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Soft Start/ Sure Start AC Problems

I had Tesla Solar and Powerwall installed this past winter (February). As part of the installation, a Soft Start was put in my AC unit. Ever since then, my AC no longer works. Worked fine last fall, has not worked yet this spring/summer. I called out an HVAC company, and they were stumped, all they could figure out is that the compressor was not coming on. The AC unit is three years old. What is the likelihood that this is connected to the soft start, how would folks recommend I proceed. Thanks!
 

holeydonut

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Jun 27, 2020
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East Bay NorCal
I had Tesla Solar and Powerwall installed this past winter (February). As part of the installation, a Soft Start was put in my AC unit. Ever since then, my AC no longer works. Worked fine last fall, has not worked yet this spring/summer. I called out an HVAC company, and they were stumped, all they could figure out is that the compressor was not coming on. The AC unit is three years old. What is the likelihood that this is connected to the soft start, how would folks recommend I proceed. Thanks!

You’ll need a tech to come out and connect the windings of the compressor back to the original connections and bypass the soft start. This will isolate if it’s the soft start that’s the problem or if your normal run capacitor or compressor are the issue.
 
I'm in an ongoing battle with Tesla. My Powerwalls in a whole home backup configuration were installed a year ago. It turns out that SureStart isn't compatible with my compressor (Carrier unit with Bristol reverse-run compressor) and it wouldn't work (on or off grid) with it installed.
Their proposed solutions so far have been to remove the AC from the backup but that isn't acceptable to me since the contract was for whole home backup.
 

holeydonut

Active Member
Supporting Member
Jun 27, 2020
3,088
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East Bay NorCal
I'm in an ongoing battle with Tesla. My Powerwalls in a whole home backup configuration were installed a year ago. It turns out that SureStart isn't compatible with my compressor (Carrier unit with Bristol reverse-run compressor) and it wouldn't work (on or off grid) with it installed.
Their proposed solutions so far have been to remove the AC from the backup but that isn't acceptable to me since the contract was for whole home backup.


Yeah, the problem with these industries (solar and HVAC) is that the pros who do it for a living seem to have a feeling that their specialized knowledge is also common knowledge when the situation suits them.

For example, if you ask an HVAC person about soft starts, they're going to tell you how stupid you are for buying normal single or dual stage scroll compressors. Because if it were their money, they'd get a variable speed inverter driven compressor because those are newer/better. They don't like hard starts and soft starts because these are hacks and kind of violate their school of training and experience. So they'll blame you for being stupid and not having a variable speed compressor if you also wanted to have fancy batteries or generators running your home.

And then if you ask solar people about soft starts, they'll say they're not HVAC experts and how they wouldn't be expected to know how your specific HVAC works. So it's your fault for not selecting the right HVAC for a whole home backup solution and informing them of your unique situation with an odd-style outdoor condensing unit.

In the end you have two industry expert groups both blaming the ignorant homeowner for failing to have the foresight to understand how stuff works. It sucks for the average homeowner... who wouldn't reasonably have this type of knowledge unless they were just born with huge amounts of innate knowledge (wwhitney? heh).

In your case you're kind of SOL unless you agree to either move the AC to a non-backup loads panel. Or you upgrade your antiquated outdoor condensing unit with a system that has a lower LRA.

Overhauling an HVAC to get a variable speed outdoor condenser paired with a variable speed air handler and with a new variable speed capable communicating thermostat is expensive though. But in this case I cannot see Tesla stepping up to do anything for you because they have no other options on the energy side. Maybe if Tesla ever started to make heat pumps and HVAC things would be a bit different where they could help you get a new HVAC system for cheaper...

PS. I screwed up and didn't get variable speed condensing units on my house. I am an idiot as I've been made aware numerous times by HVAC people. If anyone reading this ever is in the market for an HVAC replacement... I recommend you only look at variable speed units or go with mini splits.
 

h2ofun

Active Member
Aug 11, 2020
3,620
867
auburn, ca
Yeah, the problem with these industries (solar and HVAC) is that the pros who do it for a living seem to have a feeling that their specialized knowledge is also common knowledge when the situation suits them.

For example, if you ask an HVAC person about soft starts, they're going to tell you how stupid you are for buying normal single or dual stage scroll compressors. Because if it were their money, they'd get a variable speed inverter driven compressor because those are newer/better. They don't like hard starts and soft starts because these are hacks and kind of violate their school of training and experience. So they'll blame you for being stupid and not having a variable speed compressor if you also wanted to have fancy batteries or generators running your home.

And then if you ask solar people about soft starts, they'll say they're not HVAC experts and how they wouldn't be expected to know how your specific HVAC works. So it's your fault for not selecting the right HVAC for a whole home backup solution and informing them of your unique situation with an odd-style outdoor condensing unit.

In the end you have two industry expert groups both blaming the ignorant homeowner for failing to have the foresight to understand how stuff works. It sucks for the average homeowner... who wouldn't reasonably have this type of knowledge unless they were just born with huge amounts of innate knowledge (wwhitney? heh).

In your case you're kind of SOL unless you agree to either move the AC to a non-backup loads panel. Or you upgrade your antiquated outdoor condensing unit with a system that has a lower LRA.

Overhauling an HVAC to get a variable speed outdoor condenser paired with a variable speed air handler and with a new variable speed capable communicating thermostat is expensive though. But in this case I cannot see Tesla stepping up to do anything for you because they have no other options on the energy side. Maybe if Tesla ever started to make heat pumps and HVAC things would be a bit different.
Seems like the easiest option is to not just run the AC and leave things alone. I just think folks over think the power outages. But if these very seldom, usually not long events are that critical, then yep, one has to upgrade their AC to match the technology if one wants solar and batteries. Otherwise, get a good size generator and you do not have to worry about will your AC run. Just cannot have it both ways.
 

holeydonut

Active Member
Supporting Member
Jun 27, 2020
3,088
2,440
East Bay NorCal
Seems like the easiest option is to not just run the AC and leave things alone. I just think folks over think the power outages. But if these very seldom, usually not long events are that critical, then yep, one has to upgrade their AC to match the technology if one wants solar and batteries. Otherwise, get a good size generator and you do not have to worry about will your AC run. Just cannot have it both ways.


I think it depends on the situation for the homeowner.

50,000 homes out here in East Bay lost power over the weekend (PG&E doesn't know why but suspect the heat wave had something to do with it) at around 7pm. Power wasn't restored until around 9:30pm. If OP is on a "medical baseline" (or whatever it's called wherever he's at) he'll still benefit from AC even if it's a 2.5 hour outage the home would get from 78F to like 90F+.
 

h2ofun

Active Member
Aug 11, 2020
3,620
867
auburn, ca
I think it depends on the situation for the homeowner.

50,000 homes out here in East Bay lost power over the weekend (PG&E doesn't know why but suspect the heat wave had something to do with it) at around 7pm. Power wasn't restored until around 9:30pm. If OP is on a "medical baseline" (or whatever it's called wherever he's at) he'll still benefit from AC even if it's a 2.5 hour outage the home would get from 78F to like 90F+.
All I am saying is you cannot get everything for nothing. Meaning, if you want to use old technology AC with power out, will you can either get a lot of PW's to deal with the start current, get a generator, or change you AC to inverter technology. Am I missing an option?
 
Yeah, the problem with these industries (solar and HVAC) is that the pros who do it for a living seem to have a feeling that their specialized knowledge is also common knowledge when the situation suits them.

For example, if you ask an HVAC person about soft starts, they're going to tell you how stupid you are for buying normal single or dual stage scroll compressors. Because if it were their money, they'd get a variable speed inverter driven compressor because those are newer/better. They don't like hard starts and soft starts because these are hacks and kind of violate their school of training and experience. So they'll blame you for being stupid and not having a variable speed compressor if you also wanted to have fancy batteries or generators running your home.

And then if you ask solar people about soft starts, they'll say they're not HVAC experts and how they wouldn't be expected to know how your specific HVAC works. So it's your fault for not selecting the right HVAC for a whole home backup solution and informing them of your unique situation with an odd-style outdoor condensing unit.

In the end you have two industry expert groups both blaming the ignorant homeowner for failing to have the foresight to understand how stuff works. It sucks for the average homeowner... who wouldn't reasonably have this type of knowledge unless they were just born with huge amounts of innate knowledge (wwhitney? heh).

In your case you're kind of SOL unless you agree to either move the AC to a non-backup loads panel. Or you upgrade your antiquated outdoor condensing unit with a system that has a lower LRA.

Overhauling an HVAC to get a variable speed outdoor condenser paired with a variable speed air handler and with a new variable speed capable communicating thermostat is expensive though. But in this case I cannot see Tesla stepping up to do anything for you because they have no other options on the energy side. Maybe if Tesla ever started to make heat pumps and HVAC things would be a bit different where they could help you get a new HVAC system for cheaper...

PS. I screwed up and didn't get variable speed condensing units on my house. I am an idiot as I've been made aware numerous times by HVAC people. If anyone reading this ever is in the market for an HVAC replacement... I recommend you only look at variable speed units or go with mini splits.
I'll give a little more background.

First, there are soft start devices available other than SureStart. Soft start devices are common in industrial applications. The problem with the SureStart is it is a learning soft start device and the microprocessor gets confused by the reverse run operation. There are dumb soft start devices available that require manual setup. However, Tesla's policy is they only install SureStart devices.

My Carrier Infinity hybrid (propane and electric) heat pump system is a microprocessor controlled communicating system. When Tesla initially installed the SurStart, the system was throwing all sorts of error codes and would make a big bang when it shut down. When the third tech came out to fix it and couldn't, I told him to just remove the SureStart. When he removed the SureStart my system would no longer work. The tech told me there must be something wrong with my system and to call a HVAC repair place, and then he left to get to another appointment. When I compared the wiring to the schematic on the inside panel I found he had rewired the unit incorrectly. I rewired the unit correctly myself to get the unit operating again.

Tesla was doing nothing to resolve this. I was the one that contacted HyperEngineering, sent them the appropriate information, and they then said SureStart wasn't compatible with my system. They said this is the first time they had encountered this and it must be a very new application (the unit is actually 10 years old).

This got escalated to Tesla Executive Resolutions. I'm not allowed to communicate with the technical people directly. I've got numerous emails and phone calls back and forth with them not answering my questions and, but the responses I get, don't understand my system. They want to use the load shedding terminals on the Gateway and splice into my thermostat wires. However, my thermostat isn't a normal 2 wire connection. It has 4 wires (Data A, Data B, Common, and 24V) and is wired to my inside unit control board which then communicates with the control board outside unit to command how it operates. The frustrating thing about this is my system has a utility saver mode that when connected (simple open/closed command) will prevent the AC from running when commanded. It can also to be set to low stage only which would allow the unit to start off the Powerwalls during a power outage. However, it is not Tesla's policy to use this. Because of my previous experience I don't have confidence they understand my system and refused to proceed until they show me a detailed plan on how they intend to do the wiring. So far, they have refused to do this. I want to make sure my system doesn't throw a bunch of errors, inside unit doesn't continue to run when there is a power outage (it was running full blast during previous problems), my propane furnace will continue to operate during a power outage, etc.

They've stretched this out so long now there are other options available with the Powerwall 2 upgrade. The newer Powerwall 2s support 106 LRA each (I have 2). This would be more than enough to start my compressor during an outage. It may even be possible that a firmware upgrade could address this. But, again, communication with Tesla is frustrating.

At this point I'm so frustrated that I'm digging my heels in. They agreed to a whole home backup with AC and that is what I want. If their internal policies prevent using other soft start devices or my utility curtailment feature then fine. Replace my 2 Powerewall 2s with upgraded units that will do the job.
 
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holeydonut

Active Member
Supporting Member
Jun 27, 2020
3,088
2,440
East Bay NorCal
All I am saying is you cannot get everything for nothing. Meaning, if you want to use old technology AC with power out, will you can either get a lot of PW's to deal with the start current, get a generator, or change you AC to inverter technology. Am I missing an option?

You're not missing an option. What you're missing is the separate perspective that Piney999 (edit: and RKCRLR) doesn't really have a solution at the moment to get the ACs backed up. And I think telling folks in this predicament it's not that big of a deal isn't very helpful without some sort of empathy to get to that conclusion.

You were upset when you thought your PW conductors couldn't handle 7kW of continuous power because your installers didn't know about the potential upcoming change to export capacity for PW2. It wouldn't be very useful to just tell you "it doesn't really matter".

In Piney999's case, he was told he could have a whole home backup after Tesla inspected his home and loads... and they aren't helping him find a solution to achieve what he was sold on.

I think it's worthwhile to understand why backing up the ACs is important to him before you tell him it's not that big of a deal. As I noted, the problem with technology in this space is it takes an irrational amount of knowledge to make an informed decision. You and Piney999 may know a ton more about soft starts now... but now is too late for this particular AC backup scenario.

Edit: I suspect Tesla is giving RKCRLR the same old song and dance you'd expect a company to give a lowly homeowner. Basically they imply new news was encountered during the install and RKCRLR's original plan is out the window. It was RKCRLR's fault for not knowing about the intricacies of HVAC LRA and compressors before he agreed to the whole home backup contract. It is not on Tesla's responsibility to remedy the situation per the contract terms since this is one of the "unforeseen conditions" encountered during the install. After all, Tesla is an energy company... not a HVAC company.
 
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I think it depends on the situation for the homeowner.

50,000 homes out here in East Bay lost power over the weekend (PG&E doesn't know why but suspect the heat wave had something to do with it) at around 7pm. Power wasn't restored until around 9:30pm. If OP is on a "medical baseline" (or whatever it's called wherever he's at) he'll still benefit from AC even if it's a 2.5 hour outage the home would get from 78F to like 90F+.

Even in that situation, is central A/C for whole house really necessary? A portable A/C unit for a room should be fine for short outage situations like that.
 
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holeydonut

Active Member
Supporting Member
Jun 27, 2020
3,088
2,440
East Bay NorCal
Even in that situation, is central A/C for whole house really necessary? A portable A/C unit for a room should be fine for short outage situations like that.


I would agree if all blackouts were closer to 3 hours, the severity of needing whole home backup including the ACs is diminished. So maybe my use of the example over the weekend wasn't a very good one.

My home experienced a 3 hour blackout a few months ago... but then my sister's home up North had two separate 96 hour blackouts when PG&E turned off her power for PSPS last year.

If a homeowner intentionally went out of their way to get a whole home backup and paid a premium to get such a backup... it stands to reason in my mind they probably are protecting against 96 hour outages instead of 3 hours. Although I think the 3 hour variety is much more common... and could reasonably be mitigated through other means. But people don't drop all this money if they see value having portable AC units and generators around the house.
 
Even in that situation, is central A/C for whole house really necessary? A portable A/C unit for a room should be fine for short outage situations like that.
Define short outage. Two years ago my house was without power for nearly 2 weeks. The PSPS was only for a week but it took them almost another week to inspect the powerlines. They focus on the most dense populations first and leave lesser densely populated areas for last.
 
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All I am saying is you cannot get everything for nothing. Meaning, if you want to use old technology AC with power out, will you can either get a lot of PW's to deal with the start current, get a generator, or change you AC to inverter technology. Am I missing an option?
The contract with Tesla was for a whole home backup with AC. Tesla admitted they pulled the wrong version of the outside unit specification when they made the plans. And, as I said, there are other options but they are against Tesla's policy to use.
 
Seems like the easiest option is to not just run the AC and leave things alone. I just think folks over think the power outages. But if these very seldom, usually not long events are that critical, then yep, one has to upgrade their AC to match the technology if one wants solar and batteries. Otherwise, get a good size generator and you do not have to worry about will your AC run. Just cannot have it both ways.
Not running the AC only works if you are at home when the power goes out and the AC isn't running. If the AC is running it will trip the Powerwalls. And If I'm away the AC will attempt to restart every 15 minutes or so and re-trip the Powerwalls unless the solar is producing (the AC will start if the solar is producing).

If you have a generator you want to give me I may be open to it. But right now I'm trying to get what Tesla was supposed to deliver per contract.
 
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I've posted this previously but wanted to chime in here so the OP sees my solution.

I contracted for a whole home backup with a Tesla third party installer; the plan was soft starts.
3rd party installer couldn't get a HVAC company to warranty / install soft starts on my old units.

3rd party installer instead ate the cost of installing Lumin Smart and carving out circuits that can be programmed to load shed when the grid is out.

Currently my larger AC (main floor) circuit is configured to be off with a grid outage. This allowed the whole home backup (i have 3 PW) to move forward.
Could I enable the AC circuit during an outage? Yes, but I figure if something bad happened with my PW and that was discovered to be the source my warranty wouldn't hold... this gave me piece of mind that I wouldn't have extensive electrical work when I do replace my old AC units / go mini-spits or Heat Pump.
 

holeydonut

Active Member
Supporting Member
Jun 27, 2020
3,088
2,440
East Bay NorCal
I've posted this previously but wanted to chime in here so the OP sees my solution.

I contracted for a whole home backup with a Tesla third party installer; the plan was soft starts.
3rd party installer couldn't get a HVAC company to warranty / install soft starts on my old units.

3rd party installer instead ate the cost of installing Lumin Smart and carving out circuits that can be programmed to load shed when the grid is out.

Currently my larger AC (main floor) circuit is configured to be off with a grid outage. This allowed the whole home backup (i have 3 PW) to move forward.
Could I enable the AC circuit during an outage? Yes, but I figure if something bad happened with my PW and that was discovered to be the source my warranty wouldn't hold... this gave me piece of mind that I wouldn't have extensive electrical work when I do replace my old AC units / go mini-spits or Heat Pump.


I think your situation is a bit different. In the event of a blackout, you have 3x Powerwalls which should be able to start your air conditioner compressor assuming you turned off all major home loads. I think the OP and RKCRLR have a situation where the Powerwalls couldn't activate the compressor even if every home load were turned off. They'd basically need an additional powerwall or need the firmware upgrade to increase the PW's ability to export bursts of energy.

I think that's why I got lucky with the large-scale SGIP. But my problem of course was that PG&E barred my partial home backup solution entirely. So the SGIP got me the third battery that let me do away with a partial home backup. The end result is that I got more kW of juice, and I didn't have to modify my condensers since Lennox wouldn't allow the soft starts.
 
I think your situation is a bit different. In the event of a blackout, you have 3x Powerwalls which should be able to start your air conditioner compressor assuming you turned off all major home loads. I think the OP and RKCRLR have a situation where the Powerwalls couldn't activate the compressor even if every home load were turned off. They'd basically need an additional powerwall or need the firmware upgrade to increase the PW's ability to export bursts of energy.

My 2 Powerwalls will start my compressor in low stage if nothing else is running and it is a "cold" start (not a restart after a recent shutdown); or if the solar is producing. However, if the grid goes down the first thing the Gateway does is shut off the solar. The switchover isn't quick enough to keep the AC going if it is running when the grid goes down.
 
I think your situation is a bit different. In the event of a blackout, you have 3x Powerwalls which should be able to start your air conditioner compressor assuming you turned off all major home loads. I think the OP and RKCRLR have a situation where the Powerwalls couldn't activate the compressor even if every home load were turned off. They'd basically need an additional powerwall or need the firmware upgrade to increase the PW's ability to export bursts of energy.

I think that's why I got lucky with the large-scale SGIP. But my problem of course was that PG&E barred my partial home backup solution entirely. So the SGIP got me the third battery that let me do away with a partial home backup. The end result is that I got more kW of juice, and I didn't have to modify my condensers since Lennox wouldn't allow the soft starts.
Was told by third party installer that whole home back up without soft starts or the Lumin would not meet the design parameters and wouldn't be approved.
My ACs are old (2005) with very high LRA.
 

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