IMG_5375I recently realized that most of my blog posts include a lot of information about wood burning stoves and fireplaces. I’ve rarely given information about gas burners, so that’s going to be my focus for today. Many homeowners are under the impression that because they aren’t burning wood, they don’t need a properly working chimney and flue. This is absolutely not the case; all chimneys need a flue, and they all need to be cleaned and inspected regularly.

Does Your Chimney Need a Flue?

Naturally, you still need a way to vent the gases and smoke produced by the burning process. So yes, you do need a chimney and a flue. Natural gas and propane appliances don’t necessarily produce visible soot like wood burning appliances do, but they do still produce a corrosive substance that can truly wreak havoc on your chimney. A chimney without a flue is at great risk of structural damage, even with gas burning appliances.

The Price of Higher Efficiency

It’s true that some gas stoves or fireplaces are more efficient heaters than their fireplace-style counterparts. That being said, the efficiency comes at a price. A gas fireplace’s increased efficiency comes from the way the heat is produced and distributed. Much of the heat that would normally escape up the flue is pushed out into the home.

This process is, unfortunately, a double-edged sword. The same system that makes the inside of the home warmer takes away from the efficiency of the flue and chimney. The flue temperature isn’t as high, so incomplete combustion and condensation becomes an issue. If the chimney is too cool to create an adequate draft for the appliance to work properly, the efficiency is lowered, and the appliance may start producing carbon monoxide. It is unlikely that the carbon monoxide will exit through the chimney if the draft is already weak.


Strangely enough, your gas furnace creates about one and one half gallons of water per hour of use. That’s a lot of water! Cooler temperatures throughout the flue mean the gases produced by combustion liquefy quickly within the flue. Air that mixes with the condensation is generally polluted with normal air pollution, dust, pollen, and household cleaning fumes. This creates a very corrosive substance that must be cleaned out regularly.

Discuss Your Flue with a Licensed Chimney Sweep

I understand that I briefly touched on the issues, and that you may have additional questions. If you do have any lingering questions about the process, please feel free to ask them below or call me. I’m fully licensed and insured to work in Pennsylvania, and I’m based in Delaware County. Call me any time to schedule a consultation, second opinion, cleaning, or inspection.