Why My Patio Heater Flame Too High + How To Fix [Solved]

Patio heater flame too high is one of the common issues that patio heater owners face. The leading culprit for this issue includes bad thermocouples. The thermocouple is an essential sensor, and the flame issue starts when this sensor gets defects. 

The other possible reason is tipped-over safety switches. Also, due to incomplete combustion, the pilot starts burning the pure fuel and causing an uneven flame. 

 patio heater flame too high

However, there is nothing to worry about as you have already hit this effective troubleshooting guide relating to this issue. So, without getting a single bit late, go to our comprehensive article to resolve the issue effectively. 

Why My Patio Heater Flame Too High + How To Fix

Here, we have discussed each and every problem in detail with all well-proven solutions: 

1. Bad Thermocouple

If your patio heater flame is too high, the first would-be culprit is a defective thermocouple. A thermocouple is an essential safety device in a patio heater that is designed to keep the pilot lit using a small electric current. 

patio heater bad thermocouple

Thermocouple functions as sensors that works based on the thermoelectric effect and measures temperature on the basis of generated voltage. It is located near the igniter. When the igniter fails to operate, it suddenly shuts off and acts as a safety component. 

measure the patio heater thermocouple voltage

But after long wear and tear, the thermocouple gets faults and stop working, which is one of the root reason for causing too high a flame on the heater. Some of the quick signs of a bad thermocouple include:

  • Discolor on the thermocouple body
  • Crack
  • Missing insulation around wires
  • Corroded wires
  • Defective connectors
  • Dirt accumulation around the thermocouple
  • Pinholes

Anyway, first you need to establish if the thermocouple is at fault. Based on this, you have to replace or repair the sensor. Follow the below instructions:


  • Turn off the heater. Locate the thermocouple, and remove the covering on the heater. When the igniter will inspect, unscrew the screws from the ignition assembly.
  • Then, unscrew the box housing from the back of the thermocouple. Now slide it back. Take a pair of pliers and loosen the nuts that hold the thermocouple.
  • Pull the wire connectors as well to remove the thermocouple. Now do a short test to verify if the thermocouple is bad.
  • For that, take a multi-meter and measure its voltage. First, it should be zero. Then you need to heat one end of the sensor using any flame source like a lighter.
  • Connect another lead to the other end of the thermocouple by the igniter. Now, measure the voltage. It should be at a reading of 25 to 30 millimeters.
  • If not, it indicates that you need a new thermocouple. Replace the bad thermocouple. If needed, take help from an expert hand.
  • Sometimes, only cleaning the dirt and debris proves well if it is not completely defective. 

2. Tipped Over The Safety Switch

After replacing the thermocouple, if the flame level is too high, be sure that malfunctions from the safety switch are another possible reason. Safety switches are used as a safety component on the heater. 

It is located near the control knob. In the case of its tip-over, the pilot light fails to stay in a stable position. Sometimes, wires and connections of the safety switch start malfunctioning.

 Anyway, in this troubleshooting stage, either you need to bypass the safety switch wire or replace the defective switch. Follow the below instructions:


  • First of all, turn off your heater. Before touching any of the inside elements, make sure the heater is completely cool off.
  • Once the heater is cool, remove the upper body of the heater to the base. Unscrew all the screws to remove the panel. Now, near the control knob, you will find the safety switch.
  • This time, you will have to disconnect the tip-over switch which is attached to the switch assembly. Now, remove the two lead wires that are connected together through the safety switch.
  • Then, splice the wires together. For this, you may tape them together with electrical tape. But make sure they are touching, obviously.
  • You are done. Now just reassemble them and check if the flame is now all right or not. In the case of a defective safety switch, don’t be late to replace it. 

3. Incomplete Combustion

If the above two troubleshoots fail to prove well, the third major reason is incomplete combustion for this problem. In most cases, the pilot light seems too high when the pilot burns pure fuel with no air. 

The complete circumstances indicate incomplete combustion throughout the heater. For this, the user may face a yellow flame instead of blue as well as a high flame level.

When there is a lack of sufficient oxygen for the given rate of fuel flow, the flame color turns yellow, which means the air is not mixing all the way. 

The poor air or oxygen supply produces carbon monoxide and carbon in a higher amount instead of carbon dioxide.

The carbon is released as a shoot. There are several reasons for causing such incomplete combustion in the heater. For instance:

  • Dirty orifices or corroded burners
  • Building up sediment in the burner
  • Wrong gas pressure
  • The higher humidity in the surrounding area
  • Clogged air intake or venturi 
  • Wrong adjustment of the air shutter

Anyway, follow the below instructions to fix the Patio heater flame too high on one side:


  • First, turn off your heater and let it be cool.
  • Now, start cleaning the heater elements. Clean the burner, burner orifices, and holes of the burner properly. 
  • Use an air compressor to clean the dirt and debris accumulated on these elements. In the case of the corroded burner, replace it.
  • Now, do a special concentration on the air shutter. Adjust the air shutter to open more.
  • Unclog the venturi or air intakes using an air compressor.
  • You will find the shoot on the dome and burner screen. Clean them out as well.
  • Finally, reassemble the heater and check if the flame issue has been resolved or not. If not, contact any professionals to seek further suggestions.


Why does my patio heater stop working?

There have several reasons why the patio heater may stop working. That includes a defective thermocouple, a tipped safety switch, blocked essential heating elements, low gas pressure, and kinked or broken gas lines.

How do you fix a patio heater that won’t stay lit?

As the clogged pilot is the leading reason for this, so clean the pilot first. Also, ensure a snug connection between the gas valve and the pilot assembly. Clean the thermocouple or replace it with a new one. 

What does the patio heater thermocouple look like?

The thermocouple is basically made up of a tube that is placed in a bracket through the wires. There used a nut to hold the bracket and wires in place. Also, the gas valve is connected to the furnace using lead wires. 

Wrapping Words:

Well!! Hopefully, now you know why your patio heater is facing the too-high flame issue. Our guide is effective enough to resolve the problem in a very short time. We can expect you will troubleshoot the issue effectively by following each of the solutions steps. 

Still, if you face any troubles while resolving the issue, don’t be late to ask us through the comments. We always give priority to our visitors’ queries first.

About William

William is the founder of Fireplacehubs.com. 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.

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