Boiler venting Issue??

[camdids]

Started a couple of weeks ago. Never had it before. My Oil Boiler situated in th ebasement. Vented into one of two flues in a double stack chimney. The Other flue is used by my pellet stove situated in the living room. this has its own liner inside that to the roof.A double Cap is on top of the chimney.The house is a split, with open plan design. When I have the air conditioner on,situated in the window in the kitchen, next to the living room, we get fumes from the boiler come into the living room from the fireplace. If we leave a window open in the living room it stops. It also doesnt seem to occur with the windows closed and not running the AC. My Chimney Sweep told me it was the Boiler starving for air in the basement.My Heating Guys tell me its a chimney drafting issue.
I need help.

[HKestenholz]

“My Chimney Sweep told me it was the Boiler starving for air in the basement. My Heating Guys tell me its a chimney drafting issue.”

Both are two sides of the same coin. If you want help, listen to them, they might be able to solve it, if they know enough about draft.

http://www.HeatProUS.com energy businessmen’s knowledge

Yes, you really have to find out the MAKE and MODEL to get good answers. There IS more than one machine made.

[homebild]

Did they install soemthing like this?

http://www.atlantachimneydoctor.com/images/construction_photos/101_0102.jpg

There should not be a single vent cap or ‘shroud’ covering these two appliance vents.

Each must be capped and terminated separately.

To install a single cap over both vents violates the listing of both appliances and should be removed.

[Bruno1949]

However, common sense says you don’t put a dual cap over a boiler system, which I’m going to guess is also your domestic hot water system, and an undampered flue used for a pellet stove.

You could have saved a lot of time and money by venting your boiler directly into your pellet stove because that’s what you have now.

The AC is creating enough negative pressure in the house to draw air down the chimney flue and into the house. Since that flue obviously doesn’t have an air tight damper in it you are also drawing in all the gases from your boiler when it runs since they share the same cap.

Obviously the cap doesn’t have enough free air exchange to keep the gases from entering the stove flue. As was pointed out, a shared flue is probably illegal in your area. I know they are here. Despite what your neighbors have or what your chimney sweep may say, it’s wrong and it’s dangerous.

You have a couple of choices. Remove the cap and have two separate caps installed, one taller than the other, or stop using your AC unit, or plug your pellet stove flue when using the AC. The proper cap is the safe, smart, and legal thing to do.

You and your chimney sweep can argue all you want, but the fact is you are drawing in carbon monoxide every time your boiler fires up with the AC on and it’s going to make you sick or dead.

The fact remains that the cap installation is wrong and dangerous. Most of the other posters, including a couple of very knowledgeable moderators, have said that from the beginning and they are speaking the truth. For your own safety, listen to them. Please.

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