Welcome to RV U! Our New Podcast Hosted by Angie Morell is Live

Class is in session at RV U! Tune into the premier insider podcast brought to you by National Indoor RV Centers! Host and renowned RV pro Angie Morell sits down with industry experts, icons and influencers to chat about a variety of entertaining topics, including the latest RV trends, new and popular products, helpful tips, stories about guests’ adventures and more. Whether you’re an incoming freshman or have a PhD in RVing, there’s room for you in the classroom.

New episodes will be available every Wednesday, so be sure to subscribe to RV U on your favorite podcast platforms below.

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American Coach Unleash the Luxury Savings Event

American Coach is offering a fantastic factory rebate of up to $30,000 on its 2022 and 2023 Class A luxury motorhomes now through August 31, 2023!


Check out our American Coach inventory at our 6 NIRVC dealerships in Atlanta, Dallas, Las Vegas, Nashville, Phoenix and Washington, D.C.

New to American Coach? Take a walkthrough of the 2023 American Eagle and the 2023 American Dream with NIRVC’s Director of Sales, Angie Morell.


RV Hydronic Heating Systems

What are hydronic heating systems and how do they work in your RV?

Hydronic heating systems are rapidly becoming the heating system of choice on diesel pushers versus forced air furnaces. Hydronic heat offers even heat distribution and moist, comfortable heating. It utilizes a boiler that pumps antifreeze through a series of heat exchangers located throughout the coach. It also provides domestic hot water heating, eliminating the need for a traditional hot water heater. The two brands that are common in the RV industry are Aqua-Hot and Oasis.

RV Heat Sources

A hydronic heating system can be powered by a diesel burner as well as an electric heating element. In some cases a propane fired boiler is used in smaller RVs but for this article we’ll just stick to the diesel fired units common to most diesel pushers. Diesel fuel has more BTU per gallon than propane. Plus, the fuel tank is of greater capacity because it utilizes the coach’s diesel tank rather than a smaller LP tank mounted in the coach. Not only is this more cost efficient but it also greatly extends the run time between refueling.

Propane has a BTU rating of 91,500 BTU per gallon while #2 diesel fuel is rated at 139,200 BTU per gallon. Operating a 50,000 BTU burner on propane for 8 hours will require 4.37 gallons of propane while running that same burner on diesel fuel will only require 2.87 of fuel due to the higher BTU content of diesel fuel. If your LP fired burner is fed from a 32 gallon propane tank you can run that burner for a maximum of 58.56 hours while running a diesel burner from a 100 gallon fuel tank will allow you 278.4 hours of run time until you’ll need to refuel.

In addition to the diesel burner, hydronic heating systems also have an electrical heating element that can be used. A typical 1,650 watt heating element can deliver 5,630 BTU. This isn’t as great as a 50 KBTU diesel burner but it is capable of heating the coach when it’s cool (but not cold) out. It’s also possible to operate both the burner and the electric element at the same time for additional heating capacity.

Most units are also equipped with a Motoraide or engine assist connection. This allows the hot engine coolant to be used to add additional free heat to the boiler when driving. This engine to boiler loop can also be used as an engine preheat that uses the boiler’s heat to preheat the engine for cold start assistance if so equipped.

Aqua-Hot vs. Oasis

Both the Aqua-Hot and Oasis systems are similar in operation. They both utilize a boiler to heat up antifreeze so that it can circulate through a closed heating loop. There are heat exchangers placed in various locations in the loop to provide heat to the coach interior as well as any basement area that needs to be protected from freezing. They also provide domestic hot water but there are a number of differences in how the units are constructed to meet these needs.

The popular Aqua-Hot 450 supports a claimed 50,000 BTU burner, although the latest advertised specs state 65,000 BTU, and a 6 gallon boiler tank. It also sports a 1,650 watt electric heating element on a 20 amp breaker. Hot water temperature is always rated at a delta, which is the difference between the temperature of the incoming cold water to the outgoing heated water. The 450D is rated at a 60 degree delta at 1.5 GPM water flow. If the incoming water is frigidly cold then you’ll only be able to raise it by 60 degrees. If you exceed the 1.5 GPM flow rate you will also lose the ability to keep the antifreeze in the boiler tank from holding its heat so you’ll need to watch your water flow on those long hot showers or they will finish up as cold showers.

For more more on RV water systems, read Mark’s blog, An RVers Guide To Water


An Aqua-Hot 450D system.

The Aqua-Hot system also will shut off the interior heat exchangers when hot water is being used so  that all available BTU can be dedicated to heating water. The interior heating will resume once the water flow stops. The Aqua-Hot claimed BTU ratings are suspect however . The burner uses a .35 GPM burner nozzle. Doing the math you can see that this is only 39,200 BTU per hour – not 50,000 BTU. 


An Aqua-Hot 450D as installed in my Entegra Cornerstone.

An opened-up view of the Aqua-Hot system.

Oasis also makes a 50,000 BTU system called the Oasis NE, which uses a 7.5 gallon boiler tank. It utilizes a pair of 1,500 watt electric heating elements, producing up to 10,236 BTU on two 15 amp breakers. You can operate one or both at the same time. This will let you utilize the electric heat to a bit lower temperatures before needing to switch on the diesel burner. Hot water heating is also rated at a 65 degree delta at 1.5 GPM although the Oasis NE does not interrupt interior floor heat while hot water is being consumed. The burners use a .44 GPM fuel nozzle, which equates to a realistic 49,280 BTU.

The Oasis NE system

Oasis also makes a larger Oasis NE-S version. This slightly larger version is the ultimate in hydronic heating, with a claimed 85,000 BTU burner rating and a 13.75 gallon boiler tank. It has the same dual 1,500 watt heating elements as the Oasis NE but the 60 degree delta for hot water is now increased to 3 GPM with no floor heat interruption. The burner uses a 0.79 GPM burner nozzle.

The above calculations are based upon an 80% factor in the BTU of diesel fuel. While diesel fuel does have 140,000 BTU per gallon about 20% of that is lost as heat in the exhaust, leaving 80%  to do the actual work of heating. So I used 112,000 BTU when doing the above calculations.


An installed Oasis NE system in a Showhauler motorhome.


Your system will have a few switches to operate the boiler. These switches may be rocker switches, or in a dedicated control panel or embedded in a multiplex control panel such as a VegaTouch screen. These switches are used to turn on the diesel burner and electric heating elements. There may also be a switch for an optional engine preheat feature if so equipped. These controls supply power to operate the boiler. If they are not on you won’t get any heat. Once the boiler heats up to its designated cutout temperature it will stop. Once the boiler’s temperature drops below the cut-in temperature it will start up again to raise the heat level of the boiler antifreeze.


The diesel burner and electrical heating element are controlled by a switch panel.

The antifreeze in the boiler is used to circulate through a couple of closed loops via circulating pumps. Interior heat exchangers are inserted into these loops at key locations to evenly distribute heat throughout the coach interior. These circulating pumps are controlled by the coach’s HVAC thermostat controls. Whenever the thermostat calls for heat, the circulating pumps will circulate hot antifreeze through the heating loop and heat exchangers. The fans on the heat exchangers will switch on to deliver the heat to the interior but only if the boiler is hot. This is to prevent blowing cold air from the heat exchangers if the antifreeze hasn’t warmed up yet. Once it is warmed up, the fans will engage and heat the coach interior. If the boiler cools down the fans will stop, allowing the boiler to regain its temperature before switching on again. When first starting up a hydronic system, you will have to wait a few minutes until the boiler warms up.

These systems have two heating loops, each powered by a circulating pump. A number of heat exchangers can be connected to these loops and these heat exchangers are connected to up to 5 heating zones. One heating zone may be used for the main cabin interior heating while a second heating zone may be used for the bedroom and rear bath heating area. A third zone may be used for basement heat while a fourth zone may be used for hydronic floor heat, in the case of  an Entegra Coach. The layout of these zones and to which circulating loop they are assigned is up to the coach manufacturer’s discretion. Each zone will have individual thermostat control with remote sensors. This can be multiple thermostats, a multi-zone thermostat or part of a VegaTouch multiplex system. In many cases, there will be a separate manually-operated thermostat in the basement to control the basement zone that protects the fresh water system from freezing. If you just want to keep minimal heat in the coach, you will still need to leave either the electric heating element or diesel burner switched on or else you won’t get any heat.


Many coaches utilize a separate thermostat to control the basement heat.

The Motoraide loop to the engine will provide a bit of heat when driving. Typical BTU output for this is in the neighborhood of 10,000 BTU but will vary from coach to coach. It will keep the boiler hot so that you will have hot water when you stop and can give you a bit of interior heat but if it’s relatively cool out you will want to use the diesel burner as well. Still, the extra 10 KBTU is a help and will give you some free heat and save some diesel fuel. This system utilizes the engine’s water pump to circulate engine coolant through an internal heat exchanger inside the boiler via regular automotive heater hoses. You do not have to switch on any engine preheat pump for this to happen.

The optional engine preheat feature utilizes the same heater hoses but adds a circulating pump that pumps the engine antifreeze in the opposite direction. This is used to provide heat from an operating hydronic heating system boiler to a cold engine to make it easier to start. Note that this is not part of the engine block heater, which is a second preheat device supplied by the chassis manufacturer. The hydronic preheat system will actually heat up your engine faster than the block heater because it has more BTU. You can also use it when you are parked in a place where you do not have access to electricity because you can run your boiler on diesel fuel in the middle of Alaska if you need to preheat your engine. This is an optional feature so it depends on if the coach manufacturer uses it. If you stay out of cold areas it may not be of much use for you.

Hydronic systems also provide domestic hot water in addition to heat. The hot boiler antifreeze transfers heat to a coil that heats the fresh water as it passes through the coil on its way to your hot water faucets. A traditional water heater that uses a tank to store hot water will quickly run out of hot water once the tank is depleted so no long hot showers are possible. The hydronic system is a true on-demand system that will heat the water as it passes through the heating coil. The only caveat is that you have to limit the flow so that the boiler can keep up. The typical system has the ability to raise the water’s temperature 60 degrees over the temperature of the incoming water. If your water is very cold you’ll be limited in how hot you can get the water but if the incoming water is warmer you’ll be able to heat it to a higher temperature. Typically, this is rated at a 1.5 GPM flow rate. If you exceed that rate, the boiler won’t be able to keep up and as the boiler temperature begins to drop – so will the temperature of your hot water output. Using higher flow rates can work for a short time but if you really need a long hot shower, you’ll want to keep the flow rate beneath 1.5 GPM.


Anything mechanical will require a bit of maintenance every now and then. A hydronic heating system isn’t a high-maintenance item but when you consider that these systems have a diesel-powered flame that heats a boiler and circulating pumps that cycle antifreeze through heat exchangers, there are a few points to watch for.

A typical system requires an annual service, which pretty much centers on the diesel burner. The diesel burner pumps fuel through a small nozzle into the burner chamber and is ignited by a spark. The nozzle itself has a minute orifice that is designed for a specific flow rate and a precise conical pattern. During normal use, the diesel fuel that passes through the nozzle will wear out the orifice, resulting in excess diesel fuel flow. This excess fuel will cause fouling of the swirler flues that are designed to create the correct circular airflow inside the burner’s combustion chamber. The end result is that your hydronic heating system runs rich, causing stinky exhaust and puffs of smoke. This wear occurs from use, not time, so if you run your diesel burner quite often you might require service sooner than the arbitrary one year interval.


The burner nozzle, electrodes and flame sensor are part of the annual service.

The combustion chamber needs to be cleaned and vacuumed as part of the service..

Nozzles cannot be cleaned but they are inexpensive and should be replaced. The annual service also entails replacing the fuel filter and a thorough inspection of the burner. It’s important to keep the burner head clean, especially the electrodes and flame sensor photocell. At the same time a good vacuuming of the combustion chamber and cleaning of the swirler to ensure the ports are clean is necessary. Finally, a quick check of the fuel pump pressure will ensure that everything is up to snuff.


The fuel filter for the diesel burner needs to be changed annually.

Assuming that your system is functioning without any major issues, the only thing left is the antifreeze. Hydronic heating systems do not use automotive antifreeze, which includes water pump lubricants, anti-corrosion inhibitors and other additives designed for engines as well as freeze protection. A hydronic heating system uses an antifreeze that protects against freeze damage but it is designed for the best heat transfer. While most automotive antifreeze is Ethylene Glycol (EG), hydronic systems require Propylene Glycol (PG). The correct antifreeze will be available from Camco or Century and they are labeled as GRAS, which means Generally Recognized As Safe because they are not toxic, unlike EG. Your hydronic heating system will be equipped with a poly overflow tank so that you can see the level in your boiler. If it becomes discolored and smells burnt, it may be time to have your RV tech flush the system and replace the antifreeze.

While the boiler and heating loops are a sealed system, it always seems that they need a little topping off every now and then, so most owners carry a spare jug along. Pure antifreeze needs to be mixed with water about 50/50. Antifreeze is available in jugs filled with concentrated antifreeze that needs to be mixed with water or as a preformulated 50/50 mix. If you do buy the concentrated antifreeze, be sure to use distilled or deionized water when diluting it to a 50/50 mix to prevent minerals from tap water from accumulating in your hydronic system. You can dilute it a bit beyond the 50/50 mix which covers to -42F. In fact, the best heat transfer is at 60% water and 40% antifreeze. That will drop the freeze temperature a bit, but not significantly. A quick check of your antifreeze’s freeze point with a refractometer will verify your current freeze point. If the freeze point is too high, you can add a bit of concentrated antifreeze to bring the freeze protection level back to where it needs to be.

Really, with a little bit of care and understanding you’ll be able to enjoy your hydronic heat for a long time.

National Indoor RV Centers blogger Mark Quasius profile picture

Mark Quasius is the founder of RVtechMag.com, the past Midwest editor of RV Magazine, writes for numerous RV-related publications and a regular Contributor to FMCA’s Family RVing Magazine. Mark and his wife Leann travel in their 2016 Entegra Cornerstone.

Join Us for the 2024 Customer Appreciation Rally!

With all your overnight camping, catered meals, happy hours, evening live entertainment and education included, you’re sure to have a spectacular time at the 2024 Customer Appreciation Rally! Come make new friends, rekindle old friendships and create memories that will last a lifetime. 
The 2024 NIRVC Customer Appreciation Rallies will be at The Ridge Outdoor Resort. This upscale RV resort in Sevierville, Tennessee is the #1 camping and RV resort in the Pigeon Forge, Sevierville and Gatlinburg area. It’s just 3 miles from Dollywood and the heart of the Great Smoky Mountains, boasting full hook-ups, level cement sites and gorgeous amenities. Plus, there are plenty of bike and hiking trails as well as beautiful scenery, including waterfalls, that pictures simply don’t do justice!

Don’t miss this opportunity to let NIRVC spoil you. Register now!

Customer Appreciation Rally #1 

Monday, April 15 – Thursday, April 18, 2024

The price per coach is $595 for couples and $495 for singles. Additional guests are $295 per person.

Customer Appreciation Rally #2 

Monday, April 22 – Thursday, April 25, 2024

The price per coach is $595 for couples and $495 for singles. Additional guests are $295 per person.

National Parks Have Something for Everyone

Have you ever been to a national park? They are among the most popular destinations in America with visitors numbering in the millions each year, many of whom are RVers. Before we retired and started traveling in our motorhome, neither my husband nor I had ever been to a national park. Now, though, we are on a quest to visit as many of these treasured vacation spots as we can.

Taking the obligatory sign picture at the west entrance of Yellowstone National Park

So Many Places to See

Visiting any of the 63 national parks in your RV is a great way to spend time outdoors and see the vast beauty of our country up close. The national parks are only a small part of what’s known as the National Park System, which includes 424 individual areas that span more than 85 million acres!

These areas include historic sites such as monuments and battlefields as well as seashores, scenic rivers, trails and, interestingly, the White House. Located throughout the country, each area provides a unique insight into the region and includes many environments like lakes, mountains, caves, forests and even sand dunes. There’s truly something for everyone.

Playing on the giant dunes in Great Sand Dunes National Park

The Variety is Amazing

The wide variety of things to see and do in each of these national park areas is incredible. No matter what your interests are, you can be sure to find something you will enjoy. Photographing nature and observing the scenery and wildlife is always big on my list.

Beautiful flowering cacti in Big Bend National Park
Bison herd near the north rim of Grand Canyon National Park

Every park we’ve visited has had numerous hiking trails for exploring the area’s diversity. We also saw many jaw-dropping geological features. If history is your thing, you will find an abundance of information and interesting facts about both the park itself and the surrounding area on-site. Plus, the dark skies in the more remote parks allow for unbeatable stargazing opportunities.

Early morning hike to Delicate Arch in Arches National Park

My husband and I are fortunate to have experienced many exciting activities in the parks we’ve visited. We cruised around mountain lakes on a charter boat in Glacier National Park, rode on a thrilling jeep excursion in Canyonlands National Park, explored the inside of caves at Carlsbad Caverns National Park, soaked in a hot spring pool at Hot Springs National Park, walked (and drove!) through a redwood tree in Redwood National Park and flew in a seaplane to Dry Tortugas National Park and snorkeled in the ocean, just to name a few. All kinds of unique adventures await you in our country’s parks!

Jeeping fun in Canyonlands National Park
Enjoying the view at the south rim of Grand Canyon National Park

Plan Your Visit

With so many options, one of the hardest things to do is deciding where you want to go first. A great way to start is by checking out NPS.gov. The National Park System website is easy to use and allows you to learn more about the parks, including visitor center operating hours, road and trail conditions, weather, safety tips, camping information and available activities. It is important to check for any active alerts or closures that might be in effect as well as restricted access areas.

Over the past few years, several parks have implemented a timed ticket entry system to manage visitation levels. This $2 ticket is in addition to park entry fees and must be purchased ahead of time at Recreation.gov (Hint: if you can’t get a ticket, you can still enter the park at off times before or after the ticket windows). The parks currently affected are Arches National Park, Glacier National Park, Haleakala National Park and Rocky Mountain National Park, but some other parks are increasingly requiring reservations and permits to access some of their most popular areas, such as watching the sunrise on Cadillac Mountain in Acadia National Park.

Save Money with a Park Pass

If you’re going to visit several parks in a single road trip, you can save money by purchasing a National Parks Pass. Available at the park entrance or online, a pass costs $80 for annual access to all national parks and federal recreation lands for one vehicle or up to 4 people. Given that entrance fees for some parks are $35 each, visiting 3 parks makes the cost worthwhile. There are also free lifetime passes available for seniors, veterans and those with permanent disabilities, as well as free annual passes for active duty military members and all 4th graders. View all the available passes here.

When You Arrive

Planning your trip ahead of time will allow you to make the most of your time in the park. When you arrive, I highly suggest starting at the visitor center. Here, you can watch a short film to learn the history and geography of the park. Make sure you talk to a park ranger, too. They are the experts who can answer questions, offer suggestions for activities, provide trail maps and let you know about special events like guided hikes or ranger talks.

Stopping at the visitor center in Great Smoky Mountains National Park

You can use all of this information to help plan the duration of your visit, including details on where to park, getting to the most popular sites and finding unique adventures you don’t want to miss! Don’t forget to stamp your National Parks Passport and browse the gift shop for a memento to commemorate your stop.

National Parks Passport book with stamps

Get Out in the Park

After checking out the visitor center, you’ll be ready to head into the park! We often start with a scenic drive so we can stop at the overlooks and take everything in. Some of the most stunning viewpoints are at these overlooks. This is a great time to have your camera handy to capture the gorgeous scenery.

Admiring the hoodoo formations at Bryce Canyon National Park

If we plan to spend several days in the park, we usually wait until day 2 to do some hiking. Since we’ve already received trail information and have likely decided on a specific hike, we can get an early start to beat the crowds — and the heat.

Always make sure you bring the necessary supplies for whatever activities you have chosen to do. For example, you will definitely want to wear good walking shoes and pack sunscreen, a hat, plenty of water and snacks that won’t melt or spoil. If the trail has a high elevation, walking sticks are extremely helpful. Don’t forget the bear spray, if required!

Hiking a trail in Capitol Reef National Park

Respect Nature

Whatever you choose to do in the national park, please remember to minimize your impact on the park’s plants, animals and ecosystem. The motto “leave no trace” encourages visitors to respect wildlife, be considerate of others, leave what you find, stay on trails and properly dispose of waste.

We are so fortunate that conservationists and leaders had the foresight to create the National Park Service back in 1916. The government agency ensures the preservation of our nation’s natural beauty and resources so they will be around for everyone to enjoy and learn from for years to come.

Have Fun and Make Memories

Traveling in your RV is the perfect way to experience a national park. You can camp within the park or at a nearby commercial campground. We often meet up with family or friends for even more fun during our stay. Whatever areas you visit or activities you choose, you are sure to create lasting memories!

Exploring the caves with friends at Carlsbad Caverns National Park
Robin Buck

Robin and her husband, Mike, are Air Force veterans and empty nesters who have been traveling full-time in their Entegra Anthem motorhome for 5 years. Always ready to explore, they love nature and wildlife, meeting new friends and discovering America one stop at a time. Robin writes about their travel adventures, RVing tips, and the full-time RV lifestyle on her blog RVing with Robin.

2024 Entegra Cornerstone Luxury RV Tour with Angie Morell

Introducing the 2024 Entegra Cornerstone, a Class A diesel RV designed with the luxury traveler in mind.

The 2024 Entegra Cornerstone 45D features a spacious interior, plenty of storage, chic and comfortable furniture, elegant flooring and cabinetry, advanced built-in safety and security features, better visibility of the great outdoors and more.