You turn the switch on a cold night. The flame lights up, looks nice for ten minutes, then goes out. You try again. Same result. This is annoying and a little scary because it is gas.
Many homeowners tell us this problem starts when the weather gets cold and the gas fireplace is taken out of summer storage. The cause is usually small. Dust, a sensor or a dead battery can all do it. Some fixes take five minutes. Others need a technician. Below is how to tell which one you have.
Safety note If you smell gas like rotten eggs, do not touch switches or try to light anything. Get everyone outside. Call your gas company from there. Do not go in until they say it is safe.
How a Gas Fireplace Stays Lit
Most gas fireplaces have a pilot flame near the burner. When you ask for heat the pilot lights the burner. The pilot also heats a safety sensor, which is a thermocouple or a thermopile depending on the model. Long as that sensor is hot the gas valve stays open. If the sensor cools off the valve shuts. The gas fireplace does that on purpose so gas does not keep flowing with no flame.
So when your gas fireplace keeps going out something in that chain is off. The pilot might be weak. The sensor might not be reading the heat. Air might be pushing the flame around. Knowing the chain makes the rest of this a lot easier to follow.
Common Reasons a Gas Fireplace Keeps Shutting Off
1. A Dirty or Weak Pilot Light
Dust, pet hair and soot build up around the pilot over time. Even a thin layer can starve the flame. You will often see a weak pilot flame. It should be steady and mostly blue.
Turn the gas off. Let everything cool. Then blow the pilot area out with a can of air. Check the owners manual first because layouts differ.
2. A Worn Thermocouple
The thermocouple is a metal rod that sits in the pilot flame. It tells the gas valve that the flame is really there. When it is old or coated in soot the signal becomes weak.
- The pilot only stays on while you hold the button down
- It goes out soon as you let go
- The tip looks black, bent or crusty
A light cleaning with steel wool can help. If it does not the part needs replacing. It is cheap. It is a gas connection so a lot of people hand this one off.
3. Dead Batteries or a Weak Thermopile
Newer gas fireplaces with electronic ignition run on batteries in the unit, the remote or both. Older millivolt systems use a thermopile, which makes a charge from the pilot flame.
If you hear clicking but get no flame or the remote seems slow, start with fresh batteries in the receiver box and the remote. If the batteries are fine and it is a millivolt system the thermopile may be wearing out.
4. Drafts and Blocked Venting
Gas fireplaces need airflow. Wind, a downdraft or a blocked vent can blow the flame out. This triggers the safety system. Birds, squirrels, leaves and even wasp nests end up in vent pipes more often than people expect.
You might notice it only happening on windy days or that there is more soot on the glass. A chimney cleaning will clear out debris. A fitted chimney cap keeps animals out and cuts down on downdrafts, which matters on the windy Front Range.
5. The Oxygen Sensor in Vent-Free Units
Vent-free fireplaces have an oxygen depletion sensor. If the room does not have enough fresh air or if the sensor is dirty the unit shuts down on purpose. Sometimes the room is too sealed up. Sometimes the sensor just needs cleaning or replacing. Either way leave this one to a professional because it is a safety part.
6. A Gas Supply Problem
Check that the shutoff valve near the unit is fully open. If you use propane, look at the tank gauge. If your stove or water heater is acting up, call your gas provider.
Colorado note If you live in Colorado many homes near Castle Rock and Denver sit well above sea level. Some gas fireplaces require a different burner orifice because of the altitude. If the unit was swapped recently or has started to act up, ask the installer or check the manual for altitude settings.
7. A Faulty Gas Valve or Control Module
A less common cause is a faulty gas valve or control module. The valve is the part that lets gas flow. When it wears out it may not open fully. It may also close by itself. Usually the pilot and sensor work, but the main burner still does not stay on. You may also hear clicking with no flame. Replacing valves and control modules is not a do-it-yourself job.
Quick Troubleshooting Table
| What You Notice | Likely Cause | What to Try |
|---|---|---|
| Pilot dies when you let go of the button | Worn thermocouple | Clean it or replace it |
| Pilot flame is yellow | Dirty pilot assembly | Clean with compressed air |
| Clicking, no flame | Dead batteries or bad ignitor | New batteries first, then call a technician |
| Goes out on windy days | Downdraft or blocked vent | Have the vent and cap checked |
| Vent-free unit shuts off in a closed room | Oxygen sensor tripping | Open a window, call a pro |
| Pilot is fine, burner won't stay on | Bad gas valve | Call a pro |
| Other gas appliances are weak | Low gas supply | Check the valve or propane tank |
Things You Can Try Before Calling Anyone
Run through this list. It takes maybe ten minutes.
- Make sure the gas shutoff valve is open
- Put fresh batteries in the remote and the receiver
- Check that the wall switch, remote or thermostat is set right
- Look at the pilot flame to see if it is mostly blue
- Dust the glass and the area around the burner
- Relight the pilot using the steps in your owners manual
Tip: If you have relit the pilot twice and it keeps dying stop there. Doing it a third time will not change the outcome. A part is probably failing.
When It's Time to Call a Professional
Some problems are not worth a weekend of guessing. If the thermocouple, valve or ignitor needs to be replaced you want a professional who works with gas all the time. A small mistake on a gas line can quickly become a problem. A technician can check gas pressure. Test for leaks. They can also confirm that the venting is working as it should.
It also helps to have someone examine the setup instead of just the part that failed. When a technician comes for a gas fireplace repair they often notice problems you might miss such as a clogged vent or a damaged liner. Sometimes the issue goes beyond the burner. A cracked firebox is a fireplace repair and a damaged liner may require a flue liner replacement. It is better to learn this in October than in mid-January.
Keeping It From Happening Again
Most repeat shutoffs come from dust. Skipped maintenance. It is not luck.
- Get the unit serviced once a year before cold weather
- Keep dust and pet hair away from the burner area
- Change batteries every fall
- Keep the vent and chimney top free of nests and debris
- Pay attention to changes like a slow start or a yellowish pilot
Many people assume a gas fireplace does not need cleaning because there is no wood burning. It still needs a checkup. The venting also needs attention. How often a chimney sweep should come out depends on the setup.
Gas Fireplace Trouble Around the Denver Metro
The causes above show up all over the south and east side of the metro, but the setup changes from town to town. Homes in Castle Rock, Castle Pines and Parker sit higher up, so altitude settings and wind are worth a thought. Out in Franktown and Elizabeth the land is more open and the wind hits harder. A lot of homes out there also run on propane, so a low tank is a real possibility when the flame will not stay on.
Closer in, you have Centennial, Greenwood Village, Cherry Hills Village, southeast Aurora, Highlands Ranch and Littleton. These areas mix older homes with newer builds, so you see everything from old standing pilots to electronic ignition and vent-free units. The reasons a gas fireplace goes out stay the same wherever you live. What changes is the age of the unit, the type of venting and the fuel it runs on, and that decides what the fix looks like.
Start Small, Then Call Someone If You Need To
If your gas fireplace keeps going out it’s telling you something. It could be dust, a sensor, a draft or a part at the end of its life. Usually it is something fixable. But the pilot light is part of a safety system so it should not be ignored for weeks.
My advice is to start with the basics. Check the batteries, the gas valve and the pilot flame. If that does not solve the problem, get a professional to take a look so you are not guessing every time the flame dies. Then you can sit back. Enjoy the heat.
Fireplace Still Going Out? Give Us a Call
Claus Chimney Pros repairs gas fireplaces in Castle Rock and across the Denver Metro area. Call (720) 802 2868 or book online. A technician will test the pilot, sensor and venting, find the cause and get your flame staying on again.
