Why Your RV Water Heater Isn’t Lighting and How to Fix It!

Imagine you’re on a picturesque camping trip, ready to enjoy a warm shower or a hot cup of tea in your cozy RV, only to find that your RV water heater is not lighting up.

Frustrating, right?

Fear not, as this guide is here to help you understand why your RV water heater might refuse to ignite and provide you with step-by-step instructions on how to troubleshoot and repair it yourself.

Repairing an RV water heater when it is not lighting
photo: pixabay

In this comprehensive exploration of the common issues, we’ll delve into the “why” and “how” behind your malfunctioning RV water heater, empowering you with the knowledge to tackle this problem with confidence.

Let’s embark on this DIY journey to bring warmth and comfort back to your mobile home away from home.

RV Water Heater Not Lighting: Things to Consider

How Can I Determine the Type of an RV Water Heater I Own?

RV water heaters typically come in two primary types: tankless (on-demand) water heaters and tank-style water heaters, both of which can be powered by either propane or electricity.

Tankless water heaters heat water on-demand as you use it, ensuring you never run out of hot water (as long as you have continuous supply of water). They are renowned for their energy efficiency and compact size, making them a popular choice for RVs.

Tank-style water heaters, on the other hand, feature a storage tank that holds and heats a predetermined amount of water (common sizes include 6, 10, and 12 gallons).

Propane serves as the primary fuel source for heating the water. While these provide a reservoir of hot water, it’s important to note that you may run out if you use it excessively over a short period.

Electric tank-style water heaters are less common in RVs due to their higher power consumption compared to propane models. They also have a storage tank but use electricity for heating the water.

Some RVs offer the flexibility of both propane and electric water heaters, allowing you to choose your preferred power source.

I Own an RV Propane Water Heater, but I’m Uncertain About the Specific Ignition Type It Utilizes

RV water heaters can be classified based on their ignition systems, which determine how the propane or other fuel source is ignited to heat the water.

Here are the main types of RV water heaters based on their ignition systems:

  1. Pilot Light Ignition (Standing Pilot): In older RV water heaters, you may find pilot light ignition systems. These are often referred to as “standing pilot” systems. A small, continuous flame, called the pilot light, stays lit at all times to ignite the main burner when hot water is needed. While these systems are reliable, they consume a small amount of propane constantly, which can be inefficient in the long run. Lighting the pilot may require manual intervention, and if it goes out, you’ll need to relight it.
  2. Direct Spark Ignition (DSI): DSI ignition systems have become the standard in modern RV water heaters. They feature an automatic ignition system that eliminates the need for a continuously burning pilot light. When you need hot water, the DSI system electronically sparks and lights the propane burner, providing instant hot water. DSI systems are more efficient than pilot light systems as they only use propane when hot water is being actively heated.
  3. Electronic Ignition: Some RV water heaters use electronic ignition systems that are similar to DSI systems but rely entirely on electronic components for ignition. Electronic ignition systems are known for their reliability and efficiency. They often offer features like adjustable temperature controls and safety mechanisms to prevent overheating.
  4. Hybrid Ignition: Some RV water heaters come with hybrid ignition systems that combine DSI and electronic ignition methods. These systems offer redundancy and flexibility in case one ignition method fails, ensuring that you can still have hot water. They are designed to maximize reliability.

It’s important to mention that a significant portion of gas water heaters installed in RVs utilize gas valves provided by Robertshaw and White Rodger.

10 Reasons Why an RV Water Heater Is Not Lighting

There could be several reasons why an RV water heater is not lighting. Troubleshooting the issue requires careful inspection and may involve some basic maintenance or repairs.  Here are ten potential reasons why an RV water heater may not light:

1. Gas Supply Problem

When troubleshooting an RV water heater that is not lighting, it’s important to thoroughly inspect the gas supply system. The availability and proper functioning of the propane gas supply is fundamental to your unit’s operation. Here are some specific considerations:

  1. Propane Tank Status: Verify that your RV’s propane tank is not empty or close to empty. An empty tank will obviously prevent the water heater from lighting. Some propane tanks also have safety features that restrict the flow when the tank is too low, even if it’s not completely empty. RV owners have several methods to check their propane tank status. They can utilize a built-in gauge, tap the tank’s side (a hollow sound indicates it’s empty), weigh the tank, or simply open the hot water tap and verify if hot water flows.
  2. Propane Tank Valve: Ensure that the valve on the propane tank is fully open. Sometimes, users may inadvertently close the valve or partially close it, restricting the flow of propane to the appliances.
  3. Gas Regulator: The propane system in an RV typically includes a regulator that reduces the pressure of the propane gas coming from the tank. Check the regulator to ensure it’s functioning properly. If it’s malfunctioning, it can impact the gas flow to the water heater.
  4. Gas Lines and Connections: Inspect the gas lines and connections for leaks or damage. Even a small gas leak can be dangerous and can prevent the water heater from lighting. Use a gas leak detector solution to check for leaks and tighten any loose connections.
  5. Gas Shutoff Valve: Some RV water heaters have a manual gas shutoff valve located near the unit. Make sure this valve is in the open position. It’s a safety feature that allows you to shut off the gas to the water heater if needed.
  6. Propane System Pressure: If you suspect an issue with gas pressure, it’s a good idea to have a professional technician measure the gas pressure in the propane system to ensure it meets the manufacturer’s specifications.

Always exercise caution when dealing with propane gas, as it can be flammable and potentially hazardous. If you’re uncertain about any aspect of the gas supply or suspect a gas leak, it’s advisable to turn off the propane at the tank and seek professional assistance to ensure safety and proper repairs.

2. What to Do If the Pilot Light Is Out?

Checking and relighting the pilot light is a common troubleshooting step for RV water heaters that use a pilot light ignition system. Here’s more detailed information on how to perform this task:

  1. Locate the Pilot Light: The pilot light is a small, continuous flame that ignites the main burner of the water heater when needed. It’s typically located near the bottom of the water heater’s combustion chamber.
  2. Turn the Gas Control Knob to Pilot: Find the gas control knob on your water heater. It’s usually located on the outside of the water heater unit, often near the bottom. Turn the gas control knob to the “Pilot” position. This position is usually marked on the control knob itself.
  3. Depress the Control Knob: While holding down the control knob in the “Pilot” position, use a long lighter or match to ignite the pilot assembly. Alternatively, some models are equipped with a piezo igniter for lighting.
  4. Keep Holding the Control Knob: After lighting the pilot, continue holding down the control knob for about 30 seconds to 1 minute. This allows the thermocouple to heat up and send a signal to the gas valve to keep the pilot lit.
  5. Release the Control Knob: After the thermocouple has had sufficient time to heat up, slowly release the control knob. The pilot flame should remain lit.
  6. Observe the Pilot Flame: Take a close look at the pilot flame. It should be a steady, blue flame. If the flame is yellow or flickering, it may indicate an issue with combustion, such as a dirty pilot assembly or a problem with the gas-to-air mixture. A clean and steady pilot flame is essential for reliable water heater operation.
  7. If the Pilot Goes Out Again: If the pilot flame goes out after releasing the control knob or if it won’t stay lit, you may need to repeat the process. Ensure that you are holding the control knob down long enough for the thermocouple to heat properly. If the pilot still won’t stay lit, it’s possible that the thermocouple is faulty and needs replacement. Thermocouples are wear-and-tear parts that can fail over time.
  8. Refer to Manufacturer’s Instructions: Always consult the manufacturer’s instructions specific to your RV water heater model. These instructions will provide guidance on lighting and troubleshooting the pilot light, and they may include model-specific tips.
  9. Safety Precautions: When working with propane and the pilot light, be mindful of safety. Ensure proper ventilation and avoid any open flames or sparks in the vicinity. If you smell propane gas when attempting to light the pilot, immediately shut off the gas and address any potential leaks before proceeding.

3. Thermocouple Issues

Thermocouples play a critical role in the safety of gas-powered appliances by ensuring the continuous operation of the pilot light, thereby preventing potential gas leaks and hazards. The pilot light, a small, constant flame, is responsible for igniting the main burner when heat is required according to the thermostat’s signal. Its consistent operation is vital to ensure that gas is only released and burned when necessary.

The thermocouple serves as a safety feature due to its unique property: it generates a small electrical voltage when exposed to heat. As long as the pilot light remains lit, the thermocouple produces this voltage.

However, if external factors such as gusts of wind, drafts, or any other reason extinguish the pilot light, the thermocouple’s voltage decreases. This decrease signals the gas valve to close, effectively stopping the flow of gas and averting potential gas leaks.

Nevertheless, like any mechanical component, thermocouples can experience issues over time.

Dirt, soot, or corrosion can accumulate on the thermocouple’s surface, diminishing its ability to sense the pilot light. In such cases, the thermocouple may fail to generate sufficient voltage to keep the gas valve open, even when the pilot light is operational. This can result in the heater failing to ignite or remain lit.

Another indication of a potential thermocouple problem is a weak or intermittent pilot flame. The thermocouple may not consistently generate enough voltage to keep the gas valve open.

Sometimes, the thermocouple may have been displaced or shifted from its correct position. It’s essential to ensure it is properly aligned within the pilot light’s flame.

Furthermore, like all mechanical components, thermocouples can wear out or deteriorate with age, leading to reduced performance or complete failure.

If you possess a multimeter, you can test the thermocouple’s voltage output while the pilot light is on. It should generate a small electrical voltage, typically around 20-30 millivolts. If the voltage is too low or non-existent, it may be necessary to replace the thermocouple.

To maintain the proper functioning of your gas appliance, it is advisable to routinely inspect the thermocouple and clean it if necessary. If cleaning fails to resolve the issue, and the heater still does not ignite or stay lit, replacing the thermocouple may become necessary. Replacement thermocouples are readily available and can be installed by following the manufacturer’s instructions or seeking assistance from a professional technician.

4. Common Problems With the Ignition System

Thoroughly examining the ignition system is a crucial step in ensuring the reliable and safe operation of your gas appliance. This system can employ either a spark mechanism or a glow plug to initiate the combustion of gas.

To ensure the proper operation of this system, check the spark plug or electrode for any signs of damage or wear. Clean it if necessary, and make sure it is correctly positioned to generate a reliable spark.

Alternatively, certain appliances employ a glow plug ignition system. This mechanism uses an electrically heated coil to gradually reach the temperature required for gas ignition. Inspect the glow plug for any signs of deterioration, such as cracks or discoloration. Ensure that it heats up properly when the appliance is activated, as a malfunctioning glow plug can lead to ignition issues.

Examine all electrical connections and wiring associated with the ignition system. Loose or damaged connections can disrupt the system’s functionality.

Activate the appliance and observe the ignition sequence. Ensure that the ignition system initiates without delay and consistently ignites the gas. If you notice any hesitation or inconsistency, it may be an indication of an issue that requires further investigation.

5. Gas Valve Issues

Propane RV water heaters are equipped with a gas valve that requires manual operation for opening and closing. Typically, this valve is located on the exterior of the RV and it regulates the flow of gas to the burner.

Several issues can arise with the gas valve in a propane RV water heater. These problems can affect the proper functioning of the unit and may include:

  1. Valve Blockage: Debris, rust, or other contaminants can obstruct the gas valve, preventing it from opening or closing properly. This can disrupt the flow of propane to the burner.
  2. Corrosion: Over time, corrosion can develop on the gas valve, affecting its performance and making it difficult to operate.
  3. Wear and Tear: Gas valves can wear out or become damaged due to normal use and exposure to the elements. This wear can cause leaks or prevent the valve from sealing correctly.
  4. Valve Sticking: The gas valve may become stuck in either the open or closed position, making it challenging to control the flow of gas.
  5. Faulty Solenoid: The gas valve may have an associated solenoid that controls its opening and closing. If the solenoid fails, the valve won’t operate correctly.
  6. Electrical Issues: In some RV water heaters, the gas valve may be electronically controlled. Electrical problems, such as a faulty wiring connection or a damaged control board, can affect the valve’s operation.
  7. Regulator Problems: Issues with the propane regulator, which regulates the pressure of gas entering the valve, can impact the gas valve’s performance.
  8. Safety Features: Modern gas valves often include safety features such as thermocouples or flame sensors. If these safety devices malfunction or fail, the gas valve may not open or stay open when it should.

6. Burner Obstructions

Burner obstructions in RV water heaters can cause problems that affect performance and safety. Common sources of obstructions include dust, dirt, insects, and debris, leading to irregular or weak flames, inefficient heating, and lighting issues. Incomplete combustion due to blockages can produce harmful carbon monoxide gas, posing serious safety risks.

Many RV water heaters have safety mechanisms to shut down if they detect issues. Additionally, obstructions can lead to increased propane consumption and even fire hazards in extreme cases.

Preventive maintenance is crucial, involving regular inspections and clearing obstructions from the burner orifice, vent, and combustion chamber.

It is worth mentioning that the primary burner flame should exhibit a predominantly blue hue, accompanied by a hint of yellow, and emit relatively low noise.

7. Air in the Gas Line

Air in the gas line of RV water heaters can be a common issue that impacts their performance. When air becomes trapped in the gas line, it can disrupt the flow of propane, causing various problems. One of the most noticeable effects is difficulty in igniting the burner or maintaining a stable flame. This can lead to extended heating times, inconsistent hot water supply, or even complete failure to ignite.

To address air in the gas line, RV owners can take several steps.

First, it’s important to ensure that the propane tank is properly filled and that there are no leaks in the gas line itself.

Next, bleeding the air from the line by running the appliance on the “pilot” setting for a brief period can help purge the system of trapped air.

It’s advisable to consult the manufacturer’s instructions for specific steps on how to bleed air from the gas line for your particular RV water heater model.

8. Power Issues

Power issues, including problems with the battery, can significantly impact the ignition process of an RV water heater, leading to the frustrating problem of the delayed ignition, repeated ignition attempts, or even complete failure to ignite. This can result in longer wait times for hot water and potential discomfort for RV occupants. Here’s how these power-related issues are interconnected:

  1. 12-Volt Battery Dependency: Most RV water heaters rely on a 12-volt battery to power critical components, such as the ignition system and control board. The battery provides the necessary electrical energy to initiate the lighting process and maintain it during operation. If the battery is weak or depleted, it can affect the heater’s ability to initiate ignition, and it may not have sufficient power to keep the burner or pilot light lit.
  2. Battery Voltage Drop: When the battery voltage drops below a certain threshold, it can disrupt the ignition sequence. This is especially noticeable during the initial lighting process. If the battery voltage is insufficient, the spark ignition system may not generate a strong spark, or the control board may not provide the necessary electrical signals to open the gas valve.
  3. Low Battery Capacity: Over time, batteries in RVs can degrade or lose their capacity. This reduced capacity can lead to rapid voltage drops during high-demand situations like starting the water heater, which can result in lighting issues.
  4. Safety Precautions: To ensure safety, many RV water heaters have safety mechanisms in place that require a steady power supply. If the battery voltage is inconsistent or too low, the safety features may prevent the heater from lighting to avoid potential hazards.
  5. Battery Maintenance: To prevent power-related problems, regular battery maintenance is essential. This includes checking the battery’s charge level, connections, and overall condition. Keeping the battery charged and ensuring it’s in good working order is crucial for the reliable operation of the water heater.

9. Flue Obstruction

A flue obstruction in an RV water heater can be closely related to the issue of the water heater not lighting. When there’s a blockage in the flue, it can disrupt the overall combustion process within the water heater, which is essential for igniting the burner or pilot light.

A flue obstruction can impede the proper flow of combustion gases, preventing them from venting outside the RV. This disruption leads to incomplete combustion within the water heater. Incomplete combustion can result in a weak or erratic flame, making it difficult for the burner or pilot light to ignite or stay lit.

Many RV water heaters have safety mechanisms that automatically shut down the system if irregularities, such as incomplete combustion or excessive heat buildup, are detected. A blocked flue can trigger these safety features, causing the water heater to refuse to light or stay lit until the flue obstruction is addressed.

Flue obstructions can hinder the efficient operation of the water heater. This can lead to longer ignition times, repeated ignition attempts, and increased propane consumption. If the water heater struggles to light due to the blockage, it can result in discomfort for RV occupants, as they have to wait longer for hot water.

10. Safety Features

When an RV water heater fails to light, it can be due to issues related to the safety features. For instance, a malfunctioning thermocouple, a blocked flue causing poor air flow, or a high limit switch that has triggered due to overheating can all prevent the water heater from lighting or staying lit.

Therefore, troubleshooting a non-lighting water heater often involves checking the condition and functionality of these safety features to ensure they are working as intended while addressing any underlying issues that may have triggered their activation.


When an RV water heater is not lighting, it can be indicative of various underlying issues that affect its performance, efficiency, and safety. Addressing this problem requires a systematic approach, including checking the condition of critical components like the gas valve, thermocouple or flame sensor, and the flue. It’s also essential to consider factors such as the power supply, air flow, and safety features, as they are closely related to the ignition process.

Regular maintenance, timely troubleshooting, and, when necessary, seeking professional assistance from qualified RV technicians or plumbers with expertise in propane appliances can help diagnose and resolve the issue effectively. Ensuring that safety mechanisms are functioning correctly is paramount to prevent potential hazards, such as gas leaks or the release of harmful gases like carbon monoxide. Ultimately, addressing a non-lighting RV water heater not only restores the comfort of hot water but also ensures the safety and peace of mind of RV occupants on their journeys.

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