Air Conditioner Soft Start Upgrade

Ulma Doctor

Ulma Doctor

Infinitely Curious
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I live in an area that sees triple digit temperatures in the summer months.
My air conditioner is sufficiently sized for my house, but like everything else- the more you use - the more you pay!
I have no intention of giving up more than I have to…

I’m going down the soft starter path.

Soft starters reduce the inrush current and slowly ramp up the start of the compressor - drawing 1/3 to 2/3 less current in comparison to traditional hookup.

I found a candidate for trials on EBay for about $120 that is rated for 16-32A@230VAC.
IMG_6321.jpeg

The directions appear to be translated to English but they are easy to follow.

I’ll be upgrading tomorrow afternoon and I’ll take some pictures of the installation and provide some other data for those following at home.

Thanks for reading, stay tuned!
 
When I built my RPC (rotary phase converter) 35 years ago I learned the relationship between idler motor starting capacitor mfd, time to full RPM, and inrush current. It was a great lesson!

I have converted most of my 3ph machines to VFD's now. I have also turned off my central HVAC and we now have 4 mini-splits for our 3 bedrooms and our great room. The difference on our power bill was huge when I installed the mini-splits (which are controlled by what is basically a VFD). My central HVAC was crap and my duct work was REALLY crap making the change to mini-splits a pretty easy choice.

An HVAC installer sold my mother a central AC with "variable flow" technology, basically a VFD. 8 years later the central air died and the control board was no longer available. When they tried to sell her a replacement "variable flow" system I vetoed that and she has a 2 speed central AC now.

I hope you will let us know how your soft start upgrade works out for you? I would expect it to extend the life of the compressor motor and hopefully save you some money.
 
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I installed two Micro-Air soft starters on my 5T AC units, they dropped the start-up current from around 125A to 32A, they should help the compressors last a bit longer. The other benefit is I run a battery powered whole house system, the discharge rate can be an issue w/o AC soft start. The newer units also have Bluetooth which allows you to monitor the AC parameters when running.
 
Ulma Doctor said:
I live in an area that sees triple digit temperatures in the summer months.
My air conditioner is sufficiently sized for my house, but like everything else- the more you use - the more you pay!
I have no intention of giving up more than I have to…

I’m going down the soft starter path.

Soft starters reduce the inrush current and slowly ramp up the start of the compressor - drawing 1/3 to 2/3 less current in comparison to traditional hookup.

I found a candidate for trials on EBay for about $120 that is rated for 16-32A@230VAC.
View attachment 578693

The directions appear to be translated to English but they are easy to follow.

I’ll be upgrading tomorrow afternoon and I’ll take some pictures of the installation and provide some other data for those following at home.

Thanks for reading, stay tuned!
Click to expand...

We have three Carrier Infinity systems (2-4Ton and 1-3Ton) and all of them feature a slow ramp up to speed (soft start, multi-soeed) feature. It made a big difference in our summer electric bills, when we upgraded from the previous units.

Cheers!
 
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Soft starters won't lower your bills, but they can make a generator much happier!

Btw, the optimal point for fancy A/C systems is two speed. That is done with dumb relays proprietary vfds suck, are expensive, and go out of production fast.
Two speed is a pretty significant efficiency boost, and can improve humidity control quite a bit.

Sent from my SM-S911U using Tapatalk
 
Would a soft start lower the demand charge on a thirty horse 3 phase motor. Every month that pump is turned on is 5 hundred even if it is on then back off
 
In my mind, the only way a soft start will lower an electric bill is if the motor cycles on and off several times a day or hour. If it is running almost continuously, then you are not saving much over the power it uses at startup.


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Weldingrod1 said:
Soft starters won't lower your bills, but they can make a generator much happier!

Btw, the optimal point for fancy A/C systems is two speed. That is done with dumb relays proprietary vfds suck, are expensive, and go out of production fast.
Two speed is a pretty significant efficiency boost, and can improve humidity control quite a bit.

Sent from my SM-S911U using Tapatalk
Click to expand...

The Greenspeed feature on our Infinity system uses a variable speed compressor. The way it does this is by increasing and decreasing system output by increments of 1% as needed.

Cheers!
 
I was VERY tempted by the vfd A/C too, but my long-time A/C dude shared his experience on 2 speed vs variable speed long term reliability/durability.

On the demand charge for a big motor, yes a soft start might improve that, as it will pull down the peak current significantly.

What are you driving with the big motor? Or is it a rotary phase converter? You might also be able to spool it up with a small pony motor before connecting it to AC power.

Sent from my SM-S911U using Tapatalk
 
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