Soft start for replacement central AC needed?

[nyprepper]

i have a 6.6kw PV and two PW's....when the system was installed in 2018 they put what they told me was a "soft start" on my central AC to lower start-up amperage.

I'm now getting my older central AC replaced with a new Lennox Elite system.... it's a single unit, 5 ton, 17 seer.

The AC install crew has no idea what I'm talking about when I ask them about a soft-start.

Do I really it with two PW's?

thanks!

 

[DP26]

It is usually an add on by the user. Rv and off grid use them to lower the start up amps. Micro aire is reliable.

 

[brkaus]

If that model is a fully variable one with a DC inverter, I don’t believe a soft start is necessary.

I’m not seeing a full description of the unit online. But, admittedly, I didn’t spend much time.

 

[dafish]

it’s close. Much would depend on how much was in use. My 5 ton geo needs soft start to start at all on a 10kw/12.5kw surge generator. It cannot start high stage at all. I don’t think soft start applies to the upstage.

that’s with zero other load too.

I would expect a newer unit to include soft start. Call tech support

 

[RKCRLR]

Inverter based variable speed compressors don't need the soft start device (which was probably installed on your outside unit by your PW installer). Find out the LRA rating of the new unit (a variable speed compressor may not have a LRA rating) to determine if a soft start device is required (which can probably be transferred from your old outside unit although it may not be compatible with your new unit).

 

[RKCRLR]

Inverter based variable speed compressors don't need the soft start device (which was probably installed on your outside unit by your PW installer). Find out the LRA rating of the new unit (a variable speed compressor may not have a LRA rating) to determine if a soft start device is required (which can probably be transferred from your old outside unit although it may not be compatible with your new unit). Tesla or your installer can tell you the maximum allowed LRA with your Powerwalls.

 

[sorka]

Are single stage compressors even legal any more with the current EPA energy usage requirements?

 

[brkaus]

My carrier DC inverter compressor says 24 LRA.

My older and cheaper 2 speed system says 82 LRA.

Look for and compare the LRA numbers in the two systems.

 

[MyHeadHurts]

For comparison, our York unit is from 2009 and is 5 ton, 15 SEER, 118 LRA. We have two Powerwalls on whole house backup and they have no trouble starting the York. We don't have a soft start thingy installed. Tesla specs say each Powerwall supports 106 LRA, so two should be more than enough to support your new AC.

 

[sorka]

For comparison, our York unit is from 2009 and is 5 ton, 15 SEER, 118 LRA. We have two Powerwalls on whole house backup and they have no trouble starting the York. We don't have a soft start thingy installed. Tesla specs say each Powerwall supports 106 LRA, so two should be more than enough to support your new AC.

You tested this off grid, right? Also, it makes a big difference the current SOC of your powerwalls and their temperature. If they're full and warm, you won't need soft start as full warm batteries can put out far more current than cold or low batteries.

 

[ptdusn]

i have a 6.6kw PV and two PW's....when the system was installed in 2018 they put what they told me was a "soft start" on my central AC to lower start-up amperage.

I'm now getting my older central AC replaced with a new Lennox Elite system.... it's a single unit, 5 ton, 17 seer.

The AC install crew has no idea what I'm talking about when I ask them about a soft-start.

Do I really it with two PW's?

thanks!

We replaced our old A/C with a 5 ton 16 seer Bryant, (Carrier), in July of 2021 and have NO issue with it starting off of our two PWs. We didn't install a soft start.

 

[CrazyRabbit]

Is your new system inverter based?
Keep the soft start from the old system.

 

[SageBrush]

As an aside, these solid state motor starters are very cool. They use frequency to change the load impedance

 

[RKCRLR]

It also depends on the version of the Powerwalls the OP has. Earlier Powerwall 2's had less surge capacity than later Powerwall 2's.

 

[h2ofun]

It also depends on the version of the Powerwalls the OP has. Earlier Powerwall 2's had less surge capacity than later Powerwall 2's.

I never saw this proven

 

[RKCRLR]

I never saw this proven

It is (was) in the Tesla specifications. Tesla says the current Powerwalls (they don't call them Powerwall 2's anymore - the technical department refers to them as Series 3 Powerwalls) support 106 LRA each. The earlier Powerwall 2's (which I currently have 2 of) was a lot less. I have a long saga that eventually got me to get a 3rd Powerwall to start my HVAC compressor. If I had been given the current Powerwalls two of them would have been enough to start my AC.