Hi All,
The Setup
I have a 2008 Harman P38, old style 2-Knob board, with a modified burnpot that previously had the 5 air holes right next to auger (causing fire near/in auger tube), which I welded closed. It is an up and out install, about 4-5 feet of interior vertical before terminating horizontally outside. Piping is Selkirk Direct-Temp with OAK hookup.
The Issue
The fire has always burned fairly low in the pot with a blowtorch like effect, even with the 5 low auger holes welded closed. I always thought perhaps there was too much combustion air, and too much heat was escaping the chimney, but never pursued any remediation.
Stove has been burning for 1 month since last chimney cleaning, couple weeks since last stove cleaning. I got home from overnight shift to find the fire higher in the pot (about even with the lip) than I'd expect for a feed rate of 3 (usually below lip further back in pot, flame not higher than flame guide), and the room warmer than I'd expect for that feed rate at the given outside temperature. The fire had a slightly more fireplace, less blowtorch effect.
I figured something had changed and suspected exhaust, so I went outside to investigate the screen on the exhaust termination, as it has clogged with ash before. It was, so I cleared it and went back inside. After 20 mins or so the fire was burning lower in the pot, and the temp in the room had dropped by 1 degree, and eventually 2 degrees after about an hour.
The Question
This seems to me to indicate that by restricting the exhaust, the overall combustion airflow was limited, which lead to 1.Fire higher in burnpot, and 2. A noticeably hotter fire, and better heat production. In this case it resulted from a dirty exhaust screen, reducing amount of air for combustion, but I was wondering if I should do something to reduce airflow to see these benefits under normal conditions, and if so, what can be done?
I think I read about the dial on the back of one of the control board knobs that is a draft adjustment, and can be turned to reduce draft/combustion air. Also, I am not sure if something should be done on the input side, such as partially occluding the diameter of the OAK to restrict air intake.
I was wondering if anyone had any expertise to lend, if so I would greatly appreciate it.
The Setup
I have a 2008 Harman P38, old style 2-Knob board, with a modified burnpot that previously had the 5 air holes right next to auger (causing fire near/in auger tube), which I welded closed. It is an up and out install, about 4-5 feet of interior vertical before terminating horizontally outside. Piping is Selkirk Direct-Temp with OAK hookup.
The Issue
The fire has always burned fairly low in the pot with a blowtorch like effect, even with the 5 low auger holes welded closed. I always thought perhaps there was too much combustion air, and too much heat was escaping the chimney, but never pursued any remediation.
Stove has been burning for 1 month since last chimney cleaning, couple weeks since last stove cleaning. I got home from overnight shift to find the fire higher in the pot (about even with the lip) than I'd expect for a feed rate of 3 (usually below lip further back in pot, flame not higher than flame guide), and the room warmer than I'd expect for that feed rate at the given outside temperature. The fire had a slightly more fireplace, less blowtorch effect.
I figured something had changed and suspected exhaust, so I went outside to investigate the screen on the exhaust termination, as it has clogged with ash before. It was, so I cleared it and went back inside. After 20 mins or so the fire was burning lower in the pot, and the temp in the room had dropped by 1 degree, and eventually 2 degrees after about an hour.
The Question
This seems to me to indicate that by restricting the exhaust, the overall combustion airflow was limited, which lead to 1.Fire higher in burnpot, and 2. A noticeably hotter fire, and better heat production. In this case it resulted from a dirty exhaust screen, reducing amount of air for combustion, but I was wondering if I should do something to reduce airflow to see these benefits under normal conditions, and if so, what can be done?
I think I read about the dial on the back of one of the control board knobs that is a draft adjustment, and can be turned to reduce draft/combustion air. Also, I am not sure if something should be done on the input side, such as partially occluding the diameter of the OAK to restrict air intake.
I was wondering if anyone had any expertise to lend, if so I would greatly appreciate it.
