Frugal and Energy Efficient Living
In reply to the discussion: Looking for ways to lower my electric bill [View all]taxi
(2,014 posts)When the fireplace is used occasionally the heating effect is not realized, it is when the block around the flues finally get warm that the heat will pour out of the top vents. The link below has a diagram of their model which appears to be more efficient than the do-it-yourself builds, however it is possible that the diy types may produce more consistent temperatures for a longer period.
The diagram with the header "Old Style Heatilator" shows air vents above and below the firebox and include a ventilation fan - one's without a fan also work well. (please note that the diagram does NOT show the separate flue from the firebox up the chimney - the open space around the firebox that illustrates the airflow is not in contact with the fumes from the fire; there is a flue that goes up the chimney from the firebox.
https://www.northlineexpress.com/all-about-old-style-heatilators.html