Newer technology A/C systems

[s/v Jedi]

Y’all missed this one?
Inverter driven self-contained units 230V-50/60Hz VSD. Reverse cycle function

[GordMay]

Greetings and belated welcome aboard the CF, dougkimmerly.

[valhalla360]

Originally Posted by Pelagic

Something that has always confused me?
What is the proper abbreviation for Air Conditioner..... A/C or AC?
Also How does you abbreviate and differentiate it from Alternating Current......A/C or AC?

If it's not absolutely clear....air/con

[valhalla360]

Originally Posted by john61ct

Tens of thousands of years, billions and billions of humans say otherwise. Words really need to mean things.

What percentage of the population has to die before it becomes a "necessity".

Sure, the species has survived without air/con but in extreme environments, yes, there have always been deaths...particularly among the elderly...which a great many full time cruisers qualify as.

[valhalla360]

Originally Posted by TCM1968

The difference your not considering with this comparison is the variable speed ability. Yes it may be true that when both are at max output of 16000 BTU's then the amp draw is close to the same, but 16K BTU is only needed to bring the temp from temp A to temp B. Once temp B is achieved a significant less amount of BTU's is required to maintain that temp. These motors are way more efficient at slower speeds. You can't look at it as a straight give and take. Lets say the variable speed slows down to 8000 BTU speed but now runs twice as long to maintain the desired temp, the KWh's used will not be the same. The variable speed compressor may only be putting out half the BTU's but it can do that at at considerably less than half the wattage.

If you oversize your cooling system, this is true but a great many boats in hot weather wind up running flat out pretty much continuously.

Of course, I'm not buying if you drop output from 16k to 8k, you get more than a 50% drop in wattage. Usually, you see mechanical systems at peak efficiency when at max output...if there was significant efficiency gains running at 50% of max output, you would expect a lot of oversized systems being installed in houses...but you don't.

[john61ct]

Originally Posted by valhalla360

What percentage of the population has to die before it becomes a "necessity".



Sure, the species has survived without air/con but in extreme environments, yes, there have always been deaths...particularly among the elderly...which a great many full time cruisers qualify as.

Way too many people on the planet, humanity needs a lot more Darwin back in our lives.

But at the personal level, I would move to a healthier climate if it literally put my life in danger.

The systemic shock going between aircon and extreme heat is what's really stressful.

[a64pilot]

Originally Posted by valhalla360

Of course, I'm not buying if you drop output from 16k to 8k, you get more than a 50% drop in wattage. Usually, you see mechanical systems at peak efficiency when at max output...if there was significant efficiency gains running at 50% of max output, you would expect a lot of oversized systems being installed in houses...but you don't.

Actually with cooling systems this increase in efficiency at reduced power is common, look at our variable speed BD compressor fridges for instance their COP or (coefficient of performance) is significantly better at lower speeds. One reason is that al lower speeds the evaporator and condenser is significantly oversized, heat transfer is of course what is happening and the larger the transfer medium apparently the more heat that is transferred.
Last house I had, I had the most efficient cooling systems available at the time installed, each AC had two compressors, the big one when needed of course but the smaller one was about half sized and meant to run pretty much all of the time, that’s significantly more efficient that a bigger one cycling on and off.

Actually many things, even our Diesels peak efficiency wise about mid load, my 4JHE’s efficiency peak according to Yanmar is about 2500 RPM, it’s a 3600 RPM max motor.

[izzyforreal]

Originally Posted by TCM1968

I have a couple reverse cycle A/C units that need replacing. I am interested in the newer technology units that run with variable speed inverter compressors. I am curious as to why there seems to be little info on suppliers here in the U.S. Why hasn’t this technology become more mainstream yet? I was looking online at the advertisement of the Dometic Turbo units and this has been out since 2007. Surely in 12 years someone has improved their design. I don’t want to drop several thousand on replacing units with 12 year technology only to have them become the old style a year later.

I can tell you one thing; Inverter compressors in domestic refrigerators are, for the most part, junk. They have a very high failure rate and are expensive to replace.

Mark D

[Mauruuru]

The fact is that a BLDC motor isn't really a DC motor in the normal sense. It is a permanent magnet motor that uses Pulse width modulation of the input to obtain speed control and that is why the inverter is in the system to provide a conversion of battery input to the controller which provides the PWM output to the compressor and fan. Shorter pulse width = slower. The commutation of the windings occurs by the switching outputs of the PWM controller. More electronics, not necessarily more unreliable depends on quality but the motors are probably more expensive that equivalent squirel cage motors of the same HP.