A while ago I had the idea of doing simple HVAC (heating ventiation & air conditioning) tutorials, explaining how stuff works because they are far and few between on the internet, let alone steemit. I want to highlight simple things you can do yourself (within certain parameters) safely.

Today I am going to cover lighting a gas fireplace pilot. This may seem easy to you, but fireplace techs like myself get calls constantly because someone does not know how to do this. Save yourself $150-$250 visit depending on the company, and learn how, and how it works.

If you just need to light your pilot, skip to How to light pilot

How it works

This is where we start. The gas valve. Typically this is underneath the fireplace, but it can also be on the side or behind the unit (if it is freestanding)

From left to right the components above are:
A) Flame adjustment knob

This adjusts your flame height once the pilot is on and main burners are lit. Some fireplaces do not have this option.

B) Pilot safety knob

This is what you will be using in conjunction with your sparker to light the pilot light

C) sparker

This is a piezoelectric sparker, pressing this sends a spark to the pilot assembly above and ignites the gas

The components above are inside the firebox, you may need to take off the glass in order to see them, but this is where you will look for flame as you are lighting the pilot.

These components together are called the pilot assembly:
A) Thermocouple

This is what will keep the pilot flame on, once lit. Your gas valve has two small electromagnets inside that are held open by only a few millivolts. These millivolts come from heating up the thermocouple which is made of two dissimilar metals. By heating the tip of the thermocouple (where the metals are joined) it keeps the pilot flame on.

B) Sparker

This is the other end of your piezo sparker where the spark lights the gas coming out of the pilot hood

C) Pilot hood

This is where the gas will come out, to be lit by sparker, and envelop thermocouple and thermopile

D) Thermopile

This is also a millivolt generator, except this is for your main burner, and a separate set of electromagnets inside your gas valve. For a fireplace it typically needs about 350 millivolts to open the main burner valve and then will cut in half (approx) to keep it open, usually around 200 millivolts

How to light pilot

Back to the gas valve. You are going to turn pilot safety knob to pilot, and hold this down, as you do it you need to continually press the sparker until you see flame in the pilot hood.
Try this for 5-10 seconds.
If it does not light wait 2-3 minutes and try again, you may need to clear some air out of the line if it has not been used in a while, if you smell gas and there is no flame still, stop immediately.
Once you have a flame, you need to continue to hold the safety knob down for about 30 seconds, this lets your thermocouple heat up.
After 30 seconds you should be able to let go, and the flame will stay lit! SUCCESS

One last step

Turn your safety control knob to ON, and this will allow you to turn your fireplace ON/OFF from the wall switch/remote/thermostat (whatever your house has as a control)

If at any point you cannot progress/it is not sparking/the flame will not stay lit/etc you will need to call a trained technician for a diagnostic.