Seal Your Chimney Flue To Prevent Heat Escape

It’s that time of year again, when many infrequently used fireplaces are called into action.

During the winter months and holiday season, the fireplace screens get pulled aside, and we toss in those chunks of sequestered carbon either natural split wood, wood pellets, or even those nicely packaged pressed fire logs. Voila!, better soon we’re enjoying that mesmerizing flickering flame and soothing crackling sound.

Ever think about what’s going on in your fireplace the rest of the year?  

Grab a flashlight and carefully look up the chimney at the flue – that heavy metal clunky door just above the firebox and at the beginning of your chimney flue. Does it close tightly along all four edges? Most likely not. Every side of the flue doors needs to be super tight to prevent escaping heat.

Green Blizzard can almost guarantee that a gap exists somewhere along at least one of the edges. That’s a year-round breathing hole for your house. It’s essentially an open window with a lot of dust and dirt gathered around the opening. It also means that every day a steady breeze blows in and out of your home, depending on the temperature and pressure differential.

Why Bother To Close Your Fireplace Flue That’s Acting Like An Open Window?

In the colder months, the cozy, fossil-fuel generated warmth in your home is quietly sneaking up and out the your chimney – every minute, every day. Most days you don’t notice it because that room or area of your house is always be a little cooler. But when the temperature plummets, that’s when its really noticeable. And more concerning, when the barometric pressure changes, it typically forces air back down the chimney and into your house, carrying with it the soot, ash and mold that’s nesting in the chimney. Not an ideal for the air quality in your home.

Many homes have chimney flues, that heavy metal door that you open whenever lighting a fire and may remember to close a few days after the fire is extinguished. Flues were built of rough, heat-resistant metal that corrode over time and do not shut tightly. In reality most flues never really shut tightly, even when new and first installed, because they were designed and installed when heating efficiency was not a concern. Any flue older then 20 years old is probably a heat-loss culprit.

To reduce home heat loss and lower your energy bills – as well as your carbon footprint – the are some good options for keeping the warm, fossil fueled heat from quietly escaping up your chimney. Here are two ideas to consider, one home-made, one store-bought.

How To Close Your Fireplace And Prevent Continuous Heat Loss – Handyman Option
For a few dollars of foam board or cardboard insulation, you can prevent tons of heat from escaping up through your chimney and prevent tons of CO2 from being released into the atmosphere.

We actually had a loose flue fitting situation here at the offices of Green Blizzard – we’re in a 1920 urban office. Its a cheap and quick solution with almost immediate payback. For about $5 in materials and less then ah hour of labor, we came up with a simple solution to minimized the heating sneaking through our chimney flue. Green Blizzard bought a 4’x 4′ section of 2″ foam board insulation at the local hardware store and cut it to fit snuggly under the flue – it was so snug that it squeaked as we pushed it into position. Then we fashioned a board (or stick) to hold it in place between uses – we even painted the foam and supporting stick black so no one every notices it. 

Any thickness of foam is better than what you now have. The most common types of materials used in making foam board include polystyrene, polyisocyanurate and polyurethane.

Online Fireplace Draft Stopper Options

If you’re not jazzed about the home-made remedy, there’s an assortment of flue-stopper options that can be on your doorstep in days. Consider these inflated ballon options.

Be sure to remember to remove any materials before lighting your next fire.

Check out the U.S. Government’s Energy Savers website for more insights. Or this helpful YouTube video about an inflatable option. 

Keith Blizzard So, get cracking and close your fireplace window, and check out these other informative staff favorites: Green Blizzard articles that you will enjoy reading: eBook Carbon Footprint Break-Even,  Why Recycle Paper?, The Coolest Kid at the Lunch Table, Plastic Grocery Bags – Kick The Habit, or Planting Trees to Offset your Carbon Footprint    

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About the author

Keith Blizzard

A life-long environmentalist, Keith set out on the never ending journey of adjusting his lifestyle to a more sustainable one, with a goal of annually shrinking his carbon footprint. When he looked around for a dependable source of meaningful carbon footprint reduction ideas, it was pretty lame - so he launched Green Blizzard loaded with eco-friendly lifestyle tweaks. When he's not managing Green Blizzard, you'll find him on the trails around Mid Coast Maine with his trusty trail companion mutt, Moose.