---
title: "Mr Heater Big Maxx Reset Button"
canonical: "https://gadgetguides.org/mr-heater-big-maxx-reset-button/"
author: "Arian"
published: "2026-09-11T07:19:09+00:00"
modified: "2026-09-11T07:19:09+00:00"
language: "en-US"
site: "Gadget Guides"
description: "Your Mr Heater Big Maxx Reset Button just tripped, and now your shop is cold. Before you press that red button again, you need to know why it popped in…"
categories: "Troubleshooting"
attribution: "Gadget Guides (https://gadgetguides.org/)"
---

# Mr Heater Big Maxx Reset Button

Your Mr Heater Big Maxx Reset Button just tripped, and now your shop is cold. Before you press that red button again, you need to know why it popped in the first place. That reset is a safety mechanism designed to stop overheating.

 

It is not a start button you can hammer over and over.

 

The Big Maxx line from Enerco includes vented unit heaters from roughly 30,000 to 80,000 Btu/h. Every model uses a manual reset high-limit switch that meets ANSI Z83.7/CSA 2.3 standards. One trip is a warning.

 

Repeated trips mean a real problem. So let's walk through what to check, what to press, and when to call a pro.

 

## Quick Answer

 

Press the Mr Heater Big Maxx reset button only after the unit cools for 20 minutes. A tripped button means the high-limit switch detected overheating. Check airflow, the vent, and gas supply before each reset.

 

If it trips again, call an HVAC pro.

 

![Mr Heater Big Maxx Reset Button](https://gadgetguides.org/wp-content/uploads/2026/09/mr-heater-big-maxx-reset-button-mtwmkyel.webp)

 

Image source: Web (Bing) / heaterfixlab.com (Web image (fair-use with source credit))

 

## First, Why Your Big Maxx Shut Down

 

When a Big Maxx shuts down and the reset button pops out, a safety circuit opened. The high-limit switch senses heat exchanger temperature. When that exchanger gets too hot, the switch cuts power to the gas valve.

 

The heater cannot burn gas if the fan is not cooling the exchanger. That is by design.

 

What causes the overheat? Usually one of three things. Airflow problems: a dirty fan, a blocked intake, a stuck blower motor, or a heat exchanger caked in dust.

 

Venting problems: a bird nest, a closed damper, or a power venter that stopped working. Gas problems: high manifold pressure, a bad regulator, or a propane tank that cannot keep up in winter.

 

As of 2026, every Big Maxx model we have reviewed uses the same manual reset architecture. That makes the troubleshooting logic universal across the lineup.

 

Here is the decision tree that matters. If the button trips once after a long cold start and the heater runs fine afterward, that is a plausible one-time overheat. If it trips again the same day, you have a recurring problem.

 

If it trips immediately every time, do not reset it again. Check the fan and the vent first.

 

A reset button is a symptom indicator. Treat it like one, and you will save yourself an expensive service call.

 

## What the Reset Button Actually Does (And What It Does Not)

 

The reset button is part of the manual high-limit switch on or near the gas valve. It works like a circuit breaker for the heater burner. When the heat exchanger passes a preset temperature, the switch snaps open and kills the electrical signal to the gas valve.

 

That stops the flame before the unit can cook its own internals or start a fire.

 

The switch cannot tell you why the overheat happened. It only records the fact that the temperature limit was breached. Once the exchanger cools back into the normal range, the switch can be rearmed.

 

But only by physically pressing the button. There is no automatic reset. That is intentional.

 

It forces a human to inspect the unit before it can run again.

 

![high-limit switch](https://gadgetguides.org/wp-content/uploads/2026/09/high-limit-switch-mtwmkzej.webp)

 

Image source: Web (Bing) / pickhvac.com (Web image (fair-use with source credit))

 

So what does the reset not do? It does not fix poor gas pressure. It does not clear a blocked vent.

 

It does not revive a seized blower motor. And it is not a power switch. Per NFPA 54 guidelines, repeatedly tripping a high-limit switch means the system needs a qualified inspection.

 

Not another press of the button.

 

Also worth noting: on some Big Maxx models, the button is a small red cap recessed behind the burner access door. On others, it is mounted directly on the gas valve. Either way, it has one job.

 

Let it do that job, and pair it with real troubleshooting.

 

## Work Through These Checks Before You Push the Button

 

Before you touch the red button, spend ten minutes running through these checks. They will save you from pressing reset repeatedly while the heater keeps shutting off.

 

- **Check the airflow path.** Look at the intake screen, blower housing, and heat exchanger for dust, webs, or a nesting mouse. If the fan blade does not spin freely or the motor hums without moving, fix that first. The limit trips when the heat exchanger does not cool.
- **Inspect the vent terminal.** A blocked exhaust, bird nest, or snow drift stops the power venter from clearing flue gas. Most mystery shutdowns are just a plugged vent.
- **Verify the gas supply.** For natural gas, make sure the shutoff valve is fully open. For propane, check the tank level and regulator. A tank below 20 percent in sub-freezing weather will starve the burner and cause overheating.
- **Check the thermostat and wiring.** Set the thermostat to heat mode and the setpoint above room temperature. Look at the low-voltage wires on the gas valve. A loose spade connector can interrupt the control circuit at random.
- **Confirm electrical power.** Big Maxx units run on 120V for the fan and controls. Check the breaker, the disconnect switch, and the outlet. A bad outlet or loose connection can mimic safety trips.

 

The logic here is simple. If any of those checks come up short, the reset button will just make the unit trip again later. If everything looks clean and tight, let the heater cool for at least 20 minutes before you attempt the reset.

 

## How to Reset the Big Maxx Safely (Step-by-Step)

 

Once you have checked the airflow, vent, gas, and wiring, you can reset the button. Follow these steps in order. Rushing them can cause the heater to short-cycle or trip again immediately.

 

1. **Turn the thermostat down**, or switch it to off. That stops the heater from calling for heat while you work.
2. **Cut electrical power** at the disconnect or unplug the unit. You want the fan and ignition control completely dead while you access the limit switch.
3. **Wait for the unit to cool completely.** This is non-negotiable. The manual reset button will not click in until the high-limit switch returns to its normal operating range. Twenty to thirty minutes is typical.
4. **Remove the access panel** covering the gas valve. The button sits on or near the valve, often recessed behind a small opening. On most Big Maxx models it is red, though some older units have white or black buttons per the Mr. Heater manual.
5. **Press and hold the button firmly** until you feel and hear a click. Hold it for one full second after the click, then release. The button should stay latched flat.
6. **Restore power and set the thermostat** back to heat mode, with the setpoint a few degrees above room temperature. The unit should fire its normal sequence: the fan spins up, the spark igniter glows, and the burners light. Let it run for at least ten minutes to confirm it does not trip again.

 

![Big Maxx reset procedure](https://gadgetguides.org/wp-content/uploads/2026/09/big-maxx-reset-procedure-mtwml0a3.webp)

 

Image source: Bing (Web (fair-use with source credit))

 

If the button does not click in, the switch is still hot or the unit has a wiring fault. Wait another ten minutes and try once. If it still will not latch, stop pressing and call someone.

 

## Five Mistakes That Turn a Simple Reset Into a Big Repair Bill

 

A reset button is quick to press. But the repair that follows a rushed reset can be painful. Here are the five biggest mistakes we see in garage heater troubleshooting.

 

1. **Pressing reset repeatedly without diagnosing anything.** If the unit trips five times in fifteen minutes, you do not have a reset problem. You have an airflow, gas, or vent problem. Each cycle stresses the heat exchanger and the ignition control. What starts as a simple blower fix can turn into a cracked heat exchanger. That costs more than a new heater.
2. **Bypassing the high-limit switch.** Some people install a jumper wire or a higher-rated switch so the unit runs without tripping. That switch is the only protection standing between a blocked vent and a fire. Removing it turns the Big Maxx into an uncontrolled burner. Do not do it.
3. **Resetting while the unit is still hot.** The switch will not click in until it cools below the limit threshold. Pushing harder just stresses the switch body and the button mechanism. Wait the full cool-down period. Your patience is worth more than a forced click.
4. **Replacing the switch when gas pressure is the real issue.** A Big Maxx that trips right after ignition may have a manifold pressure problem. Natural gas and propane have different pressure requirements. A new switch does not fix bad gas flow. It just fails the same way.
5. **Ignoring the propane tank level.** Propane vapor pressure drops as the temperature drops. A tank at 15 percent in January will not supply enough fuel. The flame gets lazy, the exchanger overheats, and the safety trips. Check your tank first. It is the cheapest fix on this list.

 

## When to Stop Pressing and Call a Licensed HVAC Pro

 

If your Big Maxx trips a second time after you have cleaned the fan and checked the vent, stop pressing. You have done the safe DIY work. Anything more needs a licensed technician.

 

Here are the exact red flags that require a professional:

 

- **The reset button trips again within 24 hours.** A recurring trip means a failing heat exchanger, bad gas valve, or weak blower motor. These are not user-serviceable parts.
- **You smell gas.** Do not touch the reset button. Open doors, leave the building, and call your gas utility or a qualified pro from outside. That is per basic gas safety protocols.
- **The rollout switch tripped.** That is a separate safety device that detects flame escaping the burner chamber. A rollout trip means flue gases are not moving where they should. That is a dangerous condition, not a reset fix.
- **The unit fires, then shuts down after 10 to 20 minutes.** That pattern points to gas pressure issues or a heat exchanger airflow restriction deep inside. Both need trained diagnosis.
- **You are uncomfortable working near gas connections.** That is fair. A licensed HVAC technician has the tools to check manifold pressure with a manometer. Most homeowners do not.

 

If any of those apply, cut power to the unit, close the gas shutoff valve if you know where it is, and schedule a service call. The roughly $150 to $300 you will spend is far cheaper than a new heater or a house fire.

 

## FAQs About the Mr. Heater Big Maxx Reset Button

 

### Where is the reset button on a Mr. Heater Big Maxx?

 

The reset button is the small red button on or near the gas valve behind the burner access panel. On most Big Maxx models, you remove the lower front panel to see it. The button sits on the gas control valve itself, often right next to the main gas line connection.

 

### Why does my Big Maxx reset button keep tripping?

 

The high-limit switch trips when the heat exchanger gets too hot. That means the fan is not moving enough air, the vent is partially blocked, or the gas pressure is too high. A dirty blower wheel is the most common cause.

 

Checking the airflow path before every reset is the smartest move.

 

### How long should I wait before pressing the reset button?

 

Wait at least 20 to 30 minutes after the heater shuts down. The manual reset switch will not click in until the heat exchanger cools below its safe operating threshold. Pushing harder will not speed that up.

 

It just strains the switch body.

 

### Can I bypass the reset button to keep the heater running?

 

No. Never bypass the high-limit switch with a jumper wire. That switch is a fire protection device.

 

Removing it lets the heater run without airflow and overheat dangerously. Manufacturer instructions and NFPA 54 require the manual reset function to remain functional.

 

### What is the difference between the reset button and the rollout switch?

 

The reset button reacts to overheating in the heat exchanger. The rollout switch reacts to flame escaping the burner chamber, which means flue gas is not venting properly. Each is a separate device.

 

Some are rolled into one gas valve assembly, but they protect against different failures.

 

## So, Is Pressing the Reset Button Safe? Here Is Your Final Verdict

 

Yes, pressing the reset button is safe, if you follow the right sequence. Check the airflow and vent first. Let the unit cool for at least 20 minutes.

 

Press the button once. If the heater fires and runs normally, you are done. That one reset is completely appropriate.

 

Here is the final decision guide:

 

| Situation | What to do |
| --- | --- |
| Button trips once after a cold start, then runs fine | Wait 20 minutes, press reset once, restart the heater |
| Button trips again within the same day | Recheck vent and fan, then call a pro if it repeats |
| Button trips immediately every time | Do not reset again. Call a licensed HVAC technician |
| Gas smell at any point | Leave the building, call the gas utility or fire department |
| Rollout switch tripped | Call a pro. Do not attempt a DIY fix |

 

The Mr Heater Big Maxx reset button exists to protect you. It is a symptom detector, not a diagnostic tool. As of 2026, the safest approach is still the simplest one: run the checks, wait for the cool-down, press once, and let the heater prove itself over a full cycle.

 

If the heater will not cooperate after that, stop experimenting. A professional service call costs far less than replacing a cracked heat exchanger or handling the aftermath of an overheated unit. Respect the reset button, and it will keep your shop warm for years.