This system was designed to provide heat to an otherwise unheated greenhouse so plants could remain in the greenhouse regardless of the outdoor temperature. This was accomplished through the construction of a five foot high and five foot wide cylindrical compost pile adjacent to the greenhouse and ongoing additions of compost material. A reservoir in the center held water and a pump. A system of pipes and hoses transported the heated water to the greenhouse forming a complete loop. The average high temperature inside was 79.8 degrees and the average low temperature was 44.9 degrees. The average temperature within the compost pile was 124.6 degrees and the project lasted three and one half months, from December through March. The project fulfilled my expectations to maintain an adequate temperature during the cold winter months at a very modest cost of $9.00/month for electricity. Compost materials were expendable farm waste items.