Why would a commercial air conditioner be more dependable than one for a house?

I’m not sure I understand what you are asking. But commercial grade equipment is always built to more rigorous standards than your average consumer goods of comparable functions. And the price for such quality is correspondingly higher—usually much higher. That final sentence of yours throws me, but yes commercial units will have more powerful compressors along with bigger fans evaporators snd condensers. The combination will bring the ambient temperature down more quickly and the unit will cycle for shorter periods of time.

Sadly the word commercial is used as a selling point these days when nothing is commercial about the product. But sometimes you do get what you pay for.

Consumers are a lot more hip these days. If you don’t know your way around appliances, it damned sure pays to have someone you can turn to who does.

No.

That fact that it is over sized and runs less, tells me the unit was sold for maximum profit to installer. Maybe a leftover at shop.

Oversized A/C’s cost more upfront and don’t do as good a job of reducing humidity (not running means not reducing moisture).

I talked to my daughter and she said it isn’t a commercial a/c; that it’s an a/c for a 5K plus sq ft house that a very close friend of hers, who works in the a/c and heating business had that she could get at a discount from him. His entire family are friends of hers since first grade! And yes; it did cost more than what her house needed but then she added a theater room onto the house so it worked out great.

Just because it is way larger than what is needed for the size of the house does not make it more dependable.

Where I work, we needed a huge amount of AC to handle all the computers and (old) monitors putting out heat around the clock. We had the AC people out to work on it at least once a week.

I thought it would be dependable because I thought it was a commercial one. But it is just a brand new one for a large house. Not one thing has gone wrong with it yet.

What do you mean it turns off in the summer instead of constantly running? Doesn’t she have a thermostat setting?

I mean ours runs almost continually all summer, she lives near us and hers just comes on every twenty minutes then turns off. And her thermostat is set pretty low, too.

Well, it could be you have the thermostat set too low. It’s a 110 and she’s trying to keep the house at 60 or something.
Or she has crappy insulation.
Or the air isn’t flowing between the intake filter and the blower.
It could be due to a lot of things other than a bad AC.

There could indeed be several reasons for the differences in performance between the 2 units. So many in fact that the only way to draw any meaningful conclusions would be to test each unit in the same structure under similar weather conditions. Not a particularly practical solution. As an alternative, why not gather the make and model numbers of the 2 air conditioning units and google their specs. That should tell you everything. Come to think of it, the information should be listed in whatever instruction/warranty manuals that come with the units.

@Aster The fact that your ac runs constantly is not a good sign. But are you certain that it is the refrigeration unit that is chugging constantly or merely the evaporator fan?