Post by wiscojames on Sept 20, 2017 6:16:38 GMT -8
Photos: www.flickr.com/photos/159540077@N06/
Sorry for the pictures being incomplete and out of order. I will do a better job at documenting the next build. Wolf has set the bar pretty high…
My goal was to heat my small greenhouse during the coldest parts of the winter, and to do it without taking up any space in the greenhouse. The implementation is slapdash, but I wanted a proof of concept that one could improve upon.
I cast another 6” batch box from local clay and sand and ash. (at the right price!) I cast the firebox top separately, adding some waterglass to the mix. Riser is perlite, ash, clay slip and waterglass. Gabion basket supports everything above the level of the riser. Two thirds of a barrel with a door cut out covers the stove. (more on that later) An oil drum riser from a previous project (perlite, fireclay, clay slip, waterglass) sits next to the batch box. This riser acts as part of the system exhaust. Other than this portion, none of the flues are insulated. One flue travels from the “floor” of the barrel (level with the riser exhaust) down through the stones in the gabion basket and through the wall of the greenhouse. Another flue travels out the wall of the greenhouse, and up to the oil drum riser. Flue gasses then travel up another section of flue above the oil drum riser, extending about 4-5 feet above the barrel.
Bypass: Because the exhaust runs through the barrel, I can warm it up by running the stove with the door of the barrel partially open. Once that section of flue heated, I close the door and the gasses flow down the flue into the greenhouse, into the bell, out of the bell and up the chimney.
The bell is made of 4” thick concrete blocks, and took a long time to heat. I replaced the top with pavers (1.5”?) and this helped. I used pavers on end inside the bell to discourage bypass of flue gasses.
Results: I have been able to heat the bell substantially (no hard measurements – but hot to the touch on parts of the bell) after 2 hours of feeding. This was in the coldest part of the winter. It was relatively easy to heat the bell, and thus the greenhouse, during the “shoulder seasons.”
Needed improvements: insulation of flues, taller bell, thinner bell walls
, ceramic fiber blanket riser (if I were serious, and flush with cash, or had a budget of someone else's money, I'd make the stove out of ceramic fiber board)
Summary: This will not be practical, unless A) insulation and efficiency improvements are made, and B) a person is willing to make a fire outside every day that the temperature is below freezing at night inside the greenhouse. I may not make all of these improvements. Nevertheless, I may try to use the system again this winter.
Sorry for the pictures being incomplete and out of order. I will do a better job at documenting the next build. Wolf has set the bar pretty high…
My goal was to heat my small greenhouse during the coldest parts of the winter, and to do it without taking up any space in the greenhouse. The implementation is slapdash, but I wanted a proof of concept that one could improve upon.
I cast another 6” batch box from local clay and sand and ash. (at the right price!) I cast the firebox top separately, adding some waterglass to the mix. Riser is perlite, ash, clay slip and waterglass. Gabion basket supports everything above the level of the riser. Two thirds of a barrel with a door cut out covers the stove. (more on that later) An oil drum riser from a previous project (perlite, fireclay, clay slip, waterglass) sits next to the batch box. This riser acts as part of the system exhaust. Other than this portion, none of the flues are insulated. One flue travels from the “floor” of the barrel (level with the riser exhaust) down through the stones in the gabion basket and through the wall of the greenhouse. Another flue travels out the wall of the greenhouse, and up to the oil drum riser. Flue gasses then travel up another section of flue above the oil drum riser, extending about 4-5 feet above the barrel.
Bypass: Because the exhaust runs through the barrel, I can warm it up by running the stove with the door of the barrel partially open. Once that section of flue heated, I close the door and the gasses flow down the flue into the greenhouse, into the bell, out of the bell and up the chimney.
The bell is made of 4” thick concrete blocks, and took a long time to heat. I replaced the top with pavers (1.5”?) and this helped. I used pavers on end inside the bell to discourage bypass of flue gasses.
Results: I have been able to heat the bell substantially (no hard measurements – but hot to the touch on parts of the bell) after 2 hours of feeding. This was in the coldest part of the winter. It was relatively easy to heat the bell, and thus the greenhouse, during the “shoulder seasons.”
Needed improvements: insulation of flues, taller bell, thinner bell walls
, ceramic fiber blanket riser (if I were serious, and flush with cash, or had a budget of someone else's money, I'd make the stove out of ceramic fiber board)
Summary: This will not be practical, unless A) insulation and efficiency improvements are made, and B) a person is willing to make a fire outside every day that the temperature is below freezing at night inside the greenhouse. I may not make all of these improvements. Nevertheless, I may try to use the system again this winter.