States that several short-term diagnostic tests have been developed to estimate the field performance of heating boilers. Describes how two specific tests (the heat-up/cool-down test and the stop-loss test) were applied to 11 commercial boilers ranging from 266,000 Btu/h (78 kW) to 3,460,000 Btu/h (1,014 kW). The purpose was to estimate off-cycle loss rates on a variety of boilers, compare the results for consistency and examine the tests' practicality. Supplies and discusses the results. Concludes that while considerable information was gained about the advantages and drawbacks of each test method, more field experience is needed before recommendations can be made regarding the implementation of these diagnostic tests on a regular basis.

KEYWORDS: Testing, commercial, boilers, measuring, heating, monitoring.