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Started By
Message
re: Who has an A/C soft start?
Posted on 8/24/22 at 12:38 pm to DownshiftAndFloorIt
Posted on 8/24/22 at 12:38 pm to DownshiftAndFloorIt
quote:
DownshiftAndFloorIt
Good summary.
Essentially the hard start kit is a “starting capacitor” as mentioned. It technically does not reduce the LRA of the compressor but effectively does by reducing the amount of time the motor sees that peak current (will show about 30-50% reduced on a meter). The motor is able to get up to speed quicker since the starting torque is increased from the starting cap. After about 1/4 of a second the capacitor pulls out of the circuit.
The soft starter will directly reduce the inrush current by slowly ramping up the power and actually has a starting capacitor in it.
The other benefit of the soft starter is more protection than what the factory parts provide. It gives brownout protection, undervoltage, etc. and you can see live readings of the compressor. The soft starter will “monitor” the compressor as it was described to me by MicroAir. If the starter detects a fault it will shut the compressor down and restart it when appropriate. You send the report to MicroAir through the app and they’ll email you with information. Really cool to know my 19 year old compressor is being taken care of.
EDIT: meant to add - with that brownout protection you can stagger your units starting back up after an outage. This is VERY important for a generator because if both units use the same type of thermostat they may attempt to turn on at the exact same time after an outage. I have my units adjusted to 3 and 5 minutes to make sure they don’t crank up simultaneously.
This post was edited on 8/24/22 at 12:41 pm
1
Posted on 8/24/22 at 1:03 pm to bapple
Word to the wise for anyone looking to install one of these and run their central AC on the popular Firman dual/tri fuel generator - a standard 3.5 ton system seems like it would max out continuous running wattage of the Firman on natural gas. For this reason I’m going to grab some window units instead.
Posted on 8/24/22 at 1:07 pm to jordan21210
Someone here ran a 5 ton on their firman
Posted on 8/24/22 at 1:10 pm to DownshiftAndFloorIt
Nah, a hard start kit is around $60, the micro air soft start is around $300.
Posted on 8/24/22 at 1:18 pm to djangochained
quote:
Someone here ran a 5 ton on their firman
Maybe I have a really inefficient unit. My compressor RLA is 17.9. At 240 volts that’s approx 4,296 running wattage for just the compressor. Firman is rated at 5500 running wattage on natural gas. Someone please correct me if I’ve got this wrong.
Posted on 8/24/22 at 1:27 pm to Joe Cigar
Ok, cool. Hard Start kits used to be more like $200 from what I remember.
Posted on 8/24/22 at 1:55 pm to TheBoo
quote:
I actually have one sitting on my table to install this weekend on my 4 ton unit. I don’t have a meter to read the before numbers but I’m curious what the app will tell me after the fact. Can keep you updated once I do that.
Same here. Got mine in over the weekend. Was hoping to install it during the week but all the rain keeps holding me off.
Posted on 8/24/22 at 3:34 pm to DownshiftAndFloorIt
quote:
Hard Start kits used to be more like $200 from what I remember
Amrad makes one called the TurboStart and it’s $75. Best value on the market in my opinion.
Posted on 8/24/22 at 4:36 pm to bapple
quote:
Amrad makes one called the TurboStart and it’s $75. Best value on the market in my opinion.
I have this one my HVAC, though I didn’t install it with the goal trying to lower inrush amps for a portable generator. Uber easy to DYI install.
Posted on 8/24/22 at 8:35 pm to TheBoo
Did y’all buy them online or locally through a dealer?
Posted on 8/24/22 at 9:09 pm to ABucks11
Online.
Posted on 8/24/22 at 9:15 pm to jordan21210
quote:
Maybe I have a really inefficient unit. My compressor RLA is 17.9. At 240 volts that’s approx 4,296 running wattage for just the compressor. Firman is rated at 5500 running wattage on natural gas. Someone please correct me if I’ve got this wrong.
RLA isnt what you think it is. Its the maximum the unit would ever pull. Under typical conditions it will pull less. If I remember ill use my amp meter to see what running amps is on mine tomorrow. RLA is rated load amps.
This post was edited on 8/24/22 at 9:26 pm
Posted on 8/24/22 at 10:11 pm to diat150
quote:
I remember ill use my amp meter to see what running amps is on mine tomorrow. RLA is rated load amps.
In the industrial field I’m used to seeing FLA (full load amps) on a motor nameplate. So seeing the RLA rating confused me but from watching my units and reading the live data from the MicroAir, I’ve found it’s heavily dependent on temperature. In the late summer and fall they will typically pull 10-20% less current than in the summer. I’ve only seen them get close to RLA on the hottest days in summer.
I still wouldn’t depend on the generator on a knife edge like that though. Breakers are generally 80% devices and should be sized at 125% full load to account for that. So if the breaker on your generator is near 80% with that HVAC on it you will be right on the edge of tripping it with a bit more load. The only way to verify this is with a meter testing your compressor on various days and seeing what the RLA does in various temperatures. Then you can see if you should upsize your generator before trusting it.
Just because the soft starter can reduce the inrush doesn’t mean your generator can handle it comfortably at full speed.
Posted on 8/25/22 at 6:45 am to bapple
Installed two this week. Electrical is my weak point vs more mechanical stuff. 1st one took about 45 min, 2nd one about 20min. Hardest part is putting quick disconnects on the ends of the wires and crimping. Their (micro air) general directions are easy to follow and for me was just connecting 4 wires.
Don’t know what my starting point was, but my inrush amps are now:
3 ton: 27A
2 ton: 16A
So either could start under 6500W. Combined they are around 4000W running.
Don’t know what my starting point was, but my inrush amps are now:
3 ton: 27A
2 ton: 16A
So either could start under 6500W. Combined they are around 4000W running.
Posted on 8/25/22 at 7:57 am to bapple
now yall have me concerned with running a 5 ton unit with firman trifuel... maybe i should go bigger generator
Posted on 8/25/22 at 8:27 am to djangochained
I do t think you will be able to run a 5 ton. Def not on propane or ng
This post was edited on 8/25/22 at 8:28 am
Posted on 8/25/22 at 8:42 am to ABucks11
Online. I did not see anywhere local to me that carried them.
Posted on 8/25/22 at 8:47 am to djangochained
quote:
maybe i should go bigger generator
Generators are like gun safes, they are never big enough
Trade it in and get the bigger firman. I think someone mentioned in another thread they are on sale right now.
Posted on 8/25/22 at 9:00 am to djangochained
quote:
now yall have me concerned with running a 5 ton unit with firman trifuel... maybe i should go bigger generator
You planning on running on natural gas? Firman lists the natural gas capabilities as 6900 starting/5500 running.
If you have a somewhat modern compressor with a soft start, I'd guess you'd draw in the neighborhood of 30 amps...thats 7200 watts starting, which exceeds the firman rating. Still, it may start with a slight voltage drop and maybe the firman being able to squeeze out more than its rating.
That said, you won't be able to run much else. Maybe some LED lights. I think it would be frustrating if you're hoping for anything resembling a whole home system. Also, those firmans have a pretty high THD, which probably isn't as big of a deal as some people make it out to be but is a consideration.
Westinghouse/Duromax sells a 713cc Vtwin generator rated for 12,000 running/15,000 starting that requires a natural gas conversion (kits available) but is a much more serious machine. Clean power and pretty close to a whole home setup. Also more expensive, but they go on sale if you can wait (Amazon had it for $1285 as recently as May).
Posted on 8/25/22 at 9:12 am to 4WHLN
quote:
Generators are like gun safes, they are never big enough Trade it in and get the bigger firman. I think someone mentioned in another thread they are on sale right now.
Duromax makes a 13000 tri fuel. 8500 running watts on NG. It ain’t cheap though.
The other thing to consider with HVAC on the Firman is you’re not just running your compressor. For a 3/3.5 ton system, you’re looking at 4000+ running watts for just the compressor then factor in air handler and whatever else you want to power in your house. I think it’s a tall order running central AC on the Firman using NG. Two window units would probably pull 2000-2500 watts leaving over half the capacity for fridge/freezer/fans/lights etc. Just sucks having two store window units when not in use.
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