| An instrument designed to simplify the calculations for all the larger heating installations where a full analysis of the heat losses must be made. Heat losses through the structure are handled on one side of the calculator, each wall, floor, window, etc. being treated individually by simply setting length to breadth, and using the temperature difference and the transmittance coefficient to obtain the heat loss. The heat loss from air change is obtained in a similar manner. Complete in case with comprehensive instruction booklet. Size: 7.5/8" dia. Engraved in four colours. The calculator has an ingenious method of fixing pipe sizes which saves considerable time. It is only necessary to decide what pressure loss can be allowed per metre run and all pipe sizes can be read off immediately according to kW load carried and flow to return temperature drop. At the same setting the water flow in the pipe is shown; or the pipe size can be obtained directly from the flow if desired. Radiator size, boiler size, pump size are also obtained on the reverse side and a further section gives heat losses from piping, either insulated or left bare. | 
