natural gas heater how to and troubleshooting guide
Tips & Tricks

Natural Gas Garage Heater Troubleshooting

Natural gas garage heaters are energy-saving electrical appliances that will keep your home comfortable during the winter months. Other than keeping your garage warm, it prevents your house from losing heat during cold months.

Natural gas heaters are durable, but they are prone to developing issues due to poor maintenance, constant use, or regular wear and tear.

You can quickly fix most natural gas heater problems without the help of a professional, and you can avoid them with regular care and maintenance tasks. Read through this article to learn how to troubleshoot the most common natural gas heater problems.

How to vent a natural gas garage heater

Venting your natural gas heater is attaching a vent pipe or flue to the heater that directs the exhaust gases(carbon monoxide) to the outside of the house, typically through the roof.

It is important to vent your natural gas heater to prevent carbon monoxide accumulation in the garage, which can cause health issues and even death. If you have some experience using work tools, you can quickly vent the garage heater yourself by following the steps below.

Things You’ll Need

  • Tape measure
  • Metal galvanized duct
  • Metal galvanized elbows
  • Vent pipe
  • Vent and duct cap
  • Reciprocating saw
  • Cordless drill
  • Snips
  • Sheet-metal screws
  • Ladder
  • Marker
  • Screwdriver
  • Plumbers tape


  1. Measure the duct size. Use a tape measure to determine the diameter size of the vent flange on your heater.
  2. Also, calculate the length of the duct required. Measure the distance between the vent flange to the spot on the roof where the vent will attach.
  3. Once you get the duct with the correct diameter size, measure the length of the duct needed and cut the duct with the snips.
  4. Next, draw a circular outline of the duct’s circumference on the roof for the hole you’ll drill where the duct attaches to the vent.
  5. Make another circle around the first outline about one to two inches larger to allow for clearance when inserting the vent.
  6. Connect a 90-degree elbow to the vent flange of your heater with the other end facing the underside of the roof.
  7. Use a power drill to make several pilot holes of about ¼ or ½ inches along the perimeter of the larger guiding outline on the sheathing.
  8. Take the reciprocating saw and cut through the drilled holes and remove the sheathing and shingles to make room for the duct.
  9. Make an opening of the same diameter on the roof flashing.
  10. Fit the upper flange on the roof, flashing below the shingles above the hole towards the roof peak. Align the hole in the roof flashing with the hole in the sheathing.
  11. Position the ladder below the hole in the roof. Then, fit the vent duct through the sheathing and flashing until about 24 inches of the flue is above the roof.
  12. Have an assistant on the rooftop push the vent cap through the top end of the duct to the bottom.
  13. Then secure the vent onto the rooftop by tightening the screws with a screwdriver.
  14. Measure the distance from the 90-degree elbow through the rafters-where the duct vent will pass through- to the hold on the roof, and then add 16 inches of allowance to this measurement.
  15. Cut some plumbers tape and wrap it around the duct until the bottom end aligns with the top end of the 90-degree elbow.
  16. Once they are aligned, use a deck screw to tighten the other side of the plumber’s tape to the opposite rafter.
  17. Measure the distance between the rooftop duct to the open end of the elbow, add another portion of the vent if necessary, trim it off with a hacksaw, and attach the male end to the female end of the duct correctly.
  18. Disconnect the elbow from the flange on the heater, insert the rooftop duct onto the elbow’s top opening, and then reconnect the bottom opening to the flange on the heater.
  19. Use three one-inch tapping screws to secure the elbow to the flange on the garage heater.

How to convert a natural gas garage heater to propane

Not every natural gas heater can support the use of propane, but with the right heater, you should install a conversion kit to cater to the difference in pressure needed to run the heater correctly.

Modify the heater

  1. Turn off the gas supply and disconnect the power connection to the heater. Unscrew the screws holding the burner access door and remove the door.
  2. Disconnect all the electrical wires connected to the natural gas control valve.
  3. Detach the rollout switch and the flame sensors on the control valve. Remove the manifold access pipe to access the gas control valve.
  4. Remove the regulator adjustment cap and the pressure regulator adjustment screw.
  5. Remove the spring in the gas control valve and replace it with the new spring in the control valve and a new pressure regulator adjustment screw.
  6. Make sure the pressure regulator adjustment screw covers the surface of the control valve.
  7. Insert the new O-ring into the new adjustment cap from the conversion kit.
  8. Remove the old orifices from the manifold and install the new ones.
  9. Remove the screws that hold the burner to the flue panel, remove the burner assembly from its chamber while supporting the opening inlet plate on the burner.
  10. Remove the two screws that secure the air shield in place and place the new spoiler screws from the conversion kit into each burner and screw them in until the screw heads are flush with the surface of the burner.
  11. Replace the air shield to its place, replace the burner assembly, reattach the manifold pipe to the burner and reconnect all the electrical wires to the gas control valve.
  12. Ensure all the wire connections are correct, then insert the rollout switch and the flame sensor and close the burner access door with the screws.

Install the gas connections

  1. Connect the new propane supply to the heater’s gas supply line and install the manual gas shut off valve onto the gas line with the test gauge attached.
  2. Install the propane gas supply line to the garage heater and use thread sealant to seal the connection properly and avoid gas leakage.
  3. Turn off the manual shut-off valve.
  4. Take out the inlet pressure tap on the control valve and insert a 1/8 inch NPT connector to attach the pressure gauge.
  5. Then, turn on the manual shut-off valve to release the gas.
  6. Switch on the power supply to the heater and turn up the thermostat until the heater burners ignite. Check the gas pressure and ensure the pressure is a minimum of 11mm.
  7. Turn off the power and the gas supply to the heater again. Disconnect the pressure gauge tube and the hose connector from the main gas line.
  8. Reconnect the pressure tap on the gas control valve, turn on the gas supply and make sure the gas is not leaking.
  9. You can test for a gas leak by using a foaming solution.
  10. Pass the foaming solution along the supply line, and if bubbles or foam appear, it indicates there might be some leakage at that location.
  11. Turn off the gas manual shut-off valve and tighten or seal any joints where bubbles form on the pipe.

Regulate the propane input rate

  1. Switch off power to the heater. Open the burner access door and move the gas control to the ‘Off” position.
  2. Detach the outlet pressure plug on the gas valve and then install the pressure gauge on the 1/8 inch NPT outlet tap.
  3. Wait for at least five minutes and then turn on the gas control and switch on the power to the heater.
  4. Turn up the thermostat until the heater starts, and then check the pressure and make sure the reading is 10 inches of water column pressure.  
  5. If the pressure reading is more or less than 10 inches water column pressure, switch off the power to the heater and adjust the manifold pressure.
  6. Turn off the gas control, remove the cap on the gas control valve to access the regulator adjustment screw.
  7. Twist the screw clockwise to increase the pressure and counterclockwise to reduce the gas pressure as necessary.
  8. Return the tap plugs and regulator cap on the gas valve, turn on the gas control, and close the burner access door.
  9. Turn up the thermostat until the heater ignites to test if the conversion was a success, and then turn down the thermostat back to its desired setting.

How to size a natural gas garage heater

To estimate the gas heater size required is by calculating its thermal output in BTU (British Thermal Units). Install the right garage heater size allows you to get the most out of your unit.

A heater that is too small will waste your power trying to heat a space that is too big, while a large heater will consume too much power to produce heat that you do not need.

Luckily you can estimate the right size garage heater that you need quickly with a few measurements and simple math.  

  1. Measure the length and width of your garage and multiply both measurements to get the square footage of the garage floor space.
  2. For example, a garage measuring 20ft by 26 ft will be 20×26 to give you 520 square feet.
  3. Measure the volume of the garage space you want to heat in cubic feet. Multiply the square footage to the height of the room from the floor to the ceiling.
  4. As per our earlier example, if an average ceiling height is about 8ft high, the calculation would be 8×520 to give you 4,160 cubic feet.
  5. Check the insulation in your garage. An insulated garage is more energy-efficient than a non-insulated garage; therefore, it will require a smaller heater with lesser BTU.
  6. Insulation in freezing climates typically have an R-value between 25 to 30 and insulation in warm climate typically has an R-value between 13 to 15.
  7. The degree of insulation is rated based on how much more or less it is from the recommended average. If your garage has no insulation, use a rating of 5, 1.5 if it has weak insulation, 1 if it has average insulation, and 0.5 if it has strong insulation.
  8. Determine thermal output in BTU of the heater required to heat the space. The formula for the equation is;  (total cubic feet × insulation quality rating × desired temperature rise) / 1.6 = the BTU requirement. The calculation would look like this; (4,160×1×23)/1.6 = 59,800 Btu.
  9. Find a heater with the BTU rating that corresponds to your results. If you live in a place that experiences very cold winter months, you can add 10% to the BTU to provide a safety margin for such months, especially if you use the garage as a living area. Adding 10% will give you a heater size of about 65,780 Btu.

Best place to install a natural gas garage heater

The best mounting location for your gas garage heater is on a corner wall near the ceiling or floor while aiming it about 45degrees towards the garage door. Face the louvres downwards and place the thermostat away from the airflow heater.

The heater should also have a clearing of at least 10cm from the floor and other large objects like storage shelves. Proper heater placement in your garage is essential to ensure the room is safe while working there and allows the heater to work efficiently.  

Why would a natural gas garage heater suddenly stop working?

Assuming your garage heater has been well maintained, there several other reasons that can cause it not to ignite. Follow the troubleshooting steps below to get your garage heater working correctly.

Check the thermostat

  • The thermostat is responsible for controlling and regulating the heating system.
  • Check the thermostat controls and make sure it is set on “HEAT” and not “COOL” and the fan is on “AUTO”.
  • Make sure the temperature setting on the thermostat is high enough to start the heater. Turn the temperature control to a setting higher than the room temperature.
  • Make sure the time and day settings on display are correct.
  • If the thermostat is set correctly and still not working, check if the thermostat is receiving power. Check the thermostat batteries and replace them if necessary.
  • If the batteries are dead, the thermostat setting will go back to default settings.
  • Inspect the wires and fuses for any signs of a short or damage. If there are any loose wire connections, reconnect them securely.
  • Inspect the internal thermostat components for dust, dirt and grime. If you use the garage space as a workshop, the dust and debris are likely to accumulate and cause it to malfunction.
  • Clean the components with a clean cloth and appliance cleaner.
  • If the thermostat is defective, you have to replace it.

Check the electrical switches and breakers.

  • Look for a standard wall switch that provides power to the heater and make sure it is on. Check the circuit breaker and fuses to make sure that power is getting to the heater.
  • Switched on any tripped circuit breaker and replace any burnt fuses.

Check the service door on your heater.

  • Inspect the front panel covering the blower motor on the heater and make sure it is closed properly. Most heaters have a push-in switch for safety that should be depressed for the heater to run.

Check the gas supply.

  • Track the gas line from the heater to the meter and turn on the gas supply valve to make sure the heater is receiving gas to burn. Turn the handle to the parallel position.

Inspect the heater filters

  • Heater filters clogged with dust, debris and grime will prevent proper airflow to the burner, and the heat exchanger will overheat and shut off to prevent the unit from damaging.
  • The heater requires adequate air circulation to operate appropriately.
  • If you hear the blower running but no heat is being produced, replace the filter, press the reset button if your heater has one and start the heater.
  • Always inspect the filters monthly for buildup, dust them and replace them every three months. You may have to change them more frequently if you have pets or use the garage as a workshop.

Check the exhaust flue for blockage.

  • Sometimes the heat from the exhaust vent attracts birds and rodents, which can clog the vent duct and prevent the removal of exhaust gases.
  • A blocked exhaust flue will accumulate too much heat and carbon monoxide and shut off. Switch off the power and gas supply to the heater, carefully dismantle the vent system from where it attaches to the roof ad remove any obstructions.
  • You can also use a shop vac to clean the vent system and then reattach the parts in reverse order.

Check the standing pilot.

  • The heater won’t work if the standing pilot is too weak, flickers or is off. Older heaters have a pilot light which is a flame that ignites the gases in the heater.
  • Turn off the gas supply and wait a few minutes for the gas in the chamber to dissipate. Turn the valve to the pilot position, hold a light over the pilot gas tube while pressing the reset button for about 30 seconds.
  • If the pilot does not light, wait a few minutes and repeat the process for 45 minutes and 60 minutes.
  • When the pilot lights up, turn on the gas valve, and if it does not stay on, there is a problem with the thermocouple or ignition system. You can replace these components yourself or call a technician.

Clean the flame sensor

  • Over time, soot and dust collect on the flame sensor and prevents it from working. The flame sensor is a safety measure that allows gas to flow only when there is a spark to ignite.
  • If the flame sensor is faulty, the heater will either ignite intermittently or not light at all.
  • Switch off power to the flame sensor, open the heater and locate the flame sensor; it looks like a rod near the back of the heater, right on the burner’s path.
  • Remove the flame sensor if possible and clean it with a soft dry toothbrush. You can also remove the soot using a dry rag.
  • Return the sensor to its place and turn on the heater.

Reset the heater

  • Check if your heater has a reset button. It is usually a red button on the side, front or back of the heater unit. Press it and wait for the heater to power up and emit hot air. The reset button is a safety feature that shuts off automatically when there are other issues such as a clogged filter, overheating or a power surge.

Control board issues

  • If none of these tips helps, there could be more complicated issues that may need professional services. Most modern heaters have self-diagnostic abilities that trigger LED lights coded with information on specific garage heater problems.

Check this too: Reznor Garage Heater Troubleshooting & How to Guide

Why does my natural heater keep running after reaching target temperature?

If your furnace is running after reaching its set temperature, it is not getting the signal of the target temperature, which is usually due to a defective component. To fix this issue, follow the steps below.

Check the blower motor.

Inspect the heater to see if it’s the blower or the whole heater system running. Place your hand in front of the vent, and if you feel warm air coming out, it means the blower is not the issue.

If the air feels cold, you should check if the thermostat control is on the “ON ” setting. If it is, turn it to the “AUTO” setting, and the heater should be able to shut off after reaching the target temperature automatically.

Check the thermostat.

If the problem persists, it means the heater is not receiving the correct information from the thermostat. First, check the condition of your thermostat; look for frayed or disconnected wires, depleted batteries or internal components clogged with dirt. If fixing the thermostat does not resolve the issue, replace the thermostat.

Why does my garage heater smell like gas?

It is usual for the heater to release small amounts of gas when cycling, which gives a very faint smell of gas. However, if you smell the gas in the entire garage, it is an obvious sign of a gas leak in the heat exchanger.

The best solution is to turn off the gas supply and power supply to the heater. Open the windows to release the gas and call a professional HVAC technician.

Basic care and maintenance tips for your gas garage heater

Care and maintenance practices for your gas heater will ensure it works efficiently, increases its lifespan, reduces breakdowns and saves on repair costs. Below are some basic maintenance tasks for your garage heater.

  • Before performing any cleaning and inspections, switch off the power and gas supply to the heater and make sure there are no gas leaks along the gas line.
  • Clean the filter system monthly and replace them every three months. After that, you can clean them using some cold water, dishwashing soap and a soft-bristled brush.
  • With the filter system out, check the blower for any dirt. Sometimes dirt will pass the filters and collect around the blower.
  • Remove the panels that cover the filter and access the blower system. Clean the parts with a clean damp cloth.
  • Check the thermostat, calibrate it as necessary, make sure the batteries are working and check for any damaged wires or loose connections. If the thermostat is dirty, you can clean it with a shop vac.
  • Inspect the heater ducts for any damages and clean the vent ducts with a vacuum cleaner.
  • Clean the vent system using a large brush to remove dust and dirt.
  • Inspect all electrical connections in the heater, tighten them and replace any frayed or damaged wires.
  • Lubricate all the moving parts in the heater using non-detergent motor oil.
  • Test the gas lines for any leaks using a leak test solution and replace the gas hose if it has signs of breaks.
  • Call in a professional technician to do an annual furnace tune-up to ensure your unit works efficiently throughout the season.
  • It also helps to maintain indoor air quality, especially if you have house occupants with respiratory conditions.

Do I need a regulator on my natural gas garage heater?

All propane gas-fueled and natural gas-fueled appliances, including the natural gas garage heater, require a gas regulator to maintain smooth and consistent fuel delivery at the proper pressure and flow rate recommended for the appliance. Here are all the reasons why a regulator is necessary for your natural gas garage heater.

1. Gas pressure and flow rate regulation

The primary purpose of installing a gas regulator is not to control the heater’s gas pressure and flow rate. It helps to maintain the correct pressure at a constant rate.

Without a regulator, too much gas will flow into the heater and risk an explosion.

2. Automatic shut-off gas valve

The regulator also acts as an automatic on-off valve for gas. It has electrical control contacts that open to allow gas to flow to the heater when the thermostat signals more heat and closes when the thermostat reaches the target temperature.

3. Safety shut-off

Both the gas regulator and the flame-sensing thermocouple are responsible for detecting a flame’s presence and controlling the entry of gas into the burner.

If there is no flame, the valve will shut off to prevent and an explosion of unburnt gases.

4. Gas tank pressure relief

Regulators also have a vent that serves as a pressure relief valve. The vent reduces pressure buildup in the gas tank preventing the regulator from failing and the gas tank from exploding.

Keep in mind that using the wrong regulator fitting and improper installation procedure increases the risk of an explosion.

Check this too: Electric Garage Heater Troubleshooting & How to Guide

What do you do if your pilot light won’t stay lit?

The most common reasons when you have sufficient gas supply and your heater’s pilot light keeps shutting off are thermocouple problems or a blocked pilot opening. Here is how to fix both issues.

Thermocouple problems

The thermocouple automatically shuts off the gas valve when it detects the absence of a pilot light. When the thermocouple is malfunctioning, the pilot light will also behave unsteadily. Check if there is dirt or soot build-up on the thermocouple and clean it up with a brush.

Check if the thermocouple is bent or warped; if it is, gently use pliers to position it correctly. The gas valve will shut off when the thermocouple is bent away from the pilot light. If the thermocouple is too damaged, replace it.

A dirty pilot tube

When dirty accumulates on the pilot tube, it blocks sufficient gas from entering the heater, therefore, causing an unsteady flame. Examine the pilot light and make sure it is a rich blue color in the shape of a cone to indicate a clean pilot light tube.

If the pilot light tube is dirty, the pilot light will be yellow, small, and flickering. Turn off the heater, wait for it to cool down, and clean the pilot light duct with a needle; you can also remove it and blow air through it to unblock it. If the tube is damaged, replace it.

A bad gas regulator

If the gas regulator is the wrong type, incorrectly installed or damaged, it will not allow sufficient gas to flow into the heater. The regulator is irreparable, so you have to replace it with a new one.

How do I manually ignite my garage heater?

When your heater refuses to produce heat, the most common reason is the pilot light is not on. Pilot lights in older heaters burn throughout, while modern heaters have automatic pilot lights that turn on to ignite the gas and then shut off.

The automatic pilot lights, therefore, have a different manual ignition procedure from the older pilot lights. Here is the guide to manually ignite a gas garage heater.

  1. Turn the thermostat control to the lowest temperature setting.
  2. Locate the pilot light reset switch and turn the knob to the “OFF” position.
  3. Turn off your heater’s power and gas supply and wait for any residual gas in the heater to clear out.
  4. Turn on the main gas supply.
  5. Turn the reset switch to the “PILOT” position to release gas to the pilot.
  6. Hold a lighter over the pilot light opening and light it, then press and hold the reset switch until the pilot light burns steadily and then release the button.
  7. Once the flame becomes steady, turn on the power and adjust the thermostat to the desired setting.

How to Clean a Natural Gas Space Heater

Natural gas space heaters come in handy in warming up spaces both at home or the office as a supplementary source of heat or better still as a cost-effective option. 

This is because gas is naturally occurring making it cheaper as compared to electricity and you want to keep your natural gas space heater working effectively to maximize the benefits of owning one.

It is important to have a regular cleaning routine for your gas space heater as part of the maintenance in addition to having it running efficiently. 

Cleaning the space heater will take a few minutes of your time only once every year depending on how frequently you use the heater. 

The cleaning procedure is simple and easy to carry out once you’ve assembled the following items:

  • Vacuum with hose attachment
  • Compressed air spray
  • Screwdrivers 
  • Clean rugs

What to Do

  1. Start the cleaning procedure by switching off the heat and allowing it to cool if it has been in use to avoid burn injuries.
  2. Use a screwdriver to remove the front panel which is held in place by some screws depending on the make.
  3. Attach an upholstery brush to the tip of the vacuum hose and use it to remove dust and debris from the surface of the burner and all around the heater.
  4. Clean the main burner orifice and the pilot light assembly using compressed air. The burner orifice is where the gases mix before combustion takes place. Spray short bursts of air to remove all dust and debris from both components.
  5. Locate the air intake to the main burner by following the gas tube that supplies the burner with natural gas. The small gap between the orifice and the burner is the air intake that draws oxygen from the room to be mixed with natural gas for combustion. 
  6. A clogged air intake will result in incomplete combustion since the mixing of the gases is not properly balanced. Clean by spraying out the dust on the air intake and all the burner vents.
  7. Replace the heater’s front panel and tighten the screws for safety purposes. 
  8. Use a moist cloth to wipe out the outside parts of your gas space heater to remove grime and fingerprints on the surface. 

Your heater should be looking clean now and ready to heat and warm up spaces in your home or office efficiently. 


Hopefully, this natural gas garage heater troubleshooting guide has helped get your heater working properly. Ensure you take all precautions necessary, such as turning off the gas supply and electrical power when working on the heater. If you cannot fix the problem, you should always contact a certified HVAC technician.