Outdoor Furnace: Why Chimney Extensions MUST Be Insulated

Outdoor Furnace: Why Chimney Extensions MUST Be Insulated

The Single FASTEST Way To Destroy Your Outdoor Wood Boiler...

...is having an UNINSULATED Chimney Extension on your boiler.

You see, all wood contains moisture - even the most seasoned hardwood contains about 20% water. As the wood burns, the furnace water exits harmlessly in the form of steam. 

BUT, if you have an uninsulated chimney extension, the exhaust COOLS on its way out, then steam condenses on the inside of the chimney, and forms the most caustic creosote which drips back down into your outdoor wood furnace and eats through the steel. NOT GOOD!

The solution is simple - if you need a chimney extension, make sure you have a Triple Wall Insulated Extension. This prevents the exhaust from cooling as it exits the outdoor wood burner! No condensation, no creosote, NO WORRIES!

All of us at OutdoorBoiler.com have chimney extensions on our outdoor wood burning boilers - MANY customers do too. The big advantage is that it just gets the smoke away. Outdoor Wood Stoves don't produce too much smoke, but an extension just gets the smoke up and away. Very nice!

Outdoor Boiler Chimney Extensions

If your outdoor boiler is near or under a roof, you must extend the chimney above the roof using only an INSULATED chimney extension. Learn more about chimney extensions from OutdoorBoiler.com at this link HERE

All boiler experts agree that only triple wall insulated chimney extensions should be used. Our products have a perfect safety record of protecting outdoor wood boilers and providing years of service.

If you have any questions about your state requirements, or would like us to help you with your customized application, please do not hesitate to CONTACT US! You can reach our experts by clicking HERE.

Remember that you must use the proper diameter extension - they come in several sizes, but the most common are 6" and 8" diameter. Most extensions are 48" long. 

Call Us TODAY at 231-861-8200 M-F 9am-8pm EST, or go online at OutdoorBoiler.com to browse for more outdoor wood boiler parts!

Maintenance FAQs

  • Why is Outdoor Boiler Water Treatment important?

The chemical (corrosion inhibitor) coats the inside of the furnace to reduce the effects of corrosion on the metal. Click HERE to order our Liquid Armor Water Treatment and other outdoor wood furnace parts. Then submit your water sample at Outdoor Boiler lab. Click HERE for more info.

  • How often do I need to Inspect my Chimney/Flue

Inspect chimney and flue monthly and clean as needed. Clean chimney and flue annually. Perform cleaning and maintenance only when no fire is present in the firebox and ashes are cooled completely.

  • How Can I Change the Door Rope Gasket of My Outdoor Wood Stove?

The rope will settle in the first few months of use. Before you change the rope gasket try adjusting your door. This is easiest with two people, one to push the door against the chute and the other to adjust the bolts. Keep your door snug but not so tight that it is difficult to operate.

  • Why is ash management important?

If the ash becomes wet it is corrosive to the metal of the furnace. If the level of ash is too thick in the water box it does not allow for efficient heat transfer to the water in the water jacket of the furnace. The temperature of the water in the jacket is used to heat your house.


  • Why am I not getting hot water?

Check that the hot water system is connected properly. Check if the heat exchanger is partially or totally clogged.

  • Why does my furnace continue to burn when it is not operating?

Check the door seal, door adjustment, and solenoid.

  • I can't find a leak in my furnace. Why am I losing water?

Outdoor Wood Burning Boilers use a non-pressurized system, this means that the existing heating system is exposed to the air. Since the water in the system can and will be warmer than the air, there will be evaporation of the water in the system. The water must be checked and adjusted at least once a month, sometimes more.

Be the HERO to your family and Be Prepared so you can keep your family warm and toasty while saving from your heating bills and avoiding the expense of costly repairs for your outdoor boiler.