Heat Powered Stove Fan for Wood Multi Fuel Coal Lower Temperature Surface Soapstone - Warpfive Glasshopper Stirling Engine The Glasshopper Stove Fan is designed to be used with cooler fires that are fed irregularly or on cooler stove surfaces such as Soapstone. A clear Borosilicate glass cylinder enables a view of the rhythmic displacer movement that produces the energy to spin the fan. It can be used on top of any wood burner or multi fuel stove or other heat source that operates between 70 C and 300 C (158 F and 572 F). It is a small precision engineered Stirling engine with no electric components. It runs quietly and uses only heat as fuel. Made in the UK from materials such as brass, stainless steel and aluminium. Includes maintenance kit with lubricant. Every engine is individually laser engraved with a unique serial number and comes with lifetime guarantee