Patio Heater Won’t Stay Lit [9 Easy Fixes]

A common issue with Patio heaters after a few years of use is that the flame may become weak or not stay lit.

In case your patio heater won’t stay lit, the possible reason behind it can be a defective thermocouple or too much distance between the thermocouple and the pilot.

Also, a dirty pilot assembly, jammed gas valve, low gas pressure, clogged burner orifice, lack of ventilation, tripped safety switches and bad weather could be the culprit behind the issue.

Keep reading our patio heater troubleshooting guide to fix your heater and get it running.

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Patio Heater Won’t Stay Lit [9 Easy Fixes]

In this section, we will take an in-depth look at why your patio heater won’t stay lit and how to solve these problems simply.

Note: You can also read the Dyna Glo propane heater troubleshooting guide.

1. Defective Thermocouple

Your patio heater thermocouple is supposed to detect the pilot flame and then allow the gas valve to release gas at the burners to get the heater fired up. 

In the case of newer models, it detects the igniter’s spark instead of the pilot light. With a defective thermocouple, your heater’s pilot light won’t be detected and the gas valve will shut down, causing the heater to not stay lit.


You’ll need to use a multimeter to check the thermocouple. Here’s how you conduct a patio heater thermocouple test:

When you connect the thermocouple to the multimeter and set it to resistance, you should obtain a very small reading that is near zero. You have a bad thermocouple if the reading is higher. 

If you don’t have a multimeter, you can try a patio heater thermocouple bypass and see whether the heater runs without a thermocouple. In case it does, the thermocouple is bad. Replace your thermocouple with the help of an expert.

2. Distant Thermocouple And Pilot Assembly

In a working heater, the thermocouple and pilot are supposed to be close together.

Over time, the distance between the pilot and the thermocouple may increase, making it hard for the thermocouple to detect the pilot flame. 


Turn off the gas and electricity supply to your heater. Access the thermocouple and pilot assembly. Take a pair of pliers. Use them to gently pinch the thermocouple and pilot together.

3. Dirty Pilot Assembly

A dirty pilot assembly that has grease, dirt, and debris blocking it, can be why your patio heater won’t stay lit problem is occurring.

Over time, usage can cause your pilot to corrode as well. 


Cleaning the pilot is no easy task. If you have some prowess with handling heating appliances, only then go for this repair on your own.

You need to remove the pilot assembly gently and wipe it down with sandpaper or an emery cloth till it is clean.

Blow a can of compressed air to clean up any loose debris and assemble when things are looking as good as new.

You can watch this video to know the cleaning process.

4. Jammed Gas Valve

If your propane patio heater won’t stay lit, that can be because of something blocking the gas valve orifice obstructing gas flow. 

The gas heater won’t stay lit if there is a total obstruction in the gas line. A partial obstruction, on the other hand, might allow the burners to start but not keep it lit for long.


Cleaning the gas lines that run from the gas cylinder to the grill can be done with a piece of narrow but strong wire.

You should strive to get a piece of wire that is longer than the connections to clean the gas lines adequately. Instead of pulling the wire back, you’ll be able to shove it right through.

5. Low Gas Pressure

When using a U manometer, the pressure must be at least 10″ W.C. Otherwise, due to a lack of gas pressure, your heater may not light.


Only two types of gas controllers are commonly used on gas patio heaters: Robertshaw “Unitrol” and White Rodger. Both controls have a port for testing the valve’s gas pressure. Remove the cover screw and replace it with a 1/8″ pipe nipple.

While the valve is operating, the manometer should give a reading of 10″ W.C. after you’ve attached your manometer line to this fitting. If not, call your local utility company for assistance.

6. Clogged Burner Orifice

The burner orifice of your heater can become dusty and obstructed due to built-up soot from incomplete burning, grime, or debris. This can be why your patio heater pilot lights but not burners.


Your patio heater’s burner assembly needs to be cleaned. The first step is to make sure that the heater’s electricity and gas supply have been turned off.

The entire procedure is really difficult. So, if you’ve never repaired a water heater before, don’t try it yourself. Employ the services of an expert.

7. Lack of Ventilation

Fire needs air to breathe. Without enough combustible air, the fire won’t stay ablaze. So, if your heater isn’t getting proper airflow, it may not stay lit.


You need to see whether the air filter is clean or not when the furnace pilot light is lit but the burners won’t ignite. Remove the filter and wash it out with a garden hose till it is squeaky clean. Next, check on the exhaust pipe.

You need to ensure that the excess heat has a chance to leave. So, clean up the exhaust as well. You will need a vacuum cleaner, wet cloth, and wire brushes to do a thorough job.

8. Tripped Safety Switches

Depending on the brand and model of your patio heater, you will have a few safety switches that can trip to make your heater shut down.

For instance, the most common safety switches are high-limit switches, roll-out switches, and tip-over switches. 


Check all the safety switches and reset any if needed. If your roll-out switch has tripped, you will need to ensure proper airflow before resetting. For the tip-over switch, you need to ensure that the heater is upright on a flat surface.

The high-limit switch trips when the heater crosses a certain temperature. So, you have to cool the heater before resetting it.

9. Bad Weather

Sometimes, your patio heater may keep going out because of the wind. Just as simple as that. Other times, when the weather outside is too cold, the heater gets overworked and shuts down.


While there is little you can do to control the weather, use an insulating blanket to protect the flame from going out and make it easier for the heater to get to the set temperature.


Why does my pilot light go out when I release the pilot light knob?

This happens when your thermocouple has gone bad. The thermocouple should be replaced if you can ignite the pilot light but it goes out only when you let go of the control knob.

How do you clean a thermocouple?

Cleaning your thermocouple with a piece of steel wool or the rough side of a sponge is the best way to remove any soot or other residue. To wipe between the threads, use a pencil eraser.

What does a thermocouple look like?

A tube, a mount, and wires make up the thermocouple. The tubing sits above the mounting bracket, a nut secures the bracket and wires, and the copper lead wires are visible beneath the bracket.

What causes a thermocouple to fail?

Mechanical failure can cause a thermocouple to shatter over time. Metal fatigue is more frequent in thermocouples that are exposed to significant heat stress or extreme circumstances on a regular basis.

How long does the thermocouple take to heat up?

Once the flame is lit, the thermocouple needs about 20 seconds to heat up. When the thermocouple becomes hot enough to transmit a sign to the gas valve to release gas and continue to burn even if the control is released.


It is a little difficult to narrow down why your patio heater won’t stay lit. But most often, it is the thermocouple.

But in case you are sure the thermocouple is okay, it’s time to inspect the other possible causes. Hopefully, with our guide, you now can fix your patio heater when it won’t work. 

About David

David is a man who loves doing research and finding out the best solution to any type of heating appliance issues like heaters and fireplaces. Whenever he finds the perfect solutions to any issues of heating appliances after doing in-depth research, he loves to share them with his readers. In fact, his aim is to help his readers to fix the issues with their heating appliances easily.More about us .

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