Suburban RV Water Heater Not Hot Enough? Here’s What To Do!!

Suburban RV water heater not getting hot enough can be frustrating. Whether you have an electric, gas, or tankless model, several factors could be to blame.

Improper voltage, a faulty thermostat or heating element, bypass valve misalignment, or incorrect diffuser tube placement are common culprits for electric units.

For gas models, issues with the bypass valve, open mixing valves, thermostat problems, or incorrect diffuser tube installation can cause insufficient heat.

In the case of tankless water heaters like the Suburban Nautilus IW60, setting the temperature too low may be the issue.

Let’s explore these reasons and find solutions to get your Suburban RV water heater back to delivering hot water as it should.

Suburban Rv Water Heater Not Hot Enough

The reasons and their respective solutions for the Suburban RV water heater not getting hot enough vary depending on the type of water heater.

Here’s a table summarizing the reasons and solutions for Suburban RV water heaters not getting hot enough:

Based on Suburban RV water heater types, the above table suggests quick corresponding solutions for insufficient heat in these water heaters.

Now, let’s get into the detailed step-by-step solution guide.

Suburban Electric RV Water Heater Not Getting Hot Enough

Suburban electric RV water heaters not getting hot enough can be caused by various factors including:

• Improper voltage
• Faulty thermostat or heating element
• Improper positioning of the bypass valve (if equipped)
• Incorrect placement of the diffuser tubes

In the following sections, I’ll explain how to diagnose and solve every issue mentioned above. Let’s dive in.

01. Improper Voltage

Improper voltage can cause the water not to get hot enough in the Suburban electric RV water heater.

Suburban electric RV water heaters use an AC heating element to heat water. If the voltage supplied to the heating element is not within the required range, the water may not heat up to the desired temperature. The voltage required for the heating element to work properly is between 110 and 120 volts.

In addition, the AC thermostat also needs 110-120 volts to function properly. So, if there’s not enough voltage supplied to the AC thermostat, the thermostat may cut off the power even before it reaches the desired temperature. As a result, the water will not be hot enough.

How To Fix:

To diagnose the voltage issue, you need to measure the voltage supplied to both the heating element and the AC thermostat. However, the process of measuring the voltage is similar for both equipment.

Tools required:

• A flathead screwdriver
• A multimeter
• Rubber-insulated electrical safety gloves

Precaution:

As you’ll be working with 110-120 volts AC current, make sure to use proper safety gloves.

Now that you’ve got the required tools and put on the safety gloves, here goes the step-by-step guide on measuring the voltage in your electric RV water heater.

Step 1: Turn off the electric switch and open the exterior door of the water heater.

Step 2: To test the voltage on the electric heating element, remove the heating element cover screws using the flathead screwdriver. The heating element cover is shown in below picture:

Once you open the electric heating element cover, the element will be exposed as follows:

Step 3: Turn the 120-volt electric switch on. 

Step 4: Set the multimeter to the AC voltage setting and then Touch the multimeter probes to the terminals of the heating element. The voltage reading should be between 110 and 120 volts.

If the voltage is way below 110 volts, contact an expert technician to further diagnose and solve the underlying issue. But if the voltage reading is OK, move on to the next step.

Step 5: To test the voltage on the electric thermostat, remove the thermostat cover screws using the flathead screwdriver. The thermostat cover is shown in the below picture:

Once you open the thermostat cover, the element will be exposed as follows:

Step 6: Now, you need to check the voltage of the electric (120 VAC) thermostats that are located on the left side. Test the voltage supply to both the upper and lower thermostats using the multimeter keeping the same settings as earlier. You should check the voltage by touching one probe of the multimeter to the wired side of the thermostat as follows:

Touch the other probe of the multimeter to any ground/neutral connection. The voltage reading should be between 110 and 120 volts for both thermostats.

Again, for any improper voltage reading, contact an expert.

Step 7: Once the voltage issue is fixed, check if the water is now getting hot enough or not.

But if the problem still persists, move on to the next segment.

02. Faulty Thermostat

The thermostat controls the temperature of the water heater. If the thermostat is not functioning properly, it can cut the power off before the water gets hot enough.

In that case, you need to inspect the thermostat and replace it if necessary.

How To Test And Replace The Thermostat On A Suburban RV Water Heater

To diagnose the thermostat, you need to measure the resistance of the 120 VAC thermostat.

And to do that, you’ll need the following tools:

• A compatible socket to remove the thermostat’s nut
• Tools mentioned in the previous section

Now that you’ve got the tools ready, here goes the step-by-step guide on measuring the resistance of the thermostat.

Testing The Thermostat:

Step 1: Follow steps 1 & 5 of the previous section.

Step 2: Remove the wires from the thermostat while paying attention to how they are connected.

Step 3: Use a multimeter and set it to measure continuity. With one lead of the multimeter, touch the upper left side (Electric) terminal next to the reset button. Then, use the other lead to touch the other terminal on the bottom left side.

The multimeter reading should be close to zero if there is continuity. If the multimeter reading is infinite, the thermostat is faulty and needs to be replaced.

Replacing The Thermostat:

Step 1: Follow steps 1 & 2 of the previous (Testing the Thermostat) section.

Step 2: Unscrew the thermostat from the water heater tank using a compatible socket.

Step 3: Install the new thermostat by aligning it with the screw holes on the tank and securing it with screws.

Step 4: Reconnect the wires to the new thermostat, ensuring they are properly connected.

Step 5: Replace the cover on the thermostat and secure it with screws.

Tips For Replacing The Thermostat:

• When replacing the thermostat, it is important to use a thermostat that is compatible with your water heater model.
• It is also important to make sure that the thermostat is installed properly. If the thermostat is not installed properly, it can cause the water heater to overheat or not heat the water at all.

If you are not comfortable replacing the thermostat yourself, you can always call a qualified plumber to do it for you.

03. Faulty Heating Element

The heating element is responsible for heating the water. If the electric heating element is damaged or not functioning properly, it can cause the water heater to not heat the water enough.

How To Test And Replace The Heating Element On A Suburban RV Water Heater

To diagnose the heating element, you need to measure its resistance.

And to do that, you’ll need the following tools:

• A 1-1/2″ hex socket
• Tools mentioned in the previous section

As you’ve got the tools in your hand, here is the step-by-step guide on measuring the resistance of the heating element.

Testing The Heating Element:

Step 1: Follow steps 1 & 2 from the how to fix the improper voltage section above.

Step 2: Set your multimeter to ohms and place your leads on the metal plates/screws of the heating element.

A good heating element should show 10 Ohms of resistance. If the multimeter reading is more than +/- 10% of the mentioned resistance, it means that the heating element is bad and needs to be replaced.

Replacing The Heating Element:

Step 1: Drain the water from the tank by opening the pressure relief valve and removing the anode rod.

Step 2: Use the 1-1/2″ hex socket to unscrew the old heating element from the tank.

Step 3: Clean any mineral deposits or debris from the threads of the tank.

Step 4: Apply Teflon tape to the threads of the new heating element to prevent leaks.

Step 5: Screw the new heating element into the tank and tighten it.

Step 6: Refill the tank with water and check for leaks. If there’s any water leak, repeat steps 3-5. Plus, you can check out our solution guide on how to fix the Suburban rv water heater leaking issue in detail.

Step 7: Turn on the 120-volt system of your RV and test the new heating element by running hot water from a faucet.

Tips For Replace The Heating Element:

• Always disconnect the power to the water heater before working on it.
• Be careful not to touch the exposed wires on the heating element.
• Use a multimeter that is rated for the voltage of your water heater.
• Do not attempt to repair the heating element if you are not qualified to do so.

04. Improper Positioning Of The Bypass Valve

The bypass valve in a Suburban RV water heater is used to allow water to flow around the water heater when it is not in use. This can be helpful for maintenance and repairs, as it allows you to drain the water heater without having to disconnect the plumbing.

However, if the bypass valve is not properly positioned, it can prevent the water heater from heating water properly. This is because the bypass valve can allow cold water to mix with hot water, which will lower the overall temperature of the water.

Symptoms:

• No hot water coming from the water heater
• Only a short supply of hot water, then quickly turns to lukewarm then cold

How To Position The Bypass Valves?

To properly position the bypass valve and ensure hot water flow, follow these step-by-step instructions:

Step 1: Locate the bypass valve system in your RV. It typically consists of three manual valves: one at the cold water inlet, one at the hot water outlet, and one in the bypass plumbing line.

Step 2: To properly position the bypass system, rotate the manual valves as follows:

1. On the cold water inlet valve, align the handle parallel to the “cold water in” line. This will ensure that the inlet valve is in the OPEN position.
2. On the hot water outlet valve, also align the handle parallel to the “hot water out” line. It’s to ensure the outlet valve is in the OPEN position.
3. On the bypass plumbing line valve, rotate the handle until it is 90 degrees to the bypass line. This makes the bypass valve to be in the CLOSED position.

The following picture illustrates the proper bypass valve position:

After positioning the bypass valve correctly, ensure the water heater tank is completely filled with water before turning on the gas or electric switches. This prevents any damage to the water heater controls.

To check if the tank is full, lift the lever on the temperature and pressure relief valve. If water flows out, it indicates that the tank is full.

05. Incorrect Placement Of The Diffuser Tubes

The diffuser tube is responsible for directing the flow of water inside the tank. If the diffuser tube is not positioned correctly, it can disrupt the flow of hot water.

The diffuser tube has two parts: the cold diffuser and the hot diffuser.

The cold diffuser (White/Opaque) is designed to push the cold water supply to the bottom of the tank. So, if the cold diffuser tube is placed upwards, it will push cold water up mixing with hot water. As a result, you’ll not get hot enough water from the faucet.

The hot diffuser (Gray/Black), in contrast, allows hot water to be drawn from the highest point inside the tank. Hence, if the hot diffuser tube is placed downwards, it will draw water from the bottom part of the tank which is definitely not hot enough.

How To Check & Replace The Diffuser Tubes?

Before replacing the diffuser tubes, you need to inspect them for damage and placement.

Inspecting the Diffuser Tubes:

Step 1: Shut off the water supply and turn off any power sources connected to the water heater for safety.

Step 2: Locate the cold and hot lines fittings connected to the water heater. These are usually located at the backside or the top of the tank.

Step 3: Using appropriate tools, carefully disconnect the fittings of the cold and hot water lines from the water heater. Be cautious as there may be residual water in the lines.

Step 4: Once the fittings are removed, you can access the old diffuser tubes. They are typically inserted into the water heater from the backside.

Step 5: Gently pull out the old diffuser tubes from their position. If they are stubborn, you may need to use a little force or wiggle them slightly to loosen them.

Step 6: Inspect them for any damage. If the tubes are in good condition, place them back ensuring proper placement as discussed above. But if they’re damaged, you need to replace them.

Replacing the Diffuser Tubes:

Step 1: Follow steps 1-5 from the previous section.

Step 2: Take the new diffuser tubes and carefully insert them into the corresponding openings in the water heater tank. Ensure they are fully inserted and properly placed.

Step 3: Reconnect the fittings of the cold and hot water lines to their respective connections on the water heater. Tighten them securely but avoid over-tightening to prevent any damage.

Step 4: Double-check that all connections are properly secured and tightened.

Step 5: Turn on the water supply and check for any leaks around the fittings. If you notice any leaks, promptly address them by adjusting the connections.

Step 6: Once you have verified there are no leaks, you can restore power to the water heater and turn it back on.

Suburban Gas RV Water Heater Not Getting Hot Enough

The reasons and the solutions for the Suburban RV water heater not getting hot enough depends on the type of water heater. I’ll address them all in the following sections.

I) For Direct Spark Ignition (DSI) Water Heater

There could be several reasons for your DSI water heater not getting hot enough as follows:

• The bypass valve may not be in the correct position
• The plumbing system mixing valves might be open
• The thermostat might not be secured properly or faulty
• The diffuser tubes may be installed incorrectly

How To Fix:

Step 1: First, ensure that the bypass valves are in the correct position as described in the previous segment on how to position the bypass valves section.

Step 2: Close all open mixing valves including the outside shower valves.

Step 3: If the problem still persists, check if the thermostat is properly secured to the water tank.

Follow the steps below to check if the thermostat is properly secured in the Suburban RV water heater:

#1: Turn off both the electric and gas switches.

#2: If the water in the tank is hot, let it cool down before checking the thermostat.

#3: Follow step 5 of the “Improper Voltage” section to access the thermostats.

#4: You’ll see two thermostats there. The left one is for 120 VAC and the right one is for 12 VDC. Try to wiggle the 12 VDC thermostat with your hand. If there’s any free-play, secure the thermostat’s nut following the below picture using an appropriate socket until there’s no free-play.

Now, you should be getting enough hot water from your RV water heater. However, if the water still isn’t getting hot enough, the thermostat itself might be faulty. In that case, you need to check the thermostat before you replace it.

Step 4: To check the 12 VDC thermostats, follow the below steps:

#1: Follow steps 1-2 of the thermostat testing section described earlier.

#2: Use a multimeter and set it to measure continuity. With one lead of the multimeter, touch the upper right side (DC) terminal next to the reset button. Then, use the other lead to touch the other terminal on the bottom right side.

The multimeter reading should be close to zero if there is continuity. If the multimeter reading is infinite, the thermostat is faulty and needs to be replaced.

#3: To replace the 12 VDC thermostats (located on the right side as shown below), follow the thermostat replacing section described in the previous section.

Step 5: Finally, if the diffuser tube is the culprit, replace it following the guidelines described earlier in how to check & replace the diffuser tubes section.

ii) For Gas Control System

The reasons for not getting enough hot water from your gas control system Suburban RV water heaters are as follows:

• Temperature is set too low
• Misaligned main burner
• Clogged main burner or air intake
• The main burner orifice is too small or clogged
• The thermostat gas control is out of calibration

In the following sections, I’ll explain how to diagnose and solve every issue mentioned above. Let’s dive in.

01. Temperature Is Set Too Low

If your Suburban gas RV water heater has a pilot ignition system, there should be a temperature adjustment feature. Hence, if the temperature is set too low, you won’t get enough hot water.

How To Raise The Temperature On Suburban RV Water Heater?

Step 1: Open the exterior water heater panel to access the temperature adjustment knob as shown below:

Step 2: To raise the temperature, turn the dial counterclockwise until you reach the desired temperature level.

However, in the case of water heaters without pilot ignition systems, there is usually no adjustment dial available. There is a preset setting of 120°F on these units, which is recommended by the manufacturer.

So, follow the next sections for the water heater without a pilot ignition system.

02. Misaligned Main Burner

When the main burner of a water heater is misaligned, it can cause not enough hot water. This happens because the burner is not able to heat the water efficiently, resulting in a lower output of hot water.

How To Realign The Main Burner Of The Suburban RV Water Heater?

You’ll need the following tools to realign the main burner:

• A 7/16 ratchet wrench
• Some penetrating oil (optional)

Here are the steps to realign the main burner of a Suburban RV water heater:

Step 1: Turn off the gas supply to the water heater.

Step 2: Remove the access panel to the burner compartment.

Step 3: Locate the main burner and inspect it for any damage or debris.

Step 4: If the burner is misaligned, use a wrench to loosen the nuts that hold it in place. You need to loosen two nuts to get a proper alignment effectively as shown below:

First nut to loosen:

Second nut to loosen:

[Pro tip: If the nuts are stuck, use some penetrating oil on them and wait for a minute. It’ll make your job a lot easier.]

Step 5: Adjust the position of the burner so that it is aligned properly.

Step 6: Tighten the screws to secure the burner in place.

Step 7: Replace the access panel.

Step 8: Turn on the gas supply to the water heater and test the water heater to ensure that it is functioning properly.

Note: If you are not comfortable working with gas appliances, you should hire a professional to realign the main burner.

Turn off the power supply. If the main burner is misaligned, remove the burner tube and elbow and realign the elbow.

03. Clogged Main Burner Or Air Intake

A gas water heater works by burning gas to heat water. In order for the gas water heater to work properly, it needs a supply of both gas and air. The gas is used to fuel the flame, and the air is used to help the flame burn properly.

If the air intake is clogged, it can restrict the flow of air to the burner, which can cause the flame to become unstable or even go out. As a result, you might not get hot enough water.

How To Clean The Main Burner And Air Intake?

Here are the steps to clean the clogged main burner and air intake of a Suburban RV water heater:

Tools Needed:

• 7/16 ratchet wrench
• Compressed air (optional)
• Wire brush

Step 1: Follow steps 1-3 from the burner alignment section.

Step 2: Remove the burner tube from the water heater using a 7/16 ratchet wrench.

Step 3: Use the wire brush or compressed air to remove any carbon from the firebox area. Clean the burner tube and the burner chamber as well.

Step 4: Reinstall the burner tube.

04. Clogged Or Too Small Burner Orifice

When the main burner orifice is too small or clogged, it can cause not enough hot water.

The orifice is a small opening in the burner that allows gas to flow through and ignite. If the orifice is too small or clogged, it can restrict the flow of gas and prevent the burner from igniting or cause it to burn inefficiently. This can result in not water not being hot enough.

How To Clean And Replace The Burner Orifice?

Required tools to clean or replace the burner orifice:

• Needle
• 7/16 ratchet wrench
• Compressed air
• 91% Isopropyl alcohol

Step 1: Follow steps 1-2 from the previous section.

Step 2: Check the orifice for any obstructions or debris.

Step 3: If the orifice is clogged, remove it from the assembly and clean it with alcohol and compressed air. To do so, soak the burner orifice in 91% alcohol for a few hours and blow it with compressed air.

[Pro tip: Avoid using high-pressure air as it will damage the orifice and will require replacement. Also, you can use a needle to clean the orifice hole but make sure you do not enlarge the orifice hole.]

Step 4: If the orifice is damaged or cannot be cleaned, replace it with a new one.

05. Thermostat Gas Control Is Out Of Calibration

When the thermostat gas control is out of calibration, it can cause not enough hot water.

The thermostat is responsible for regulating the temperature of the water in the tank. If it is not calibrated correctly, it may not be able to accurately control the temperature of the water, which can result in water that is not hot enough.

How To Fix:

If the thermostat gas control is out of calibration, you need to replace it. However, before replacing the thermostat, make sure to check if the thermostat has actually gone bad or not.

Follow step 4 of the solution section of “Direct Spark Ignition (Dsi) Water Heater” section above to test and replace the thermostat of RV water heater.

Suburban Tankless/On-Demand RV Water Heater Not Getting Hot Enough

The Suburban Nautilus IW60 tankless water heater may not get hot enough if the temperature is set too low. You can adjust the temperature by using either the ON/OFF switch or the On-Demand control center. Here’s how to do that:

Adjusting The Temperature Using The ON/OFF Switch:

Step 1: Turn off the water heater and wait for 15-20 minutes to cool down.

Step 2: Remove the service panel as shown in the figure below:

Step 3: Locate the set of four DIP switches located on the module board.

Step 4: Change the temperature settings as desired using the DIP switches. Follow the table for proper dip switch settings:

[Warning: Do not move dip switches 1 and 2 from the factory setting.]

Step 5: Replace the service panel.

[Note: If you are using an ON/OFF switch with your Suburban RV water heater, you can only choose between certain temperature settings (108°F, 120°F, 125°F, and 130°F)]

Adjusting The Temperature Using The On-Demand Control Center:

Step 1: Press the UP or DOWN arrows on the On Demand Control Center to increase or decrease the SET water temperature.

Step 2: Wait for the water to reach the desired temperature.

Note: Tankless water heaters operate by flow, so a hot water faucet must be open at least 0.5 GPM for them to function.

Caution: Water temperatures exceeding 125°F (52°C) can cause immediate severe burns or even death. Take precautions while using hot water. Children, disabled individuals, and the elderly are particularly vulnerable. Always check the water temperature before bathing or showering.

So, that was all about fixing the “Suburban RV water heater not getting hot enough” problem. If you’re facing other issues with your Suburban RV water heater, I highly recommend you read our comprehensive guide on Suburban RV water heater troubleshooting.

FAQs:

Wrapping Up

To wrap up, if your Suburban RV water heater is not getting hot enough, there are various factors to consider depending on the type of water heater.

For electric models, improper voltage, a faulty thermostat or heating element, bypass valve position, or incorrect diffuser tube placement could be the culprits.

In the case of gas water heaters, issues such as incorrect temperature settings, misaligned or clogged main burners, or faulty thermostats can affect the hot water output.

For Suburban tankless water heaters, adjusting the temperature settings using the ON/OFF switch or the On-Demand control center may solve the problem.

If you encounter other water heater issues, such as leaks, or maintenance concerns, refer to our guide on Suburban RV water heater maintenance for further assistance.