Locked rotor Amps Vs In Rush Amps

[OliLt]

I had my air conditioner checked recently as part of a regular service check. It is a 2019 Lennox, 4 ton, 220 volt, single phase. The specified Rated Load Amps are 21.8, and the Locked Rotor Amps are 117. The technician measured the in rush amps (starting amps) at 102 amps. He recommended a Hard start Kit, and Soft start kit to reduce the amp draw and duration at start up in order to increase the life of the unit. Is this oversell? At what value would the in rush amps indicate a problem or impending failure of the unit. I am aware that a motor draws significantly higher amps at start up vs the rated normal load. Thanks, Oli

 

[joeysmith]

You definitely dont want both together.
If he wanted to install both you need a different guy cause they wont play nice with each other.


102 isn't horribley high for that unit but a hard start or soft isn't a horrible idea either.

if you do go with a hard start the 5-2-1 kits are better than the simple 2 wire ones.

Relatively easy to diy if you're a little bit handy an decide to tackle it

 

[Gambles]

I’ll openly admit that I’m not a HVAC tech. But around here, the hard start is installed when the unit is getting up there in years and is more of a last resort.
Most units, if registered when new, have a 10 year warranty on the compressor. What does yours have?

 

[joeysmith]

Ohhh yea forgot my train of thought
My bad

They are an easy upsell for sales type companies/techs

We normally only sell them on older units that are on their last leg.

They will help if you have light flicker an such when the unit kicks on

 

[Stan Coryell]

I had my air conditioner checked recently as part of a regular service check. It is a 2019 Lennox, 4 ton, 220 volt, single phase. The specified Rated Load Amps are 21.8, and the Locked Rotor Amps are 117. The technician measured the in rush amps (starting amps) at 102 amps. He recommended a Hard start Kit, and Soft start kit to reduce the amp draw and duration at start up in order to increase the life of the unit. Is this oversell? At what value would the in rush amps indicate a problem or impending failure of the unit. I am aware that a motor draws significantly higher amps at start up vs the rated normal load. Thanks, Oli

In my opinion, there is a lot to this. Line set length, wire size, difference in elevation between the condenser and evaporator, head pressure, ect.

The amp draw seems inline with the LRA.

Do you trust the contractor?

 

[da.bees]

We could jaw on this for a week and the facts wouldn't change. Fact #1. Tech with hands on can better determine what's best than every web bud in the world combined. Fact #2. If you don't trust the tech, ask contractor for a second opinion or change contractors and start over with one you trust. Have you ever considered giving your barber advice picked up on the web for cutting hair? How about giving the doctor second hand advice on checking your prostate?

 

[Ray,IN]

At 27 yrs old, I assume the caps have been replaced already? They have been known to weaken with age and use. Look up the definitions and specs of both, hard-start and soft-start before making a decision. As joeysmith said, never install both together!

 

[moresmoke]

We could jaw on this for a week and the facts wouldn't change. Fact #1. Tech with hands on can better determine what's best than every web bud in the world combined. Fact #2. If you don't trust the tech, ask contractor for a second opinion or change contractors and start over with one you trust. Have you ever considered giving your barber advice picked up on the web for cutting hair? How about giving the doctor second hand advice on checking your prostate?

I don’t know much about hvac, but the baber does ask what type of cut I want when I sit in the chair. I don’t have to just accept whatever style they feel like giving me. Well, I generally do as I have little left to work with in the hair department.

 

[Fred Werring]

How about giving the doctor second hand advice on checking your prostate?

OMG, TWO hands????

 

[joeysmith]

OMG, TWO hands????

Those aren't my pants on the floor

 

[miangus]

Is installing a soft start ever a bad idea?

 

[OliLt]

Thanks to all who replied. Here is some additional information to better answer my question: Is a soft start or hard start kit a necessary add on to extend the life of this 7 year old unit? My lights do not dim when the unit kicks on, breaker does not trip. Breaker is 220 volt, 45 amp. Dual run capacitor is original and within specification according to technician. It is under warranty, expires in 2030. It is serviced / checked twice a year (spring / fall) to maintain the warranty. Runs normally. Compressor is on ground level, air handler is in 2nd story attic. Operation is seasonal, not continuous - Charlotte NC. As to trusting the contractor, BBB A+ rating. Thanks, Oli

 

[joeysmith]

2019 should have a bleed txv so no you do not need either unless you're equipment short cycles which usually the thermostat protects it from.

The txv allows the pressure to bleed off in between cycles


Biggest reason for a hard start now a days on newer equipment is a long lineset with a shutoff solenoid valve on the liquid line.
This is to prevent refergerant migration back to the condenser in cool weather


Reason being the compressor is starting "loaded" when it starts

 

[Stan Coryell]

2019 should have a bleed txv so no you do not need either unless you're equipment short cycles which usually the thermostat protects it from.

The txv allows the pressure to bleed off in between cycles


Biggest reason for a hard start now a days on newer equipment is a long lineset with a shutoff solenoid valve on the liquid line.
This is to prevent refergerant migration back to the condenser in cool weather


Reason being the compressor is starting "loaded" when it starts

Spot on.

There should be a bulletin for his long line-set/ elevation from Lennox. If this system was installed correctly the hard-start kit and solenoid should have been added then.