wanted them to where the wife wanted the outside unit. Overall pleased with the purchase and saved a ton of money compared to what the local HVAC guys wanted for similar installed units at 4 times the cost.


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## Highbeam (Sep 9, 2022)

I also recently self installed a Mr cool DIY minisplit unit. 24k sized to heat the home. Very cheap after utility rebates and even some federal rebates I expect. We all hate how the inside units look and they make noise and blow air so you don't really want it real close. 

I stuck my inside unit in sort of an adjacent room with no doors and plenty of airflow to the main space. It blows into the main space quite well at least with cold air. We will soon find out if heat moves as easily. You don't have to put the dang thing in your living room!

Our other heat source is wood and electric wall heaters. It was in the low 40s last night and the house was 67 this morning. We have a LONG heating season that is not too intense so I'm hoping the minisplit can reduce the burning season.


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## tlc1976 (Sep 9, 2022)

Highbeam said:


> I also recently self installed a Mr cool DIY minisplit unit. 24k sized to heat the home. Very cheap after utility rebates and even some federal rebates I expect. We all hate how the inside units look and they make noise and blow air so you don't really want it real close.
> 
> I stuck my inside unit in sort of an adjacent room with no doors and plenty of airflow to the main space. It blows into the main space quite well at least with cold air. We will soon find out if heat moves as easily. You don't have to put the dang thing in your living room!
> 
> Our other heat source is wood and electric wall heaters. It was in the low 40s last night and the house was 67 this morning. We have a LONG heating season that is not too intense so I'm hoping the minisplit can reduce the burning season.


Your install looks great! I’m curious how it works for you this winter too. More often than not, my stove runs on 1, which works out to about 10k BTU. If I could offset that much with a mini split, and it would still deliver a decent ROI, then I’d go for it. It would also allow me to keep my boiler pilot off permanently, which would save a little more during the heating season.


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## hockeypuck (Sep 16, 2022)

tlc1976 said:


> Your install looks great! I’m curious how it works for you this winter too. More often than not, my stove runs on 1, which works out to about 10k BTU. If I could offset that much with a mini split, and it would still deliver a decent ROI, then I’d go for it. It would also allow me to keep my boiler pilot off permanently, which would save a little more during the heating season.


I use mine for heating more than I do for cooling.  I never intended to use it for heat.  It was an after thought.  Mine is a 3rd gen Mr. Cool.  I use it for heat down to 25.  It goes lower than that, but usually turn to wood and pellets if the weather is going to stay in the 20s for an extended period of time.


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## peakbagger (Sep 16, 2022)

I use mine mostly for heat. It covers my entire house heating load down to about 25 F overnights. The key it just set it to one temp and leave it there. If the house and cold needs to be warmed up to higher temp it takes a long time. I crank up the wood boiler when overnight temps go below 25F


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## Highbeam (Sep 18, 2022)

peakbagger said:


> I use mine mostly for heat. It covers my entire house heating load down to about 25 F overnights. The key it just set it to one temp and leave it there. If the house and cold needs to be warmed up to higher temp it takes a long time. I crank up the wood boiler when overnight temps go below 25F


Just tested out the heat function today on my 24k mrcool mini to bump the home up four degrees. How do these things behave? Do you set the fan speed or leave it on auto? It was mid 50s outside and the outdoor fan was slow which I assume is because at such high ambient temperatures the heat pump easily makes full output. It will take me some time to learn how it acts like whether on a set fan speed if the fan slows to low when the room temperature hits setpoint.

It’s not quite cold enough to just leave it on heat all the time. It warms up so much during the day outside that the house would overheat. 

Do you recommend just letting the algorithms take over?


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## hockeypuck (Sep 18, 2022)

Highbeam said:


> Just tested out the heat function today on my 24k mrcool mini to bump the home up four degrees. How do these things behave? Do you set the fan speed or leave it on auto? It was mid 50s outside and the outdoor fan was slow which I assume is because at such high ambient temperatures the heat pump easily makes full output. It will take me some time to learn how it acts like whether on a set fan speed if the fan slows to low when the room temperature hits setpoint.
> 
> It’s not quite cold enough to just leave it on heat all the time. It warms up so much during the day outside that the house would overheat.
> 
> Do you recommend just letting the algorithms take over?


Just set it at medium, make sure you hit the "follow" button and put the remote in a central area.  The follow button senses the temperature at the remote rather than the unit it self.


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## stoveliker (Sep 18, 2022)

I have the fan on auto. If I heat up the home by a large amount (e.g. 8 degrees), it'll start with the fan inside on high, but in a few minutes it'll dial down to barely audible.

The thing has a thermostat and won't overheat the home because the compressor will stop once the temperature of the room has been reached.

My outside unit controls itself. Fan speed varies.


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## Highbeam (Sep 18, 2022)

The remote must be “line of sight” for the follow me function to work. That’s almost impossible for me where the air handler is in a sort of adjacent room but with plenty of  doorless connections. The higher fan speed seems to help throw the heat farther away so the onboard thermostat isn’t satisfied too soon. 

In cooling the thing does great on auto fan speed because the coolness pours out like a waterfall. 

I was getting some cycling when on auto (meaning very low most of the time) and heating. 

When you set it to medium for heating, does the indoor unit just run on medium forever? Or does it idle down when the thermostat is satisfied?


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## hockeypuck (Sep 18, 2022)

Highbeam said:


> The remote must be “line of sight” for the follow me function to work. That’s almost impossible for me where the air handler is in a sort of adjacent room but with plenty of  doorless connections. The higher fan speed seems to help throw the heat farther away so the onboard thermostat isn’t satisfied too soon.
> 
> In cooling the thing does great on auto fan speed because the coolness pours out like a waterfall.
> 
> ...


If you are not using the follow function, it will idle down when the thermostat at the inside unit is satisfied.


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## EbS-P (Sep 18, 2022)

Highbeam said:


> The remote must be “line of sight” for the follow me function to work. That’s almost impossible for me where the air handler is in a sort of adjacent room but with plenty of  doorless connections. The higher fan speed seems to help throw the heat farther away so the onboard thermostat isn’t satisfied too soon.
> 
> In cooling the thing does great on auto fan speed because the coolness pours out like a waterfall.
> 
> ...


Is the remote IR (infra red)??


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## peakbagger (Sep 18, 2022)

I set the temp and auto fan. Mine runs the fan at high for awhile while getting up to temp but eventually its starts to slow way down and cycle as its sees the return air temp dropping. As I mentioned best thing is set it and forget it. I will be doing that overnight and turning it off in AM as my house has good sun exposure to the east and south so it warms up quick. I turn it back on in the evening nearing sunset.


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## Highbeam (Sep 18, 2022)

EbS-P said:


> Is the remote IR (infra red)??


I don’t know, I assume so. These Chinese mini splits are all made the same and the directions were clear and my experience backs up that you need to be line of sight for the mini to communicate with the remote. Kinda lame in my situation but I’ll make the best of it.


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## Highbeam (Sep 18, 2022)

peakbagger said:


> I set the temp and auto fan. Mine runs the fan at high for awhile while getting up to temp but eventually its starts to slow way down and cycle as its sees the return air temp dropping. As I mentioned best thing is set it and forget it. I will be doing that overnight and turning it off in AM as my house has good sun exposure to the east and south so it warms up quick. I turn it back on in the evening nearing sunset.


Okay so maybe I’ll do the same until “real” winter. This can also be scheduled on the newer Chinese minisplits. 

The other variable is the thermostat setting. Since I’m heating the whole home with this I will need a little higher temperature at the air handler when it’s really cold out to keep distant rooms warm enough. Not unlike our woodstove rooms are hotter when outside is colder.


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## EbS-P (Sep 18, 2022)

Highbeam said:


> I don’t know, I assume so. These Chinese mini splits are all made the same and the directions were clear and my experience backs up that you need to be line of sight for the mini to communicate with the remote. Kinda lame in my situation but I’ll make the best of it.


One would think that for some smarty pants it would not be that hard to reverse engineer the the remote/thermostat.   Why they are not selling a product that is easily integrates into smart home Ecosystem is beyond me.  Or at least has a wired thermostat option.  

I get the line of sight but for bigger rooms and units I really would not want the air being able to blow on the remote could a well placed mirror be a solution?


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## Nealm66 (Sep 18, 2022)

I have the daikin. The installer said it only has the thermostat inside the wall unit. I believe if you set it on auto, it seems to struggle this time of year deciding wether to be in ac or heat mode.


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## stoveliker (Sep 18, 2022)

Highbeam said:


> Okay so maybe I’ll do the same until “real” winter. This can also be scheduled on the newer Chinese minisplits.
> 
> The other variable is the thermostat setting. Since I’m heating the whole home with this I will need a little higher temperature at the air handler when it’s really cold out to keep distant rooms warm enough. Not unlike our woodstove rooms are hotter when outside is colder.



I do think that it is best to look at a minisplit as a space heater - just like a stove. 
While it may be possible to heat more than the space it is in, it requires a careful thinking of how the heat flows.


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## Highbeam (Sep 18, 2022)

Nealm66 said:


> I have the daikin. The installer said it only has the thermostat inside the wall unit. I believe if you set it on auto, it seems to struggle this time of year deciding wether to be in ac or heat mode.



There’s auto control of heating and cooling but also auto is an option for the indoor blower speed. When auto fan setting is chosen, the fan barely blows much air if the thermostat thinks it’s close to setpoint but ramps up if there’s a big difference. 



stoveliker said:


> I do think that it is best to look at a minisplit as a space heater - just like a stove.
> While it may be possible to heat more than the space it is in, it requires a careful thinking of how the heat flows.



Like with a stove, this is a space heater and the space I’m heating is my whole home. The expectation needs to be that there will be some variation in temperature from room to room but I refuse to believe that the heat won’t travel to some extent. It’s a feature actually, we prefer cooler bedrooms.


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## stoveliker (Sep 18, 2022)

I agree. All I'm saying is that minisplit are often meant to have a few heads at different places in a home. (At a small efficiency cost vs 1 compressor and 1 head). 

Doing it differently is possible, but with heating and having the head mounted high up, one has to think a bit. Just like with a stove indeed.


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