Abstract: A coil cleaning device and system for spraying a pressurized cleaning medium against the coil to dislodge the dirt therefrom, in which a plurality of the devices are arranged in front of the coil and operate either simultaneously or individually. Each device includes a flexible hose section connected at one end to a relatively rigid supply line from a medium supply source, and to a nozzle at the free end. The medium discharged through the nozzle causes the hose to whip about and direct the medium against the coil over a relatively large area.

Abstract: A heat recovery apparatus in which an exhaust gas section and a fresh air section are disposed in side-by-side relationship to form an integral unit, for recovering heat from a stack or flue and discharging fresh air into a space to be heated. Heat pipe units extend from the hot gas passage of one section into the fresh air passage of the other section to transfer the heat between the two passages, the air flow in the exhaust gas section being in a series flow relationship and the flow in the fresh air section being in a parallel flow relationship. Louvers are provided for controlling the flow of exhaust gases and fresh air through the respective passages, and blowers are used to force the exhaust gases and fresh air through the passage. The passages of each section are provided with a main and by-pass passages controlled by louvers which are used to regulate the heat recovery and output of the unit.