I installed a soft-start unit in our air conditioning condenser. There have been a couple of annoyances with our AC system that I was hoping a soft-starter would solve:
- The condenser makes a loud noise when starting up. This is due to the high inrush current that is supposed to kickstart the compressor. In reality, the compressor doesn’t necessarily need that much current to start, which is why a soft-start unit does the job of “ramping up” the current until it detects that the compressor has started.
- When the condenser starts, the lights in the house flicker momentarily. This is also due to the high inrush current, but the root of this problem extends beyond our house. I believe this is caused by the power transformer that serves our entire street of houses; the transformer is improperly sized, and its capacity is too low to handle these spikes of current. This is also evidenced by the fact that our lights flicker just a bit when our neighbors’ AC unit starts.
After much research, I decided to go with the MicroAir Easy Start Flex. It’s a little pricey, but it’s intended to handle most types of condensers, regardless of its “tonnage”, referring to its BTU output (our condenser is a 5-ton unit, which translates to 60,000 BTUs.
Installing it was an absolute breeze, and took less than one hour. Afterwards, there was an enormous improvement in the startup noise, and the lights no longer flicker at all. I also made a video of the installation, with before- and after recordings of the startup noise:
If you’re considering installing one of these units in your AC system (which you should), make sure you’re completely comfortable working with household electrical wiring, completely familiar with the wiring of your AC unit, and take all the necessary safety precautions. If you are unsure about anything, please contact an HVAC professional.