Split Air Conditioner install

[TouringDan]

Originally Posted by TouringDan

I have removed a couple of mini-splits from a residence, but I have never installed one. I am going to install one of the removed units (Senville) in our home where we expanded the kitchen. It is about 5 years old and is 9,000 btu/hr and 120v. The compressor looks like it came from the same factory as the C&H compressor. I have an installation guide for both units and they are the same except for the title page showing the model numbers.

Glad to hear your installation went well. They really are unbelievably quiet. After I install the Senville unit in our home I will install the C&H unit in our 34’.

Dan

We doubled the size of our kitchen about 15 years ago and installed a lot of windows. I knew that the HVAC would not be adequate but it has been tolerable and I really didn’t have a great idea how to increase the HVAC capacity to the enlarged kitchen. A good solution just fell into my lap when I removed a couple of mini splits from a home that really needed a normal ducted heating system installed. I figured by installing this mini split in the enlarged kitchen this would provide the additional capacity to keep us cool enough in the summer and warm enough in the winter.

I finally finished installing the 9,000 btu/hr mini split in our home. Here are a couple of photos of the installed unit.

I was looking forward to getting the unit installed because I wanted to take some important test measurements. I was a home inspector so I have tested a lot of regular heat pumps. I am also somewhat familiar with RV air conditioners and heat pumps. I knew mini splits were different mainly because they were very quiet but I now realize they are incredibly different and that is a good thing.

Mini splits are much better than RV heat pumps and regular residential heat pumps in the following ways.

- Low startup power requirements
- Much higher efficiency ratings
- Much quieter.
- provides full heating capacity at low temperatures.

I used a watt meter to test the energy consumption when I started the 9k mini split today. It started out at about 200 watts then ramped up to a maximum of 513 watts.

After a while the energy consumption settled down to about 450 watts. If this minisplit were installed in an RV it could be operated with a 1,000 watt inverter or a 1,000 watt generator.

I took some noise level measurements with a phone app. The outdoor compressor noise level was 57.9 dB.
The indoor air handler noise level was 41.5 dB. I have to get close to it to even hear it.

Mighty impressive performance. I couldn’t be more pleased.

Dan

[TouringDan]

I have often wondered why mini split heat pumps were so quiet compared to window air conditioners and RV air conditioners. I didn’t wonder enough to actually try to figure out the answer, but I think I stumbled across the reason. Regular air conditioners typically have a drop in temperature as the air flows through them of about 20 degrees. This means that if you are maintaining a temperature of 75 degrees, the temperature of the air exiting the unit is about 55 degrees. After I started up the mini split it was maintaining an air temperature of 70 degrees. I went to measure the air temperature exiting the unit and it just kept dropping, way past the expected temperature of 50 degrees. It went all the way down to -12.1 degrees the lower limit of my infrared thermometer.
This is more than 80 degrees below the 70 degree air temperature it was maintaining or 4 times the normal 20 degree temperature drop in an RV air conditioner! This means the air flow required in a mini split only needs to be 1/4 the air flow in an RV air conditioner to transfer the same amount of heat. This is the reason mini splits are so quiet imho.

I have checked on the energy consumption periodically. It usually is about 450 watts. One time when I checked on it the energy consumption was 616 watts. This is the highest number I have seen. Next I will be installing a 12k minisplit in our 95 34’. Assuming the same efficiency as the 9k unit installed in our home, the energy consumption should be 33% higher. This would mean a normal consumption of 600 watts and a maximum consumption of 821 watts. This means that a 12k minisplit can be powered by a 1,000 watt inverter or a 1,000 watt generator.

Dan

[OTRA15]

A Delta T of >80F is not right, by a long shot IMO. Put that thing in your freezer, maybe, and see what it says.

Where did you stick the probe, deep inside a coil area, or were you measuring the discharge air? If your thermometer has a long metal tip, which was actually touching the metal coil deep inside, maybe the Freon [etc.] inside of the coil does get down to minus 12?

Peter

https://duckduckgo.com/?t=ffnt&q=min...mp+drop&ia=web

[OTRA15]

Originally Posted by truckasaurus

It's not mine but this is very close to what I'm planning on the A frame.

What kind of Delta T are you expecting from your planned unit?

Thanks,

Peter

[TouringDan]

Originally Posted by OTRA15

A Delta T of >80F is not right, by a long shot IMO. Put that thing in your freezer, maybe, and see what it says.

Where did you stick the probe, deep inside a coil area, or were you measuring the discharge air? If your thermometer has a long metal tip, which was actually touching the metal coil deep inside, maybe the Freon [etc.] inside of the coil does get down to minus 12?

Peter

https://duckduckgo.com/?t=ffnt&q=min...mp+drop&ia=web

Peter

I stand by my test measurements showing a delta T of 80 degrees, 70-(-12). I measured again last night after reading your post and measured the same air outlet temperature of -12F. As you suggested I then measured my home freezer and got 0F same as the fridge indicated. I measured the air outlet temperature this morning and it was 72F, essentially the same as the air inlet temperature of 71F since the compressor is off as it has not heated up enough yet to turn it on. Here is a photo of that measurement taken with my non contact infrared thermometer.

These mini split heat pumps are completely different animals than the heat pumps and air conditioners we are used to. They are a huge improvement. I am very thankful.

Dan

[OTRA15]

Originally Posted by TouringDan

. . .
. . . Here is a photo of that measurement taken with my non contact infrared thermometer.
. . .

Bingo -- there is the source of our apparent difference IMO. Your IR thermometer is looking inside, and is probably reading the surface of the metal coil with the coolant inside. That could easily be as low as you say.

Turn on your unit, wait a few minutes, confirm your existing negative reading, and then rotate your hand to the left or right, and aim the thermometer at the plastic vanes on the discharge openings. Closer to a Delta T of 20-30F IMO.

I have quite a bit of experience with these residential mini split systems, as we discussed earlier in this thread, or maybe in your thread, or both? [edit -- see quote below] I had a big go-around with my landlord this winter, about the cottage not heating well, and did quite a bit of reading. The Google search results in my recent post confirm what I found about a normal Delta T.

What brand and model is your IR thermometer? Guessing the instructions have some guidance about its narrow field of vision IMO. Does it project a visible beam of light onto the exact measuring spot?

Cheers,

Peter

PS -- Here is my quote in your thread -- click on orange arrow to go there:

Originally Posted by OTRA15

Great thread, thanks!

I have lived in small cottages with mini-split systems, and they are great, especially if you use the manual settings to customize the vane orientations, and fan speeds, according to the season and need for heat or A/C. A very small [independent] fan, on the other side of the room, can really help keep the room air moving in a large circle, to avoid too much cycling from the unit kicking on and off. This also makes the room temp more uniform L/R and Hi/Low.
. . .

PS2 -- A discharge air temp of -12F would freeze your skin fairly quickly IMO, so maybe stick your index finger in there and see what happens?



[That was a joke . . . ]

[TouringDan]

You are absolutely correct Peter. My apologies. The infrared thermometer is not reading the air temperature but the surface temperature behind the air. I measured the air temperature with the thermometer I used for home inspections (I needed to change the battery) and the air temperature was 42.4F, so a delta T of 30F. This makes a lot more sense. I am still puzzled though how it can be so quiet, not that I’m complaining though.

Thanks for setting me straight.

Dan

[OTRA15]

Thanks for the update. I think that these mini split systems rely on having the unit very high on a wall, and discharging the air semi-horizontally, in order to create a room-sized "sphere" of rotating air.

In that other thread we had a brief discussion about using additional fans to improve this convective process. In one winter rental a few years ago, I got a really quiet and small 120-volt fan which sat on the floor, right under the mini split, and aimed it straight up. This "jump started" the wall unit's rotating sphere of air in the room [warm in the case of the winter rental]. It was, if you will, in harmony with the mini split's return air intake, typically in the bottom of the unit.

Most traditional residential air conditioning systems aim for the same general approach, but their discharge supply registers are not nearly as efficient at directing the air as is a mini split. The horizontal length of the discharge window [~30-36" ?] also makes this an efficient "air mover" IMO.

They are great units!

Peter

[TouringDan]

I have had the minisplit running for 5 days now. I installed it to supplement our heat pump and help with the heating and cooling of our enlarged kitchen. I decided to turn the main heat pump off and just use the minisplit to see how it would do by itself. The weather has not been too hot and so far it has done fine. After all, we are empty nesters and only use less than half of the house- namely the kitchen, living room, master bathroom and master bedroom. Yesterday it got to 93F and the minisplit couldn’t quite keep up. It maintained 72F until about 3:00 pm when the room temperature started going up. I looked at the energy consumption and it was much higher than I have seen before- 812 watts. The room temperature got to 75F, really not too bad. I decided not to turn on the main heat pump and just see what happened. After it
started cooling down outside the minisplit started catching up and by this morning it was 72F again. We may just run the minisplit as it is 50% more efficient than the main heat pump.
I have been monitoring operation of the minisplit. The compressor doesn’t turn off when it hits a set point and then turn back on when it gets a degree or two hotter, like a regular heat pump. The minisplit tends to operate at the capacity that is needed to maintain a uniform temperature. For example it has mostly been operating at 450 watts. The compressor never really turns off until the middle of the night or very early morning when no cooling is needed.

Dan

[OTRA15]

Thanks for the update, Dan. Do you also have a supplemental small fan or two running on low, to keep the room air circulating well? That can help IMO.

[TouringDan]

Originally Posted by OTRA15

Thanks for the update, Dan. Do you also have a supplemental small fan or two running on low, to keep the room air circulating well? That can help IMO.

Peter- We have not found a need for supplemental fans. The kitchen stays at 72F with the other 3 rooms at 74 or 75, cool enough for us plus when we are in those rooms we typically aren’t doing anything. Most of the activity is when we are in the kitchen.

Now when I install the minisplit in our 95 34’, we will have 3 Maxxair fans. We will probably use those to keep the air circulating and to help maintain a uniform temperature. We shall see.

Dan

[truckasaurus]

I finally placed the order. LG LS120HX2, as far as I can tell it's the smallest external unit available for an 115V system.

Next up I tried welding with a 115V DC inverter welder and made a frame for it to sit on, the cardboard template is the external dimensions of the unit. I wired in a kill switch and will add rubber isolation mounts in a bit.

I hope to separate the 2 insulated fluid lines and run each one into the trailer using stainless marine passthroughs to keep it watertight. I plan to run all the lines behind cabinetry but where they can be accessed or replaced as need be.

[TouringDan]

Originally Posted by truckasaurus

I finally placed the order. LG LS120HX2, as far as I can tell it's the smallest external unit available for an 115V system.



Next up I tried welding with a 115V DC inverter welder and made a frame for it to sit on, the cardboard template is the external dimensions of the unit. I wired in a kill switch and will add rubber isolation mounts in a bit.



I hope to separate the 2 insulated fluid lines and run each one into the trailer using stainless marine passthroughs to keep it watertight. I plan to run all the lines behind cabinetry but where they can be accessed or replaced as need be.

truckasaurus

You have built a beautiful frame for your outdoor unit. It really looks like a stock factory built frame the way it matches your trailer A frame.

Glad to see that you are installing some rubber mounts for the compressor. I am planning on doing the same.

I have gotten side tracked from my mini split install by some house projects and installing a new furnace in our 66 Tradewind before we head to the UP in Michigan and the Colorado rockies.

Dan

[Hittenstiehl]

I am cheering for this to function and work out well. I so do not want to put a top mounted unit on our two vintages trailers. Although we know there are slim units and they can be painted to look the same there's something about the slick roof with the vents that makes it look more time correct.

[Bubba L]

Originally Posted by truckasaurus

I finally placed the order. LG LS120HX2, as far as I can tell it's the smallest external unit available for an 115V system.

Next up I tried welding with a 115V DC inverter welder and made a frame for it to sit on, the cardboard template is the external dimensions of the unit. I wired in a kill switch and will add rubber isolation mounts in a bit.

I hope to separate the 2 insulated fluid lines and run each one into the trailer using stainless marine passthroughs to keep it watertight. I plan to run all the lines behind cabinetry but where they can be accessed or replaced as need be.

We have the Dometic trucker’s unit with ducted air. We are not satisfied with the performance and Db level. Here are my thoughts; I am kicking around the idea of a mini split with heat pump. I could place the condenser in the curbside storage area on the outside. I would lay the unit down for storage and travel, which would not hurt the unit. When camping, I would pull the unit out and set it in the rear outside of the trailer. It would have 12 feet of flexible line sets (rubber made for air conditioners). The air handler would be placed in a modified head locker inside. The head locker would be insulated and function as a plenum. I would duct out of one end of the insulated head locker to ducting. The existing duct has two registers to evenly distribute air. Don’t know of this will work, but need to talk to an engineer to see if this feasible or need to modify my thoughts. This stuff comes to me while I’m weeding the garden. Just thinking outside the box. Thoughts?

[truckasaurus]

Originally Posted by Hittenstiehl

I am cheering for this to function and work out well. I so do not want to put a top mounted unit on our two vintages trailers. Although we know there are slim units and they can be painted to look the same there's something about the slick roof with the vents that makes it look more time correct.

I can't recall if I gave you credit for the thermal break tape but it's awesome (I think I even ordered it from the same source) :-)

[truckasaurus]

Originally Posted by Bubba L

We have the Dometic trucker’s unit with ducted air. We are not satisfied with the performance and Db level. Here are my thoughts; I am kicking around the idea of a mini split with heat pump. I could place the condenser in the curbside storage area on the outside. I would lay the unit down for storage and travel, which would not hurt the unit. When camping, I would pull the unit out and set it in the rear outside of the trailer. It would have 12 feet of flexible line sets (rubber made for air conditioners). The air handler would be placed in a modified head locker inside. The head locker would be insulated and function as a plenum. I would duct out of one end of the insulated head locker to ducting. The existing duct has two registers to evenly distribute air. Don’t know of this will work, but need to talk to an engineer to see if this feasible or need to modify my thoughts. This stuff comes to me while I’m weeding the garden. Just thinking outside the box. Thoughts?

That sucks that the Dometic unit hasn't worked out well. Your plan is way out of my knowledge base but if it works sounds good. I'd worry that I'd do something like turn it on before getting it out or something equally disastrous so then I'd fit pin switches and then I'd stress about them failing...it's a rabbit hole for me. On my Overlander I had a window unit that I had an avionics friend modify with thermal cut out and back up fans etc but I just didn't feel it was safe enough and just ditched it. If I can run a stock unit, switch it out if I get a failure or want to update it that has quite a bit of value to me. Still I have a long way to go to get this up and running. I did get an RV 30 Amp installed on my garage so that's 1 more off the list to cool air. Also crazy plan for the day is to consider using the original fresh fill upside down as a line set inlet, that or a marine exhaust fitting... It never ends.

[55AS]

Have installed mini splits on 2 AS so far. Very pleased with results.

[truckasaurus]

That’s a great install! Do you have any learning points? Especially interested in the clamshell fitting and if you used anything in it to bug/ waterproof around the lineset. I like the pole too, simple.

[TouringDan]

Originally Posted by Bubba L

We have the Dometic trucker’s unit with ducted air. We are not satisfied with the performance and Db level. Here are my thoughts; I am kicking around the idea of a mini split with heat pump. I could place the condenser in the curbside storage area on the outside. I would lay the unit down for storage and travel, which would not hurt the unit. When camping, I would pull the unit out and set it in the rear outside of the trailer. It would have 12 feet of flexible line sets (rubber made for air conditioners). The air handler would be placed in a modified head locker inside. The head locker would be insulated and function as a plenum. I would duct out of one end of the insulated head locker to ducting. The existing duct has two registers to evenly distribute air. Don’t know of this will work, but need to talk to an engineer to see if this feasible or need to modify my thoughts. This stuff comes to me while I’m weeding the garden. Just thinking outside the box. Thoughts?

Bubba

Sorry you are having trouble with your Dometic trucker’s unit. It doesn’t make much sense to me that they won’t sell you a compressor for it.

I like that you are thinking outside the box. There wouldn’t be any design improvements without thinking outside the box. However I don’t believe rubber refrigerant lines will work. The pressures are just too high, especially in the heating mode. Now having said that I don’t know what the design pressures are.

From watching Utube videos the critical part of minisplit installation is getting a good seal when making the flairs when shortening the refrigerant lines. That is why you see a lot of the DIY videos with the extra refrigerant line all rolled up. The key is to get a good flair just like the factory flair. To get a good flair they recommend an eccentric flairing tool.

I would install the compressor on the tongue and route the refrigerant lines under the belly pan just like the propane lines are run.

As far as mounting the air handler I have wondered myself if it has to be mounted horizontally. Is mounting it vertically an option?

My understanding is that Midea makes many of the mini splits- Pioneer, Senville and Cooper & Hunter. I would contact their technical department and find out what the refrigerant line design pressure is and if the air handler can be mounted vertically.

Dan