HVAC hard start

[meackerman]

had my heater maintenance done today, they found that the outdoor unit an American Standard Gold series heat pump was drawing 134amps on startup when it should be pulling a little over 100.

They suggested a hard start be installed.


After they left, I got to thinking if its drawing that much over what it should be, isn't that indicative of some other problem?  A hard start is just masking that issue?

or is a hard start the thing to do?


it seems to work just fine.

[crokett™]

what did they mean by hard start?  have you seen my thread? is it the same thing? if so did they suggest a specific kit?

[meackerman]

what did they mean by hard start?  have you seen my thread? is it the same thing? if so did they suggest a specific kit?

hard start I think its a capacitor that takes the load?  as opposed to a soft start that's used with generators.

I'm not exactly sure the difference between the two.

[blackhat]

A hard start is essentially a big start capacitor and a relay to drop it out of circuit. It will increase the torque to get the compressor turning. They do solve a few issues and can extend the life of a compressor. If the unit starts fine now I don’t see the need. I have never used one as a precaution. I use them to get a few more years out of a system that has some issues.

[crokett™]

hard start I think its a capacitor that takes the load?  as opposed to a soft start that's used with generators.

I'm not exactly sure the difference between the two.

Ah.  my assumption was that pretty much all compressors have a start cap.

[blackhat]

Most compressors in residential HVAC units are PSC, permanent split capacitor, motors. They essentially only have a run capacitor and are low start torque motors. Hence the high inrush current on start up. A hard start kit converts it to a cap start, cap run hybrid with a higher start torque.

[meackerman]

so am I correct that the higher than expected amp draw on startup indicates some problem?

[blackhat]

Maybe. That’s a reading that I could duplicate just by being impatient and not allowing the system to equalize pressure between cycles. Tossing that number out without context is meaningless. Honestly, I wouldn’t sweat it without other indications of problems.

[meackerman]

Thanks.


every time I get the annual service they always want to upsell me something.

after I had a new system installed at my previous place, the company's tech came out to do the annual service and tried to upsell me stuff...to which I replied some like...if my brand new system needs that, why didn't my salesman say anything about it?  Do I need to call him and complain?  The tech shutup pretty fast.