Soft Starter Recommendation Home AC

gbradley

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gbradley
Join Date
Apr 2002
Location
Corona, Ca.
Posts
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We have a 5 Ton Rheem A/C unit at home
We only run it in the Summertime, and sometimes in the Fall.
It does have a habit of blowing fuses at inopportune moments.
Have you seen the prices of fuses lately?

I was thinking about installing a Soft starter to improve the overall startup of the unit.
I'm guessing that it will also reduce or eliminate the nuisance of blown fuses.
What do you think?
Do you have any recommendations?
 
If it’s I your home them it would be a single phase motor
Single phase motors cannot be used with a soft start or a vfd
The motor design is either CAP start, CAP Run or start switch
If you connect then a soft start you will burn up the motor
If you are having a problem with blowing fuses I would change them out for breakers, even with that there is clearly something wrong most likely low line voltage. I have seen that often in rural areas.
A soft start would do same thing it either one could burn up you motor.
Contact your local power supplier and get them to check it out. You may need a boost transformer to get you line voltage into the correct range.
 
What are the fuse sizes? Are they blown when the compressor kicks in? Have you check the Cap?
 
Look up microair easy start. I have zero affiliation with them. I uses to be a HVAC guy in a previous life, so i still listen to HVAC podcast everynow and then just keep the gray matter flowing.


You would be surprised at what a capacitor out of range will draw. A good cleaning will just about always drop the run load.
 
Last edited:
JeffKiper said:
Look up microair easy start. I have zero affiliation with them. I uses to be a HVAC guy in a previous life, so i still listen to HVAC podcast everynow and then just keep the gray matter flowing.


You would be surprised at what a capacitor out of range will draw. A good cleaning will just about always drop the run load.
Click to expand...

Microair Easy Starts are the hot new thing. Heard good stuff but haven’t physically installed any. Lots of YouTube videos and reviews on them.

I believe they were developed for dealing with inrush when on whole home generators.
 
I would be very careful here
A few things to think about on is this
All motors have an inrush current when power is first applied. On a standard motor that can be as high as 10 X the full load rating. How long that inrush last’s depends on the amount of time it takes the motor to get up to running speed. This application is a refrigeration compressor so the load would be constant on every start the only variable will be the line voltage. Single phase motors have a start winding he start winding pull a lot of current while the motor is starting and gets up to speed then once the motor is up to running speed it drops out with CAP start motor the cap kicks the start winding out of phase with the running winding to get the motor started.
Then you have to look at the fuses or breakers they all have a trip curve designed in, this allows the start inrush current to exceed the ratings for a short time to allow the motor to get up to speed. If that inrush current remains too high for too long the breaker opens. The normal inrush only lasts for about 1 or 2 sec at most longer that that could burn up the motor windings. When you have low line voltage the motor starting inrush time will be longer and exceed the trip curve on the breaker or fuse
On all soft starts do is reduce the voltage to the motor to reduce the current in the motor. That sounds great and works very well on 3 phase motors but on a single phase motor the reduced voltage will keep the motor in start sequence longer heating the windings and keeping the inrush current high longer granted it will not be as high as normal.
Before you do anything check to see if your line voltage is low or in the normal range. If it’s already low the soft start will make the problem worse. I have seen cases where they installed induction coils in series with the motor to have the same effect. But here again you must do the checks and evaluate it each time
I looked at the soft start you posted, all it is doing is reducing the motor voltage for a short time to reduce the inrush current but again if you stay in start to long the problem get worse or could burn up the motor. I have seen many motor problems due to low line voltage.
In my area the power company will install boost transformers to help with it.
The reason the lights dim when you start a motor is generally because the supply transformer on the on the incoming line is sized wrong and can’t supply the necessary current to start the load.
You may want to talk to your power company
 
If this unit has been in service for awhile without any problems, I would first try to find out what has changed before installing the soft starter. If it's new, you won't void warranty by installing it according to the linked document from Rheem. And the warranty coverage includes the motor.
 
id check all of your wiring and make sure everything is tight.


as far as the soft start. I installed a microair on mine and it made a huge difference on startup current, but of course that is what it is designed to do.
 
Maybe it's time to change it for an Inverter system?

I have a Fujitsu Inverter A/C for 17 years without any problem and low electricity consumption.
 
gbradley said:
That's what I was looking at MicroAir Easy Start

I know it is single phase, and No, I am not on portable power or Solar yet.
Has it been working out well?
Click to expand...

Em not sure about portable power, But solar is working good now a days.
It also depends the quality of the solar power that it will work good or not!
 

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