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Told by Tesla I can't run AC on Powerwalls

JayClark

Member
Aug 6, 2019
224
181
Arizona
Has anyone had an issue with PowerWalls and mini-splits?

I have a Mr. Cool 18,000btu mini-split on my garage/shop, the the PWs have no trouble running it, and the 4.5 and 3 ton main AC units simultaneously here in the worst of az heat, but I have 4PWs. The mini-split I have only runs at about 2400-2700 watts during normal cooling operations, and seems to have a slow ramp-up feature - so I've never really seen it spike above 2800 watts or so. Not sure if that's true of all mini-splits. But 2800watts will be fine for even one Powerwall if the rest of your peak load isn't much above 3000 watts continuous, or 4000 watts peak.

You have measure your normal house baseline load, and add test/measure the other large loads that are specific to your house... something that's a bit unique to each home that you pretty much have to measure for yourself before purchasing. I spent $99 on a whole home mains load measuring device that works with my Smarthings hub, that gives me live readings so I could turn on various devices, ultimately turning on all my main "large" load devices at the same time to insure I knew my peak loads before investing in solar and PWs.
 
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JayClark

Member
Aug 6, 2019
224
181
Arizona
@JayClark what’s the device that you use for monitoring?

Sorry for the delayed response, been a while since I've check-in on the forums. I use the Aeotec Home Energy monitor. It's a z-wave device so will work with any z-wave compatible hub. I happen to use Smartthings, but am very slowly switching over to Hubitat, so it should work with Hubitat too. This is a screen shot of the Data on my phone in the Smartthings app. I also use a Smartthings to Google Sheet connectors, that records Total power, and cummulative power (kWhs - since the last reset/timestamp) to the Google sheet every 5 minutes. That's ultimately how I mapped my usage in detail, finding my peak days, and even my max 5 minute usage during the hotest and busiest day in the house during summer, and winter, for sizing my system.


IMG_E286E7060147-1 2.jpeg
 
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MIT_S60

Active Member
Nov 23, 2016
1,048
892
Orange County, CA

Davestic

New Member
Jul 13, 2020
1
0
Lafayette, CA
When I was in talks with Tesla about backing up our new Lennox system with only 20 LRA per unit they implied there was even more to it than LRA. Still not sure what - maybe power factor? In any case I sent them the spec sheet and it worked out, but it would be nice if they published all the criteria.

Hello - I am about to go solar and upgrade my HVAC to the units you have. 3800SF home with one XC20 36 per floor (LRA 13 3 Ton). I want to get the power-wall for backup when PGE does its brown outs. Would love your experience on how long you topped off batteries run your ac units and home. Thanks in advance for your help/advice!
 
Dec 2, 2017
358
339
Arizona
Hello - I am about to go solar and upgrade my HVAC to the units you have. 3800SF home with one XC20 36 per floor (LRA 13 3 Ton). I want to get the power-wall for backup when PGE does its brown outs. Would love your experience on how long you topped off batteries run your ac units and home. Thanks in advance for your help/advice!
Sorry for the late reply - I haven’t logged on for a while. Here in the Phoenix area during summer, with 2 Powerwalls I can usually run the house through our entire peak period of 2-8pm without using any grid. It does eat through most of the battery though by end of peak.
 

holeydonut

Supporting Member
Jun 27, 2020
1,512
884
East Bay NorCal
I recently had a 4-ton Lennox XC16 installed, and am planning to install two Powerwalls (no solar, used for TOU shifting). It looks like the AC has a Copeland scroll 2-stage compressor. Does the Emerson Copeland SecureStart sound correct for allowing the AC to be backed up by the Powerwalls?
SecureStart™ for Copeland Compressors | Emerson US

https://climate.emerson.com/documents/securestart-overview-presentation-en-us-4475400.pdf

I had a Lennox tech come out to install the Emerson soft starts on my Signature SL18XC1 (single stage) and XC21 (dual stage). These units were installed in early 2020.

When the tech called HQ to confirm compatibility, he was told by HQ that the SecureStart would void my warranties. The tech was also told Lennox has no record on file of their new model compressors requiring the soft starts.
 

wjgjr

Active Member
May 11, 2020
1,217
952
Silver Spring, MD
I had a Lennox tech come out to install the Emerson soft starts on my Signature SL18XC1 (single stage) and XC21 (dual stage). These units were installed in early 2020.

When the tech called HQ to confirm compatibility, he was told by HQ that the SecureStart would void my warranties. The tech was also told Lennox has no record on file of their new model compressors requiring the soft starts.

I have an SL18XC1 and have the securestart installed. Can't speak to the specifics of the warranty issue, but I will note that just because Lennox says it voids the warranty doesn't necessarily mean it does. It could depend on the specifics of what failed and if it can be attributed to the modification.

I will note that those units are designed to work with Lennox's solar product, so I suspect they are designed to work with soft start devices in general. I even asked the Tesla guy if there was something they could hook up to as it looks like they document a second power source option at 16 Amps. But he did not see anything he could use.
 

holeydonut

Supporting Member
Jun 27, 2020
1,512
884
East Bay NorCal
I have an SL18XC1 and have the securestart installed. Can't speak to the specifics of the warranty issue, but I will note that just because Lennox says it voids the warranty doesn't necessarily mean it does. It could depend on the specifics of what failed and if it can be attributed to the modification.

I will note that those units are designed to work with Lennox's solar product, so I suspect they are designed to work with soft start devices in general. I even asked the Tesla guy if there was something they could hook up to as it looks like they document a second power source option at 16 Amps. But he did not see anything he could use.


How did you get the Lennox tech to do the install? Since Lennox Industries wouldn’t authorize the part, the tech couldn’t do the work.

I was informed by Lennox that having an unauthorized tech work on Lennox gear also voids the warranty.

I think Lennox sucks btw, should have went with anyone else but them.
 

wjgjr

Active Member
May 11, 2020
1,217
952
Silver Spring, MD
How did you get the Lennox tech to do the install? Since Lennox Industries wouldn’t authorize the part, the tech couldn’t do the work.

I was informed by Lennox that having an unauthorized tech work on Lennox gear also voids the warranty.

I think Lennox sucks btw, should have went with anyone else but them.

Tesla did the work. And it is not on the gear, I would argue, but added to the power feed to control the current. I have had an HVAC tech out since then and had no comment on the sure start device.

And I tend to agree that I've not been overly happy with Lennox. Their "smart" thermostat hasn't much impressed me and is even more of a closed environment than Tesla.
 

holeydonut

Supporting Member
Jun 27, 2020
1,512
884
East Bay NorCal
Tesla did the work. And it is not on the gear, I would argue, but added to the power feed to control the current. I have had an HVAC tech out since then and had no comment on the sure start device.

And I tend to agree that I've not been overly happy with Lennox. Their "smart" thermostat hasn't much impressed me and is even more of a closed environment than Tesla.

Yeah I think ultimately the soft start does nothing but positive things for your equipment (less stress on the condenser inrush). I just hope you never need to use that Lennox warranty.

BTW, since you have the Signature series SL18XC1 you probably have a SIgnature SL series furnace or air handler. Did they hook you up with the E30 touchscreen thermostat or the S30 touchscreen thermostat?

The E30 is basically a glorified Nest or Ecobee with a wifi hub that sits near the blower. You're literally better off with Nest if they put a E30 on your wall.

The S30 is the good one that actually communicates properly between the Condenser, Blower, and Thermostat to optimize fan controls and gives better humidity management. It also enables advanced diagnostics and better info about your equipment. Assuming you also have a Signature blower on the air handler, you'll want the S30 for sure.

You can tell which one you have by opening the plastic flap of the wifi hub. It'll say on a sticker whether you have a communicating S30 or a "non communicating" E30.

You should also confirm if your evaporator coil is sized properly to your tonnage. My installers put a 0.5 ton smaller evaporator. and its costing me about 12% efficiency as measured by the SEER rating and AHRI data. Lennox as a corporate policy that waterfalls down to their licensed contractors have a habit of nickel and diming people on stuff so they can afford their overpriced equipment.
 

wjgjr

Active Member
May 11, 2020
1,217
952
Silver Spring, MD
Yeah I think ultimately the soft start does nothing but positive things for your equipment (less stress on the condenser inrush). I just hope you never need to use that Lennox warranty.

BTW, since you have the Signature series SL18XC1 you probably have a SIgnature SL series furnace or air handler. Did they hook you up with the E30 touchscreen thermostat or the S30 touchscreen thermostat?

The E30 is basically a glorified Nest or Ecobee with a wifi hub that sits near the blower. You're literally better off with Nest if they put a E30 on your wall.

The S30 is the good one that actually communicates properly between the Condenser, Blower, and Thermostat to optimize fan controls and gives better humidity management. It also enables advanced diagnostics and better info about your equipment. Assuming you also have a Signature blower on the air handler, you'll want the S30 for sure.

You can tell which one you have by opening the plastic flap of the wifi hub. It'll say on a sticker whether you have a communicating S30 or a "non communicating" E30.

You should also confirm if your evaporator coil is sized properly to your tonnage. My installers put a 0.5 ton smaller evaporator. and its costing me about 12% efficiency as measured by the SEER rating and AHRI data. Lennox as a corporate policy that waterfalls down to their licensed contractors have a habit of nickel and diming people on stuff so they can afford their overpriced equipment.
We have the S30. The issue for me has been that it is even more of a closed system than Tesla. I had hoped they might add an API, but they have not (I believe they eventually added support for Alexa, but not SmartThings.) Additionally, I've found their away feature, which is supposed to be based on geofencing, to be unreliable. It has improved some since we installed it 3+ years ago, but it still does not reliably detect our phones and occasionally fails such that we just have to re-register them. By comparison, SmartThings has been extremely reliable for us with the geofencing.
 

boaterva

Supporting Member
Apr 2, 2016
7,565
3,737
Northern Virginia, USA
Tesla installed the soft start on my Lennox and the local HVAC people (Lennox dealer who installed the system) doesn’t care about it. Hate the thermostat myself since you can’t swap it for a Nest without a ton of rewiring (non-standard cabling).
 

TSLA Pilot

Active Member
Mar 12, 2013
1,733
2,382
United States
Tesla installed the soft start on my Lennox and the local HVAC people (Lennox dealer who installed the system) doesn’t care about it. Hate the thermostat myself since you can’t swap it for a Nest without a ton of rewiring (non-standard cabling).

Just FYI, but it appears that Nests do NOT work with high-end HVAC systems.

See:

Incompatible system wiring
Too many stages of cooling or heating
Nest Learning Thermostats are only compatible with systems that have one or two stages of cooling.

Source:

How to tell if your system is Nest thermostat compatible - Google Nest Help

Thus, a high-end AC, with a variable speed air handler and/or compressor will likely NOT work with the Google Nest.
 
  • Informative
Reactions: boaterva

SMAlset

Well-Known Member
Mar 4, 2017
9,066
9,784
SF Bay Area
Tesla supplied the soft-start for our unit. We wanted it backed up and provided them with the info on it early on and made sure that they had the sure-start to bring out after being assured it would work on it. We have 3 PWs. Our old 2004 Carrier 5-ton 38CKC060-37 (60 hz) split system for our upper and lower floors is a 10 SEER unit. They've come a long way since then. Unit has been running fine however so haven't wanted to get it replaced yet. Will probably be our next big ticket appliance. At least now with our solar/PWs we know to be careful what we buy. Our Carrier unit has a Scroll compressor, LRA of 165.00, RLA of 28.9, fan FLA 1.4.

Unit has been working fine since the soft-start was installed and we did notice a big drop in the initial start up readings when we compared the before and after on the app. It actually use to make a kind of loud sound vibration on start up and now with the soft-start on it's a more gentle start up sound.
 

jedmo

Member
Sep 9, 2020
115
49
Northern California
Tesla supplied the soft-start for our unit. We wanted it backed up and provided them with the info on it early on and made sure that they had the sure-start to bring out after being assured it would work on it. We have 3 PWs. Our old 2004 Carrier 5-ton 38CKC060-37 (60 hz) split system for our upper and lower floors is a 10 SEER unit. They've come a long way since then. Unit has been running fine however so haven't wanted to get it replaced yet. Will probably be our next big ticket appliance. At least now with our solar/PWs we know to be careful what we buy. Our Carrier unit has a Scroll compressor, LRA of 165.00, RLA of 28.9, fan FLA 1.4.

Unit has been working fine since the soft-start was installed and we did notice a big drop in the initial start up readings when we compared the before and after on the app. It actually use to make a kind of loud sound vibration on start up and now with the soft-start on it's a more gentle start up sound.

Thank you for the info.
 

jboy210

Supporting Member
Dec 2, 2016
5,097
3,168
Northern California
Does Tesla supply the soft start device? or do I need to purchase it prior to them installing my solar and powerwalls and ask for it to be installed?
Tesla supplied ours, but the installed gave us a warning that they do not work with all AC units. Ours was within the unit's capacity, but just barely. We have tried it once, and it did start. However, the drain on the PWs was large. Made me wish I bought 3 Powerwalls instead of 2.
 

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