The addition of an Aqua-Hot or hydronic heating system to your RV is a valuable one. While they are usually factory additions, they could add around $7,000 to the value of your vehicle. Working with this system is excellent once you understand how it functions. If you are considering whether to invest in this upgrade for your RV, you’re in the right place.
Let’s dive into the Aqua-Hot or Hydro-Hot system now.
Table of Contents
What Is Aqua-Hot?
What is an Aqua-Hot system? It may be complex, but it’s fascinating how the whole process works. The system provides heat and hot water inside your RV, no matter where you are parked.
These are boiler-based systems that use a special antifreeze solution to circulate heat into the coach.
In addition to heating the air in the coach, the system also heats the water. With this setup, you could wash the dishes and take a hot shower without waiting for the water to heat up again. Aqua-Hot is the icing on the cake when you’re into “glamping.”

The Aqua-Hot system will also preheat your diesel engine when you’re traveling in cold climates. It can run off the heat from the engine, an AC plugin, your generator, or the RV’s diesel burner. The power versatility means you’ll never have to go without a warm cabin and a hot shower.
How Does a Hydronic RV Heating System Work?
The Aqua-Hot hydronic RV heating system transfers heat from various energy sources into a liquid antifreeze solution. Frequently the heat sources are electric elements or a diesel boiler but sometimes it can be propane as well. The hot liquid flows through system loops within the RV that flow past a series of vents inside.

Small fans pass air through those vents that is warmed by the hot liquid, giving the interior of the RV a pleasant and even temperature throughout each room. Usually, there are many zones that are controllable so its easy to control the heat.

However, that’s just one part of the Aqua-Hot system. In addition to heating air it also heats the water in the coach. Before the hot liquid passes into the interior heat exchangers it goes through a water exchanger to transfer the heat into the water supply. This in turn can provide unlimited on-demand hot water as long as the boiler is running.
The hydronic system can also pump heated fluid into your diesel engine to preheat it before hitting the road. This feature is especially helpful when you wake up to freezing temperatures but need to get on the road in a hurry.

In addition to all this, the system also can use the preheat circuit to get the heat off the engine while driving. The system works in reverse taking engine heat and heating the boiler fluid. This way the coach can be heated through the air exchangers while driving.
The versatility of the system is impressive.
Pro Tip: We found 7 of the Best RV Water Heaters that we think your RV water system would benefit from!
How Do You Fill Aqua-Hot?
Since the aquahot is a hydronic system it has its own working fluid that is sometimes called coolant, antifreeze or boiler fluid.

The system will have an overflow tank somewhere nearby that needs to be kept at the recommended fill line. You dont want this too full as its also used for system fluid expansion.
If you’re looking to refill or flush the coolant in the system, that’s a much more technical question. It is also a question you should know the answer to before purchasing an Aqua-Hot heating system.
You should flush and replenish the coolant in your system every two years to keep it well maintained.
You’ll have to drain the coolant, mix some fresh fluids, pump the new coolant into the system, and flush the excess air from the lines to complete the refreshment. If you need a thorough walkthrough, you can find plenty of “how-to” videos on the subject online.
How Long Does It Take for Aqua-Hot to Heat Water?
If the system is already hot, you will get hot water to your taps in a matter of seconds. If the primary burner is on it should last as long as the tap is on.
A full heat up with your Aqua-Hot heating system including air vents could take around an hour, depending on the circumstances and size of the system. The system will heat up faster when switching on the electric and diesel power sources.

How Do You Winterize an Aqua-Hot System?
Winterization of the hydronic heating lines is not necessary because they utilize a an antifreeze solution that will not freeze. This is why its critical to use the correct fluid in the system.
The water heating size of the system will need to be winterized, however. This can be accomplished by blowing out the lines or flushing them with antifreeze. If you expect freezing temperatures be sure to do this or you will have serious damage to the system.
Pro Tip: Prep your RV for the cold with these tips on How to Heat Your RV Tanks and Prevent Freezing.

How Much Is an Aqua-Hot?
We recommend that you purchase an RV already fitted with an Aqua-Hot system. Retrofitting the hydronic heating system will cost a pretty penny. A retro-fitted system could be pricey to install.
The unit itself may only cost around $6,000, but the work you’ll need to do to install a whole hydronic heating system in your RV is extensive. You’ll get a bit of equity in your RV with the installation, but be prepared to make a few payments.
Is Aqua-Hot in an RV Worth It?
In short, definitely! You get unlimited on-demand hot water, quieter efficient interior heating, engine heating, and heat of the engine all in one system. The ease of use and comfort with an Aqua-Hot system is worth the investment. You’ll have a pearl of an RV with this fancy heat source, and there’s nothing amiss about adding value to your bus.
What size system does your RV need to suit your travel party? Drop a comment and let us know!
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Read More From The Mortons:
Richard
Wednesday 17th of May 2023
I have the Aqua Hot in my 2006 Beaver coach and the invention of the system is amazing, I can see why parts are still available with OEM
Mortons on the Move
Saturday 24th of June 2023
We love ours for sure!
John
Saturday 26th of February 2022
Having an on demand system is a wonderful luxury. Having really hot engine-heated water when you are stopping for lunch when travelling is especially convenient.
I look forward to a follow-up post "aqua hot vs oasis: which is the better unit?" .