Post by Dan (Upstate NY, USA) on Oct 25, 2014 1:34:52 GMT -8
So I am headed into my 4th heating season with my J-tube rocket mass heater.
Its an 8" system, with an over insulated feed, burn tunnel and riser, going into 30 feet of 8 inch pipe and then into 25 feet of external 6" triple wall chimney.
You can see it here My stove...
It has been a safe a reliable system until yesterday when I mis-operated it.
I just got around to cleaning out the chimney and tunnels from last year, I vacuumed out all the fly ash and scrubbed out the creosote that forms when the stove it started up cold.
So we lit our first fire of the year and she came right to life no problems...
24 hours later WAY after the fire was put out she started putting off some heat, more than normal after 24 hours, and it started to smell weird.
I thought "I no, I didn't clean the creosote out good and there is a slow burning fire in the bench."
So I opened all the cleanouts and no fire.
BUT what I did do DIFFERENT 24 hours earlier was to completely close off the feed, something I had NEVER done before to keep the house air from being sucked out the chimney.
I usually left the feed open a crack.
Well the cold air reversed direction and came down the chimney into the house.
To remedy this I decided to put a propane torch in the last clean out to warm up the chimney and get the air flow in the right direction.
We didn't need a fire last night, it was sunny out and the house was a little overheated due to solar gain.
After I got some hot air going up the chimney I decided to build a small fire in that last cleanout to warm up the chimney like I do before I build a fire when the whole system is cold.
At first it worked and then, due to the cold chimney the air flow reversed again and started to belch smoke and fire into the living space.
I QUICKLY capped the last cleanout and realized it was only 30 feet away from belching a lot of smoke back out my feed!
So I ran outside and opened the bottom cleanout of the external triple wall pipe and dumped all the cold air column coming down the chimney onto the ground and got the air flow going up the chimney with the propane torch.
Lit a small fire to make sure the system would keep flowing the right way and left the feed opened a crack like I always do to ensure the flow would remain to the outside.
LESSON LEARNED: best to burn a little more wood to keep warm and give up some house air to the gods of entropy than to have to fight a stove flow reversal!
And my chimney clears my house roof by at least 4 feet at the peak, and my house is (mostly, still a work in progress) super-insulated house (R60 ceilings, R40 walls) with a tight sealing second floor.
Only a little air leakage from the 4 upstairs windows and we still had a stove reversal with a really warm core!
Its an 8" system, with an over insulated feed, burn tunnel and riser, going into 30 feet of 8 inch pipe and then into 25 feet of external 6" triple wall chimney.
You can see it here My stove...
It has been a safe a reliable system until yesterday when I mis-operated it.
I just got around to cleaning out the chimney and tunnels from last year, I vacuumed out all the fly ash and scrubbed out the creosote that forms when the stove it started up cold.
So we lit our first fire of the year and she came right to life no problems...
24 hours later WAY after the fire was put out she started putting off some heat, more than normal after 24 hours, and it started to smell weird.
I thought "I no, I didn't clean the creosote out good and there is a slow burning fire in the bench."
So I opened all the cleanouts and no fire.
BUT what I did do DIFFERENT 24 hours earlier was to completely close off the feed, something I had NEVER done before to keep the house air from being sucked out the chimney.
I usually left the feed open a crack.
Well the cold air reversed direction and came down the chimney into the house.
To remedy this I decided to put a propane torch in the last clean out to warm up the chimney and get the air flow in the right direction.
We didn't need a fire last night, it was sunny out and the house was a little overheated due to solar gain.
After I got some hot air going up the chimney I decided to build a small fire in that last cleanout to warm up the chimney like I do before I build a fire when the whole system is cold.
At first it worked and then, due to the cold chimney the air flow reversed again and started to belch smoke and fire into the living space.
I QUICKLY capped the last cleanout and realized it was only 30 feet away from belching a lot of smoke back out my feed!
So I ran outside and opened the bottom cleanout of the external triple wall pipe and dumped all the cold air column coming down the chimney onto the ground and got the air flow going up the chimney with the propane torch.
Lit a small fire to make sure the system would keep flowing the right way and left the feed opened a crack like I always do to ensure the flow would remain to the outside.
LESSON LEARNED: best to burn a little more wood to keep warm and give up some house air to the gods of entropy than to have to fight a stove flow reversal!
And my chimney clears my house roof by at least 4 feet at the peak, and my house is (mostly, still a work in progress) super-insulated house (R60 ceilings, R40 walls) with a tight sealing second floor.
Only a little air leakage from the 4 upstairs windows and we still had a stove reversal with a really warm core!