10 Important Things to Know About Your Aqua-Hot System 

By  Luann Street



If your motorhome has a hydronic heating system, also known as Aqua-Hot, this is an additional RV system to learn about and maintain.  This is one of our favorite upgrades in our motorhome.  Having one on your motorhome adds approximately $7,000 to the value of your coach.  If you are shopping for an RV this is an option you will want to would definitely consider.


10 Important Things to Know About Your Aqua-Hot System | An Aqua-Hot is a Hydronic Heating System for your RV | www.streetwander.com



10 Important Things to Know About Your Aqua-Hot System

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Here is a simplistic Youtube Video to help you understand what an Aqua-Hot can do for you.



Recently, Bryan attended the certified technician training for Aqua-Hot systems.  Since we have an Aqua-Hot, he wanted to learn more about it and make sure we were using and maintaining it correctly. He says the class was very informative and a great asset to his cadre of skills in his RV life. If you would like to take the same class you can travel to Colorado to take it at the Aqua-Hot training center.

After attending this training, we wanted to share tidbits that can help you in using and maintaining your Aqua-Hot system.


What is an Aqua-Hot?

An Aqua-Hot is a miniature boiler that heats up boiler type antifreeze (propylene glycol) to deliver heat to your motorhome in the form of interior heat and endless hot water.  It runs on your coach’s diesel fuel system or propane.

The Aqua-Hot system does three things depending on model:

  • Provides heat for preheating your engine – If temperatures drop below 40 degrees and you need to travel, you will need to preheat your engine using your Aqua-Hot for approximately an hour to make sure you are ready for the road. The Aqua-Hot can preheat an engine from 30 to 90 degrees in one hour.
  • Provides heat for your living space – this heat is very even and consistent front to back, top to bottom.
  • Provides heat for endless hot water.

The following tips can help you understand the needs of your Aqua-Hot and keep the system happy.

  • You can leave on your electric hot water to help your Aqua-Hot be more efficient and use less fuel.
  • Your antifreeze level must be maintained monthly to the levels designated on the side of the fill tank. If your reservoir tank registers empty, it is not enough to just fill the system, you may have to open the bleeder valve to release air out of the tank.
  • It is better to use your Aqua-Hot than to let it sit. The diesel fuel left sitting too long can clog your nozzle.
  • Run burner and heating zones monthly to keep your Aqua-Hot running smoothly.
  • Perform maintenance on your burner annually. The best time to do this is in the spring if you have winterized your coach.  This will help your system run smoothly for all your summer adventures.


You can get the maintenance kit if you feel you can do it yourself. Bryan says it’s a hard job and requires a certain amount technical knowledge to do it.  This handy list of RV tools can make sure you have the tools you need when doing RV maintenance yourself.

If storing your RV for the winter, you must winterize this system. You must use your typical winterization antifreeze to avoid damage to your system. Blowing air to clear the water from the system will not work. Not winterizing correctly can damage your system and could become a very expensive repair.

Be sure to check your propylene glycol annually with a refractometer to make sure to verify your solution is between 40 – 50% or at a -10 degrees.

If you are traveling and your Aqua-Hot won’t come on (start) three common reasons are:

The fuel tank may be too low.

The glycol antifreeze level is below the sensors

The power source may not be enough.

You should never buy a commercial showerhead for your RV because the output of gallons per minute is greater than the Aqua-Hot can produce hot water. The temp of the hot water is preset and not adjustable, so if you are experiencing less than desirable hot water check your showerhead.

Servicing your Aqua-Hot

If you need service on your system be sure to only go to an authorized service center for repairs. Authorized service centers have certified-trained technicians to service and repair this unique system. Click here to find an authorized service center near you.

The Aqua-Hot website is filled with lots of information to help you if you need it.  You can download your manual, register your unit, find service if you need it and even call Aqua-Hot and talk to a tech about problems you may be having.

We really enjoy having this system on our RV.  It is a more complicated system to understand but wouldn’t travel without ours now that we have it!  Also, if you are still shopping for an RV, consider a coach with this system, it is a very nice addition to your RV lifestyle. 😊

For more RV advice that will help you make the most of your RV life, get one our Get Started RoadMaps below. 

Choose where you are in your RV journey and get some RV tips to make your RV life designed the way you want it!  The RoadMaps are FREE – get yours below


Luann Street

I have a passion to help people who want to travel, design an RV life they love! I was a full-timer along with my husband, Bryan for 5 years. I am now learning to RV solo.

I have created many products that enhance and improve the RV lifestyle:
-The Complete RV Travel Planner
-Your Next RV Destination Membership
-The Full-time RV Framework
-Trading Stuff for Memories Downsizing System
-The RV Buying Method

Luann Street

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    1. Hi Mark, If your RV has an Aqua-Hot it can heat the water for your washer but doesn’t have anything to do with the washer directly. Hope that help1 – Luann

    2. Good info … But for shower head ….
      Not true at all, our aquahot never ever no matter what the use, of hot water, that what makes an endless supply and been using commercial shower head for 6 years .. to maintain glycol temp at 195 unless you only have 1 electric heater or even 2, then diesel burner will take over, but you have to have it on too ..

    1. Hi Randy! Are you talking about when you are driving down the road? Unless you are using the aqua hot for heat, you wouldn’t have it on while traveling. We have never done that, if we need heat while driving we use dash heat and/or our overhead heat, not the aqua-hot. If you have questions – you can call Aqua-Hot directly for answers at 800-685-4298. Hope this helps!

  1. My diesel Auqahot suddenly quit igniting!
    It will spoil up the fuel but never ignite!
    It was working fine then all of a sudden this problem arose.
    It was serviced by Tiffin in Red Bay in June with clogged line from previous owners not serving & running it properly which led to new (3) pumps installed and still wouldn’t work until Tech’s used a bigger pump to move aforesaid clogging. They got it working but now I’m handicapped and stuck in Jonesboro, Arkansas having doctors run tests.
    What could be causing it not to ignite?
    (After The Service they didn’t replace anything that was replaced prior to clogs being pushed out!)

    1. Oh Jack, I’m so sorry! It does sound like the line nozzle is clogged again! That is such a bummer. I hope someone can help you where you are….Aqua Hot Service is great…you might want to try them and see if they can direct you on preventing it from happening again. AquaHot’s phone number is 800-685-4298

  2. I order to keep the basement heated we need to run our aqua hot. Should we use the generator while running the aqua hot traveling down the road to keep things from freezing ?

    1. You shouldn’t have to run the Aqua-Hot while traveling. Your engine heat should be enough while you are moving down the road. If you still have questions you can call Aqua-Hot Customer Service at 800-685-4298…they are super helpful! Happy Travels!

    1. Hi David! We keep our electric water heater on all the time so we have hot water when we need it. We only turn on the Aqua-Hot when we shower so we don’t run out of hot water. The only time the Aqua-Hot is on all the time is when it’s cold and we are using it for our heat source.

  3. Why does my Aqua-Hot not heat my coach well unless I am running the diesel side for heat? The electric comes on and will blow hot air but it does not ever really heat the coach well. It’s 20 degrees outside and just replaced the diesel nozzle and filter etc. it heats the coach great on diesel and on the main engine but on just electric the heater only runs for 3 minutes or so. Not enough to really heat thoroughly.

    1. Hi Ric,
      In our coach, you have to turn on the AquaHot and you have to set the thermostat to gas (instead of electric) to get the AquaHot to run heat into the RV. Your rooftop heat pumps will not warm your RV in 20 degree weather. They are only designed to heat when the outside temp is above 40 degrees. Hope this help! Keep warm!

    2. The electric side of the aquahot will not raise the inside Temp of your coach significantly. It is designed to maintain the Temp. As a matter of fact if you raise your temp more than 5 degrees using electric it will call for the deisel burner. Watch your thermostat. It will start flashing “gas” it’s telling you to turn on the aquahot deisel burner because your asking for a significant heat increase that set in electric mode can not handle.

  4. Where is Aqua Hot antifreeze desapiring? Can’t find leakage anywhere but TWICE monthly, when coach is used, side antifreeze tank has to be topped up.
    Thanks, Mike

    1. Hi Mike! Aqua-hot has a great customer service line – we have used it several times. Good Luck!
      Aqua-Hot Technical Questions
      Aqua-Hot Technical service department
      Phone: 800-685-4298
      Email: [email protected]
      Hours: 7:00 a.m. to 4:00 p.m. Mountain time

  5. Our Aqua hot doesn’t shut off. We used the diesel on switch this am. Everything worked fine. Drove all day, got to our site and it is running. 2 hours later, it’s still running. Both electric and diesel switches are off. How can we shut it off?

    1. That’s a bummer! Call AquaHot…there customer service is great! Aqua-Hot Technical Questions
      Aqua-Hot Technical service department Phone: 800-685-4298 Call them- I hope they can help!

  6. Hello, do your coach batteries have to be in the coach for the aqua hot to work? it is firing up but none of the heat pumps are coming on. Its the only thing I can think of as I just did the mailtenance on it. No red lights. But orignally the low voltage light came on.


    1. Well, those purple monkeys keeps messing up our adventures don’t they! Sorry you are having trouble. Aqua Hots are great until something happens….just like everything else! Call AquaHot…there customer service is great! Aqua-Hot Technical Questions
      Aqua-Hot Technical service department Phone: 800-685-4298 Call them- I hope they can help!

  7. Our Aqua Hot does not shut off when on electric. Diesel seems to work fine – it shuts off when reaches temp. When electric is turned on it boils the anti freeze. Any clues? We have flushed and refilled the tank with new boiler anti freeze mixture with water. Changed thermostats and still have the problem. Thanks

    1. That’s a bummer! I wish I could help you but your best bet is to contact AquaHot customer service. There customer service is amazing! A tech can troubleshoot with you over the phone. Their number is: 800-685-4298 Best of Luck!

  8. New to Aqua Hot (450D). When we purchased the coach it was already winterized. We have an all electric coach. Can we turn on the Aqua Hot using diesel when dry camping with it being winterized to help heat the coach? Thanks,

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