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Gas fireplace back drafting

I have a gas only fire place that is vented thru the wall in my master bedroom. The vent exits the wall about 24in above the top of the fireplace and the vent hood faces north. The problem I’m having is that I have a open field and a pond on the north side of my house and the prevailing north wind in the winter hits the north side of my house and causes my fireplace to backdraft. Does anyone know of a wall mounted vent hood that will prevent back drafting for this situation?
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Comments
Albert Einstein
Combustion air comes from a connection on the back of the fire box - it pulls air from the chase behind the fireplace.
Another item, at times we have a significant amount of cold air blowing in around the sides of the glass on the front of the fireplace. I have had to shove insulation in the gap around the glass at times to stop the cold air from blowing in.
I did find a high wind termination kit that basically looks like a round piece of stainless pipe that is open on top and bottom. Not sure if it will be compatible with the existing flue pipe, but i may be able to get creative and get it to fit.
Thanks for your input.
It sounds like you have an installation issue.
Albert Einstein
No IOM
Tell us more about the "backdrafting". Does it set off CO detectors? Is it obviously combustion byproducts?
Albert Einstein
The backdrafting doesn’t set off a co2 detector but frankly I’m not sure if my detector is any good, it’s never gone off. I need to replace it.
I notice combustion odor and get a headache when I run it for more than 30 minutes. It only seems to occur with north wind. I have run it before with little or no odor, but odor is present more often than not.
I’m new to heating help and not sure how to add pics. The wall termination hood is a standard Lennox vent for the model. (I did find a manual online)
The vent hood has a large piece at the top that angles away from the house to deflect heat I’m sure. Unfortunately it seems to make an excellent air scoop for catching the north wind and channeling it into the combustion air space around the flue.
I have an idea about shortening the height of the heat deflector to try and reduce the air scoop effect. It should still deflect heat away from the side of the house.
Albert Einstein
Since you "notice combustion odor and get a headache when (you) run it for more than 30 minutes" when the wind blows from the north, that's a good indication of poor combustion, which produces carbon monoxide. Yes, I know you have a CO detector, but most such detectors do not alarm right away.
Is it possible to vent this thing up the chimney?
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I was hoping to find a high wind termination hood that would solve the problem but Lennox uses 4.5in flue size which appears to be non standard so I haven’t been able to find any high wind wall caps.
My plan at this juncture is to cut down the metal on the top of the hood to reduce the air scoop effect. It’s a pretty simple modification that could solve the problem. (See attached detail of the wall termination cap). I’m going to take off about 1.5in and bend the metal down a bit. It should still vent combustion gases effectively. I’ll take pic tomorrow after I do the modification.
I had the installer out after we had used it about 6 times during the first season of use and they said nothing was wrong that the smell was normal break in. That was two years ago. I’ve used it sparingly since because of the fumes.
Im not sure if they checked the vent connection when they came out. I have access to a pipe camera so I can check the vent to make sure it’s connected.
I live near KC Mo.