Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: gandgracing on January 22, 2013, 01:56:17 PM
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So I did a little experiment by shutting down the fan and then leaving the ash door open about 3-4". Such a better fire than with the fan. Chimney got really hot! My air comes from under the fire. Be nice if I could modify it to work with draft.
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where does teh fan blow the air in relation to the ash door letting air in?..perhaps you need a bigger fan.
if the natural draft appears to make a better fire i would only guess that leaving teh ash door open allowed more cubic feet of air into the stove.
i get a pretty good raoring fire with my blower, it puts air in under the door at teh rate of 150 CFM (although witht he door wide open it roars harder but i can see flames rushing right into the chimney)
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I asked the dealer if I should get a fan setup on my CB5036 His reply was, "only if you want to burn more wood". I can get a nice intentional chimney fire (cleanout), or boil over with the door open too long. Otherwise the natural draft of 16' of chimney works great. Only during warm temps with too much wood in the firebox have I thought a fan would be useful. I guess it depends on design and need of recovery time.
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Yeah natural draft works...But the only problem is that natural draft smokes a lot more and longer during a burn time where a fan is short and a quick recovery time..All your EPA phase 2 stove that Ive seen is fan injected.. Smoke is the why the OWB is on the hot seat from time to time..
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The fan is on the back of the stove and blows to the front and up thru a grate. It's a 75cfm fan. It just seems maybe that the fan blows the heat out the chimney. ??
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A draft fan makes for a cleaner burn, Meaning higher temps, and more efficiency.
Think of a torch, it has the same amount of fuel going to it, it's lazy, shoot it some u2 and she turns blue
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fan forced fires smoke less, taht to me equals mor btu collected from the wood as smoke equals unburnt btu so they may actually be about equal (not sure just guessing) natural draft means you get more smoke but perhaps the smoke is moving through the firebox more slowly so more of the btus released are collected?
fan forced means you get more btu's because the fire burns hotter but perhaps moves through the firebox faster so less of the available btu are collected? (but buy forcing the air in you actually are burning more of the smoke so you are have the potential of harvesting more of the available btu than the natural draft)
this is all just guessing on my part but with the forced air i think your recovery time to satisfy your aquastat is quicker and that may mean something if your stove is close to maxed out. it could mean the difference of keeping your home where you want it on an extremely cold night (such as tonight) or not being able to hold the house at the desired temp???
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When empyre tests there natural draft 250 vs the forced draft, the forced draft gets better numbers, for what that's worth, empyre firebox is basically a central boiler with grates and an ash pan
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In my hardy when the blower is on I don't see any smoke after a bit but the. I open the door and there is quite a bit of smoke in the fire box so that makes me believe that smoke is being burnt. I hope to make one of the baffle plates I saw on here. They say it cuts wood usage up to 50% all it does is make the exit holes smaller
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I made the baffle plate for mine and just installed it. tonight will be the test. Im at work for 12 hour shift and I usually get home as the furnace is loosing ground in the heat battle.I will report on my findings tomorrow.
My baffle plate sits just below the plentum inside the boiler.makes sense that it would direct the flame more forward.
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Sounds good please let me know I am not sure how your cb is made but please post pics if you can I believe I am going to make one also
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Today I let the boiler get down to low (127*) and when I filled it and tried the draft air and the chimney was about 700* (hickory wood) but when I shut the draft and turned the fan back on it dropped to about 525-550*. Definetly a hotter fire. It took about 40min. to get to that 700*.