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Post by chazvan on Feb 2, 2015 20:46:11 GMT -8
Thanks again. I am planning to use a fan (like the one that you use) to a WYE duct branch to the vent pipe that exits the room vertically. I was thinking it best to draw cold air from outside into the vent forcing the air upward into and out the flue...in this way, i hope to at least stop any wind blowing down the flue and perhaps if i am lucky, create a draft too. How is your fan system set up? Do you draw in outside air? Is your fan within a duct of some sort? This is a bit off of rmh but I think it could help those who have draft problems. Last week I had a draft inducer installed in the flue pipe of a triple barrel 55 gallon wood stove I have used for several years. Its a Tjerlund D-3. What a dramatic difference. No more smoking out the load door or anywhere else. Dramatically faster startup. Temperatures at least two to 3 hundred F hotter. I think it will dramatically reduce the soot buildup problems I have had. I don't think wind will have much influence anymore. This unit is rated for up to 300,000 btu/hr input on a system with a six inch flue and a bit over 500 F flue temperature. While not for a rocket stove purest, if you already have an installation investment, it might be a viable fix. Mine is an grid powered unit but I believe one could get it with a DC motor and power it with Solar/Battery combination when need as burn runs for an rmh should normally be only a few hours. My combustion air is coming from the crawl space via a vent in the floor in a closet a relatively modest distance away but I plan to shorten the path to about 3 feet. Again, this is not and RMH application but I think some of the principals still apply.
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Post by pinhead on Feb 3, 2015 8:45:22 GMT -8
What is a draft inducer? A flu fan?
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Post by chazvan on Feb 3, 2015 15:47:18 GMT -8
It is like a smallish blower with paddle wheel like blades that stick into the flu from the side. You open a couple inch wide slot in the flu pipe and mount it from the outside. This is a link to the smaller version of what I installed. www.ebay.com/itm/TJERNLUND-DJ-3-Blower-Draft-Inducer-/221571144216?pt=LH_DefaultDomain_0&hash=item3396ab5a18. What I think of as a flu fan is something that is actually fully in the flu path like those used on a pellet stove or a chimney top unit. I have not found any of the first type big enough for a 6 inch duct or with a high enough temperature rating. The top of chimney type seem to be more expensive as in thousand plus dollar range plus you have to get power to the top of the chimney. This is the draft inducer mounted to the flu pipe just before it goes into the attic. The stove in question is a 3 barrel with the exhaust coming out the top of the third and going through a wall at a small upward angle The draft inducer is on the other side of the wall The smoke comes out vigorously. It is relatively black so not getting a very clean burn but it is not white either. Soot buildup seems pretty much no longer an issue--it had been plugging the chimney frequently. Temperatures are up a couple hundred degrees compared to how it ran without the inducer. Range is over a thousand down to about 350 F at the inducer. My IR thermometer is limited to 1000 so I am not really sure what the hottest part of the lower barrel is getting to. Again, this is not RMH but it still should apply in those cases where draft is not adequate, as long as you have enough electricity available.
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Post by rocketron on Feb 6, 2015 17:56:03 GMT -8
You could use a product called the draw collar. It's a heater band that surrounds the flue, and warms the flue for starting the draft. The nice feature is that it does not inhibit the exhaust in the flue pipe.
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Post by chazvan on Feb 27, 2015 11:41:21 GMT -8
If it were just a starting draw issue, that sounds like it would be great. In my non-rmh case, lack of draft was a problem no matter when.
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Post by chazvan on Feb 28, 2015 17:55:23 GMT -8
An update on the triple barrel stove with draft inducer.
I saw smoke leaking out of the stove today. Had noticed stove did not seem to be working as well the last few days. Turns out the draft blocker/damper had come loose from the handle and had vibrated into a mostly closed position. Had the same problem on the stove in the shop last week. Have now removed both of them. Originally included them as a safety factor but never used them.
There was some build up of soot but not enough to block off the draft like has been the case in the past before the draft inducer. Thing is, I don't know that we had cleaned the soot when we put in the inducer so can't say if it was from before or after. It was nearly all in the upper barrel and stove pipe leading away from the top of the stove. Cleaned it out of course while I had things opened up. Draft inducer would still suck a sheet of paper up into it.
We have been running a lot of fire lately due to cold weather. Normally don't keep it cranking over night but have several nights in the past week or two. Just guessing we are running a couple hundred pounds of wood a day when it is really cold. Internal wood storage area is about 3 by 3 by 6 foot and we fill it a couple times a week when the outside temperature is staying in the teens. We are heating about 6000 square feet of "office/work" space. It is pretty well insulated now except lots of windows that are at best two panes of glazing.
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