Does the hard start kit make the modern A/C work better?
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- Опубліковано 3 жов 2024
- This one describes how the hard start kit works and compares it with the run capacitor start system on the scroll compressor. This video is part of the heating and cooling series of training videos made to accompany my websites: www.graycoolingman.com and www.grayfurnaceman.com to pass on what I have learned in many years of service and repair. If you have suggestions or comments they are welcome.
If you are a homeowner looking to repair your own appliance, understand that the voltages can be lethal, the fuels are highly flammable and high pressures are used. Know your limits.
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Great demonstration! Under ideal conditions, I'd agree about a hard start not extending the life of the compressor. However, where I live, we see a lot of momentary power interruptions/flickers, which tend to stall the compressor and cause it to trip the overload when it isn't able to restart against the pressure. With a hard start, they normally start right back up no issue. In the long run, don't you think avoiding several stalls a week would be beneficial to the compressor's longevity? I'd think stalling and overheating the windings until the overload trips would be very bad on the compressor over time, but I'm no engineer.
A soft start may be a better solution to that issue, but that's a different discussion hopefully for another video.
I know that I personally missed your wisdom. Be blessed!
Great video GFM. As always, thank you for the knowledge.
FROM CHICAGO EXELENT VIDEO. HOPELY YOU GET MORE VIDEOS THANK YOU SO MUCH
I had asked you a question last week about my Trane factory start assist from Trane. It's not a 5-2-1 or kick start type. Working fine, just wanted your opinion on the Trane factory start assist. Thanks, love your videos !
You absolutely have to use a Trane potential relay on a Trane. They are a specific cut in and cut out voltage.
Thanks for sharing. I like your videos a lot.
The 33 amps startup surge is a bogus number. As you mentioned, clamp on meters are not accurate for short current bursts surge peak readings. They need 0.3 to 0.4 seconds of burst current to average the reading.
A hardstart kit actually slightly increases startup peak surge current but it reduces the length of time the surge current lasts.
A typical Run capacitor only A/C compressor startup time is about 0.4 secs. If you add a hard start kit the startup time will reduce to 0.1 ot 0.2 seconds for a normal system with proper AC wiring to outside unit. The clamp on meter will read low for peak surge current because the surge burst time is too short for meter.
You need a closed loop hall effect current sensor and an oscilloscope to measure true peak current reading and its time period.
If your A/C compressor power line has a long wire run from breaker panel, too small of wire gauge for the wiring run length, or grid voltage is low in your area, a hard start kit will help compensate for low supply voltage. The lower the AC voltage on compressor the longer the startup period. Commercial/Industrial installs with three-phase single phase branch voltage of 208vac and typically longer wire runs to roof mounted compressor/condenser are more likely to have this problem. Once startup time extends to about 1 second there will be enough time to heat up and pop the compressor's internal safety breaker.
The start (auxiliary) winding provides maximum motor torque when the series capacitor value provides 90 degrees of current phase lead to start (auxilary) winding. The proper Run capacitor value does this during run mode, and it improves motor efficiency and power factor.
During startup period the motor is like a transformer with a short-circuited secondary winding. The stator-rotor air gap creates a large amount of leakage inductance. This makes the startup load very low impedance and very inductive. This requires the start capacitor to be much larger in mfd. value than mfd value of Run capacitor in run mode to achieve the optimum start winding current phase shift during the startup period.
The startup torque improvement is more due to getting the start winding phasing closer to 90 degrees from run winding then the slight increase in start winding current magnitude from the larger mfd value start capacitor.
Also as you mentioned, 0.1 to 0.2 seconds startup time due to increased startup torque from larger value start capacitor is mechanically more stressful to compressor. Going from zero to about 3500 rpms in 0.1 seconds can break the shaft coupling bushing or other scroll compressor mechanical components.
Electrolytic based, high mfd value, start capacitors are less reliable than foil-based Run capacitors and potential relay to disengage the start capacitor is another component to go bad and reduces the system reliability.
It has been my experience that a compressor with a hard start kit will not growl as much at start up as one not using a hard start. The growl that it does have is a shorter duration with the hard start kit installed. I stay away from 2 wire hard start kits. They seem to fail at a higher rate than a hard start with the potential relay with it. Just my observation and opinion.
Great video ,every one should watch a lot of videos on power factor.
Great videos man!
Licensed tech out of CT
So glad to see another video from you. It's been a while. Thanks
Great video. Thanks
Explain to me why a unit has worked for many years, & now won't start without a hard start kit . It's because it's beginning to fail internally, probably bearings, I've put many on refrigerators, hundreds, & most work for years
GFM, 5-2-1 states that the relay must be installed with the mounting tab pointing up.
Do you have any information on whether this can be detrimental to the operation if the relay is mounted other than vertical with the tab up?
In any position other than straight up, the relay armature, which is dropped out by gravity, could hang up. If it cant drop out quickly, you will burn out the hard start kit.
A hard start put new life into my 20-year-old condenser
All Goodman condensers 2.5 ton or less come with a rotary compressor made in china and a factory installed hard start kit. I know because I had a new 2.5 ton installed 2 months ago. I thought all goodmans came with a scroll but after I had this one installed I found out different. Still has a 10 year warranty.
Caps change the wave by 90 degrees out of phase
Great video .My 10 year old system has a reciprocating compressor- The lights in the house started dimming on start (the capacitor was in spec). A hard start kit solved the problem. After watching this video, I am wondering it hard start kit will shorten the life of the compressor?
In your case, the hard start is probably a good idea. The light dimming is a result of a slow start and a slow start is worse than the increased starting torque.
GFM
Can you do an analysis on soft start kits like micro air? You should use one of those inexpensive oscilloscopes to show the amp surge and volts that occurs at the compressor.
What is your opinion of installing a soft start unit like the microair EasyStart to prolong the compressor life ?
Only if you need a soft start, I.e. high frequency inverters like I have. All of my 7.5 Tons of hp that are not inverter compressors have soft starts. Do not use a hard start or soft start unless you absolutely need it.
what about the weight of the liquid going up several stories? I also see systems run with half weak capacitors. With this logic a 35 cap might be better with a 25 if starts slower and no issue.
The goat of HVAC
For units with weak power supply,that blows run caps yearly,USA made,the hard start seems to make them last longer.IMHO.
My 3 ton r410 ruud system with a txv and scroll comressor came with a start cap and relay. It ran fine for years with a bad start cap. I replaced the start cap. Now i'm wondering if i should just let it run with the dual run cap? Great video
One question I couldn’t figure out is on any normal system, the more modern start caps are way bigger then older ones; years ago a 25 or 35 mfd cap was common, now they use 75 mfd or larger. Why is that? Is it just to get a phase shift that bigger for start?
The run capacitor's primary function is to make the compressor motor more efficient. The increase in capacitor size is the result of efforts to increase efficiency of the compressor. The start function did not need more strength.
GFM
@@grayfurnaceman thank you. Makes sense!
Agree with you 100%. I do not feel very comfortable when comfort advisors try to push customers to get hard starts added to their brand new systems.
I feel that hard starts should be used when the system gets to the point that it’s starting to have a hard time starting.
compressor starts maybe 10000 times in a cooling season less amps every time means lower light bill why not save a little money unless you got money to burn
Great info. Appreciate!
I have never installed a hard start kit on a good starting unit to me it's like a guy with a good heart and the doc says wat the hell let's put a pace maker in just incase waist of money and not good for the equipment
HVAC and 47 kW of solar guy. You’re 100% correct. Now for solar systems SOFT STARTS are the way to go.
My home is powered by 20 KW solar. I have used both normal and soft start on my A/C. It has not, so far, made any difference. The inverter is the Sol-Ark 15.
GFM
@@grayfurnaceman 2 12K’s for me. The high frequency inverter electronics will last longer if they do not have those high inrush currents on startup. Soft starts are the way to go, unless you have low frequency inverters like my shop system Schneider or my van system Magnum.
I agree with you grayfurnaceman. I'm going to pretend I don't know this so I can keep selling start kits😅
What company do you work for?
@@mandrcooling6714 Condensate Kings 👑 💧
Hard start kits help overcome improperly sized feeders to your condenser. Nothing else.
and low voltage from power company
I worked for a guy that fooled customers into buying these when there not needed. If compressor is starting fail then yes try to use one bit not just sell them.