My coal and oil boilers share the same chimney. Here is a pic of how it's setup. Thanks to a member of this forum I finally have a set of replacement grates so this is the first year we will be using the coal boiler since we bought the house.
I plan on burning coal when the weather turns colder but I've been burning a bit of wood during the milder fall weather. This old 1957 coal boiler is not very air tight. Even with the baro-damper from the oil boiler set to stay closed, I can't close the manual damper on the coal boiler at all because smoke rolls out around the door, so we won't be using that...lol.
I got a good deal on a draft gauge so as an experiment I set the draft on the coal boiler breech to 0.05 using the baro-damper on the oil boiler which enters the chimney above the coal boiler smoke pipe.
The wood fire is much more controllable and I seem to get more heat to the house and a longer burn from the wood.
I'm a little concerned that the air entering the chimney through the baro-damper might cool the smoke enough to cause creosote buildup.
What do you think? What are your thoughts on how it is set up and how I should run it?