# Linking indoor woodstove furnace to existing gas furnace ductwork.



## winsormcbeth (Jan 24, 2013)

I bought an Englander model 28-3500 wood furnace and have it in my unfinished, uninsulated basement. My existing propane fueled Furnace is on one end of the basement and the wood furnace is at the other end so they are at least 50-60 feet apart. It is my understanding that you want the hot air outlet ductwork from the wood furnace to connect to the main central furnace right above the actual furnace, right? Is the fan that comes with the Englander (850 cfm) going to be powerful enough to push air through 60 ft of duct work to get to my main furnace ductwork and then let my main furnace fan do the rest of the work? Or maybe i can run ductwork from the stove only halfway to the main propane fueled furnace and then enter the supply ductwork so everything "down stream" kitchen/dining room, and bedrooms are heated? Can i hook up flexible/soft duct work to my woodstove furnace or is that not rated hot enough? Just looking for some advice. Thanks!


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## blades (Jan 25, 2013)

No flex duct allowed unless solid metal. You need 2" clearance of duct work ( hot line) for the first 10 ft and 1" there after to combustibles for code compliance. The fact that you have some 60 ft before getting to your other furnace is actually a blessing, if you have an AC coil on the propane rig. Those coils won't withstand the high heat of a wood furnace so normally it would have to have a bypass damper installed or just one to prevent high heat back flow to that area. It is very important to tie the cold air return to the wood furnace also so you get a full loop, otherwise it just will not work correctly. Note : conventional duct work does not have the code clearances for solid fuel appliances now days. This would apply to most homes constructed since the 50's. 

Conventional furnaces have a high limit cutoff and a low limit on, this is why they cycle and won't overheat ductwork or themselves. Your wood unit does not.


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## double E (Jan 25, 2013)

I have that same furnace I used 8" black stove pipe for the first 5' coming off the furnace then regular duct work with a one way butterfly damper in it to my homes furnace. The duct work connects to the main supply trunk just above my A/C coil with a 90* elbow inside turned upward, the temp. above the elbow averges 110 to 125 with the ocassional 135 depending on how I am running the stove, below the elbow at the coil never seen it above 90* (heat rises). The blower on the stove operates with a tstat that has high an low cut on/ off switch when the blower is off the butterfly damper is shut, this also helps in the summer when the A/C is on so you are not blowing a/c through the stove and up the chimney. 
Do not run your house furnace blower this will fight the Englander's blower and could over heat the furnace, you do not need to do anything with your return side of your duct work, the englander will pull air from the room its in. Been running it this way for 3 years with no problem (this way is also per Englander's installation specs).
My run of duct work is approx. 25', it heats 3200 square ft, the last few days never got above 30* with nights in the 9-12* range can maintain 75* in basement and 1st floor, second floor duct work is not hooked into it but still stays between 68 an 70. So at a 60' ft run you will loose a little umph but I think you should be ok. The damper and other supplies including installation guide for your stove can be found at Englanders website. 28-3500 Add-On Wood Furnace Parts


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