Why won't my gas fireplace light when I turn on the switch? Pilot on.

As said before, this is something you should leave to a professional, but here is my read on it...

There are actually two systems that generate electrical energy from the pilot light. Both are usually located right next to the pilot burner, on opposite sides of it:

1. The THERMOCOUPLE is right next to the pilot, and is usually quite skinny. This generates a small current to tell your gas valve that the pilot is on, and ensures that the gas is turned off if it goes out. The fact that your pilot does stay on means that this is working.
2. The THERMOPILE is also right next to the pilot, and is usually the larger of the two. This generates a much larger electrical current from the heat of the pilot flame, and is used to open and close the main gas valve. Usually when you have a pilot, but no main burners, it's either the THERMOPILE or the entire gas valve itself that is defective. If the pilot has deposited a lot of soot on the THERMOPILE, it may also be insulated from the heat and not generate enough current. Check it out and clean it with some emery cloth, and see if this helps. A service person can easily check this.

One other thing that many people forget is to also check the actual On-Off switch, as these can go bad. Check it out for continuity, as this may also cause the same symptoms.

If the pilot is on but your gas fireplace won’t light when you flip the switch, a few common issues could be the cause:

1. Wall switch problem – Many switches use low-voltage wiring. Dust, loose connections, or a worn switch can interrupt the signal.
2. Thermopile not generating enough power – The thermopile converts heat from the pilot flame into electricity that opens the gas valve when the switch is flipped. If it’s dirty, misaligned, or weak, the main burner won’t ignite.
3. Gas valve issue – Even with the pilot lit, the valve may not be opening to send gas to the burners.
4. Remote or control module malfunction – If you use a remote, check batteries or reset the module.
5. Blocked burner ports – Dust or debris can prevent ignition.

If simple fixes (switch replacement, battery check, cleaning) don’t solve it, call a certified fireplace technician for safe diagnosis.

On the Heat & Glo all you need to do is tap on the gas valve gently with a hammer or rubber mallet. Turn it on so the pilot is lit. Tap on the round flat part of the valve that is facing you, and voila, the burner will light. Not sure why that works. If anyone knows why, please let me know.