- Nov 27, 2012
- 0
Question:
How much more efficient is a fireplace that uses outside air for combustion than a conventional one drawing air from within?
..........if the combustion air comes from within- wouldn't it be replaced with outside air via infiltration? It seems that in any case- using outside air is a plus. I'm trying to get a guestimate from an expert as to how much better.
Answer:
Actually- it has not really been proven that the use of outside air increases efficiency..why?Well- a fire burns hotter and better when it is fed with warmer air - using outside air can cool the fire down- and make it burn dirtier.Ideally- pre-warmed outside air could be used. This would result in an efficiency gain.Since most fireplaces have a negative efficiency- it's tough to say how much it would be increased. In tighter home- outside air is a must. If the home is older/looser...then it's optional.
Yes- it would be replaced by infiltration- but the lower efficiency of cool outside air can even out this difference. There are- of course- too many variables to accurately guess the efficiency difference- but it might be fair to say that it is only in the 5%-10% range- depending...of course. Of course- outside air- in combination with a good set of glass doors- in combination with a good burning grate system- in combination with an interior fireplace and chimney...well- you get the point !
How much more efficient is a fireplace that uses outside air for combustion than a conventional one drawing air from within?
..........if the combustion air comes from within- wouldn't it be replaced with outside air via infiltration? It seems that in any case- using outside air is a plus. I'm trying to get a guestimate from an expert as to how much better.
Answer:
Actually- it has not really been proven that the use of outside air increases efficiency..why?Well- a fire burns hotter and better when it is fed with warmer air - using outside air can cool the fire down- and make it burn dirtier.Ideally- pre-warmed outside air could be used. This would result in an efficiency gain.Since most fireplaces have a negative efficiency- it's tough to say how much it would be increased. In tighter home- outside air is a must. If the home is older/looser...then it's optional.
Yes- it would be replaced by infiltration- but the lower efficiency of cool outside air can even out this difference. There are- of course- too many variables to accurately guess the efficiency difference- but it might be fair to say that it is only in the 5%-10% range- depending...of course. Of course- outside air- in combination with a good set of glass doors- in combination with a good burning grate system- in combination with an interior fireplace and chimney...well- you get the point !
