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i just purchased a wood burning furnace that is designed to tie into and supplement the main furnace which in my case is a geothermal unit.

after spending a few days reading about "best practices" with respect to the setup of the exhaust pipe, i'm planning to:

  1. have the total length of the exhaust pipe approximately 30 ft - i've read more is better then less. 30 ft happens to be what i need.

  2. have the top of the exhaust pipe exiting out of the roof near the roof's highest point and then extending the pipe 2-3 ft higher - read that this is optimal with respect to how wind can cause back drafting.

  3. have the exhaust pipe routed thru the house rather than in a chase outside where the temp of the exhaust pipe would be significantly lowered - i've read that the lower the exhaust pipe temp, the less draft u have.

  4. have the exhaust pipe exiting the wood furnace straight up for nearly 20 ft before hitting any bends in its path

  5. have the exhaust pipe made of Class A, triple wall ($50/ft, yikes!) insulated pipe that requires only a 2 inch spacing from combustibles

everything i listed above is supposed to help with the draft. my question comes at point #4 above. at around 20 ft up the exhaust pipe i would like to bend 90 degrees then travel horizontally around 2 ft then bend another 90 degrees then straight up for the balance of the run.

many setups have an elbow near the furnace then another to get into the chimney chase. my concern is that having these 2 elbows so far from the furnace itself is somehow more detrimental to drafting vs having them right near the furnace and so that creosote may build up near these 2 elbows and will be difficult to access for cleaning so will possibly increase the chances of a chimney fire over time.

please share any experiences/thoughts u have on the subjects touched here.


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