Truma Water Heater Reset Button
That red button on your Truma water heater. The one that seems to pop at the worst possible moment, freezing morning, full RV, no hot water. You are probably here because it happened to you, and you want to know if pressing it again is safe or if you are about to make things worse.
The Truma water heater reset button is a high-limit safety cutoff. It trips when internal water temperature exceeds roughly 210°F on AquaGo models or when the heat exchanger overheats on Combi units. Per Truma technical documentation, this button is not a convenience feature.
It is a last-resort protection device. Before you push it, you need to understand what caused the trip. The wrong move can turn a simple gas-line air bubble into a costly service call.
Let us walk through exactly what that button does and how to handle it safely.
Image source: Bing (Web (fair-use with source credit))
Quick Answer
Press the Truma reset button only after the water heater is cold and the propane supply is good. Find the red button behind the exterior access panel. Press and hold it for three to five seconds.
Wait for the ignition cycle to start. If it does not light or the button trips again within minutes, stop. The underlying problem needs fixing first.
Why the Reset Button Exists and When It's Safe to Use
The red button is a high-limit thermostat. It is not a power switch or a circuit breaker. It is a mechanical safety device that cuts the gas supply when temperatures inside the unit reach dangerous levels.
Think of it like the thermal cutoff on a hair dryer. It pops when something is wrong.
What Triggers the Reset Button
Manufacturer specs confirm the button trips when internal water temperature surpasses 210°F on AquaGo models. That is well above normal operating temperature. Several things cause that spike:
Inadequate water flow. If the pump fails, a valve is closed, or a filter is clogged, water sits in the heat exchanger and keeps getting hotter. No flow means no heat dissipation. The button pops.
Air in the propane line. After swapping tanks or running the tank empty, air gets trapped in the gas line. The water heater tries to fire, fails repeatedly, and the control board may trigger overheat protection because the burner runs lean or not at all.
Blocked combustion air intake or exhaust. Mud dauber nests, ice buildup, or debris block airflow. Without proper air, the burner runs hotter and less efficiently. Heat backs up into the unit. The button pops.
Scale buildup in the heat exchanger. If you camp in hard water areas, mineral deposits insulate the heat exchanger walls. The water inside gets hotter than the sensor expects because heat cannot transfer properly. This is a slow, hidden problem.
Freeze damage. If the unit was not winterized and water froze inside, ice can distort the heat exchanger or block flow. When you fire it up, the trapped water expands and overheats. The button trips immediately.
When Is It Safe to Press?
It is safe to press the reset button once, and only once, after a basic two-minute walkthrough covering three things:
Is the water heater cold? Never press the button on a hot unit. Let it cool completely.
Is the propane tank full and the valve open? Check the tank level. Open the valve fully. Light a stove burner to bleed air from the line.
Is there obvious blockage? Look at the exterior vent for ice, mud, or debris. Clear anything you see.
If all three checks pass, reset the button. If the unit fires up and runs normally, you are good. If it trips again within the same use cycle, stop.
The problem is persistent.
When Not to Press the Button
Do not press the reset button if:
You smell propane near the water heater. That is a gas leak. Evacuate the area and call a certified technician.
The water heater is hot and you cannot tell why it tripped. Let it cool, then perform the walkthrough.
The button feels loose, does not click, or shows visible damage. The physical switch may be broken.
The unit has tripped multiple times in the last 24 hours. Repeated resets mask the real issue.
Aggregate reviews from RV owner forums and Truma service bulletins confirm that the most common cause of a single trip is air in the gas line after a tank swap. The second most common is a blocked exhaust from overnight frost. Both are easy fixes.
Everything else points to a bigger problem.
Where to Find the Button and How to Know It's Been Tripped
The reset button is not hidden, but it is not sitting in plain view. You need to know where to look.
Image source: Bing (Web (fair-use with source credit))
Exact Location on AquaGo Models
On an AquaGo, the reset button lives behind the exterior access panel on the side of your RV. That panel is usually a white or black plastic door held by two latches or screws. No tools are required for most models.
Just pop the latches and pull the door off.
Once the panel is open, look at the top of the water heater unit. You will see a small red button recessed into a plastic housing. It is about the size of a pencil eraser.
It sits near the control board and is the only red thing in that compartment.
Exact Location on Combi Models
On a Combi combination water heater and furnace, the reset button is behind a similar exterior access panel. The layout is different. The Combi unit is larger, and the button is typically on the side of the combustion chamber housing.
You may need to crouch to see it clearly. It is still red and recessed.
Visual Signs the Button Has Tripped
The most obvious sign is the button itself. When it is in the normal position, it sits flush with the plastic housing. When it has tripped, it pops out slightly, about 1/8 inch.
You can feel it with your finger.
The second sign is the LED indicator on the control board. On most Truma units, a blinking red or amber light accompanies a tripped overheat protection. The blink pattern varies by model, but a steady slow blink usually indicates an error related to high temperature or ignition failure.
Check your owner's manual for the specific blink code for your unit. Truma's website has a full error code guide for each model as of 2026.
Why the Button Is Recessed
Truma designed the button to be recessed to prevent accidental presses. If the button stuck out, someone could bump it while working in the compartment and reset the unit without knowing why it tripped. The recessed design forces you to intentionally check the cause before pressing.
A small screwdriver, a pen, or a narrow dowel works fine to reach it.
Step-by-Step: How to Properly Reset Your Truma Water Heater
This process takes about five minutes. Do not rush it. Every step exists for a reason.
Image source: Bing (Web (fair-use with source credit))
Step 1: Let the Unit Cool Down
Before you touch anything, confirm the water heater is cool. If it tripped while running, the internal components are hot. Pressing the button while hot can damage the internal switch contacts or burn your finger.
Touch the exterior access panel. If it is warm, wait another 15 minutes. If it feels like ambient temperature, proceed.
In cold weather the unit cools faster, but do not rush.
Step 2: Check the Propane Supply
Most reset button trips are caused by gas supply issues, not overheating. Confirm your propane tank is not empty. Open the valve fully.
If you just swapped tanks, there is almost certainly air in the line.
Go inside your RV and light a stove burner. Let it run for about 30 seconds. You will see the flame sputter and then stabilize.
That sputtering is the air purging from the line. Once the stove burner burns with a steady blue flame, the gas line is clear.
Step 3: Inspect the Exterior Vent
Look at the exterior vent openings on the access panel. Are they clogged with mud, ice, leaves, or insect nests? This is especially common if you have parked under trees or in an area with mud dauber wasps.
Clear any blockage with a soft brush or compressed air. Do not use a metal tool that could damage the fins.
Step 4: Press and Hold the Reset Button
Use a small screwdriver, a pen, or a narrow tool to reach the recessed button. Press it firmly. You should feel a slight click as it seats back into position.
Hold it for at least three seconds. Some owners report needing five seconds on older AquaGo units. Release the button.
Step 5: Verify the Ignition Cycle
After you release the button, listen. The control board starts an automatic ignition sequence. You should hear a faint click of the gas valve opening, then the spark igniter ticking for a few seconds, and then the whoosh of the burner lighting.
The whole sequence takes about five to ten seconds.
If you hear the burner light and it stays lit, the reset worked. Let the water heater run for a full cycle and check for hot water at the tap. If you do not hear any ignition activity, or if the burner lights and goes out immediately, the button has tripped again.
What to Do If the Reset Does Not Work
If the unit does not fire up after the reset, do not press the button again immediately. Wait about 60 seconds. The control board may need time to reset its internal logic.
Try the reset one more time. If it still does not work, move on to troubleshooting.
| Step | Action | Time Needed | Common Mistake |
|---|---|---|---|
| 1 | Let unit cool | 15-30 minutes | Pressing button while hot |
| 2 | Check propane supply | 2 minutes | Not purging air from gas line |
| 3 | Inspect exterior vent | 1 minute | Missing blockage behind panel |
| 4 | Press and hold reset | 3-5 seconds | Quick tap instead of held press |
| 5 | Verify ignition | 10 seconds | Walking away before confirming |
What to Check If the Button Trips Again
A single reset that holds is normal. A second trip within the same day means something is consistently wrong.
Gas Supply Problems
The most common reason for a second trip is still gas related. You purged the air, but maybe the tank is actually running low. Or the regulator is struggling.
Or there is a secondary air pocket that did not clear on the first purge.
Run the stove burner again. If the flame is weak, orange, or sputtering, your propane supply is insufficient. Check the tank level.
If the tank is full, the regulator may need replacement. Regulators can fail over time, and a failing regulator delivers inconsistent pressure that causes the water heater to overheat as it tries to compensate.
Low Battery Voltage
This one surprises many owners. Truma water heaters run on 12V DC power from your RV house battery. The control board needs clean voltage to operate the gas valve and ignition system.
If your battery is low, the control board may allow partial operation that leads to overheating or ignition failure, which then trips the reset button.
Check your battery voltage at the water heater connection. It should read at least 12.0V with no load. Below 11.0V, the control board may behave erratically.
Charge your batteries and try the reset again. This is common after a few days of boondocking without solar charging.
Blocked Combustion Air Intake
You checked the exterior vent, but did you check the actual air intake opening on the water heater itself? Mud dauber nests can form inside the vent housing behind the access panel. You would not see them from the outside.
Remove the access panel completely and inspect the intake grille with a flashlight. Remove any debris carefully with compressed air. Do not poke anything into the intake that could damage the burner assembly.
Scale Buildup in the Heat Exchanger
This is the hidden cause that gets overlooked. If you have used your water heater for a full season in hard water areas, mineral scale can build up inside the heat exchanger. The scale acts as insulation, trapping heat inside the unit.
The water temperature rises faster than the thermostat expects, and the overheat protection trips.
Descaling a Truma water heater requires a specific procedure. You need to isolate the unit, connect a pump and a descaling solution, and run the solution through the heat exchanger for a set period. Truma sells a descaling kit, and many RV service centers offer this service.
If you are in a hard water area, plan to descale every 6 to 12 months as preventive maintenance.
Freeze Damage
If the button tripped after a freezing night and you did not winterize the unit, freeze damage is a real possibility. Ice expanding inside the heat exchanger can distort the metal and create hot spots. The reset button will trip every time because the physical geometry of the exchanger has changed.
Freeze damage is not repairable in the field. The unit needs to be inspected by a certified technician. If you suspect freeze damage, do not keep resetting the button.
You risk cracking the heat exchanger and causing a water leak inside your RV.
Common Mistakes That Can Damage Your Unit
Some mistakes cost you time and frustration. Others can damage your Truma water heater permanently.
Resetting Without Checking Anything
The number one mistake is walking outside, popping the access panel, pushing the button, and walking away. If the button tripped for a reason, resetting without checking is like clearing a check engine light without looking at the engine. The problem is still there, and the next trip may happen under worse conditions.
Using Excessive Force on the Button
The reset button is a small mechanical switch. It does not need much pressure to click back into place. If you have to push hard or use a sharp tool to jam it, you are probably damaging the contact points inside.
A gentle firm press is all it takes.
Ignoring Air Purging Before the Reset
Many owners go straight to the water heater and reset the button without turning on a stove burner first. The water heater then tries to ignite into a gas line full of air. It fails.
The button trips again. Two minutes of purging the gas line would have fixed it.
Running the Water Heater on Low Battery
Low voltage causes erratic control board behavior. If you know your house battery is low, do not attempt to use the water heater until you have charged it. Running the unit on low voltage can cause the gas valve to open inconsistently, which leads to incomplete combustion and soot buildup inside the burner chamber.
Skipping Annual Maintenance
Truma recommends annual inspection and maintenance for their water heaters. That includes checking the burner, cleaning the combustion chamber, inspecting the heat exchanger, and testing the overheat protection. Units that have repeated reset button issues are almost always the ones that have never seen a maintenance schedule.
Winterizing Incorrectly
If you winterize your RV by blowing air through the water lines but forget to bypass the water heater, you push air into the heat exchanger. That air can create an air lock that causes the reset button to trip when you start the unit in the spring. Follow the winterization procedure in your owner's manual exactly.
Resetting with Ice or Moisture in the Panel
If you open the access panel and find ice around the water heater, do not press the reset button. Ice means water has entered the compartment. Pressing the button while there is moisture inside can short the control board.
Thaw the unit completely, dry the compartment, and then attempt the reset.
When to Stop Troubleshooting and Call a Technician
Some problems cannot be solved with a reset button. You need to know when to stop and call for help.
Repeated Tripping After All Basic Checks Pass
If you have checked the gas supply, purged the line, verified the battery voltage, cleaned the vents, and the button still trips, stop. There is an underlying issue that needs professional diagnosis. Continuing to reset the unit can cause damage to the control board or heat exchanger.
Physical Damage to the Button or Control Board
If the reset button feels loose, does not click, or shows visible cracks or damage, do not attempt to operate the water heater. The safety system is compromised. A certified technician needs to evaluate the unit.
Burnt Smell, Soot, or Visible Flame Issues
If you smell burning plastic or metal, or if you see soot around the vent openings, there is a combustion problem. The burner may be running rich or the heat exchanger may be damaged. Either way, this is not a reset-button fix.
Turn off the propane at the tank and call a technician.
How to Find a Truma-Certified Service Partner
Truma maintains a network of certified service partners who are trained on their specific systems. You can find a list of authorized service centers on the Truma North America website. These technicians have access to genuine parts, diagnostic tools, and factory training.
Your independent RV mechanic may be excellent, but Truma systems have unique requirements. A certified partner is the safest choice for complex repairs.
Frequently Asked Questions
Can the reset button break from too many presses?
Yes. The internal switch contacts can wear out over time, especially if you press the button while the unit is hot or use excessive force. If the button stops clicking or feels spongy, the switch may need replacement.
How long should I wait between reset attempts?
Wait at least 60 seconds between attempts. The control board needs time to reset its internal logic. Waiting longer on a hot unit, until it cools to ambient temperature, is even better.
Does the reset button work differently on the Truma Combi versus AquaGo?
The function is the same, it cuts gas flow when temperatures get too high, but the location differs. On the AquaGo it is at the top of the unit behind the exterior panel. On the Combi it is on the side of the combustion chamber housing.
What does it mean if the button does not click at all?
If the button feels stuck or does not produce a click, it may be broken or the internal mechanism may be jammed. Do not force it. Have the unit inspected by a certified technician.
Can I bypass the reset button with a jumper wire?
No. Never bypass the reset button. It is a critical safety device.
Bypassing it eliminates overheat protection and can cause a fire. If the button fails, replace it with a genuine Truma part.
Is it safe to reset the water heater while driving?
No. The water heater should be off while the vehicle is in motion or refueling. If it trips while driving, wait until you are parked and stationary before attempting a reset.
Similar Posts
