If you’re planning on living in your RV year-round or taking it off-grid for periods of time, you likely know about some of the tradeoffs involved and some of the gear you’ll need to stay comfortable. RV diesel water heaters are a great way to ensure that you have hot water wherever you’re at and can stay in your RV no matter the season.
There are three key factors you need to pay attention to when choosing a diesel water heater for your RV:
- Efficiency: your diesel water heater needs to be efficient in both it’s battery and fuel usage.
- Reliable: you have to be able to count on your system to provide hot water when you need it.
- Easy Install & Operation: your RV diesel water heater shouldn’t be complicated to set up or use.
Read more: RV Diesel Hot Water Heater Buying Guide
X Best RV Diesel Water Heaters
| Eberspacher Espar S3 D5E CS 12V RV Diesel Water Heater |
| NewHigh YJH-Q10A RV Diesel Water Heater |
| Aqua-Hot 250D RV Diesel Hot Water System |
| Warmda S1250 RV Diesel Water Heater |
Eberspacher Espar S3 D5E CS 12V RV Diesel Water Heater
The Espar Hydronic S3 D5E is an upgraded version of the popular D5S diesel heater, and is great thanks to it’s silent brushless motor, compact size, and improved fuel pump piston.
It also has a residual heating system that allows the heater to continue to operate without the motor running, and the full installation kit from Espar is plug and play with no extra parts or fussing required.
There’s an optional EasyStart Pro controller that allows it to operate at altitudes up to 9,900 feet, and it can operate between -40 F to 175 F.
It comes in both 12V and 24V options and can put out to 132 gallons per hour of hot water, which is more than enough for anyone’s needs.
Eberspacher Espar S3 D5E Specs:
- Electric: 12V or 24V
- Heat Flow: 6142-17060 BTU
- Fuel: Diesel
- Fuel Consumption: .06-0.23 gal/hr
- 79 gal/hr
- Size: 8.46” x x 3.58” x 5.67”
NewHigh 12V Hydronic RV Diesel Water Heater
NewHigh’s YJH-Q10A diesel water heater for RVs is powered by diesel fuel and 12V electricity and works between temperatures of -40 F to 158 F, so you’re covered no matter what mother nature throws at you.
There’s an optional GSM control and then you can run this water heater via SMS or smartphone app, which is pretty slick.
It’s stainless steel and features a 1-year warranty so you have some extra protection.
NewHigh YJH-Q10A 12V Specs:
- Electric: 12V
- Fuel: diesel
- Weight: 30.8 lbs
- Size: 17.13” x 8.27” x 7.09”
- Fuel Consumption: .34 gal/hr
Aqua-Hot 250D Ultra Compact RV Diesel Water Heater
The Aqua-Hot 250D is fueled by diesel and operated by 12V for off-grid situations, and also comes available as a 110V option.
The all-in-one design provides considerable space and cost savings, and it delivers residential-style interior heating that can deliver a continuous supply of hot water at 110-120 F at a rate of 1.5 gallons per minute.
The ports are all located on the top of the tank for easy connection access, and the heat is controlled by your thermostat.
Aqua-Hot 250D Specs:
- BTU/hr: 40,000
- 110-120 F at 1.5 GPM
- Fuel: Diesel
- Electric: 12V or 110V
- Size: 11.69” T x 12.45” W x 21.61” L
- Weight: 84lb (empty), 113lb (full)
Warmda S1250 RV Diesel Hot Water System
The Warmda S1250 RV diesel water heater was specially designed for campers, RVs, trailers, and motorhomes, and is an all-in-one complete system that uses a heat exchanger.
It can heat your cabin air and domestic water simultaneously, and can even provide hot water for radiant underfloor heating setups.
This heater system is designed to be maintenance-free in order to reduce the expense and hassle of constantly fussing over your RV’s diesel hot water heater.
Warmda RV Diesel Hot Water System Specs:
- Output heat: 16,000 BTU
- Size: 9” x 6.51” x 3.54”
- Weight: 17.7lb
- Working Voltage: 9V-16V
- Electrical Consumption at 12V: Less than or equal to 3.2 Amps
- Fuel Consumption: 0.13 gallons per hour
Benefits Of RV Diesel Water Heating Systems
There are plenty of reasons RVers choose diesel over other fuel options when possible. Here are a few:
Better Heat Distribution
Diesel heat systems can distribute heat across multiple pathways (i.e. your water heater, air system, and radiant flooring) more easily than a propane system can.
Propane requires multiple stages and zones to do this as effective as diesel.
Diesel Is Quieter
Propane systems are generally noisier than diesel, so if you’re a light sleeper or noise bothers you, this will make a difference.
Diesel Burns Slower
Diesel produces more BTUs per gallon, so it produces more heat with less fuel.
For example, one gallon of diesel fuel produces around 130,000 BTUs of heat, while one gallon of propane produces just over 91,000 BTUs of heat, making propane about 30% less efficient than diesel!
Diesel Is Easier To Find
When your system runs on diesel fuel, you’re usually only as far away from your fuel source as the next gas station.
Propane on the other hand can be trickier to find, especially if you’re refilling larger tanks.
RV Diesel Water Heater Buying Guide
Here’s what to look for when selecting your RV diesel water heater:
Efficiency
Can your RV water heater run simultaneously off of battery and fuel, or can it run primarily off of power when hooked up and only tap into the diesel fuel when it needs to?
This is a key consideration you should pay attention to so that you can ensure you’re not unnecessarily going through fuel, especially if you’ll be off-grid for long periods at a time.
Reliable
There’s not much point in having a dedicated RV diesel water heater if it’s going to be out of service half the time.
Make sure whichever heater you select is ideally backed by a manufacturer warranty and has received high marks from other RVers who’ve used it.
Easy Install & Operation
Many RV water heaters are “plug and play”, meaning they come with all the hoses, attachments, and some very clear instructions to make installation simple for you.
If you’re not sure how to install your RV’s diesel water heater, head online to a forum or grab a mechanically inclined friend to help you.
As a last resort, you can also take your water heater to an RV mechanic to have them install it professionally.
Size & Placement
RV hot water heaters come in different sizes and weights, and some are designed to be installed either inside or outside of the cabin, while others can be installed wherever you want.
Consider the manufacturer’s guidelines and your particular setup when making your choice.
Fuel Consumption
Usually, the cheaper your RV water heater, the less fuel efficient it’s going to be.
Consider where you’ll be traveling, the size of your fuel reserve tanks, and how long you plan on going between fuel-ups to ensure that your water heater is up to the task.
Gallons Per Minute
Most diesel water heaters for RVs should put out enough gallons per minute at a long enough point for you to take a leisurely, hot shower on demand.
Double check the GPM (gallons per minute) rating on your water heater when purchasing.
Additional Considerations
Some systems will heat the domestic water only, while other heaters can also heat the air (helping you to get through those cold nights and even an RV one night freeze), and can provide heating throughout radiant floor heating systems.
Keep your setup in mind as you pick your heater to make sure it can do everything you need it to.
Wrapping Up RV Diesel Water Heaters
We hope you’ve found this guide helpful and are on your way to switching over to a diesel-fueled RV water heater system for your rig.
If you’re into RV customization, check out our guide to the best RV outdoor kitchen mods for some extra inspiration.