[f. THERMO- + SIPHON.] A siphon attachment by which the circulation in a system of hot-water pipes is increased or induced. Also attrib.
1834. Loudon, Encycl. Gard., § 2142. Fowler’s method of circulating hot water in his thermosiphon.
1906. Daily Chron., 3 March, 3/6. Water from a reservoir is circulated around the cylinder, in the water-jacket, either by a pump worked by the engine, or on the thermo-syphon system.
