How much diesel does the generator use while running?

[duneviper]

I have a 2021 DX3 37RB, and was wondering how much diesel the generator uses per hour of usage. I am sure someone has figured this out, thanks in advance. Also how much does the AuqaHot system use when running on diesel?

[RobbieH]

Before my trailer now, I had a Class A Monaco for 4 years. The generator and AquaHot ran off the 100+ gallon fuel tank. Consumption on both will vary depending on load and usage. I've boondocked for 5 days and 4 nights and barely used over 1/8 of a tank, and this was in the summer so the A/C units were running a lot, as was the fridge. Of course in the winter I would not have used as much on A/C but more on the AquaHot furnace to keep the coach warm. I have found that really the AquaHot doesn't use much fuel at all, and with over a hundred gallons of fuel for the generator, it barely makes a dent in the fuel even under fairly heavy usage.

Since yours is new, I'll tell you one "gotcha". If you run the fuel down to the point the generator shuts off to make sure you have a quarter tank to get to the station, you'll find that it's pretty darn hard to get your generator started and running the next time.

[TowPro]

its all related to BTU.
I use about 1 gallons of propane per hour to run my AC on my 3500 generator.
If propane has 91500 BTU per gallon, I took 91,500 to run for 1 hour.


diesel is about 137,000 BTU per gallon so to produce that same amount of energy I would expect to have to burn around 91500 BTU which means I would expect 1 gallon of diesel to run my generator for around 1.5 hours to carry the same load, based on same 3600 RPM generator design.

[bclemens]

Originally Posted by duneviper

I have a 2021 DX3 37RB, and was wondering how much diesel the generator uses per hour of usage. I am sure someone has figured this out, thanks in advance. Also how much does the AuqaHot system use when running on diesel?

I think Onan actually figured this out already. Per their data sheet.
https://www.rvtechlibrary.com/genera...0specsheet.pdf
The 8k is on there as well. (page 2 under the engine section)

[bclemens]

and so did Aquahot.
400D – Aqua-Hot Duel Fuel Motorhome Heating

[RobbieH]

It's still an "it depends" though. You wouldn't expect the generator to use as much fuel sitting doing a float charge on the batteries and running a couple of fans as it will if you are running both A/C units full blast all the time. Same for the AquaHot, if you are only using it for showers, that will be one usage but if it's trying to provide heat to the coach when it is 45 degrees outside, that's a different rate. I found you will get a feel for how much it's using as you do use it and watch the fuel gauge.

[duneviper]

That answers my questions, thanks bclemens. I am about to do our first cold weather dry camping this month and was curious since the fuel gauge in the camper is useless lol.

[bclemens]

Originally Posted by duneviper

That answers my questions, thanks bclemens. I am about to do our first cold weather dry camping this month and was curious since the fuel gauge in the camper is useless lol.

Well...unlike a normal car or truck, its pretty easy to verify fuel level. Open the fill and shine a light in there.

[duneviper]

that is true, but I may fall out of the camper going down the road trying to look down in there lol

[DynaDuo]

A little late to chime in here, but I just returned from a 2900 mile trip with our DX3 37BH. We had a mix of state parks and KOAs as well a destination of a famous racetrack in Texas. We ran generator and Aquahot a fair amount. We saw at most a little over a gallon per hour. Usually a little less. Hope this helps!

[Tom48]

Originally Posted by RobbieH

Before my trailer now, I had a Class A Monaco for 4 years

Since yours is new, I'll tell you one "gotcha". If you run the fuel down to the point the generator shuts off to make sure you have a quarter tank to get to the station, you'll find that it's pretty darn hard to get your generator started and running the next time.

I can second that. AND DO NOT BELIEVE THE GAS GAUGE. Mine said 3/8 tank when the gen quit. THATS WHEN THE GEN QUIT. It was correct. 72 gals to fill then a real struggle to get that 8kw with only 300 hours to start again. It took really good batteries and a lot of time and patience.

DON'T DO IT.

[Shawn M.]

Just an FYI in case you run your generator out of fuel;


Your generator has a built in prime feature. Push and hold the the rocker switch in the off/stop position and the fuel pump will prime/run as long as you hold it.

[vlamgat]

On some coaches the generator fuel pick up is set at a level that will not allow it to empty the tank. On the Born Free models this was about 1/8 on the gauge and I verified it, of the main 40 gallon tank of the F55.

Summer temps in very exposed parking areas, over 6 years with frequent if not continuous use of AC has resulted in an estimate of 3/4 of a gallon per hour, and no AC at 1/2 gallon per hour on 3 Onan generators of 6, 7 and 8 Kwh.

[duneviper]

Originally Posted by DynaDuo

A little late to chime in here, but I just returned from a 2900 mile trip with our DX3 37BH. We had a mix of state parks and KOAs as well a destination of a famous racetrack in Texas. We ran generator and Aquahot a fair amount. We saw at most a little over a gallon per hour. Usually a little less. Hope this helps!

Thank you, great information from everyone.

[johndjmix]

Interesting on the tank level on the gauge vs when gen quits. I have had my gauge down to almost zero, and still the gen runs for hours. In face ive never been able to get the gen to run out of fuel!

Keep in mind on the M2, when the gauge is at E you still have a little over 1/4 tank left.

On the road I start looking for fuel when I’m down to 1/8 tank.

—john

[duneviper]

That's interesting because when my light comes for the fuel gauge the most I have been able to put in the tank was 55 gallons. so still have at least 35-40 gallons left.