the box is made of cedar boards with a 1/4″ plywood back
upper crossmember is dadoed to capture top edge of back
back has layer of bubble wrap insulation
crossrails are attached with pocket screws
the midrail minimizes heat loss through front glazing
air passes though 4 layers of window screen
front glazing has 3/8″ air space between two layers of insulating film
plastic film shows the airflow exiting the heater
output temperature 25C (72F) – temperature rise of 15C (22F)