Patio Heater Lights Then Goes Out? Pilot Flame, Thermocouple and Shutdown Troubleshooting
A patio heater may appear to light normally, then go out the moment you release the control knob. In other cases, it stays on for a few minutes before shutting down. These problems are frustrating, especially when the heater was working normally not long ago, but they are also important safety signals.
A stable flame depends on more than ignition. The heater must have an adequate propane supply, a steady pilot or burner flame, proper ventilation, and functioning flame-safety components. Wind, low fuel, moisture, visible debris, or an incorrect lighting sequence can sometimes interfere. However, a thermocouple, regulator, gas valve, internal pilot restriction, or tip-over safety issue requires professional inspection.
This guide explains what homeowners can safely check when a patio heater lights but will not stay lit—and when to stop using it.
Begin With Basic Safety Checks
Turn the control knob to OFF and close the propane cylinder valve before inspecting the heater. Allow it to cool fully before touching the burner area, pilot area, or any nearby metal surfaces.
Do not continue troubleshooting if you smell propane, hear gas escaping, see a damaged hose or regulator, notice a cracked quartz glass tube, or find a loose or damaged gas connection. Avoid flames, smoking, electrical switches, and potential sparks. Leave the area and contact your propane supplier, emergency services, or a qualified professional from a safe location.
Before trying the lighting procedure again, confirm that:
- The propane cylinder contains fuel.
- The regulator is securely connected.
- The heater is standing upright on a firm, level outdoor surface.
- The required clearances around and above the heater are maintained.
- The burner and pilot area are dry.
- Strong wind is not reaching the burner or pilot area.
- You are following the exact lighting sequence and hold time in the product manual.
Why Does My Patio Heater Go Out When I Release the Control Knob?
Many propane patio heaters require you to keep the control knob pressed for several seconds after the pilot or burner lights. This allows the flame to heat the thermocouple, a flame-sensing component that helps the safety system confirm that a flame is present.
If the knob is released too soon, the heater may shut off even though the flame appeared at first.
Try the lighting procedure again exactly as stated in the manual. Make sure the control knob is pressed fully and held for the required time after the flame appears. Do not guess the hold time based on another heater model.
If the heater repeatedly goes out when the knob is released, possible causes include:
- The knob was not held long enough.
- The lighting sequence was incomplete.
- The propane cylinder is low, or the gas flow is restricted.
- The pilot flame is too weak or unstable.
- Wind is moving the flame away from the sensing area.
- Moisture or debris is affecting the pilot flame.
- The thermocouple is not being heated correctly.
- A thermocouple, valve, regulator, or other safety component requires service.
Do not use tape, clamps, wire, or any other object to hold the control knob down. Do not reposition the thermocouple or bypass the safety system.
Why Is the Pilot Flame Weak or Inconsistent?
On patio heaters equipped with a pilot system, the pilot flame must remain stable enough to support ignition and activate the flame-safety system. A very small, flickering, or frequently extinguished pilot flame may cause the main burner to go out or prevent the heater from remaining on after the knob is released.
Common causes include:
- A nearly empty propane cylinder
- Restricted gas flow
- Strong or shifting wind
- Moisture near the pilot area
- Dust, pollen, or surface corrosion
- Cobwebs or insect debris near an accessible air opening
- A restricted internal pilot tube or gas orifice
- A regulator or gas-supply problem
After closing the cylinder valve and allowing the heater to cool, remove only loose material from accessible exterior surfaces with a soft brush or dry cloth, if the manual permits it.
Do not push anything into the pilot tube or gas orifice. These openings are calibrated to control gas flow. Using a pin, wire, drill bit, or screw can damage them, change the gas-and-air mixture, and create a more serious problem.
If the pilot flame remains weak after the basic external checks, the internal pilot and gas-supply system should be inspected professionally.
Why Does My Patio Heater Keep Shutting Off During Use?
A heater that lights and stays on briefly, then shuts off several minutes later, has a different symptom from one that immediately goes out when you release the knob.
Look at what may be changing during operation:
- Is wind repeatedly reaching the burner or pilot?
- Is the propane cylinder nearly empty?
- Is the heater standing on an uneven or unstable surface?
- Does the hose appear kinked, cracked, or damaged?
- Is externally visible moisture or debris present near the pilot area?
- Are furniture, umbrellas, walls, or other objects affecting required clearances or airflow?
Some patio heaters include a tip-over safety switch that interrupts operation if the unit tilts or becomes unstable. Place the heater on a firm, level surface and make sure it is fully upright.
Never intentionally tilt the heater to test the switch. Do not bypass the thermocouple, tip-over switch, or any other safety device.
If the heater is upright, fuel is available, wind is not a factor, and the unit continues to shut down, a flame-sensing component, regulator, gas valve, or other internal safety device may require inspection.
Why Is the Flame Uneven or Producing Soot?
Normal flame appearance varies by heater design. A traditional standing patio heater should generally produce a reasonably even flame pattern within the burner area. A pyramid flame patio heater, including the Legacy Heating CAPH-GT-S flame patio heater, is designed to show a tall orange-yellow flame inside its quartz glass tube. That visible flame color alone is not automatically a sign of poor combustion.
What matters is a clear change from the heater’s normal operation. Stop using the heater if you notice:
- Persistent black smoke
- Heavy or rapidly increasing soot
- Flame outside the intended burner or glass-tube area
- An unusually low, uneven, or unstable flame
- A sudden decrease in heat output
- Repeated flame outages
- Unusual burner or gas-flow noise
- A continuing propane odor
Loose surface dust or debris near an externally accessible air opening may affect combustion. But an internal obstruction, damaged burner, incorrect gas pressure, or regulator problem requires professional inspection.
Do not enlarge, reshape, or attempt to clean an internal gas orifice with a sharp object.
What Can Homeowners Safely Check?
Homeowner troubleshooting should stay within a clear safety boundary:
- Verify that the propane cylinder contains fuel.
- Follow the correct model-specific lighting sequence.
- Hold the control knob for the required time after ignition.
- Confirm that the heater is upright and stable.
- Check that required clearances and ventilation are maintained.
- Wait for calmer weather if wind is disturbing the flame.
- Allow externally visible moisture to dry naturally.
- Remove loose debris from accessible exterior surfaces only.
- Inspect the visible hose, regulator, and cylinder connection for damage.
- Reconnect the cylinder only according to the product manual.
- Perform an approved leak test if required by the manual.
These checks can address common operating issues without disturbing the gas-delivery system or safety controls.
When Should You Stop Troubleshooting?
Stop using the heater and contact Legacy Heating support, your propane supplier, or a qualified service technician if you notice:
- A persistent propane odor or hissing sound
- A leak that remains after reconnecting the cylinder
- A pilot flame that stays unusually weak
- A heater that repeatedly goes out when the knob is released
- Frequent shutdowns in normal, calm operating conditions
- Heavy soot or black smoke
- Flame outside the intended burner or glass-tube area
- A cracked quartz glass tube
- A damaged hose, regulator, valve, fitting, or control assembly
- Unusual burner or gas-flow noise
- A thermocouple, tip-over switch, or other safety device that does not appear to operate normally
Do not remove, tighten, reposition, or adjust the thermocouple, gas valve, regulator, internal pilot tube, burner orifice, pulse-ignition module, or tip-over-switch wiring. Never bypass a safety device or use an unapproved replacement part.
The Propane Education & Research Council’s safety guidance advises consumers to stop using propane appliances when a leak or unsafe condition is suspected and have the system inspected by a qualified professional.
A Safer Way to Handle Patio Heater Shutdowns
When a patio heater lights but will not stay lit, start with the basic causes: verify fuel supply, repeat the correct lighting sequence, hold the knob for the required time, check for wind, make sure the heater is stable, and remove only loose debris from accessible exterior areas.
If those checks do not solve the problem, taking the heater apart usually creates more risk without providing a reliable diagnosis. Weak pilot flames, thermocouple problems, regulator faults, gas-valve issues, and tip-over safety concerns require model-specific parts and proper testing.
If your patio heater will not ignite at all or produces no clicking sound, read our safe troubleshooting guide for patio heaters that will not light. For preventive care that may help reduce seasonal ignition problems, see our guide to [patio heater maintenance, cleaning, inspection, and storage].