Question about home central heating furnace flue

Hello all,
I usually try to search for all my answers online but given them number of questions I have I thought it's about time I engage the community and hopefully learn from some experts.
I've always dabbled in (less technical) home improvement/maintenance projects but now I want to learn about central heating. Long story short, my wife has a house that has not been taken care of and we want to get it in saleable condition, doing what we can ourselves and getting professional help where we can't.
Hopefully my first question is a simple one: why does the furnace flue (apologies if I'm using the wrong terms) have a mesh covered opening near where it connects to the furnace (oval shaped, facing down, caked with dust)? What is the purpose of this? See attached pictures.
Thank you for all replies​​​​.

 

Welcome to the forums.

I am not the boiler pro but that screened device was added to improve the draft for the oil burner. I've seen barometric units installed but never an open screened unit like that.

The guys that know these systems will be by.

 

I cannot get pics to post.

 

Sorry spott..... I'm running a program to see photobucket pics.
They won't post to the board though.

I hosted them locally.

 

From the size of the flue pipe I was guessing you had oil until I saw the gas valve.

Honestly this is a first for me. I've never seen anything like this before. Having a wide open flue on an already low temp gas flue I wouldn't think is good for creating draft.

That is why gas units do no not require draft regulators like oil does.

I have no idea why that is there unless they were trying to get some heat back into the basement but I would get a draft gage and most likely remove it.

Just my thoughts.
.

 

I was just about to ask if this is common on gas furnaces, since Pete mentioned oil!
I'll perhaps clean off the dust and peek under the mesh (which is held on by wire wrapped around the flue) to see if there's anything more to it.

Note this house is a real mess. My wife's parents have apparently had some really useless people in to work on things over the years (i.e., Chinatown guys off the street, very likely unlicensed).

Pete, should I start a new thread for each separate question I have about this system?

Thanks again.

 

My bad.... I saw the black circulator on the front of the boiler
and thought it was an oil burner.

I agree.....it shouldn't really be on a gas burner.

Feel free to add more questions right here.