04:33 Solar Thermal Air Heater! (SLV) – Homemade “STEEL DOWNSPOUT” Air Heater! – Easy DIY 140F Homemade Solar Thermal Air Heater! This “steel downspout” solar air heater may be my best one yet. is easy to make, sustains hot temps (130-140F+) …has a 3 speed fan … 0