2xPowerwall whole house backup - HVAC sure start problem

[af88]

I will just shut the thermostat to off, running the wires would require permits and another panel I'm not interested in dealing with. The wireless option using the API and a relay is really more trouble than just flipping the switch on the thermostat personally.

I'm more interested to see if a sure start if wired properly would solve the problem and see what the solar company wants to do.

 

[aesculus]

The wireless option using the API and a relay is really more trouble than just flipping the switch on the thermostat personally.

Yes, if you are home to do it. My fear is that I am away and it either drains my whole battery or worse the battery just never gets used because it would be in a starting standoff with the HVAC system.

 

[af88]

Understand. But why have the AC on if you are not home.

 

[mongo]

Understand. But why have the AC on if you are not home.

So the house is livable when you do get home. Keep pets happy.

 

[bob_p]

WiFi/smarphone apps are available for many devices - we have them for our highest energy devices - HVAC and pool pumps.

If we aren't at home and anticipate a long outage, we can turn those devices off from anywhere.

For short-term outages, we want the solar/PowerWall system to provide power to everything we normally use in the house - and should have enough battery reserves to operate for several hours. And if we suspect a longer outage, then we'll turn off the non-essential systems (either via an app or by turning devices/circuits off).

 

[SSonnentag]

The Solar City/Tesla guys that wired our AC units up with soft start mechanism also miswired things. They ended up burning up our 5-ton compressor. This is after I told them in writing and received confirmation that the AC units would NOT be backed up by the critical load center. Everything has since been corrected, with neither the AC units nor the HPWCs being backed up. In the event of a long power outage I can always trickle charge via 120V.

 

[jboy210]

Thanks for the feedback guys, I had an HVAC expert come out and they removed the sure start and replaced it with an OEM Carrier Soft start kit made for this compressor. They also discovered since the sure start was not wired properly the Run Capacitor 7uF side was burnt out due to miss wiring so they replaced it and all is working with 2 PW with the AC running on a single test shutting off shore power the compressor continued to run on the PW. Will test again tomorrow with the compressor off and on battery power to see if it fires up. I suspect it will but will test to confirm.


This guys has been doing this for a long time and said the sure start is a generic module not compatible with all compressors. Coincidentally hyper engineering (maker of sure start) said it could be a compatibility issues with the logic board which could have been the issue as well.

Long story short without the sure start b/c of the 134 LRA there is no way the compressor would work switching to the batteries. But I will do a test tomorrow with the compressor off initially than go to battery and than turn the compressor on to see what happens.

Thanks for the update. I have a Carrier compressor and 2 PWs being installed. I will be sure they use the Carrier Soft start

 

[af88]

I believe the carrier is a Hard start and unfortunately it didn't help. So right now I'm still waiting to hear back from my solar company who is supposed to reach out to Tesla. I would like them to try sure start but it is a risk if it is misswired again.

 

[Sjohnson20]

I contacted Tesla about removing my AC from battery backup. They said they would and sent a tech out. He ended up putting a sure start on the AC instead of taking it off the backup. He claims that the way the house was built means there’s no way to remove it. I’m not sure if that is true or if he just didn’t want to do the work required.

My breakers are in the middle of the house and the powerwalls are outside where the grid comes in. The gateway is connected right after the meter. So he’s saying there’s no way to remove anything from backup. I wanted to at least take my pool pump off backup but they couldn’t do that either.

I really didn’t want another soft starter but I guess I have no choice.

 

[mongo]

I contacted Tesla about removing my AC from battery backup. They said they would and sent a tech out. He ended up putting a sure start on the AC instead of taking it off the backup. He claims that the way the house was built means there’s no way to remove it. I’m not sure if that is true or if he just didn’t want to do the work required.

My breakers are in the middle of the house and the powerwalls are outside where the grid comes in. The gateway is connected right after the meter. So he’s saying there’s no way to remove anything from backup. I wanted to at least take my pool pump off backup but they couldn’t do that either.

I really didn’t want another soft starter but I guess I have no choice.

It takes a little work, but they should be able to add relays to the control lines for the AC and pool pump that are enabled by having grid power.

 

[Dan123]

Sure enough after the test today the Compressor does not run when it is off and tries to start in battery backup. Very upset about this and I'm holing the Solar company responsible for telling me it can run with 2 PW. Waiting to see how they want to rectify the problem.

I believe the carrier is a Hard start and unfortunately it didn't help. So right now I'm still waiting to hear back from my solar company who is supposed to reach out to Tesla. I would like them to try sure start but it is a risk if it is misswired again.

I have a feeling that you AC will start under the following conditions. PW state of charge below 92%, and daytime with good solar production. Once started, you can operate it all day (however, it if it is not variable speed, then you will freeze).

 

[aesculus]

It takes a little work, but they should be able to add relays to the control lines for the AC and pool pump that are enabled by having grid power.

I'd like to know what these are.

I asked too and they just said turn them off. I also have done extensive search here on TMC and on the internet too and have come up blank.

 

[mongo]

I'd like to know what these are.

I asked too and they just said turn them off. I also have done extensive search here on TMC and on the internet too and have come up blank.

Basically, have them add a grid side low current fused tap to feed a 24V transformer. This may be tricky if you are set up with a direct connection from meter to gateway. Ideally, the gateway would have a status signal, but I don't know of one. This 24V line is the control/ enable signal for the rest of the systems. You feed this to the coil of 24V relays whose contacts are placed inline with the AC control signal. (can be done between thermostat and furnace to disable blower also).

There are also wireless thermostat extenders that can be be used if running the 24V enable singnal is an issue.

 

[aesculus]

Basically, have them add a grid side low current fused tap to feed a 24V transformer. This may be tricky if you are set up with a direct connection from meter to gateway. Ideally, the gateway would have a status signal, but I don't know of one. This 24V line is the control/ enable signal for the rest of the systems. You feed this to the coil of 24V relays whose contacts are placed inline with the AC control signal. (can be done between thermostat and furnace to disable blower also).

I should have been clearer. In my case I cannot do this because of wiring issues. See your next statement

There are also wireless thermostat extenders that can be be used if running the 24V enable singnal is an issue.

Yes. This is actually what I have been pursuing. I am really having a hard time finding something that is Normally Open, has good range (better that 50 or 60 feet line of sight). So many of these devices are focused on remote thermostat applications like down the hall etc.

I need one that can work outside over 100 feet and around a building since my meter panel is a long way away from my heat pumps. And then finding one that will open and stay open when it does not get a signal or it looses power. I found one promising one that met most of the criteria but it had a 100 second pulse time and would stay in its last state (ie not go off when power cycled).

 

[gpez]

I'd like to know what these are.

I asked too and they just said turn them off. I also have done extensive search here on TMC and on the internet too and have come up blank.

Not sure if it is helpful for you but I've implemented the API + relay solution and it works great for my setup. I have a HomeSeer based home automation system that control lights, locks, garage door, water leak sensors, etc and I wrote a Powerwall plugin that allows the home automation to monitor the status of the grid, solar, and Powerwall. Using an outdoor Z-Wave 120v relay I have the home automation configured that if the power goes out it disables my outdoor lighting. Z-Wave is a mesh network and has decent LoS range (spec is 100m). Since the devices are wireless they require power for a control signal but since my Powerwall backs it up it does.

https://www.amazon.com/GE-Weather-Resistant-Required-Works-SmartThings-14284/dp/B06W9NWFM3

 

[mongo]

I should have been clearer. In my case I cannot do this because of wiring issues. See your next statement


Yes. This is actually what I have been pursuing. I am really having a hard time finding something that is Normally Open, has good range (better that 50 or 60 feet line of sight). So many of these devices are focused on remote thermostat applications like down the hall etc.

I need one that can work outside over 100 feet and around a building since my meter panel is a long way away from my heat pumps. And then finding one that will open and stay open when it does not get a signal or it looses power. I found one promising one that met most of the criteria but it had a 100 second pulse time and would stay in its last state (ie not go off when power cycled).

Something like this:
iO HVAC Controls
might work for you.
Basically, set up the transmitter with the grid side 24V input. Use the receiver to enable the cooling control line.

 

[aesculus]

Something like this:
iO HVAC Controls
might work for you.
Basically, set up the transmitter with the grid side 24V input. Use the receiver to enable the cooling control line.

I looked at that and maybe discounted it too quickly thinking it was just a thermostat extender.

Maybe I could put in a 24V power supply and have it connected to the base station and just dummy (short out) the on port. And the receiver would only be detecting the on state. Not sure how that would work if everything else did not pass through the controller.

An additional worry is this:

Each transceiver has a built in inactivity timer to detect a loss of communications. If no data is received from a paired set for one minute, all outputs are turned off and the LED will display solid red.

It's an minute that the heat pumps would try to restart (possibly depending on their state) before the receiver went dead and terminated the "on" output, but that is better than retrying forever.

 

[mongo]

I looked at that and maybe discounted it too quickly thinking it was just a thermostat extender.

Maybe I could put in a 24V power supply and have it connected to the base station and just dummy (short out) the on port. And the receiver would only be detecting the on state. Not sure how that would work if everything else did not pass through the controller.

An additional worry is this:


It's an minute that the heat pumps would try to restart (possibly depending on their state) before the receiver went dead and terminated the "on" output, but that is better than retrying forever.

If you power the transmitter from the backed up panel and use a 24V feed from the non backed up side of things as the control input, it may get around that 1 minute response issue.

 

[aesculus]

If you power the transmitter from the backed up panel and use a 24V feed from the non backed up side of things as the control input, it may get around that 1 minute response issue.

That might be an interesting hack. I need to determine how much time my PW need to cut over during a power outage. They were tested when installed but I did not time them.

None the less it would seem that your idea would at least lesson the one minute to whatever the cut over time is, hopefully just a few seconds.

But of course if those pesky heat pumps trip the PW's off during that period ...

 

[af88]

Thanks for the update. I have a Carrier compressor and 2 PWs being installed. I will be sure they use the Carrier Soft start

Did you have any luck?

I'm still waiting for another sure start which i'm not optimistic will help but the solar company is taking their sweet time to resolve this.