Barometric Damper Questions

1) I have an oil fired boiler with a power venter attached. I am curious as to the proper location for the Barometric Damper to be placed. Is it better to be close to the boiler or some distance away? The original install had the damper ~6" off the top of the boiler and through the years it had been moved 20 some inches up by a burner tech.

2) I'm not 100% sure of the actual purpose of the damper is (my best guess is to adjust the draft) and then it's relationship to the power venter and it's post purge cycle. Is the post purge on the power venter to pull excess heat and fumes out of the burner after the burner cycle? If this is so then why once the burner flame shuts off the damper opens up more to pull in more room air and not close to evacuate the boiler? Should there be a physical stop in the damper so the maximum opening is not more then what is required while the burner is running?

Gawd, can't even make sense out of what I am trying to say. Hopefully someone understand a broken thought process.

 

When the boiler is connected to a chimney the damper must be at least 18" away from the boiler. When a power venter is added it depends on the manufacturer of the venter. Some don't even use the barometric damper when power venter. The manufacturer of the venter rules here to determine if and where it is located.
Just curious.....is the boiler now vented through the sidewall or into the chimney still. A power venter is a sidewall vented product but the is a draft inducer which will still allow the boiler to be vented into the chimney.

 

Thyanks for the quick response.

I have a Tjernlund power venter http://tjernlund.com/Tjernlund_8504060.pdf and it does not specify where to put the damper only to use one. So is there any benefit of having it closer the the burner or am I wasting my time? Would it make the post purge more efficient? Would it quiet the burner or make it noisier?

And what about the damper opening more on the post purge after the flame goes out? When there is flame the opening is about 1" and when the flame goes out on post purge it opens about 3". Seems to me that it would make more sense to have the damper not open as much during post purge to help draw the heat out of the burner and just not from the damper out.

 

I believe the difference in the amount of damper opening is because when the burner is operating the fan on the burner is blowing air into the combustion area. During the post-purge, the burner fan is off, so more of the air gets pulled through the barometric damper.

Steve