Conventional damper VS. barometric type damper with Gasification Boiler

[WRVERMONT]

I would like to hear some opinions on the use of a conventional "butterfly" type damper (cast iron mounted with two 1/4" holes in the flue) as opposed to a barometric damper (mounted in a TEE in the flue, like the one typically used on a oil furnace). Thanks.

 

[jebatty]

My first answer is neither. Next, why (unless recommended or required by the mfr)? Is there a specific problem you need to address that you cannot solve by adjusting the controls and internal dampers, if any, in your boiler?

 

[WRVERMONT]

My thought is one of efficiency. Trying to create a highly efficient system. It is the recommendation of some manufactures to use a barometric damper to promote better efficiency. (The thought is that less heat will go up the chimney.The installation of the damper can lead to more smoke out the door when loading. I would love to hear more discussion.

 

[RJP Electric]

I understand your thoughts but I don't believe it will work for most gasifiers. My biomass works on a negative pressure system, the air gets sucked from the fire box to the combustion chamber through the heat exchangers through the fan then gets power vented up the chimney. If there is a damper there it will impede the gasification process for my unit.

 

[deerefanatic]

Exactly. On a gassifier, the heat that goes up the chimney is there to stay. Nothing you can really do about it. If you restrict the chimney, it won't burn right.

Heck, my homemade outdoor has basically zero draft, it's all via the fan pushing things along..... (I wish I'd done a negative draft, it smokes pretty bad when loading!