RV Fuel Issues & Prices - Post 'Em Here!

Fezziwig

Actually heat pumps are not greater than 100% efficient as nothing can be. They get greater heat input than the power for the compressor.

Work out/Work in has more inputs. In the end there are losses.

Speaking of upside down, the efficiency I was talking about was that of the solar panel, not the AC. Had you not seen the temperature data from the Univ of East Anglia the gold standard of global warming showing that there has been no warming in the last decade and a half? Getting your "science" from those treehugger website always leads to confusion. Hope you are not too affected by the snow and flooding in your area. I know you could use some global warming now.

pianotuna wrote:
Hi Lindsay,

I don't know why, but my 13500 btu ac only draws 960 watts (measured with a kill-a-watt unit).

Heat Pumps always have efficiencies greater than 100% because they suck even more heat out of already-cold reservoirs. Usually about 300% to 1000%. Otherwise they wouldn't be much use, would they? Huge shopping centers use heat pumps to control electrical costs.

It's an old trick in freshman Physics course tests when students are just learning the Carnot cycle to ask them to calculate heat pump efficiency. Most of them turn the equation upside down so that they get a more satisfying percentage less than 100%. But they are wrong. Heh heh heh. Happily, they never make THAT mistake again!

A little lesson there: the science is right and your seat-of-the-pants beliefs are wrong. Please apply that to the current Global Warming 'controversy'. Some people see things upside down. Trust Science.

Looks like some do not understand the hows and whys of solar. Batteries are an int regal component for any system. Out here in the west we see much more usage then just 2 years ago.

And you can get 1,000 mpg on your vehicle too. Why are so many people leaving then?

Looks like some do not understand the hows and whys of solar. Batteries are an int regal component for any system. Out here in the west we see much more usage then just 2 years ago.

LindsayRichards wrote:
I don't see a 1,000 solar panel running a 960 watt AC. That requires nearly 100% efficiency and that won't happen except under the most perfect conditions.

And then only during the peak four hour period of the day.
In addition to running the air, the oversize battery would need to get charged to run into the evening. I figure 3000 to 5000 watts of solar to actually accomplish this. Of course if the panels are mounted over the RV it will reduce the cooling load by also providing full shade ;)

Hi Lindsay and Del,

I can already run the air conditioner from my battery bank. It is one reason I chose marine batteries.

I think you would have to charge about 3 hours for every hour of running. Need some hefty batteries. (AGM)

The starting amps being 250% of running get you with it's inherent voltage drop. Because the compressor cycles so often a capacitor would not have time to recharge even if power were available.

I don't see a 1,000 solar panel running a 960 watt AC. That requires nearly 100% efficiency and that won't happen except under the most perfect conditions.