Project du Jour – How to supercharge your wood furnace

Everytime I think I know everything, my dad always comes along and teaches me something new. How does that always happen?

So I was telling him about my furnace, how cold air is getting downstairs and all that and he suggests I’m creating a vacuum by allowing air from the basement to be sucked into the wood furnace (which then simply goes up the chimney). The effect is that the fire cycles air out of your house and up the chimney, air that was relatively warm. So the fire gets relatively warm air for combustion. This isn’t ideal.

So the solution is to pipe in fresh air for the fire to consume. This has the following effects:


  • the furnace no longer uses house air which by so using creates a vacuum and causes cold air to leech in all around the house causing more air in the house that needs to get warmed up
  • the furnace now has a fresh cool air source which is both more dense – especially in the winter, and my oxygenated potentially. Both aspects combine for more efficient and hotter combustion
  • The air downstairs can now warm up fast, a) because less cold air is coming in because of the vacuum effect and b) because the relatively warm air already there can be warmed up a bit more and is not immediately replaced with cold outdoor air.
  • The level of the furnace in the basement means that air coming in causes a nice amount of air pressure due to its weight which provides a pressurized stream of nice cold fresh air into the furnace


  • If we heat with the oil furnace which flows through and around the firebox, the cool air coming in will act to cool the air just heated up by the oil furnace so this will need to be disconnected during the summer or shoulder seasons where the wood furnace is not in use to prevent unwanted cooling

So I can’t really see much bad about this idea, it seems on so many levels to improve the efficiency of the house and the heating of it at the same time. ¬†Genius! Thanks dad for the suggestion!

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