The "140°F" $35 ALUMINUM MESH Heater... Here's What It Really Heats

A 4 by 8 aluminum screen heater really can push air past 120°F on a single-digit January morning. At its peak, it makes about as much heat as one hair dryer. A viral video says a $35 panel of black aluminum blows 140°F air into your house on an 18°F morning, no gas needed. On January 11, 2011, near Bozeman, Montana, Gary Reysa of Build It Solar logged a box like that with a small duct fan: 125°F at the outlet with 8°F outside, and a peak of 4,214 BTU an hour, about 1,235 watts. The 125°F reading came at the lowest airflow of the day, and that's the clue. Heat is how much hotter the air gets times how much air goes through it, and a fanless box running 140°F is probably moving its air slowly. This video adds up his whole day, about 4 hours of one plug-in space heater, and checks it against the viral video's own claims: a parts list that actually adds up to $60 to $82, the 4 to 6 hours of furnace time that comes out closer to 25 to 40 minutes, and the $300 to $500 a season that works out to roughly $25 to $44, depending on the gas price. Also in here: why the screen still earns its place, the night damper that matters more than any other part of the build, and a 240 square foot shop wall that gets into furnace territory at midday. If this kind of building physics breakdown is useful to you, more here: www.youtube.com/@TheMeasuredHouseYT Sources cited: Gary Reysa, Build It Solar (builditsolar.com): screen collector test log, January 11, 2011; screen versus pop can collector comparison and parts cost table; aluminum soffit collector test, January 2011; summer screen collector test; thermosyphon barn collector notes; Ivan's shop thermosyphon collector write-up. U.S. Energy Information Administration, average residential natural gas price, 2025. U.S. Department of Energy minimum furnace efficiency standard. The viral video's own transcript for its parts, furnace and savings figures. New videos Tuesday, Thursday, Saturday and Sunday.