Mr Heater Big Maxx Problems [7+ Easy Solutions]

The most common Mr. Heater Big Maxx problems experienced by users are- 

  • Ignitor won’t spark or the burner won’t light
  • Delayed ignition
  • Burner backfiring during operation
  • Whistling noise when the burner is lit
  • The blower won’t turn off
  • The heater keeps blowing the fuse

Read our Mr heater big max troubleshooting guide to fix any of these issues ASAP. 

Mr Heater Big Maxx Problems [Easy Solutions]

We’ll now take a comprehensive look at the problems that we commonly see in Mr. heater big max and the possible causes behind each problem. To solve the issue, you must first diagnose what is causing the problem and then perform the corresponding solution that we mention.

1. The Ignitor Won’t Light

When you turn your big max igniter doesn’t light, there can be several causes behind it. You’ll need to figure out which one is the culprit in your case. Here are the possible reasons why your heater igniter not igniting.

  • Incorrect positioning of the ignitor electrode or failed ignitor electrode.
  • There is no connection between the ignitor electrode and the ignitor.
  • The ignitor cable has been pinched or is moist or the ignitor cable is damaged.
  • The ignitor is defective itself.


Start by testing the ignitor. If it’s faulty, you need to replace it.

How To Test An Ignitor

Here’s how you conduct an ignitor spark test to see if it’s working properly or not.

Step 1:  Turn off the heater. In the burner junction box, disconnect the ignitor wires.

Step 2:  Release the screws or clips that are holding the ignitor in place. Open the ignitor plate completely.

Step 3:  Bend the copper ignitor clips to a distance of 5/8″ to 34″ between the clip ends. Connect the ignitor leads in the burner junction box to a test power cable with a switch.

Step 4:  To power the ignitor, turn on the test power cord switch.

Step 5:  Examine the ignitor clip ends for spark. If a spark happens, move on to the secondary coil test.

Step 6: If the spark does not leap the gap or jumps only sometimes, the ignitor is malfunctioning and needs to be replaced.

Step 7: Turn off the ignitor’s electricity.

In case the ignitor is working, you can try the following things.

  • Change the electrode’s position or replace the electrode.
  • Reattach the ignitor cord.
  • If the ignitor cable is squeezed by any metal or tubing, it must be freed. Keep the ignitor cord dry at all times. And change the ignitor cable if it’s defective.

2. Burner Won’t Light

Mr. Heater Big Maxx heating sequence works by first pre-purging the system for 30 seconds. The gas valve releases gas by opening up the solenoid valves in them and the ignitor is ready to spark.

The flame sensor then detects the flame at the burner. Upon failure, it tries igniting the burner twice before closing the gas valve to prevent any possible fire accidents.

So, in this process, a few things can go wrong. The ignitor may not be sparking, so the gas burner won’t light up, the gas pressure may be too low from the gas valve, or the gas valve can be defective. Another possibility is that the flame sensor isn’t working and it is failing to detect the burner flame and locking out your heater.


We already laid it out in detail what you should do if the ignitor won’t spark. You need to check the unit gas pressure next. Follow the steps below.

  1. Keep the unit lit at maximum rate and at the same time, check gas line pressure. For natural gas, you should get a minimum pressure of 5.0” w.c. LP or propane gas should give out 10.9” w.c of pressure. 
  2. Make adjustments if necessary. Call your local utility company for help.
  3. Next, you need to check the manifold pressure. You will find the ratings for your unit on a rating plate on the unit’s body. Check the figure given below to find the gas pressure adjustment screw. After adjusting the gas pressure your unit should be working fine.

In case the issue is still not fixed, you should inspect your gas valves and replace them if necessary. Next, check the flame sensor for proper functioning. You may need to replace that.

3. Delayed Ignition

Delayed ignition puts you in a very risky position. As gas will keep building up till the burners ignite resulting in explosions. You’ll most likely hear booming noises if your heater has this problem.

Take a look at what might be causing this problem-

  • The pressure in the manifold is too low.
  • A clogged burner orifice can also be the cause.


To fix delayed ignition ASAP, you can try to-

  1. Call your gas utility company. 
  2. Clean or replace the burner orifice.

Whatever is causing ignition delay should be diagnosed quickly. Call in a professional if you’re not sure how to go about fixing it. This is not a problem you can sleep on. 

4. Burner Backfiring During Operation

You should treat this problem carefully. Fix this issue ASAP. Call in a licensed professional for help if you don’t have much experience with home appliances. Here are the possible causes behind this problem.

  • The aperture of the burner is clogged or damaged.
  • The burner assembly has been damaged.


To fix your heater and stop your burner from backfiring during operation, you should- 

  • Clean the burner orifice. You need a wire brush to clean it thoroughly.
  • Replace the burner with a new one.

5. Whistling Noise When Burner Is Lit

If you hear a whistling sound every time your burner is lit, there can be some issues behind it. Let’s take a look at the possible causes.

  • There is air in the gas line.
  • The heater’s air channels are clogged.
  • A partially clogged or dirty burner orifice.


Figure out which cause is behind the whistling sound with some inspection. After you’ve diagnosed the cause, depending on your diagnosis,  here’s what you need to do.

  • Run the burner until all air is out of the pipe, then have the gas line checked by a local gas provider.
  • Keep minimum installation clearances in mind. Check your user’s manual for relevant info.
  • Clean or replace the burner orifice.

6. Blower Won’t Turn Off

The reasons behind your big max blower not turning off can be various. The most common is that the heater is too small for the room and you have set the thermostat too high. As a result, the room never reaches the desired temperature and the blower keeps running. 

However, turning down the temperature on the thermostat may not solve your problem. 


After turning down the set temperature if the issue persists, try checking the following issues one by one to see if your blower turns off. 

  • Your thermostat may be incorrectly wired. Check the instruction manual of your thermostat to fix the issue and correct any inconsistencies.
  • Check the thermostat for proper operation. It may be malfunctioning. You may need to replace it.
  • Your heater has some safety switches. The air pressure switch, flame rollout switch, and high limit switch. They may trip and that can result in your blower running continuously. Set the switches back in place. 
  • The Control board may be incorrectly set up or faulty. Fix the issue. You may need to invest in a new control board. 

7. Heater Keeps Blowing Fuse

Your Mr. Heater Big Maxx has a 3 Amp fuse in the circuit board. It can keep on blowing and turning off the heater for various reasons. 


Try the following things to fix this situation.

  • Clean up your heater. Excessive dirt can be responsible for this issue. 
  • Lack of proper ventilation can also result in a blown fuse. Ensure that your heater isn’t mounted close to walls that will obstruct airflow. 
  • Loose wiring can also be an issue. Ensure that your control board, thermostat, and other essential parts are wired correctly. 
  • A bad control board may also be responsible. In that case you should replace it. 

Mr Heater Big Maxx 3 Flashes [Meaning + Solutions]

Mr. Heater Big Maxx 3 flashes indicate the failed pressure switch. Now the question is, can a faulty pressure switch cause your Mr. Heater to shut off? The answer is, yes.

The heater pressure switch is a safety feature like the flame sensor. It identifies the condition of pressure in the furnace. Sometimes the draft inducer motor can create excessive negative pressure in the system. 

When this happens, the pressure switch signals the heater and shuts the whole device off. It does so to avoid damages the negative pressure can cause.

When you face this problem you can fix it easily by releasing the pressure. The problem usually lies in the vent, and pressure switch tube. You can clean both using a can of compressed air

Apply the air in the vent and use a brush to clear out as much dirt as possible. In the case of the tube, detach it first. Then clear out the debris using the canned air. You may need to use a thin wire to clear out the stubborn dirt.

If this doesn’t solve the issue, then your heater pressure switch is faulty. Here’s how you can replace it:

  • Turn off the heater power and disconnect the heater gas supply. Then 0pen the heater top cover panel.
  • Disconnect the hose connected to the pressure switch and remove the wires. Now unscrew the old pressure switch and remove it from its slot
  • Get a new pressure switch with the same pressure rate.
  • Align the new pressure switch into its designated spot and tighten up the screws. Reconnect all the wiring and the gas connection.

Now your pressure switch should work just fine. If it still doesn’t work then don’t waste a minute and call an expert right now.

“Also read how to fix Mr Heater Big Maxx 2 flashes.


How much propane does a Mr heater use per hour?

The burn rate of a gallon of propane is roughly 100,000 BTUs (British Thermal Units) per hour. This means that if you operate your heater continuously (30,000 BTUs), you’ll use around 1/3 gallon of propane every hour. Your heater would use around 1 gallon per hour at 33,000 BTUs.

How long will a 20 lb propane tank run a heater?

In an outdoor gas heater, a regular 20-pound propane cylinder can last up to ten hours. 

Can you use a Mr heater inside?

While parabolic propane heaters are typically considered to be suitable only for outdoor usage, the Mr. Heater brand portable infrared heaters can be used indoors. The manufacturers expressly advertise this point.

Do you need ventilation when using a propane heater?

Yes, proper ventilation is necessary for your heater to operate normally. Your heater needs oxygen to combust and without it, the risk of producing carbon monoxide is increased. 

Can you use a Mr heater in a garage?

Absolutely. Mr. Heater is a portable garage heater that may be used in enclosed spaces like garages and workshops, as well as other locations like storage buildings, barns, sheds, construction sites, tents, and more. It is more effective indoors than outside, and it must be maintained away from flammable or combustible things.


Hopefully, our guide on the solutions to Mr Heater Big Maxx problems helps you out. If you have more questions, let us know in the comment. We love hearing from our readers. 

About William

William is the founder of He has real life practical skills in fixing smoker & heating appliance issues. He loves to share his knowledge & helps others in fixing their appliances & saving their money. William firmly believes that anyone can repair his or her unit with the correct guidance & knowledge. See more at about us.

14 thoughts on “Mr Heater Big Maxx Problems [7+ Easy Solutions]”

  1. My Mr. Heater Big Maxx is very noisy when it first comes on, (burner is running) until the flame goes out..why? and can I fix this or is this just the way it works?

    • Hi Norris

      The possible causes are:
      1. When the burner is cold, turn the control knob to the HI position.
      2. There is air in the gas line.
      3. The heater’s air channels are clogged.
      4. A partially clogged or dirty burner orifice.

      Check all these issues and fix them.


  2. Q – I have the 80000 btu garage heater the upper burner tip where the flame sensor is will not light , the unit has good supply and drop across gas valve . The flame roll up from the burner tip below does not seem to be catching the upper one .

    • Hi Don

      Try cleaning the flame sensor. It might be dirty. If cleaning doesn’t work, then contact a technician. You may need to replace the flame sensor.


  3. I have 2 of the 80000 BTU units, the fans for each unit never turns off. When I push the reset button for the roll out switch the units will fire up. Once the heat reaches the temperature in the garage the burners shut down but the fans contue to run and the units will not fire back up without resetting them.

  4. I got a new mr Heater 50,0000 everything is new . The problem is it won’t shut off. I got it set to the lowest temperature I can.

    • Hi David

      To fix your Mr. Heater won’t shut off issue, it would be wise to contact the Mr. Heater customer support center or your local Mr. Heater dealer.

      Wish you all the best!

    • Hi Andy

      To fix the rattling sound, readjust all the screws so that the unit fits snugly against the wall.

      If it doesn’t work, you may need to replace the motor.

      Best of luck!

    • Hi perry

      Check the blower motor to fix the issue. If you get it faulty, you may need to replace it.

      But before replacing the motor, it’s worth to take help from a professional.

      Best of luck!

  5. My 50,000 btu Big Maxx heater has an igniter that ignites for about five seconds and the heater runs smoothly half of the time. The other times, the igniter won’t stop igniting during the whole run process. Should I start with cleaning the flame sensor?


Leave a Comment