It seems to me that the temp of stack and the temp of the plenum on a furnace are directly related. I had the ash pan door opened today and stack temp got up to 350 and the fan on my oil furnace came on. The coal and oil furnace are tied together with a 12 round pipe. The coal furnace has a blower on it and I have not been able to get the fan on oil furnace plenum to come by using the coal the coal furnace untill today.
It seems to me the hotter the coal is burning the hotter the plenum is going to get as well as the stack temp is going to increase. I know that I have a short chimney and have a draft that is not real good I am going to order a draft inducer to help increase the draft. Which I think will help the coal to burn better.
I did have a baro installed but had burnt some wood when the weather was warmer so I had removed the baro and capped the tee off as to not mess up my new baro. So I am burning with out a baro right now.
My co alarm stared going off at 2:00 A.M. so I got up and vented basement and opened up ash pan door to get draft going the left the screw in damper opened up a little farther no more co alarm yet. I checked the draft with mano meter @ 2:00 A.M. and draft was .02
I am hoping that the draft inducer will correct the draft issue outside temp was 45 degrees last night when alarm went off.