# mixed fuel venting? **URL:** \ **Category:** Inspecting HVAC Systems\ **Created:** [April 15, 2006, 9:55pm UTC](https://forum.nachi.org/t/mixed-fuel-venting/3476 "2006-04-15T21:55:15Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![sfalvey](https://avatars.discourse-cdn.com/v4/letter/s/c37758/32.png) [@sfalvey](https://forum.nachi.org/u/sfalvey)\ **Post date:** [April 15, 2006, 9:55pm UTC](https://forum.nachi.org/t/mixed-fuel-venting/3476/1 "2006-04-15T21:55:15Z")
Venting oil furnace exhaust with wood burning, ok for combined venting in chimney flue? Thanks, Scott ---
**Author:** ![system](https://global.discourse-cdn.com/internachi/original/3X/d/f/df7ced6a9ca05e7c93fa949dfc12a8c10d06c887.png) [@system](https://forum.nachi.org/u/system)\ **Post date:** [April 15, 2006, 10:04pm UTC](https://forum.nachi.org/t/mixed-fuel-venting/3476/2 "2006-04-15T22:04:01Z")
> [@sfalvey](#): > > Venting oil furnace exhaust with wood burning, ok for combined venting in chimney flue? > > Thanks, > Scott As long as the flue pipe is not galvanized. ---
**Author:** ![jhagarty](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jhagarty/32/78584_2.png) [@jhagarty](https://forum.nachi.org/u/jhagarty)\ **Post date:** [April 15, 2006, 10:55pm UTC](https://forum.nachi.org/t/mixed-fuel-venting/3476/3 "2006-04-15T22:55:14Z")
**No.** Violation of NFPA Standards Each should be vented into a separate flue. Multiple connections can cause flue gases and sparks to pass from one flue opening to another, reducing efficiency and igniting unburned gases in the flue. ---
**Author:** ![jwilliams4](https://avatars.discourse-cdn.com/v4/letter/j/278dde/32.png) [@jwilliams4](https://forum.nachi.org/u/jwilliams4)\ **Post date:** [April 15, 2006, 11:20pm UTC](https://forum.nachi.org/t/mixed-fuel-venting/3476/4 "2006-04-15T23:20:49Z")
In my past life I installed a number of “Longwood” wood burning furnaces with oil starters and the manufacturer’s instructions were for a single flue of specific materials. I don’t remember the type of material, but I recall that it was not uncommon. Manufacturer’s specifications prevail over any other… ---
**Author:** ![jhagarty](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jhagarty/32/78584_2.png) [@jhagarty](https://forum.nachi.org/u/jhagarty)\ **Post date:** [April 16, 2006, 12:12am UTC](https://forum.nachi.org/t/mixed-fuel-venting/3476/5 "2006-04-16T00:12:54Z")
Jae: Mixed Fuel Furnaces and Boilers (Woodsman, Longwood, Eagle, etc…) are designed for this application as a single unit. [http://www.yukon-eagle.com/leftright.htm](http://www.yukon-eagle.com/leftright.htm) An Oil Boiler/Furnace can not share a flue with a Wood Stove or wood burning Fireplace. ---
**Author:** ![jwilliams4](https://avatars.discourse-cdn.com/v4/letter/j/278dde/32.png) [@jwilliams4](https://forum.nachi.org/u/jwilliams4)\ **Post date:** [April 16, 2006, 2:38am UTC](https://forum.nachi.org/t/mixed-fuel-venting/3476/6 "2006-04-16T02:38:40Z")
Went back and took a better look at the first post…I didn’t pick it up as two separate units the first time. And I don’t even drink “darn margaritas”. What can I blame it on, other than old age??? ---
**Author:** ![sfalvey](https://avatars.discourse-cdn.com/v4/letter/s/c37758/32.png) [@sfalvey](https://forum.nachi.org/u/sfalvey)\ **Post date:** [April 16, 2006, 4:34am UTC](https://forum.nachi.org/t/mixed-fuel-venting/3476/7 "2006-04-16T04:34:37Z")
Thanks guys. They are seperate units with the boiler in the basement and a wood burning stove on the first floor. Scott ---
**Author:** ![jcampbell](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/jcampbell/32/177236_2.png) [@jcampbell](https://forum.nachi.org/u/jcampbell)\ **Post date:** [April 17, 2006, 1:23pm UTC](https://forum.nachi.org/t/mixed-fuel-venting/3476/8 "2006-04-17T13:23:31Z")
some folks have gotten blessings to have one connected/used at a time, but never both in use at the same time… I would not recommend that, but occasionally the local jurisdiction has blessed it… separate flue per fuel is the safest!