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Should I get the EG4 mini-split?

Erik17

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Dec 12, 2020
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Does the EG4 mini-split make sense for me or is there anything else I should consider? I am looking at the 9000 BTU, SEER 29.5, AC only, plug-N-cool version from signature solar for $1249. Is there anything else I should consider?

I have a 2400 sq. ft. 2-story house with a 24-year old 4-ton AC that is only SEER 10. I am going to install the mini split in a 200 sq.ft. upstairs bedroom that is going to be used as a nursery. I have 3 goals for the mini split:
  • Better temperature control for the nursery
  • Reduced load on the center AC and therefore saving energy and money
  • Second source of cooling if the center AC dies during the summer when it can be as hot as 108F

I have a cement pad to install the outside unit on, however it's approximately 17’ below where the indoor unit is. Will the 16.4’ lines make it or do I need to wall mount. I can't find the inside until line length in the manual.

Here is some more info:
  • Live in Southern California
  • $0.24/kWh electricity
  • Small 2.7 KW grid tie system and I use more than I make
  • Very stable grid connection
  • Central AC on average runs for 489 hr per year.
  • Plan self install
  • Prefer system with pre charged lines as I don't own a vacuum pump or other HVAC tools
 
I self-installed the EG4 12,000 BTU (1 ton) unit with1.4kW of PV in my master bedroom (MBR). My distance was relatively short, and I had to coil the excess next to the outdoor unit. Sounds like you're going to need to go the wall-mount approach, to get close enough to the indoor unit. Be certain to allow for extra piping, you *don't* want them to be under stress. Also, make the wall exit hole extra big. Trust me.

I'm about 3/4 mile from the water in Huntington Beach, and haven't needed AC in the 20+ years we've owned the place. That's changed in the last five years. The house is ~1500sf, one story. One mod I made to the house was to run a 6" insulated duct in the attic, with a decent duct fan, from the far end of the MBR to the far end of the house, in our great room. It's automated. This sets up air circulation, so the heat pump can affect the rest of the house, too. Right now, it's running all day (on PV!), and heats the entire house at about 72F. Our natgas furnace gets the house up to 72F in the morning, and the mini-split can keep it there the rest of the day. Our natgas bill has dropped to half of what it was last year. I can't wait for this summer, when we can keep the house at 70-ish on the few days it gets to 90F. I super-insulated the house during a remodel, and it "only" got to 80F inside, when we had two (rare) days of over 100F temps in 2022, without AC. We typically turn off the natgas furnace from about March to November.

We run the mini-split at night, to keep our MBR at about 63F. The unit's flip from cooling at 63F to heating at 74F is seamless, and takes about 15 minutes. Interesting that on the remote, if you hit the display light button, it not only turns off the display, it shuts down the entire unit. Oops! The app works great, though. IMO, the EG4 mini-split is awesome.

You might be wondering why we don't just do a whole-house fan, and pull cool night air through the house at night. We did that for many years, but pulling all that moist air through the MBR created a mildew problem. Talking to our neighbors, it's a common issue around here. Using a mini-split solves that problem.

I'm putting up another 6.4k of PV (on top of 5kW existing) and 14kWh of battery (on top of 27kWh existing) in the next month or so. This should make up for the night-time consumption increase. I plan to take half my house off-grid with this new system.

BTW, I did the EG4 mini-split with 1.4kW of PV entirely on my own. I'm 68.
 
One thing jumped out at me in the specs, even though 29.5 SEER2 sounds good, the actual EER is only 13.2 (385% efficient at 95F) which is great but still less than cheap Midea window units (15 EER). Other mini splits are rated at 33 SEER2 are 18.2 EER or 530% so the EG4 SEER2 threw me off maybe it's a typo and actually a SEER1 figure?
 
Why would you want the AC only version? If you get the straight from solar you can use grid AC or your grid tied system or slap some used panels up for assisting on the cheap.
I originally wanted to get the hybrid version but it's not as efficient. The AC only version is SEER 29.5 and the hybrid version is SEER 22. At 25% lower efficiency I would need to run it with 25% solar power to break even. I also don't have a great place for putting the panels, but could likely make some work.
If I had power outages or nice place to put panel I would probably go with the hybrid version. It's a really cool product.
 
And if you do want just AC, I think there are other DIY line options now to consider besides Mr. Cool and EG4??
Are there any models you recommend looking at?
I saw Klimaire and Aire for around the same price but they are less Effect at SEER 19 and 19.5 respectfully. The Klimaire did have 25' lines so that's a plus for me.
 
One thing jumped out at me in the specs, even though 29.5 SEER2 sounds good, the actual EER is only 13.2 (385% efficient at 95F) which is great but still less than cheap Midea window units (15 EER). Other mini splits are rated at 33 SEER2 are 18.2 EER or 530% so the EG4 SEER2 threw me off maybe it's a typo and actually a SEER1 figure?
The differences in ratio between SEER2 and EER2 is interesting. If it was just the EG4 datasheet I could see it being a typo, but it's basically the same on energy stars website.
I will have to ponder this more.
 
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Are there any models you recommend looking at?
I hadn't seen anything with high efficiency either - but had not really looked either. Just had noticed other DIY stuff popping up. Sounds like you are on top of it already.

Something else to note, on the EG4 non hybrid is the indoor head is 42" wide...which is pretty enormous. It's the same size as my 24k btu hybrid.

At any rate, I have a pair of the 12k btu hybrids, and they sip so little power even on AC not Solar its amazing. Keep in mind for maintaining a temp in a room it's probably throttling down to 3 to 6k btu.
 
I am going to install the mini split in a 200 sq.ft. upstairs bedroom that is going to be used as a nursery.
You can probably appreciate this then lol. GET A BOOM LIFT don't do this on a ladder, you'll be so much more safe and comfortable. I have a view out basement so it's about 21'. Temporary power at this point while I was completing install 😅

20231129_133610.jpg20231111_085027.jpg
 
Thanks for the input everyone and the install pics.

I asked my friend who does building science for commercial buildings about the large differences in SEER to EER ratio for different mini-splits. He said that in theory seer should be more important since it measures the unit at part load. Where EER is at full load which shouldn't happen too often with a mini split assuming you size it correctly. The EG4 AC power only unit is likely more effective at light loads and might be able to run at lower loads then some other mini-splits.
 
Advertised EER is at "rated" BTUs which are often 10-25% less than max BTUs. If you compare 2 units that are rated at the same BTU, the EER is a direct comparison of efficiency at that load and at 95F outside 80F inside.

At lower loads, all inverter units will benefit in efficiency but looking at these numbers it would take a miracle for the EG4 to catch up enough to earn that SEER2 rating. In reality it likely falls even further behind the other units at lower loads and even more again if we look at the heating numbers.

Not hating on EG4 overall but gotta call this one out, make numbers objective again

EG4 9K rated 29.5 SEER2
@3K BTU 15.8 EER (min BTU)
@9K BTU 12.5 EER
@10K BTU 10 EER (max BTU)

GREE 9K rated 38 SEER1
@1.5K BTU 30.7 EER (min BTU)
@9K BTU 16.5 EER
@13K BTU 9.3 EER (max BTU)

Mitsubishi 9K rated 29.8 SEER2
@1.7K BTU ? EER (min BTU)
@9K BTU 16 EER (rated BTU)
@12K BTU 12 EER (max BTU)

Fujitsu 9K rated 33 SEER2
@3.1K BTU 28 EER (min BTU)
@9K BTU 18 EER (rated BTU)
@12K BTU 14.1 EER (max BTU)
 
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EG4 9K rated 29.5 SEER2
@3K BTU 15.8 EER (min BTU)
I understand as an Engineer, EER is simple enough to calculate, EG4 9k using 190W at 3000 BTU = 3000/190 = 15.8 and so on down the line per published specs. And, I went and verified the EG4 numbers are out of line with similar equipment, as you said, at Energy Star.

I don't understand how the SEER/SEER2 magic happens- and that is AHRI certified (tested) and Energy Star (rated?? Or tested. Don't know). Jump in with info - anyone??

However I will point out, @SmitHVAC found the similar Solar hybrid units operating well OVER the published info in efficiency on heat?? COP 5 vs (13.38 / 3.41 BTU/W) = 3.9 COP published. My point: I QUESTION some of the things Deye / EG4 publish in specs, as they are "new" at this mini split game :)

We previously discovered there was a misunderstanding about the published Isc for the Solar units, and Deye themselves admitted that.


2:16 of video:
 
I have an EG4 12k mini split hybrid, no PV connected at this time. It cools fine. The heat mode is crazy and the thermostat ignores the room temperature some times. Today room was 75 F, which was above Setpoint. I lowered the Setpoint to 62F and the heat stayed ON, still drawing 380W from grid. I looked at my grid power for the last two days and use was way up due to this flaw. You will not save money with a Wacko thermostat.

The problem might be PID Integral Windup, which is a control system problem beyond the scope of this forum.

I would like to see the mini splits have upgradeable firmware. Victron is awesome.

EG4 is NOT energystar, so no 30% rebate.
I found Santan Solar sells a hybrid heat pump branded Airspool. Look at Airspool.

I would like to ship my EG4 back to Signature Solar and replace it with the Airspool if the Airspool thermostat actually works. Shipping would be a hassle.
 
I do find the thermostat overshoots 5 degrees or so in my case. There's been discussion here about this with mini splits that don't have remote thermostats vs measured room Temps and so on. Jim, do you think you're outside this range?? How long have you been operating yours??
 
I have two Daikin mini-splits in two different buildings, and a Mitsubishi in a third. ALL of them overshoot the setpoint temperature, because the temp sensor is in the head u it of the indoor air handler, not terribly far from the ceiling. I can go down to a setpoint of 50F with each of these (using wifi dongle - the IR remote goes down to just about 62). So, we end up with the room at about 54-55 on heat mode. And if I want the room 70? I set it for about 65-66. In cooling mode, the room temp runs about 2 degrees nigher than the setpoint, so to get to about 76, I set it to 74. A temp sensor at the thermostat (or on the remote) would likely solve all of this, but eventually, you get a feel for it. Hope this info helps.
 
Quick update. I ordered the 12k BTU/hr AC/DC model today after showing my wife the size of the of the inside units (9k vs 12k). Signature Solar has free shipping right now, so that was nice.
Now I just need to install it, which might be April so my Dad can help me. And I need to try to convince my wife that we should have some backyard solar panels.
 
Quick update. I ordered the 12k BTU/hr AC/DC model today after showing my wife the size of the of the inside units (9k vs 12k). Signature Solar has free shipping right now, so that was nice.
Now I just need to install it, which might be April so my Dad can help me. And I need to try to convince my wife that we should have some backyard solar panels.
Perfect application for this type of system IMHO. Mostly grid but want to tip toe into solar and offset some energy bills in the process.
 
Not sure how they compare, but I got these cheap from China.
 

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Why would you want the AC only version? If you get the straight from solar you can use grid AC or your grid tied system or slap some used panels up for assisting on the cheap.
They're far more efficient, first of all. Around 30% more

second, if you are already doing solar, imo it's better to just expand the overall system than to have dedicated panels that only run that and nothing else
 
Am I too late? Don't buy EG4 anything. Period. You can get a Pioneer for wayyy cheaper.
 
Am I too late? Don't buy EG4 anything. Period. You can get a Pioneer for wayyy cheaper.
highest I see is 21 SEER2 rating which is ~30% less efficient than the EG4 non-hybrid one.
I prefer to have the most efficient stuff (at least the constant running stuff) so I have to expand the overall size of my solar array less

mrcool and eg4 are also pre vacuumed lines, nobody else offers that as far as I can tell
sure hope you bought a vacuum and vacuumed yours before installing lol


They have ~220volt ones though, I wish eg4 did as well for the high efficiency units because that keeps inverter loads balanced better
 
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Last week with the help of my Dad I installed the mini split. Including planing where to place it, it took us about 8 hours but we took our time. The 5m line set was just long enough. I still need to install some more line cover and finalize the drain line. Drilling a 3" hole through the wall was "fun". My internal wall is 7/8" cement board and the outside wall was 2" stucco. There was no insulation in the wall, so I stuffed in some loose cellulose insulation.
 

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Am I too late? Don't buy EG4 anything. Period. You can get a Pioneer for wayyy cheaper.
Too late. For $1,300 before tax credits I will see how long it lasts. The pre-charged lines were easy, hopefully they don't leak. So far I like it. The indoor unit is very quite. I will provide an update if something bad happens.
 
Too late. For $1,300 before tax credits I will see how long it lasts. The pre-charged lines were easy, hopefully they don't leak. So far I like it. The indoor unit is very quite. I will provide an update if something bad happens.
Prob gonna last same length of time, nearly all of them are made by midea. Pioneer isn't anything special.
Also since SEER2 is linear and pioneer has nothing close to the 29.5 it'll pay for itself in a year or a few years (depends how much you use it obviously)
 
I hope to be able to answer this in about two months, when it finally gets hot here in Maine. I went with EG4 for two reasons: 1) Very high SEER2 / HSPF,, and I'm trying to squeeze every watt possible out of my system in cloudy weather. 2) CurrentConnected has just started carrying them, and I wanted to get some experience with them before designing and ordering a system for our new property in about a month to six weeks. Very nice people to deal with.

BTW, I think all of these DIY units are overpriced, and I agree that a Pioneer or similar is a much better idea for most people, who don't have the two needs I note above.
 
Great thread. We are going with a unit soon.
I am stuck wanting the AirSpool unit. It may be more $$, but it comes with the tools, and I will need a longer line set he can make to my needs.
We will connect it to 120V first, then have 4 Solar panels installed as we save up for them.

One thing I was considering - to go off-grid with this AirSpool AC unit:
  • Can I use an EG4 3kW off-grid inverter (Yellow @ $675), with a 48V 100 AH battery and a couple of solar panels to keep the battery up.
  • If I have a 120V AC output/plug off the inverter, the unit will run on the 120V when Solar is low.
    • No grid use at all. To have the 120V plugged in to run cloudy/rainy/dawn and dusk.
    • The Inverter will shut down the 120V when the battery reaches a certain level I set. Then we wait until the next day to charge up the battery, as the AC is running off the Solar.
Does that sound about right? Thanks for the info and insight -
 
Hey Mike. Sounds good on the mini split part, assuming I read correctly your plan that you ARE NOT sharing the panels between inverter and mini split, an oft-asked question as you may be aware! :)

Others can opine on the EG4-3K and battery?? Or if your eventual goal is off grid, do you need the hybrid mini split?? (I agree multiple-redundancy why not??? Guessing UPS to Honduras takes awhile...)
 
Hey Mike. Sounds good on the mini split part, assuming I read correctly your plan that you ARE NOT sharing the panels between inverter and mini split, an oft-asked question as you may be aware! :)

Guessing UPS to Honduras takes awhile...)
Correct on 'not' sharing the panels. Each will have its own array.
The Mini-Split, three 575W/46V Trina panels, the inverter, one or two panels.

With UPS ... Ha! I know, right?!!?
We will ship the mini-split to our Florida freight forwarder. The panels I can source locally for about $170 ea.
 
Or if your eventual goal is off grid, do you need the hybrid mini split?? (I agree multiple-redundancy why not??? Guessing UPS to Honduras takes awhile...)
The issue of wanting to 'Hybrid' as much as possible is due to the utility charging about .41/kW. There are also frequent accidents and planned outages throughout the calendar year.
Living on the Beach, along the Sea, on an island has SOME drawbacks. But the beauty outweighs the negatives by far.
 
I guess I got pretty lucky. I have 2 *Comfortotal* branded el cheapo 18k 240v units in my house. I bought them to replace window units that were in this house when I bought the land as the central air handler was destroyed. I paid 600.00 for each unit and 200 for install on each one. I could have done the installs as I have all needed equipment, but I was working 60 hour weeks and did not want to mess with it.

I am on nearly a month having my solar running 6000ex inverter and 3500w of panels. With both units set to 69*F running 24/7, my draw in the house is between 250w-1800w. My little system runs both these mini's and also a portable 120v AC unit with zero issues. I wouldn't fret over a few points of efficiency so much as the real world differences will be pretty minimal.
 
It's been a fairly cool spring in SoCal, but we got 2 90F days last week. The EG4 mini-split did a good job of keeping our house cool. I don't have solar connected to it and it used around 4 kWh each day. This is much better than my 23 year old 4-ton center AC which draws 6 kW.
With around 50% humidity it produced around 3 gallons of water per day. I modified a bucket to collect the water for watering plants and rinsing off cars since it's mineral free. The bucket has an overflow and spigot to fill containers. For the picture I removed the lid that prevents mosquitoes from getting in.
 

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I took these thermal imaging before turning on the mini split. My house doesn't have wall insulation, but I stuffed loose cellulose insulation into the wall during the install. I was impressed with how well it filled the cavity.
 

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