Sure Start AC Soft Starter - How to properly size

Install help and sizing for Hyper Engineering Sure Start AC Soft Starters.
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Joined: Sat Aug 04, 2018 8:46 pm
Location: Clawson, MI

Learn how to properly size a Hyper Engineering Sure Start AC soft starter unit for your air conditioning system. The sizing is actually very simple with some basic information from the AC unit's nameplate. The Sure Starts are sized based on the Running Load Amps or RLA from the nameplate of the AC. This is the amperage that the unit draws once it's started up and running, not the amperage that it draws to actually start (LRA).

The nameplate will normally list RLA or FLA as the number that we're looking for. There will normally be one for the fan motor (which we don't care about) and one for the compressor section (the number we want to know).

Sure Starts are sized based on this number. We offer 2 sizes for almost all residential AC unit applications:
SS1B08-16SN 8-16 RLA/FLA shown here: ... -a-c-units
and SS1B16-32SN 16-32 RLA/FLA shown here: ... -a-c-units

The goal of installing a Sure Start is to reduce the LRA of the compressor motor. LRA is Locked Rotor Amps, or in simple terms, what the compressor motor draws when it first starts. This amperage draw is what causes flickering lights when your AC starts. A Sure Start will dramatically reduce this draw by up to 60%! We've seen excellent results from all of our installs here in Michigan and have had nothing but success stories from them. An example draw would be a normal LRA nameplate reading of 62A which we reduced to just 25A with an 8-16 RLA Sure Start. The 11kW generator didn't even notice the AC unit was starting once it was installed. Prior to that, the customer couldn't start the AC at all on the generator due to other loads and a poor sizing job by the original installer... :sad:

If you need more assistance, please start a new topic with your specific needs listed so that we can better help you get what you need!
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