Electric - OR - Gas ??

[Ford truck guy]

I will be dry camping this weekend at the track with the temps forecasted to be lower 90's . . I will be runnning the genny and wondering which setting to put the HW heater on? Last year I just turned it on to gas, buy really did not know any better.... My thought process was that it would have less electrical draw on the genny ...

[spindrift]

With a 6.5kW genny, you have more than enough capacity to run your electric water heater.

[travelin' texans]

Either way you're burning propane.

[MuddFlap]

If generator load isn't the issue, as Spindrift noted, then I would say the water heater is more efficient on gas. Reasoning: A typical gas fueled heating appliance is about 80% efficient. An internal combustion engine is about 20% efficient. Even though the water heater will be 100% efficient with it's electricity use, the amount of propane required to generate that electricity will be more than what the water heater alone would use.

[MuddFlap]

Oh yeah forgot to mention my sources. Heating appliance efficiency: I read it on a label on a water heater at a big box store.

Internal engine efficiency: I remember something about that in thermodynamics class once upon a time, in a land far far away.

[spindrift]

What's the end game here? To save $$ on propane? If the genny is already running, take advantage of it.

[Ford truck guy]

so I am hearing that it is 6 of one, half dozen of another . . Basically does not matter which setting . ..

[spindrift]

I must be dense since now I have absolutely no idea what you're trying to accomplish.

[MuddFlap]

Hmmm. Somehow I interpreted the original question to be a consideration of which option would extend the propane supply to last the duration of the camping trip.

[bergeman]

Each time you convert energy from one form to another, there is a loss.

So, my money is on heating water with gas is the most efficient. If you use electric, you are adding on more conversion step.

gas -> Heat

or

gas-> electric->heat

[atom ant]

Run it on both.

Assuming yours was like mine where the electric was set high enough to maintain the temp in the tank without the propane coming on. Setting it to run on both will allow it to automatically run on electric whenever your generator is on, and propane when it is off.

Efficiency has no bearing on the issue when the generator is being used to power other things such as AC. At that point, the electricity is already available so its near 100% efficient.

[spindrift]

100% convenient, or 100% efficient?

Either way, this is the proverbial mountain and mole hill discussion.

[Ford truck guy]

I will run it on both, thanks to all who answered.

[Romy]

I thought of tankless type myself. I did some research and yes, they can be fussy, and they need more servicing and maintenance, and they cost more, and a few other things that I came across that made me make up my mind that I would just buy another “normal” tank one of this type if I had to replace the old one.

[atom ant]

There are some RV tankless water heaters out there that use gas. I think Tiffen Phaeton uses one.

[johnboytoo]

Maybe because it was an early version,
but we had a Girard tankless in our 2012 5'er (before the Redwood) and it was horrible !

Changes in propane flow or water pressure or incoming water temp or the clouds in the sky seemed to affect the temp of the showers and dangerously so !!! Almost scalding to ice cold in a 30 second swing sometimes...
And this was AFTER the 'improvements' that the mfg came to us to do upgrades.


I trust they are better now than then !

[atom ant]

I never understood the point really. Our Redwood 12 gal seemed like endless hot water and once it was up to temp it took very little to keep it there. We only have a 10 gal now and I was worried, but still plenty.

[johnboytoo]

Agree, and why the new one has the standard 10 gallon heater too...

[mhs4771]

Good Friends have one in their new MH and say it's really fussy about the water flow rate.

[RCAircraft]

At the risk of getting tossed into the mountain/mole hill category, the EE side of me is begging for me to speak even though the dollars saved is minuscle, the consideration could be extending a run the store to refill the propane tank. Running the gen to produce power, is as some noted above very inefficient so....ooooo powering the hotwater heater directly with propane would reduce overall propane usage thus reducing trips to refill the propane tank which will burn more fuel for the vehicle trip to the store. Of course a run to the store could be combined with a more necessary six pack replenishment run which could be a far more critical factor in this analysis!!