"modern" wood stove + Heat exchanger = BAD NEWS

[Ricky]

A few weeks ago (perhaps a month) I posted up that i had finally found a great deal on a sealed '84 Kent Sherwood stove. finally was able to replace my old non-airtight double walled (mobile home approved) stove. The constant heat and controllable burn of the new to us Kent was amazing to us. I had installed a vogelzang heat reclaimer above the old stove because so much heat was going up the flue and i had to burn it hot just to keep the fire going.

Well installing this new stove i figured i'd leave the heat reclaimer on there. It barely ever turned on anyway as the stove is great at putting out heat at the stove and not up the flue. Well after only about 2-3 weeks we started noticing a decrease in draft and stove temps. I figured it was the wood i was burning wasn't as dry or something of that nature since i had just seen the flue a few weeks ago when i installed the new stove and it was fine (never cleaned it last winter).

Well boy was i wrong! a few days ago (in the evening of course) i go to turn on the stove and i can't get it going. I'm thinking it's that darn greenish wood again, so i try a bit of paper, a small firestarter.... nothing but smoke. then i notice smoke coming out the lower seams in the flue....uh oh. after closing up the stove we wait a bit and start taking apart the flue...... completely sealed. the reclaimer was completely plugged with fluffy black deposits. it was a bit better past the reclaimer but still bad the whole way up (short single story flue).

So i repositioned the stove to eliminate the small elbow and removed the reclaimer completely. I'm shocked at what a huge difference the stove made. My old stove never had a problem but we went through wood like crazy and it never lasted more than a few hours max. This stove is comfortable, even heat for hours (all night turned down) but the amount of creasote is ridiculous. I'm going to open the flue up in a few weeks to see what difference the reclaimer and elbow made. If that still isn't enough i plan to replace the flue with double walled pipe. Besides that i don't know what else i can do other than wait for the wood to get dryer. I had to cut 20 cords of wood this year for my shop, my house and my folks house so it's not like i can just buy drier wood. Next year i'll have a bit more experience and start cutting earlier so it's drier by late fall.

So anyone else experienced a completely plugged flue in 2-3 weeks?

 

[begreen]

Greenish wood + heat reclaimer = creosote. It sounds like there are multiple issues here. The wood, short flue are not good combos for a modern stove.

What is the flue height and what stove make/model is this?

 

[pen]

It sounds like you have a good plan.

As of now, you are stuck with the fuel you have so the best thing you can do is keep a close eye and see how much difference there is not that the heat reclaimer is gone. Keep us posted.

How much single wall pipe do you have? Any elbows? When attaching the single wall pipe, did you line up the vertical seams in the pipe or did you stagger them? If there is a lot of single wall, a lot of joints, and / or gaps where the seams meet, re-positioning things and using some furnace cement to seal the joints, or spending the bucks and going to double may be your best options.

Another thought if you are sure your fuel isn't as dry as it should be, would be to try buying some of the man made bio-bricks or eco-blocks, envi-etc, and mixing in to see if there is any difference.

Experiment and see what works best.

Also, I can't remember is the chimney a class-A unit from the ceiling up? Or masonry? What's the diameter of the chimney? Is it the same as the flue collar's diameter?

 

[Ricky]

it's a Kent Sherwood from '84. And yes i agree it's kinda like the perfect storm of creosote buildup. I still had no idea it would be so fast. The full height of the flue from top of stove to top of chimney is maybe 9-10 feet max. The wood is dry enough to burn ok, it's not totally green but I know it's not totally dry either. there was one bend in flue before. I had an adjustable elbow just to off set it about 6 inches or so to keep it equal distances from the walls (it's corner installed) but i took that off as well so now it's about 3 inches closer to one wall than the other.

From ceiling to the top is class A chimney. around 4 feet or so. below that is standard single wall. The joints are lined up now, not sure how they were before. I think/hope things will get better now. I know i'll have to do regular cleanings due to the greenish wood but if it's more than once a month or once every two months I'll probably install double walled flue to see how that changes things. I'd imagine it'll only decrease the buildup amount and since i'm not really getting much heat out of the flue now anyway i don't see a negative to it.

 

[Ricky]

oh and yes it's a 6" all the way from stove to top.

 

[pen]

I'd be adding another length of class-A up top. The lack of draft may not be making the stove operate as efficiently as it should, and certainly would be welcome if the wood isn't up to par.

Also, don't skimp on those clearances! Make sure moving that stove some didn't put you inside of what that stove requires without building proper wall protection.

 

[begreen]

Sorry, I should have caught the stove. Cellphone reading is not so good at times. Would it be possible to add some pipe to the chimney? 9 feet is very short. Another few feet will improve burning during milder weather I think and may help the fire burn hotter.