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How can I quantify the heat loss of brick masonry fire place?

american green | Posted in GBA Pro Help on

I am trying to convince the owners of a small 800 sq ft cottage that the existing brick fire place should be removed as it will always be an out of control heat and cold conductor along with moisture transference and hard to seal air gaps in damper and contact with the wood structure. Fire places are now illegal where the house is anyway so it will never be used as one.
A blower door and infrared shows the air infiltration but not the daily, seasonally, hot and cold and moisture fluctuations.
The main brick flue is on the exterior of the wood frame house while the combustion and hearth is half in and half out down to the foundation.

Is there any way to calibrate the heat, moisture and cold transference into real money loss so I can say to the owners; “leaving this relic of the pioneer days will cost you around $87 a year” after I calculate cost of energy?
Or, is there any way I can reduce the energy loss down to a reasonable amount? (what ever that means)
I am hoping to get this cottage down to a net zero building and am assuming leaving the fire place will put a big dent (more like a big hole) in that goal. What do you think?

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  1. Riversong | | #1

    Brick is about R-0.2/inch, so you can determine the average thickness and calculate heat loss. To calculate exfiltrative heat loss, you'll have to measure the average passive airflow past the damper.

    Have you considered an air-tight woodstove insert? It won't address the conductive losses through the masonry, but it will allow the homeowner the pleasure of a fire without the terrible ineffciency of an open fireplace.

  2. 69tbird9 | | #2

    An airtight woodstove would be a good answer if they actually plan on using the insert to heat with. Otherwise, is is an awfuly expensive plug.
    You could go with a Chimney Balloon to plug the damper area tight. That will stop the air infiltration through the chimney from the damper area up. But again you have the conductive losses through the brick...Although it sounds like that is the least of your trouble with this particular fireplace since you have air gaps between the wood structure and the chimney structure. Wouldnt just a standard 2 part foam fix those gaps? Or is this in an area that would need to be heat exposure rated?

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