Eager to start saving on fuel costs, Whitman installed the panels shortly after they were delivered, with help from his brother, Scott. "We had sunshine for about an hour that first day, and I think we got up to about 101 degrees," he said. "It was probably around 60 in the paint room-a 40-degree rise."
The next week was largely overcast, but many sunny days followed. According to Whitman, when the sun shines, the panels blow out air heated to 110, 115, and even 122 degrees, raising the room temperature 12 to 13 degrees.
Whitman checks the probe in his low-tech panels regularly, learning what kind of heat he can expect under different weather conditions at different times of year. "I'm really looking forward to seeing how high the sun gets before I don't get a good effect. When it was 3 above and windy and so clear-no wisp of a cloud-temperatures came up to 105-degree air from the collector, and the room was about 50," he says. "Even today with marginal Sun, it's brought the temperature up 5 degrees, and it's about 20 to 21 degrees out there."
Although Whitman won't know how much he saves until he can measure his fuel use, he's confident that he's already beginning to get a return on his investment in solar space heating. "When the main furnace cycles several times throughout the day and the furnace in the paint room doesn't, I know the panels are working." Kohn points out that reflected light from snow cover increases the effect.
Solar Heat Vermont began demonstrating FreeHeat panels at local farmers markets in 2009, after Kohn had tested them on his own home and garage for two heating seasons. He saw that people had a grasp of solar hot water and solar electricity but needed to experience passive solar space heat for themselves. At these events, people could put their hands in front of the panel's top vents and feel the heat blasting out. Now the demo unit invites hands up to the vents with the message "Feeling is believing."