Output of radiators at reduced flow rate

Abstract

The heat output from conventional hot water radiators falls as the return temperature is reduced. Experimental results show a much lower heat output from a pressed steel radiator than that calculated using the conventional formula based on the mean of flow and return water temperatures. The fall in output is especially marked when using bottom, opposite end water connections to the radiator, as in conventional British practice. This reduction in output has implications for the design of systems which are designed to operate at low flow rates.