Harman Mark I ran great last year, different story now..

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Bluelighttaxi

New Member
Oct 15, 2020
8
Maine
Hello all, I have a Harman Mark I that I installed last fall and burned 2.5 tons of nut anthracite last year with awesome success. I also supplement with a basement Jotul F600 on those deep freezes. This past summer my wife and I needed to replace all of the windows in our house as they were original (1989), the gas leaked out of them, and they were cloudy and gross. Our house was buttoned up much more since the new windows installed. I also insulated and air sealed my rim joists and basement last winter as well. My Harman is on the first floor, next to a large natural stone open wood burning fireplace. Fireplace has its own original clay liner and works great, I put a lock top two damper on it this summer. Last summer before hooking up the Harman, I relined the second flue with two ovalized SS liners, one that vents the Harman on the first floor, and a second that continues to the basement and vents the Jotul wood stove. I had a custom chimney cap made that fits both of those oval liners and worked great last winter. I also insulated around the liners with the vermiculite.

All last winter I ran the coal stove and the wood stove from basement when I wanted or needed to with no issues. Both worked flawlessly and safely. This year I can’t seem to get my Harman to take off with the coal. A kindling fire burns hot with rage and makes great coals. As soon as I start adding my coal in small bathes to build up to a red bed it’s like the draft shuts off and it won’t take off if I close the bottom door. I’m in southern Maine, temps have been mostly in the 40s during the day and getting down to the 20s at night. I started burning coal almost exactly a year ago in that stove without issue. Coal stove used double wall pipe to thimble with a probe thermometer made for the double wall. A tee at the thimble holds an RC baro damper that has always worked well and barely moves unless there’s a big gust of wind outside. Am I being premature in trying to light the stove for the season or did I mess up my draft with all new windows and an insulated basement? I don’t have a manometer but am considering getting one. The draft is awesome with the wood and then dies out with the coal.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
28,441
central pa
Hello all, I have a Harman Mark I that I installed last fall and burned 2.5 tons of nut anthracite last year with awesome success. I also supplement with a basement Jotul F600 on those deep freezes. This past summer my wife and I needed to replace all of the windows in our house as they were original (1989), the gas leaked out of them, and they were cloudy and gross. Our house was buttoned up much more since the new windows installed. I also insulated and air sealed my rim joists and basement last winter as well. My Harman is on the first floor, next to a large natural stone open wood burning fireplace. Fireplace has its own original clay liner and works great, I put a lock top two damper on it this summer. Last summer before hooking up the Harman, I relined the second flue with two ovalized SS liners, one that vents the Harman on the first floor, and a second that continues to the basement and vents the Jotul wood stove. I had a custom chimney cap made that fits both of those oval liners and worked great last winter. I also insulated around the liners with the vermiculite. All last winter I ran the coal stove and the wood stove from basement when I wanted or needed to with no issues. Both worked flawlessly and safely. This year I can’t seem to get my Harman to take off with the coal. A kindling fire burns hot with rage and makes great coals. As soon as I start adding my coal in small bathes to build up to a red bed it’s like the draft shuts off and it won’t take off if I close the bottom door. I’m in southern Maine, temps have been mostly in the 40s during the day and getting down to the 20s at night. I started burning coal almost exactly a year ago in that stove without issue. Coal stove used double wall pipe to thimble with a probe thermometer made for the double wall. A tee at the thimble holds an RC baro damper that has always worked well and barley moves unless there’s a big gust of wind outside. Am I being premature in trying to light the stove for the season or did I mess up my draft with all new windows and an insulated basement? I don’t have a manometer but am considering getting one. The draft is awesome with the wood and then dies out with the coal.
Is it a different coal supply than before? I would say absolutely get a manometer as well though.
 

Bluelighttaxi

New Member
Oct 15, 2020
8
Maine
Is it a different coal supply than before? I would say absolutely get a manometer as well though.
Yes the brand of coal did change, I was buying it form tractor supply last year by the ton as I went because I wasn’t sure how much I’d like the stove and didn’t want to commit to a whole bunch and then have to get rid of it if I didn’t like it. Since I love how the stove worked out I ordered 2 tons of Blaschak nut and one ton of pea this year and had it delivered.

I was wondering if the new chimney cap I put on my clay liner for the fireplace was affecting the draft for the coal stove now because I basically have the two caps side by each on top of the chimney. I had to build up the fireplace side of it about two inches with mortar as the clay liner stopped short of the chimney. I took the new cap off the fireplace side (left the locking fireplace damper in place) and tried lighting the coal stove again last night, still wouldn’t get going with the coal but the wood burns hot and fast. I’m disappointed and frustrated, racking my brain thinking of anything else that might have changed since last year… I clean my chimney and flues myself and have all the proper brushes, technique, etc. I even used a USB scope camera to check above the baffle plate in the stove, the flue outlet, thimble connection, for anything I might have missed..all looks great. I’m stumped.
 

begreen

Mooderator
Staff member
Nov 18, 2005
93,149
South Puget Sound, WA
This might be due to tightening the house envelope. If a nearby window is left open 1" does that help the coal burn better?
 

Bluelighttaxi

New Member
Oct 15, 2020
8
Maine
Got the stove up and running today just like it used to. Perhaps I lost my coal burning finesse over the summer..¯\_(ツ)_/¯

Thanks for taking the time to read and reply bholler and begreen.