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Uncle Dave · 07-09-2011, 09:52 AM

Looking for Known red flags in a project like this.

Heres the scoop.

I have a 98 beaver monterey 36foot diesel pusher.

The run time and economy on my fixed speed Onan 6300 is pretty bad. It gulps about .65 gallons an hour idling and around 1+ gallon an hour under any kind of load. This rips through my onboard 40 gallons pretty quickly.

I live in so cal and its always hot and need to run roof air a lot while driving and I boondock regularly where air is needed.

I dont have the space for a 6-8KW quiet diesel unit in my 36 footer. This was first choice. at 350+ pound plus a physical package 1/3 larger it just isnt going to happen.

The best option I can find in a propane genny in like wattage is the Yamaha 6300 inverter genny converted to propane. This will about double the run time I'm getting now and result in a quieter experience and vastly improved economy.

Based on what I can find about the yamaha will idle at about .2 gallons an hour, and run a single ac at well under 1 gallon an hour more like .4 roughly double the economy.

Id also get 240V Ac from this genny although I really have no onboard use I know of for it. (I know all 50 amp coaches are 220-240) to some extent but dont think anything in the coach is really 220.

I have a handle on the mechanical switch to fire it from the coach.
I have a handle on the exhaust piping.
I have a handle on the mounting of it

I need info on converting from liquid propane feeding the Onan to vapor propane.

Anything else anyone catches electrically would be helpful as well.

I already have solar- and its not an alternative for my intended use.
Solar works great for me when camping in the winter here.

Thanks!

Uncle Dave

John Hilley · 07-09-2011, 12:06 PM

I think you only have to pull it from the top of the tank rather than the bottom to get vapor rather than liquid.

Uncle Dave · 07-09-2011, 01:08 PM

Quote:

Originally Posted by John Hilley

I think you only have to pull it from the top of the tank rather than the bottom to get vapor rather than liquid.

I have a vapor tap on the top of the tank now,that feeds the Fridge and cooktop.

Im guessing Id just plumb a T in there.

..... or can you convert liquid back to gas at the genset with one of those disk looking things?

Uncle Dave

She and I · 07-09-2011, 02:00 PM

Quote:

Originally Posted by Uncle Dave

I have a vapor tap on the top of the tank now,that feeds the Fridge and cooktop.

Im guessing Id just plumb a T in there.

..... or can you convert liquid back to gas at the genset with one of those disk looking things?

Uncle Dave

Johns right Uncle Dave,...Pull liquid from tank, if the gen is already LP as you say make sure you get the mixer and the regulator, I think a 6500 gen is to large for vapor, Sounds strange to draw liquid then convert to vapor...but the volume is what is needed for the larger gen..to run properly, I don't know how much savings and if it would be worth it. The fuel numbers you stated were for LP?...I would do more checking but this is a start...

Richard

Uncle Dave · 07-09-2011, 05:08 PM

Quote:

Originally Posted by She and I

Johns right Uncle Dave,...Pull liquid from tank, if the gen is already LP as you say make sure you get the mixer and the regulator, I think a 6500 gen is to large for vapor, Sounds strange to draw liquid then convert to vapor...but the volume is what is needed for the larger gen..to run properly, I don't know how much savings and if it would be worth it. The fuel numbers you stated were for LP?...I would do more checking but this is a start...

Richard

Which Fuel #'s the Onans or the Yamahas?

I was surprised when I saw the Yamaha wanted vapor vs. liquid.

I have an email into the company selling the converted genny with questions.

UD

She and I · 07-09-2011, 05:39 PM

Quote:

Originally Posted by Uncle Dave

Which Fuel #'s the Onans or the Yamahas?

I was surprised when I saw the Yamaha wanted vapor vs. liquid.

I have an email into the company selling the converted genny with questions.

UD

The Yamaha fuel numbers.....I looked at Onan 6.5 on LP and it said 3.9 #s of fuel per hour 50% load.....Lp weighs 4.2 #s per gal... That Yamaha must be stingy on LP...If they say it runs on vapor it might be a dual fuel,gas and LP...
Richard

Uncle Dave · 07-09-2011, 05:53 PM

Quote:

Originally Posted by She and I

The Yamaha fuel numbers.....I looked at Onan 6.5 on LP and it said 3.9 #s of fuel per hour 50% load.....Lp weighs 4.2 #s per gal... That Yamaha must be stingy on LP...If they say it runs on vapor it might be a dual fuel,gas and LP...
Richard

Got the yamaha #'s from the conversion company.

The Yamaha is stingy- it's an inverter so it matches rpm to load.

I looked at my Onan 6300 emerald spec from the manual and got a direct gallon per hour rating vs the pounds.

The yamaha is a tri fuel deal converted by a third party.

UD

She and I · 07-09-2011, 06:03 PM

Quote:

Originally Posted by Uncle Dave

Got the yamaha #'s from the conversion company.

The Yamaha is stingy- it's an inverter so it matches rpm to load.

I looked at my Onan 6300 emerald spec from the manual and got a direct gallon per hour rating vs the pounds.

The yamaha is a tri fuel deal converted by a third party.

UD

That would help in cold weather, you could start it on gas and then switch to lp

Uncle Dave · 07-10-2011, 08:31 AM

Quote:

Originally Posted by She and I

That would help in cold weather, you could start it on gas and then switch to lp

I'd probably keep it on propane the entire time I ran it in the RV.
I dont really have "winter" to deal with here.

Does your mail suggest I may have a starting problem in cold weather?
Ive always been amazed how quick quick my propane genny fires off.

Here is my tank setup, everything is well labelled, but tight in there.
I think I can just T another line after the vapor regulator.

Uncle Dave

Uncle Dave

pkunk1 · 07-14-2011, 08:49 PM

My propane powered pickup starts just fine at -20°. The liquid to vapor converter/regulator is a common item for propane fueled gensets and provides better fuel flow in a high demand situation. Your existing vapor regulator would not be adaquite for the amount of vapor the genset would require especially if you wanted hot water and stove.

patty98311 · 07-15-2011, 10:19 PM

One thing you might look out for is if you have a cooling issue, I converted a Honda/Winco trifuel generator to replace my deisel Onan when it went bad. My only issue was with cooling which I solved by installing a Corvett cooling fan to provide more cooling which did solve my problem. I did not ever get around to tapping into the LP system and just used the Gasoline side, it worked well and was able to easily supply all needed power to operate both a/c's(it was a 6KW unit).

Uncle Dave · 07-16-2011, 09:49 AM

Quote:

Originally Posted by patty98311

One thing you might look out for is if you have a cooling issue, I converted a Honda/Winco trifuel generator to replace my deisel Onan when it went bad. My only issue was with cooling which I solved by installing a Corvett cooling fan to provide more cooling which did solve my problem. I did not ever get around to tapping into the LP system and just used the Gasoline side, it worked well and was able to easily supply all needed power to operate both a/c's(it was a 6KW unit).

Did you have any issues with grounding?

Does your RV use gas or diesel?
The reason Im looking to tap the propane is that I dont want to carry a third fuel with me and I don't like carrying gasoline in enclosed environment.

I was wondering about cooling but if a constant speed onan 6300 stays cool wont a variable rpm Yamaha run even cooler? ...OR maybe it really doesnt run cool at all and needs help?

Uncle Dave

patty98311 · 07-16-2011, 05:19 PM

That was my old RV that I performed the mod on, it was a 94' Allegro diesel (5.9 Cummins) with a diesel generator that went bad. The Onan gen was liquid cooled that went bad. When I first replaced it with Honda/Winco gen I did not add any extra cooling(it was an air cooled unit) as long as we were moving I had no cooling issues, not moving the unit appeared to me to be getting ecessively hot(it never shut down due to heat). The generator was a trifuel generator that will run off LP/NG/Gas, I only used the gas portion but all the systems required for LP operation are included. I used the generator on gas for about 2 1/2 years with no problems or heating problems after I installed a radiator cooling fan above the generator. The biggest issue I believe about cooling is that the compartment for the generator severely limits the natural circulation of air away from the generator due to the closeness of the compartment.

As for your question about grounding, there was a grounding strap that went from the engine case to the frame of the generator, I just extended it to one of the bolts that I use to mount the genny to the frame of the RV.