Woodstove with outside air source backdrafting
I’ve read the other posts about woodstoves with outside air sources backdrafting, but of course there are always so many specific details that don’t match up, so I’m posting about it as well.
I live in central Vermont. We moved from northern Vermont in October, so this is a new house for us.
We just installed a new VT Castings Dauntless, in front of our fireplace. This house is 1600 sq ft and terribly insulated, very leaky. We are working on it now. Before we installed the woodstove, I had a 3 1/2″ hole drilled through the side of the chimney, at a point where it should have lined up with the port for the outside air. They had trouble keeping a straight line when they hit the steel liner in the fireplace, so it didn’t. The duct leading from the woodstove (it is connected directly to the stove) exits the fireplace about 2″ higher than the woodstove firebox.
烟囱是砖砌的，在房屋的朝南墙上，在筛选的门廊内（So To House - Cold），带有6英寸的烟道。烟囱的顶部在房屋的峰值上方。
我们烧了炉子4天3晚，没有任何问题。然后，昨晚，第四晚，我们意识到我们的卧室（楼上）烟熏。它永远不会引发我们的烟雾报警器，但是我们可以闻到并在眼中感受到烟雾 - 还不错，但这肯定不是正确的。我们检查了炉子等。当大火燃烧时，它终于减轻了。
今天，在白天，一旦我关闭了炉子上的阻尼器（与催化转换器相关），我们开始再次获得低级烟雾。我们今天有安装程序来检查它，他认为我们可能一直在炉子足够热之前关闭阻尼器（我正在按照手册中的说明进行说明，这对我来说没有意义）。但是今天下午和晚上，我故意在500时燃烧着火，然后将其关闭 - 我们再次烟。当我们打开阻尼器时，吸烟就停止了。
This woodstove replaced an old, cracked Jotul with a damper that didn’t work. We couldn’t shut that down, so we never built the fire up that hot. We never had any backdrafting from that stove.
Any ideas on what is happening? It has been cold this entire time (20 degrees and below), and not particularly windy. It’s not windy now and we just got the backdrafting when we shut the damper.
Would it make a difference if we raised the stove on 2″ blocks of stone (hearth is soapstone – we could use blocks of soapstone)? Or would it make a difference if we extended the air duct outside so that the end of it dropped below the level of the firebox in the house?
I’m having a particularly hard time with this since the woodstove in our previous house was in the basement with an outside air source that exited the basement at least 5 feet above the firebox and we never had an issue. That chimney, however, went straight up through the center of house, through 4 floors -so lots of draft and it was warm. I suppose that may have made the difference?
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Replies
knh1VT,
I'm sure you will get some good advice here, but the best place for your question is:https://www.woodheat.org/questions-and-answers-about-wood-heat.html
I would bet that when the damper is closed, you do not have adequate draft. How is the stove connected to the fireplace flue. Is it closely sealed? Was this install checked by a building official?
knh1VT,
从Hearth.com查看此链接：https://www.hearth.com/talk/threads/regency-2450-backdrafting.183295/
This is a different brand but it seems there was a change in the EPA design requirements that added a more restrictive deflector and people are claiming it is choking the firebox causing smoke/backdrafting.
我一直使用Kozy热火本赛季Z42very tight house with no issues. This a fireplace as opposed to a stove and built in 2019 so any 2020 design change requirements would not apply. It has airtight box and OAK that provides air directly to the firebox. For 10-years prior to this season, I was using a QuadraFire 7100 with an OAK in a very drafty house. I did have to crack a window on start-up to get the draft flowing in the right direction, but once the flames started to "dance" I was fine.
我希望确保不会阻碍您的堆栈流。我一直在经营一个小洛皮（Lopi）9年，加热约1,400英尺：制造的房屋，因此炉子具有新鲜的进气口。我遇到问题，因为沉积物在砖头上方积累并限制了烟囱的流动，从而导致了背景情况：但是只有几个月的不停止燃烧后（这是我们的主要加热装置）。我清洁炉子（烟囱非常短，因为炉子位于外墙附近，屋顶俯仰较浅），而且又有很多月的时间。我承认，炉子会被抑制，这肯定会导致更多的积累（然后倾向于倒下）。
Refer to section 4 chimneys and venting, of your installation manual. The first paragraph states "When there is a good match between all the parts, the system works well." If you read further to section C for masonry chimneys it states that a minimum size chimney is to be 8 in diameter. If your chimney is only 6 in then you may have a velocity problem associated with the drafting especially if you are burning a hot fire as you said you had. Once you close the damper, you are restricting this flow even more. Unfortunately, the damper is either full open or full closed with no intermediate positions for better balancing. Burning a smaller fire may be your solution to reduce the need for faster flow. This is even mentioned in the manual.
流运动越快移动更大体积的exhaust that has to be matched by the intake which would have to be increased in size in order to match the flow by reducing friction. Hopefully you can see how closing the damper will affect this flow. So best to experiment and find what operating temperature works best which may only require one log every few hours or so.
Thank you so much for all the very helpful replies. I've been looking into all the different avenues suggested - then the installers came out again today (Jonathan Blaney asked if the install was inspected by a building inspector - that put a smile on my face. I live in the wilds of Vermont, where there are codes but no enforcement. The installers, however, are certified, work with the state on efficiency and have a very good reputation.)
结果似乎是（我们需要在几天内对此进行测试），问题是遵循所有者手册中的指示引起的。我不是在开玩笑。我将年满62岁，除了我一生的大约20年以外，所有人都加热了木头。我知道如何使用木棍，但这是一个全新的模型，等等，等等 - 我决定阅读手册。我们已经开火了三个晚上（和2 1/2天），没有任何问题。但是我开始在安装后的第二天开始阅读手册 - 在手册中，至少在2个位置，也许还有更多的地方，他们特别注意，在添加木材之前，您应该“将煤朝炉子的后部耙开”。这对我来说似乎很奇怪 - 机场在那里。但是手册清楚地指示您这样做。所以我做到了。当安装人员今天第二次回来时，他们发现机场上挤满了灰烬。 Gee, I wonder why? Of course I felt like an idiot - but I was doing what the manual said to do! The manual also tells you that after raking the coals and adding the wood, to then shut the damper! Not to wait until the temp reaches 500F - just shut it down. The installer agreed that was also nuts.
At any rate, I think the installer fixed it when he cleaned the ash out of the ports.
I am going to keep a record of all the great responses I got here - I so appreciate everyone's time and energy on this. If the installers didn't solve it, I'll let you know. And by the way, if you're in Vermont, the installers were Montpelier Stove and Flag Works. They know their stoves and they know about draft and chimneys, etc. They've been very responsive - they have come out twice on this issue and made it clear they'll come back until it's solved.
Makes sense since the faster flow out the chimney is acting like a vacuum cleaner sucking the ash up and into the air ports.
We've been burning the stove, shutting it down, and no smoke! Every time I add wood now, I pull the ash and coals away from the back wall instead of following the owner's manual instructions to rake them back against the wall. Works perfectly. It's a great little stove. Too bad the manufacturers don't know how to run it! :)