I've got a big Oasis hydronic heating system on my coach and when I take long showers, I have to turn on the diesel burners. Ideally, I'd love to just leave the diesel burners on, however, I don't like wasting diesel fuel.When I'm parked and hooked up to electricity, my Aqua-Hot can heat the water from two sources, two 110 volt electric heating elements and from a diesel burner. When the water reaches a low temperature and the system calls for heat, it will turn on the electric heating elements and / or the diesel burner. I would like the system to use the electric heating elements first and only kick in the diesel burners if the electric fails to keep up with the demand.It seems like a waste of diesel for the burners to come on if the electric is capable of reaching the set point eventually. I would like to program my burners to come on only if the temperature is 2 degrees or so lower than the set point for the electric heaters. Does anyone know if this is possible?

I Would expect that yes, the diesel burner comes on when the fluid temp drops below what the electric can supply. At least my older one works that way.

We have the 450D Aqua Hot which only has one electric element so we just leave both the electric and the diesel burner switches turned on. I never feel like I am 'wasting' fuel if that is what it takes to heat our water and keep us warm.I was under the impression that the larger units (the 600 series) with two heating elements would provide enough hot water for a decent shower without using the burner. Suggest you post the question on Roger Berke's Hydro Hot/Aqua Hot forum. He will surely have the answer.RV Hydronic Heating Forum

The dual 120 electric Heat Element Aqua Hot units, "usually" WILL supply enough on demand hot water. That is why the larger units have the 2 Heat elements. But, the systems are designed to use the Diesel burner when the 120 or demand cannot keep up. If your Diesel burner comes ON, it is because it needs to for your demand. This is the operating for your system. You cannot change the parameters. DougUsing the Domestic Water Heating SystemWhen the Aqua-Hot is at operating temperature, the domesticwater is automatically heated as it is being used. Because theAqua-Hot does not store any hot water, simply open any hotwater faucet, and a continuous supply of domestic hot water willbe present within a few seconds. This hot water feature is continuousand is accomplished by the Aqua-Hot’s domestic waterheating system. The diesel-burner switch on the interior switchpanel must be ON in order to obtain a continuous supply of hotwater (e.g., during showers); be sure to also activate the electricelement switch, and place the “high/low” switch on HIGH formaximum hot water capacity.

Holstein13, we had the Aqua-Hot in our previous coach with the two electric element system and it gave us the hottest water, we never needed the diesel. Now, I'm talking for just two people, you have a whole family to serve.Our new coach has the Espar 83,000 btu heating system with 20 gallon hot water tank and a tankless heater for the shower. Just on electric, we have never needed the diesel for hot water.Another thing about our new coach is that we never have a fluctuation with water pressure. I can flush a toilet while the shower is being used and the pressure stays solid or flush both toilets and there is no reduction in flow. With our other coach, I had to be aware if the shower was on and I wanted to flush as it reduced flow a lot. MM.

I just realized I have the Oasis 34900, and not the Aqua-hot. Any ideas on that?

Can my Aqua-Hot pull from electricity first? | Good Sam Community

22 Replies

holstein13
Explorer
Feb 16, 2015
DSDP Don wrote:
This is your model here - CH50M

The CH50M has an 8 gallon tank
The Ch50V has a 16 gallon tank.

The smaller units are green, yours should be white.
Mines' actually green. I'm surprised that Newmar wouldn't put in the bigger unit in our 1.5 bath coach with dishwasher and washing machine, but apparently, it's the 8 gallon version.

I think that might explain why I've run out of hot water in the past on electric only. After reading your post, I've tried it with the winter loop off and told everyone to not use hot water while I'm in the shower. I was able to successfully take a decent shower with electric only.
DSDP_Don
Explorer
Feb 16, 2015
I read through my manual several times and it just didn't answer a lot of my questions. I called Oasis a couple of times and they were very helpful, but I didn't want to play 20 questions. It took some really cold weather to figure mine out, which we rarely see in California.
holstein13
Explorer
Feb 16, 2015
Golden_HVAC wrote:
It should work fine to heat only hot water and not the rooms. The electric is limited Btu rating, if it pulls 4,000 watts, that is limited to about 12,000 Btu's. The diesel burner seems to be 140,000 Btu's or about 1 gallon per hour input.
Golden, the label says the maximum BTU of this unit is 50,000. Does that mean that the burner can put out 50,000 BTU or is this the combined output of both the burner and the electric heating elements?
holstein13
Explorer
Feb 16, 2015
Thanks Don,

I downloaded the manual and read through it. The Newmar version is definitely slightly different in the controls. Also, the manual does a terrible job of describing the Summer / Winter loops. In fact, the manual doesn't even describe this feature at all.

Your write-up was far more informative than the entire manual. Thanks again for posting your information. It made a huge difference this morning when I took my shower. You're a great example of why I keep coming back to this forum for knowledge.
DSDP_Don
Explorer
Feb 15, 2015
This is your model here - CH50M

The CH50M has an 8 gallon tank
The Ch50V has a 16 gallon tank.

The smaller units are green, yours should be white.
holstein13
Explorer
Feb 15, 2015
dougrainer wrote:
Something I do NOT understand and not just you but others. You state you have no manual, yet you are on the internet asking for help. It took me 2 minutes to find and download the manual for your system. Their website IS listed on the pic you posted. Doug
Hi Doug, I'm very glad you brought that up. You see, the manual you found doesn't match my system. I don't have controls on it like the ones in the manual you found. As a matter of fact, I don't know what model of Oasis heater I have. If you look at the tag I photographed, you will not find any model number that corresponds to a model on their website. That's why I asked the question on this forum.

Now, my guess is that I have the CH50 that's modified a bit specifically for Newmar and I plan to call them on Tuesday morning to get the manual, but when I posted this, both Newmar and Oasis were closed so I figured I'd try here first. I'm really glad I did because I got some great information here that I would never have been able to get even if I could have identified the manual online. But clearly, the manual isn't online or it isn't easy to find.
dougrainer
Nomad
Feb 15, 2015
holstein13 wrote:
Ivylog wrote:
I understand what you're trying to do but if Doug says you can't change the parameters on the AHot, then you can't change the parameters.
I mistakenly said it was Aqua-hot when in reality it's Oasis. Here's the data sticker. I don't have a manual for this heater.

Something I do NOT understand and not just you but others. You state you have no manual, yet you are on the internet asking for help. It took me 2 minutes to find and download the manual for your system. Their website IS listed on the pic you posted. Doug

http://itrheat.com/wp-content/uploads/2011/08/Oasis_Service_Manual.pdf
Mr_Mark1
Explorer
Feb 15, 2015
Don, an excellent post.

MM.
Golden_HVAC
Explorer
Feb 15, 2015
It should work fine to heat only hot water and not the rooms. The electric is limited Btu rating, if it pulls 4,000 watts, that is limited to about 12,000 Btu's. The diesel burner seems to be 140,000 Btu's or about 1 gallon per hour input.

The best reason to not run the diesel burner in a campground is smell. Using it for only 15 minute shower should be fine, but longer use might not smell so good, especially if you are near the burner output flue gas. It might just smell, or it might have a lot of carbon monoxide, and trip the CO meter of the neighbor's RV.

Good luck,

Happy Camping!

Fred.
holstein13
Explorer
Feb 15, 2015
Thanks Don,

I think you just solved some major mysteries I had. Particularly with regards to the summer / winter loops. I noticed that my system hums when I switch to Heat and I never understood why until now. I can't wait to turn off the heat and take a shower with electric only tomorrow. I'm guessing it will work fine.

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Can my Aqua-Hot pull from electricity first?

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