Full Description

Claims of energy savings of 20% to 40% for space heating have been made by marketers of rapid cycling furnace controllers (cyclers). The present testing method of the ANSI/ASHRAE, 103-1982 Standard cannot be used to evaluate the heating seasonal efficiency of furnaces or boilers with these cyclers installed. To develop a test method that will reflect possible changes in efficiency, NBS has tested a furnace under various cycling conditions, A supply air temperature based cycler was tested, a time-based unit was simulated, and tile test results were compared with results using a simulated standard thermostat control. The comparisons were made using cycles corresponding to the average outdoor air temperatures of four weather condition bins of approximately the same total heating hours. A test method has been developed which can evaluate the effect of cyclers on furnace efficiency. No proposal is made to use this method because: (i) the test is more difficult to perform and replicate, (2) change would require retesting of all furnaces and would destroy the present data base of past test results, and (3) changes in furnace efficiency attributable to cyclers were too small to justify a change.

Units: Dual

Citation: Symposium, ASHRAE Transactions, 1986, vol. 92, pt. 2B, Portland, OR