Closing off fireplace intake vent


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Old 06-12-17, 12:12 PM
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Closing off fireplace intake vent

I'm having an attached garage put on my house and it will enclose the chimney, which has an intake vent. Is it okay to plug the vent (with mortar) or should I run a duct up the wall, across the attic, and to the outside? If I did so, it would be about a 25' run. Or should I just plug it up and let the fireplace draw inside air for combustion? It's an open wood burning fireplace, so I don't use it for heating anyhow, just ambiance.
 
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Old 06-12-17, 12:20 PM
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The Virginia Residential Code states:

Factory-built or masonry fireplaces covered in this chapter shall be equipped with an exterior air
supply to assure proper fuel combustion unless the room is mechanically ventilated and controlled so that the indoor pressure is neutral or positive.


My living room is mechanically ventilated and the pressure is positive, so it sounds like closing it off permanently is fine. I've blocked off the intake from inside the firebox on numerous occasions and it was fine (no smoke came inside the home).
 
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Old 06-12-17, 01:56 PM
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An open wood burning fireplace in a home that has not been sealed up extremely tight (most have not) should be fine burning inside air.
As a caution, the high risk time comes when the fire is burning out and everyone has headed to bed. As the chimney cools it loses its draft and as the final coals burn slowly buried in the ashes they produce large quantities of deadly CO. This often becomes a concern when people need to open a window for combustion air of draft and then close it when they head to bed.

BTW, your title "ductless fireplace" is a reference to "no exhaust ducts" ie no chimney which is not what you have.

Bud
 
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Old 06-12-17, 09:42 PM
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Thanks Bud. Title changed.
 
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Old 06-13-17, 08:25 AM
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I have CO detectors throughout the home, so I should be fine. Thanks for the warning!
 
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Old 06-13-17, 09:38 AM
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Do some reading on CO detectors and you will find they aren't as great as they sound. Last I reviewed them they were not very sensitive and could allow low levels to persist with bad effects. Better than nothing but not something you would want to bet your life on.

As an added note, I have switched to a sealed wood stove to gain efficiency and still enjoy the view through the glass front door. Also, be prepared for your insurance co to frown when they review your home. They are becoming increasingly cautious about anything burning wood. Document chimney cleanings and inspections.

Bud
 
 

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