RandyBennett
I'm sure this is an old topic but today I started the Generac 22 for the first time. The transfer switched worked right on time and the power was right on 243V. After i switched over and I brought the house power back on both AC outdoor units were buzzing pretty loud. I also installed these Trane's several years ago. I went in and turned both units off and brought them back on again and everything was smooth. What can I do to eliminate this issue? It almost sounds like the contactor isn't pulling in all the way causing a voltage loss and it is just shy of sounding like there's a phase out? Thanks
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78buckshot
I suspect that the compressor was running backwards, I have seen it happen on a return to utility due to the VERY quick transfer and no time for the compressor to stop. The topic has been discussed here before with no real consensus on a fix. You can try adding a "delay on make" timer to the condenser 24 volt control wire but it might not see the break in power because of the fast transfer.
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BillM
Do you have your A/C's set to bypass for 5 minutes with your transfer switch?  If you lose power, your compressors should come to a complete stop with their tray tables in the locked and upright position.  Then if you used the A/C load delay built into the transfer switch you have delay your first A/C an additional 5 minutes and the second one a little longer.  If you didn't do that, you can also look into adding Hyper Engineering Sure Start modules to your A/C which have wiring that will detect that condition.  
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grsthegreat
Hyper engeneering’s soft start is supposed to prevent this. I hear it usually only an issue with the high end ac units.....too much electronics onboard.
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grsthegreat
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Goofy4TheWorld
While I have zero personal experience with a Trane, based on the chronic issues with Trane units not playing nice with generators posted on this forum, I would be surprised if Hyper's soft start would be the easy fix it would be for any other brand other than Trane.  But that's just my speculation.

However, what I do know for sure is that the most effective and direct fix for the "backwards compressor" problem when switching between two live power source is to have all HVAC units that are connected to a generator to also be connected to a Generac load shedding module (the one that goes in the transfer switch, not the standalone units).  These load shedding modules would break the thermostat wire for 5 minutes for any HVACs run through it ANYTIME the transfer switch changes position (moves to/from utility/generator power).  The load shedding board will shut down the compressor for 5 minutes anytime there is change in power source.  As an added bonus you also get the "load shedding" feature of turning off the HVAC if the generator is ever overloaded.

Just my two cents.
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grsthegreat
While I have zero personal experience with a Trane, based on the chronic issues with Trane units not playing nice with generators posted on this forum, I would be surprised if Hyper's soft start would be the easy fix it would be for any other brand other than Trane.  But that's just my speculation.

However, what I do know for sure is that the most effective and direct fix for the "backwards compressor" problem when switching between two live power source is to have all HVAC units that are connected to a generator to also be connected to a Generac load shedding module (the one that goes in the transfer switch, not the standalone units).  These load shedding modules would break the thermostat wire for 5 minutes for any HVACs run through it ANYTIME the transfer switch changes position (moves to/from utility/generator power).  The load shedding board will shut down the compressor for 5 minutes anytime there is change in power source.  As an added bonus you also get the "load shedding" feature of turning off the HVAC if the generator is ever overloaded.

Just my two cents.
that wont work. I tried it before. It works when power fails and generator starts, but when transfers back does not always sense the power drop as its so short. It didnt stop my ac unit when power transfered back.
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RandyBennett
BillM wrote:
Do you have your A/C's set to bypass for 5 minutes with your transfer switch?  If you lose power, your compressors should come to a complete stop with their tray tables in the locked and upright position.  Then if you used the A/C load delay built into the transfer switch you have delay your first A/C an additional 5 minutes and the second one a little longer.  If you didn't do that, you can also look into adding Hyper Engineering Sure Start modules to your A/C which have wiring that will detect that condition.  


If your referring to the load shed devices no I have not installed them because my total amp draw is maxing out around 50-60 on the 22KW. I have emailed Hyper Engineering but have not received a response back yet. I can easily put a 5-2-1 start kit with a time delay adjusting both at different intervals say 4 and 5 but others are suggesting to be careful that the 24v dropout may not pick it up fast enough to drop out the line voltage? Very confusing but shaking my head why all the intelligent engineers haven't designed something on the line voltage side yet if so please send it to me thank you. Thanks for all the good advice I was surprised being a newbie!
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Cobranut



If your referring to the load shed devices no I have not installed them because my total amp draw is maxing out around 50-60 on the 22KW. I have emailed Hyper Engineering but have not received a response back yet. I can easily put a 5-2-1 start kit with a time delay adjusting both at different intervals say 4 and 5 but others are suggesting to be careful that the 24v dropout may not pick it up fast enough to drop out the line voltage? Very confusing but shaking my head why all the intelligent engineers haven't designed something on the line voltage side yet if so please send it to me thank you. Thanks for all the good advice I was surprised being a newbie!


The solution is to use a transfer switch with in-phase transfer capability.
My Thomson switch waits for the generator and utility to be in-phase with each other before transferring the load.
This allows transfers back to utility without the equipment even noticing, as well as seamless exercise under load.
Often I don't even know the utility has returned until I open the back door to see if the generator is still running. 😎

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RandyBennett
Cobranut wrote:


The solution is to use a transfer switch with in-phase transfer capability.
My Thomson switch waits for the generator and utility to be in-phase with each other before transferring the load.
This allows transfers back to utility without the equipment even noticing, as well as seamless exercise under load.
Often I don't even know the utility has returned until I open the back door to see if the generator is still running. 😎

What model is the Thompson? I'd like to look up the specs for the next one thanks

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Birken Vogt
Almost all transfer switches with their own controllers have in-phase transfer available.
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