Notes that intermediate-sized, low-pressure steam boilers are commonly found in multi-unit residential, commercial, institutional and small industrial applications for space and process water heating. As a group, their performance is the least well documented among all the heating plant technologies. Reports on efficiency measurements of nine steam boilers based on two methods - a modified benchmark method based on ANSI standards and a simplified method that is appropriate for low-pressure steam boilers. Supplies and discusses the results. States the findings indicate the need for optimising boiler control and boiler sizing, and for investigating the efficiency of the several types of available replacement boilers. Includes recommendations for standardising the efficiency measurement methods used in the study.

KEYWORDS: Boilers, measuring, efficiency, steam boilers, low pressure, space heating, hot water supply, domestic, commercial, industrial, USA, testing, site testing, controls, sizing.