Should I get the EG4 mini-split?

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.

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.

SolarScott said:

Why would you want the AC only version?

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And if you do want just AC, I think there are other DIY line options now to consider besides Mr. Cool and EG4??

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?

SolarScott said:

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.

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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.

Plum Crazy Rob said:

And if you do want just AC, I think there are other DIY line options now to consider besides Mr. Cool and EG4??

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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.

SupraSPL said:

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?

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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.

Erik17 said:

Are there any models you recommend looking at?

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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.

Erik17 said:

I am going to install the mini split in a 200 sq.ft. upstairs bedroom that is going to be used as a nursery.

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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

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)

SupraSPL said:

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

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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.

Airspool is another Deye rebrand, same as EG4..

Guy has upped his game of late with videos, Santan selling his product, and a DIY lineset adapter, but I wasn't excited when I googled and get HQ as a closed down bar in Vegas. I guess everyone has to start somewhere

Here is Energy Star for both, note model no.

Airspool and EG4 Energy Star

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.

Erik17 said:

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.

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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.