What size generator to run AC??

Gdetrailer wrote:
Regardless, propane is overall less desirable "alternative" to gasoline when it comes to loss of wattage (the terminology you are looking for is "DE RATED").

Propane contains LESS energy per GALLON than gallon of gasoline.

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to build a trailer to haul a 250 gallon propane tank with you you are stuck with retail by the pound pricing.

Propane gens also have additional demand regulator, which can foul up, propane doesn't vaporize fast in cold temps which can cause fuel starvation and can even stop vaporizing in cold temps..

Propane isn't always propane, some areas you may get butane at a higher mix in your propane and butane is less BTUs and burns at a slower rate which affects just how well your engine performs and final wattage output.

Something else to consider, "dual fuel" setups are a "COMPROMISE" and overall most small engines are built and tuned for gasoline, the timing and compression are typically optimized for gasoline and not propane..

It sounds good on paper, but in real world use, a compromise is a compromise..

If you don't mind moving 20 lb to 30 lb cylinders (which weigh 38 lbs and 58 lbs each respectively) all the time while camping then have at it, but myself that sounds like a real hassle..

Some of you guys are really way over dedicated to making camping a lot more about doing chores than relaxing.

If you are trying to operate on a single 2000-2200w generator, the derating is an issue as you are marginal running the air/con at the full gasoline rating. When talking about a 4500w generator or a pair of 2000w generator's ganged together, the derating is irrelevant as it's still more than enough power.

Yes, propane is less energy dense but propane is also cheaper per gallon. Largely it's a wash (or close enough that I don't care):
- 4.6gal propane (#20lb tank) is equivalent to 3.4gal of gasoline in terms of total stored energy. I paid $20 to fill a 20# tank last week. At current prices, that would be $17 in gasoline. I don't run the generator 24/7 for weeks on end, so it's close enough as to not matter.
- If you are comparing to a 250 gal propane tank, you would need 185 gal gasoline tank...neither is a great option when mobile though if you are talking about a seasonal site, lots of propane places will drop a big tank for free if they can bring the truck by and fill it up for you (In fact, we have friends who did just that).

Extreme cold is an issue at peak loads but I don't usually run the air/con in those conditions.

Any place with lots of butane in the mix is not going to have extreme cold. Of course, in N. America, it's largely urban legend with most places having less than 5% even in warm areas.

Yes, propane cylinders weigh a little more but it's lift out of the truck and set next to the generator...done. With the 5 gal jug, I then need to hold it up while pouring, using the asinine eco-spouts that require 6 hands to operate and still drizzle fuel over the top of the generator for 2-3 minutes...so as you say...on paper it sounds good being lighter.

But really the driving issue is reliability. Propane is far less likely to gunk up. Even if after 10yrs, the regulator fails, that's a 5min replacement to swap out with a new one. I fought with the old Yamaha gas generator for a couple years surging. Even had a couple small engine guys try with limited success. $300 for a new carb that will gunk up again or sell it for $300 and get a bigger dual fuel unit for $800.

Yes, there are use cases where gasoline makes sense but for your average RVer who uses it a few days per year, propane is really the way to go.

PS: With dual fuel, I can always revert to gasoline if I do run across a use case where gasoline is preferable.