Oasis Fuel Usage

[Jim]

I've been heating my coach using the Oasis, no electric. This morning, mostly out of curiosity, I checked the fuel gauge to see what kind of consumption there has been. From when I turned the Oasis on about 10 days ago, until today, it looks to have burned about 30 gallons of diesel. So that's about 3-gallons a day, which I guess isn't really all that bad, considering that it's been below freezing every day since I've been home.

Does that seem to be in keeping with what everyone else experiences?

 

[redbaron]

Seems high to me. Do you also have electric 1/2 on?

 

[Jim]

Seems high to me. Do you also have electric 1/2 on?

No, was using the burner exclusively.

 

[Neal]

If you're on shore power use AC I and/or II (electric elements) unless diesel burner is needed.

The continuous fuel consumption I believe is 1/2 gal per hour (again, continuous run).

I used mine over a winter in storage and it was about 30 gals for the entire winter. Now that I'm on shore power in storage I set my T-STATS to 50F and use only electric elements. I monitor temps using various sensors I have in the coach from these temp sticks to also my solar setup and its sensors.

https://www.amazon.com/gp/product/B01M1OPOZB/?tag=rvf01-20

 

[Rich W.]

I always leave the AC Heat switch on so whenever I’m plugged in, I only have to use the diesel burner as supplemental heat as needed. It’s quiet, doesn’t burn fuel, doesn’t affect the maintenance interval (although it probably does run the hour meter - need to factor that in) and is usually sufficient.

Also according to my understanding of the system (and there has been much debate on this), leaving the AC Heat switch on allows the pumps in the distribution box to run as long as the transfer fluid is up to temp (which it will be as soon as the engine warms up) providing hot water and cabin heat while driving. This also causes everything to be warmed on arrival. IIRC @Neal investigated this more thoroughly a couple years ago.

Anyway the point is, I leave my diesel burner off unless I need hot water or cabin heat while parked and don’t have shore power to plug in to, or have higher cabin heat or hot water demands while on shore power (really cold days or while using the shower). This allows me to use less fuel use and keeps the noise down.

 

[Neal]

Good point, if on shore power I see no reason why NOT to have AC I/II on unless there is a reason to reduce electrical loads. The burner will come on automatically only if needed. I think though in my case while in storage the system may struggle and not meet the 50F setpoint, but that's fine. I opt to not have diesel burner on while in storage if on shore power. Now if I get an alarm that the temp is below my alarm level I'll have to use diesel burner as backup.

But to the OP, I don't think 30 gals is accurate. Keep in mind these fuel gauges are not that accurate, at least mine falls of FULL pretty fast and stabilizes from there.

 

[MemoriesByTheMile]

30 gal seems high to me.

I find that the fuel gauge on our rig does not represent volume in a linear manner. Seems to represent the height of the fuel, and because the tank is a cylinder on its side, that first 1/4 of the gauge is much much less than that in volume.

 

[redbaron]

No, was using the burner exclusively.

When boon docking, the usage seems correct.

When on shore power, the demand of oasis is largely met by ac1/ac2.

Even better, use your heated floors. You will find the diesel is cycled ever 1-2 hours but runs less than 5 minutes. Greatly reduces overall costs.

 

[Rich W.]

Ok, I just re-read all 59 posts on the thread @Neal started at that other place in Oct. 2019. My new understanding, which I believe to be correct but will test anyway next time I drive the thing, is that the inside switches can all be off (power to the Oasis unit on of course) and you will still have hot water and cabin heat available from the Oasis system once the engine is up to temp.

It is also suggested that you pre-heat the Oasis system with either AC Heat or the diesel burner before departing, but this seems unnecessary unless you want/need heat or hot water in the first 10 minutes of driving. It would also seem to be irrelevant if you are leaving a site where you were plugged in, or even boondocking. @Neal, care to comment/clarify?

Another thing I didn't consider is that leaving the AC Heat switch (either AC I or AC I & II) on while traveling could put extra stress on the contacts in your transfer switch when you plug in since it can create an instant electrical demand if the transfer fluid isn’t already hot enough (from engine heat). I‘m not sure how this would occur, but it’s something to consider.

So on my next trip, my method will be to turn the AC switch off when breaking camp, and back on after plugging in. It seems to me that this method will work as my AC Heat switch selection up until now has been somewhat random, but I think I always have hot water on arrival. @Neal?

 

[Neal]

I don't remember what I wrote but I can say whatever I wrote may or may not be accurate as I'm always learning and this OASIS system has been one to learn and there are a lot of myths out there as with other things with these RV's. Facebook groups is a real indicator of how poorly we all are trained on these systems and why I mentioned on this site somewhere that someone or a dealer could produce YouTube videos and really help educate on these systems. Newmar for example could and should do YouTube videos on every system they have in their coaches. Would probably dramatically reduce their call center volume.

For driving with OASIS AC I / II don't do anything unless the GEN is on. They are 120V circuits.

In winter if you want turn diesel burner on while driving you can but it won't run when the engine is up to temp and supplies the heating of the OASIS fluid.

When in storage on 30A you can use AC I. On 50A I or II and/or diesel but diesel will only run when AC elements can't do what the demand calls for.

Diesel consumption is 1/2 gal per hour of continuous run I believe, maybe it was 1/3rd, but it parallels the GEN fuel consumption. The diesel burner probably runs a total of 4-6 hours in a 24 hour period I'm guessing (continuous time) if even that. As we know it cycles short periods and is highly effective.

That's what "I know" which doesn't mean any of it is right, but that's my understanding after 5+ years with the system. And far too intimate knowledge of the wiring after multiple shorts and one replaced relay and doing annual service annually.

 

[MemoriesByTheMile]

So on my next trip, my method will be to turn the AC switch off when breaking camp, and back on after plugging in. It seems to me that this method will work as my AC Heat switch selection up until now has been somewhat random, but I think I always have hot water on arrival. @Neal?

^^^
This is what we do, part of our “tear down” checklist.

The Oasis system works effectively, but like everything else on the RV, provides an opportunity to constantly learn.

 

[Jim]

When boon docking, the usage seems correct.

When on shore power, the demand of oasis is largely met by ac1/ac2.

Even better, use your heated floors. You will find the diesel is cycled ever 1-2 hours but runs less than 5 minutes. Greatly reduces overall costs.

Learning as I go along! I didn't want to run the heatpumps constantly, so I figured I'd give the Oasis a shot and see how it performed. And it performed well, just hasn't been all that cost affective for what I'm trying to do.

I'll try the AC1/AC2 setup for a couple of weeks and see how that works.

 

[NWIP]

I would say floor heat is a great source for heating the interior.
On diesel fuel usage back in 2017 without floor heat I ran the oasis burner for about 3 weeks with temperatures barely getting above freezing I used about 40 gallons. This was a 40’ DS. Just an FYI on usage

 

[redbaron]

Learning as I go along! I didn't want to run the heatpumps constantly, so I figured I'd give the Oasis a shot and see how it performed. And it performed well, just hasn't been all that cost affective for what I'm trying to do.

I'll try the AC1/AC2 setup for a couple of weeks and see how that works.

Just to be clear..ac1/2 is the electric element of the oasis, not the heat pumps

 

[Jim]

Just to be clear..ac1/2 is the electric element of the oasis, not the heat pumps

Yes, understood.

 

[MemoriesByTheMile]

Learning as I go along! I didn't want to run the heatpumps constantly, so I figured I'd give the Oasis a shot and see how it performed. And it performed well, just hasn't been all that cost affective for what I'm trying to do.

I'll try the AC1/AC2 setup for a couple of weeks and see how that works.

I’ll be curious if AC1/2 works for heating your coach. For us it does not put out enough BTUs to heat the interior air, only the water. IIRC, 50,000+ BTUs on the diesel burner vs 5,000 on AC1 and 10,000 on AC2.

But, heated floors will maintain the Coach temp approx 25 degrees above the outside temp if it isn’t too windy.

 

[Rich W.]

I’ll be curious if AC1/2 works for heating your coach. For us it does not put out enough BTUs to heat the interior air, only the water. IIRC, 50,000+ BTUs on the diesel burner vs 5,000 on AC1 and 10,000 on AC2.

But, heated floors will maintain the Coach temp approx 25 degrees above the outside temp if it isn’t too windy.

I find that a small electric “cube“ heater in the kitchen area is better for maintaining a comfortable overnight cabin temp because it puts put enough heat and doesnt make near the noise of the Oasis fans, much less that of a heat pump. If I had heated floors I would try that first to enjoy absolutely quiet heat. The slightest noise wakes me up so cycling fans of any kind are a problem for me.