What Makes your Furnace Hot?

Have you ever thought about how your furnace works? If you’re reading this blog then chances are that you have. However, if you happened to stumble across this blog while doing a little bit of research while trying to fix your furnace, I’ve got a little bit of information for you. If you have a natural gas or propane furnace there are a few steps that occur before you can even tell it has kicked on.

First, there is a call for heat from the thermostat. The thermostat sends a signal to the induced draft blower to remove any excess gases from the system. For about the first 30 seconds the furnace is running it isn’t providing any heat to the home. However, after the extra flue gas is taken out of the system the gas valve opens and the ignitor lights it. This fire is what brings the heat to your home. And the ignitor is what we want to discuss today.

Furnaces use 3 different types of ignitors. A spark ignitor, a hot surface ignitor, or it could have a standing pilot light. There are differences for each different ignitor, but they all serve the same purpose, to get your furnace hot.

Spark Ignitor – This one does exactly what the name says it does. As the gas is released from the gas valve the ignitor kicks on and creates a spark. That spark catches the released gas on fire and the burners keep the hot air flowing until the desired temperature is reached.

Hot-Surface Ignitor – This one plugs in and glows red hot when the need for heat is called for. Have you ever seen an electric stove’s burners when they’re on high? That’s what your ignitor looks like when it kicks on. When it gets hot enough it ignites the gas that was released and the burners hold the fire until the call for heat is settled.

Standing Pilot – A standing pilot is always on. Gas is constantly expelled to keep the flame on. Because it is always on, when the call for heat comes in the system is already prepared for ignition. The thermocouple verifies that the pilot light is lit already and once that is done the gas valve opens to give enough gas to ignite the system and bring heat to the home.

Each ignitor is effective, but current systems have moved away from the standing pilot light because it is inefficient. Too much gas is used in those systems and because of that the HVAC industry has moved away from those. Depending on the age of your HVAC system you could have any of these three ignition systems. If you have any further questions on ignitors or you want to have your HVAC system looked at, feel free to call us at 913-432-3342 and we’ll be happy to help out! Thanks for reading our blog and we look forward to working with you in the future!