This really is pretty basic stuff and should be obvious

And also is wrong

Once steady state is achieved (the condition in which the inverter unit winds down), the air conditioning unit output, averaged over time, equals the heat loss (or gain, if we are in the summer) through the room walls. This heat loss depends linearly and exclusively on the temperature difference between the room (chosen by the user) and outside (determined by the weather), and insulation resistance of the room walls

The air conditioning unit has no effect on the heat loss. In case of an on/off switching unit, the hysteresis beween the on and off temperatures is way less than the temperature difference between indoors and outdoors, so in average it still has no effect on the heat loss

The air conditioning unit then must pump the same quantity of heat/time unit in or out to maintain the temperature difference constant. Heat is energy, heat per time unit is power

Consider 2 compressors with identical COP but different power. One is of the exact power required to counter the heat loss, and the other is 2x the power. The 1x one will work continuously, the 2x one will work with 50% duty cycle. Twice the power for half the time is the exact same energy

So no, thermodynamics absolutely don't confirm this basic stuff



Now let's look at the electrics :

The on/off unit has a simple induction motor. There is no principal limit on the efficiency of such motor. Having to work only in a single set of conditions (same power, same refrigerant pressures, ...) it seems obvious to optimize this motor for working at this exact set of conditions

Limiting the efficiency of such motor is only cost - If using a bigger motor with room for thicker winding, Using lowloss steel in the laminations, etc. The motor can be made to any desired efficiency

The inverter unit has a similar induction motor. It is basically a plain 3 phase motor, though most of them are not for 50/60 Hz but for somewhat higher frequency

Higher frequency allows for smaller cores and less turns in each winding (which means thicker wire can be used in the same motor size), same as in lighting ballasts. However, there are few parts that can pull efficiency down as well :

 - The stator is still made of laminations, which dont behave well above few 100s Hz. (Eddy currents, hysteresis losses, increasing loss in general)

 - The motor must work efficiently in a broad range of speeds and pressures. Is it optimised for the exact ones at which it'll run in your case ?

 - The inverter itself also got losses

Considering that 50/60Hz induction motor efficiency is typically 85%..90%, this gives the theoretical upper limit of energy you might save if the inveter and inverter powered motor would be 100% efficient

In reality, the motor is probably closer to the same 85..90% as the other motor, and the inverter has a few % left behind as well



And at the mechanics :

Running at higher speed (due to higher RPM motor) allows pumping the gas faster, or at the original speed but with smaller pistons

Smaller pistons and all the other mechanical bits have less friction surface, however they work faster for the same output, so the friction loss happens more times

Similar considerations would apply to other compressor types as well (Scroll, vane, etc)

I am not sure how the less surface vs. faster running exactly balance vs each other

Same as with the electrics, the mechanics are the same in principle and only differ in size. Both have losses of the same order of magnitude



At this point, it is no longer about any significant energy savings, but other things :

 - Cost cutting. We have reached the point where a complete inverter circuit cost is cancelled out by the savings on smaller and cheaper motor and mechanics which have to work faster. (And question remains whether the mechanics will last as long as the bigger slower running ones)

 - Blatant shoving of advanced technology everywhere it is not needed

That’s what I’m wondering as well. There aren’t any others nearby to check, but I had thought I heard at other stores they weren’t on clearance.

I remember they clearanced them in the past when switched from the Sylvania brand to GE, but that doesn’t seem to be what’s happening this time, and then it was all bulbs.

Yeahhh!

Yeah haha, gone now.l sadly.

Dang, if only the price was lower

They are truly beautiful!

There was one on ebay about a year ago in working condition, looked great too, just $2000

Have you been to any other Lowe's stores if they're doing the same thing? I might check them out soon if this is happening to other Lowe's stores and pick up a few modern HIDs that I might not have yet or as possible spares. I was at one recently and didn't see any HIDs on clearance.

Just a side note about their life expectancy when in used dusk to dawn mode in street lights. We have 5 heritage lanterns with SDW-T 50W lamps still in use. The first failed lamp we notice after 3 years. We always replace all lamps together after the first has failed. As the lanterns are situated along the river they are cleaned thoroughly. Some ballasts and controllers are still original from 1987/88 with brown resin potted inductor and large electronic controller. The newer ones are the grey painted chokes and smaller potted controller.

I noticed lately that all the remaining HID (MH and HPS) and fluorescent (tubes, CFL, circline and PL) at Lowe’s have been on clearance. I grabbed a circline for my bedroom fixture and a 70 W Lucalox HPS for my NEMA last time. Decided to go again tonight and they were gone. Looked around and everything had been moved to a tall movable cart in another aisle, so grabbed a few more.

My guess they’ll be donating what’s left soon and it’ll all wind up at Habitat. I guess this is it for that selection at Lowe’s.

High wattage incandescents still remain. Oddly some LED circline retrofits on clearance cart as well.

Ooh, heard those are pretty much non-existent nowadays.