Many modern RVs feature tankless or on-demand water heaters. While these RV water heaters offer nearly limitless hot water when connected to city water and sewer hookups, they can still require troubleshooting like all RV appliances. Is your RV tankless water heater not working? Let’s outline some basic RV troubleshooting you can perform before scheduling a service appointment.
Key Takeaways
- Common Issues & Causes: RV tankless water heaters may experience problems like cold water spurts, mineral buildup, system overload, error codes, or lack of flame, often due to water flow inconsistencies, propane issues, or electrical faults.
- Basic Troubleshooting Steps: Check for sufficient water supply, power, and propane; verify external and internal switches are on; inspect for leaks, blockages, or venting issues; and clean or descale components as needed.
- When to Seek Professional Help: If troubleshooting efforts don’t resolve the issue, especially with persistent ignition failure or complex error codes, an RV service center should be contacted for further inspection.
How Does a Tankless Water Heater Work in an RV?
Effective troubleshooting starts with understanding the basic operating procedures of an RV tankless water heater. Most models have an On/Off switch on the unit’s exterior, which you can find by opening the outside access panel. This switch must be in the On position for the inside command panel to work.
Technician Tip: Turn that switch off when storing or winterizing your RV to remove power from the water heater and avoid battery drain or other issues.
With the exterior switch on, you can control the water heater from the interior panel. This lets you turn it on and off and control your preferred temperature setting. With the inside panel turned on, the water heater automatically supplies hot water anytime an interior hot water faucet is opened.
Common RV Tankless Water Heater Problems
Whether you’re new to an RV with a tankless water heater or your heater has begun acting out of the ordinary, you’ll benefit from knowing about these common RV tankless water heater problems.
- Cold Water. With water heaters that have tanks, hot water comes from that tank when a hot faucet is opened. With tankless water heaters, you might experience spurts of cooler water between hotter water. Some call this the “cold water sandwich” problem.
- Mineral Deposits. Most common in areas with harder water, minerals can build up inside the water heater over time. As mineral deposits grow, your tankless water heater’s performance and efficiency may decrease.
- Error Codes. The interior display may signal various water heater issues. Some of the most common error codes relate to insufficient LP supply, improper venting, or lack of power. Each water heater manufacturer’s error codes may signal different problems.
- System Overload. This occurs when water demand exceeds what the water heater can deliver. Conversely, it can happen when the supply is lower than the water heater is calling for. The two leading causes are insufficient water pressure and opening multiple faucets simultaneously.
- Lack of Flame. A failed ignition could have several causes, such as insufficient LP supply, a faulty ignition switch, or a burner blockage.
What To Do if Your RV Tankless Water Heater Is Not Working
Addressing your water heater issue requires identifying the most likely cause. Start by asking these simple questions:
- Are you connected to city water? Or do you have substantial water in your fresh water holding tank?
- Is the water heater display on? If not, does the unit have sufficient power, and is the exterior switch turned on?
- Does the water heater have sufficient propane to supply the burner? And do you hear the burner igniting when a hot fixture is opened?
These basic questions help you ensure your water heater has its three essentials for proper operation: water, power, and propane. If you’re still having trouble with your RV tankless water heater not working, try these basic troubleshooting tips based on the primary water heater problems outlined above:
Cold Water
When I bought my first RV with a tankless water heater, my walkthrough technician recommended using only the hot faucet when showering, as opposed to mixing hot and cold water as I’d traditionally done with my propane-electric DSI water heater. I turned the temperature setting on the water heater down to a more reasonable level so that I could use only hot water when showering.
Technician Tip: When using hot and cold, the risk is occasional cool water spurts that are annoying but harmless. When using hot water only without turning the thermostat down to a safe level, there will be no cool water to temper the heated water, and burns could result if the temperature spikes.
This may be an option for you, but here are two more tips for fixing your cold water issue:
- Adjust water flow until you find a more consistent temperature
- Add a mixing valve to create a steadier hot water supply
Mineral Deposits
Water quality varies greatly from source to source. Most owners use an RV water filtration system to remove minerals, chemicals, and other contaminants before water enters their RV plumbing. However, not all systems filter out 100% of contaminants.
So, while you can reduce mineral buildups using a filter or an RV water softener, tankless water heaters are extremely sensitive to the volume of flowing water and won’t work properly if the flow is reduced.
Technician Tip: Filters and softeners can reduce the flow to the point that the water heater doesn’t come on, especially if they aren’t regularly maintained. Water softeners rely on a surge tank so that water systems aren’t starved for flow, but they are limited in size in RVs, so they may create a limit to the length of time a hot shower can last.
Use the following tip if you suspect a buildup in your tankless water heater:
- Descale the unit regularly using vinegar or a commercial descaler designed for this purpose. Always follow the manufacturer’s instructions.
Error Codes
Read the owner’s manual for your RV tankless water heater to understand its error codes. Your troubleshooting steps will depend on the error code you’re seeing, but here are some common checks:
- Is the LP supply connection secure and leak-free?
- Is the water heater properly vented?
- Are all power connections fully plugged in?
- Is the battery disconnect turned on?
- Is the battery properly installed, charged, and regularly maintained?
System Overload
All RV owners should be mindful of water usage when camping. One downside of tankless RV water heaters is that they can lead you to use more water than traditional models. However, there are several ways you can protect against system overload beyond monitoring water usage and avoiding opening multiple faucets simultaneously:
- Upgrade to an adjustable RV water pressure regulator or a high flow volume pressure regulator to optimize water pressure and flow
- Consider a more powerful RV water pump as long as it’s safely rated for your RV plumbing.
Lack of Flame
A lack of ignition is the most likely cause to have your RV on-demand water heater professionally inspected. However, try these quick RV water heater troubleshooting tips before seeking further assistance.
- Verify an adequate amount of LP gas in container(s)
- Ensure LP gas valve(s) are fully turned on
- Check, clean, and re-install faucet aerators
- Check LP connections for leaks and/or obstructions
- Remove blockages in the burner tube, if present
- Inspect for loose wiring connections in the exhaust openings or evidence of critter activity
Still Have RV Tankless Water Heater Problems?
We hope these troubleshooting tips have solved your issue. But if your RV tankless water heater still isn’t working, contact a certified RV service center to schedule an inspection today.
Troubleshooting is just a part of RV life. Use these additional resources in case you’re tinkering with other RV systems:
Is your RV tankless water heater not working? Tell us more about the issue so we can offer customized troubleshooting advice!
