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Performance Testing of a Family of Type I Combination Appliances.

pdf icon Performance Testing of a Family of Type I Combination Appliances. (1589 K)
Liu, S. T.; Kelly, G. E.; Terlizzi, C. P.

NISTIR 5626; 30 p. April 1995.


Department of Energy, Washington, DC

Available from:

National Technical Information Service
Order number: PB95-220521


Annual Fuel Utilization Efficiency; ANSI/ASHRAE Standard 103; ASHRAE Standard 124; boiler; building technology; combination appliance; combined annual efficiency; DOE test procedure; domestic water storage tank; energy factor; heating seasonal efficiency; integrated appliance; linear interpolation; rating; space heating; steady state efficiency; water heating


ANSI/ASHRAE Standard 124-1991 specifies the laboratory test and the calculation procedures for estimating seasonal and annual performance of combination appliances which are designed to provide both space heating and water heating. A boiler that includes a tankless coil for water heating or in combination with an indirectly heated storage tank is classified by ASHRAE Standard 124 as Type I combination appliances. It is common for single size tankless coil or storage tank to be used in combination with a series of boilers (called a family series) of different sizes. In an effort to minimize the test burdens on manufacturers, a family series of gas-fired hot water boilers were tested to determine if a subset of a family series of Type I combination appliances could be tested and used to predict the performance of the rest of the appliances in the family series. Tests were conducted on a family series of three different size boilers (rated input of 22, 33, and 44 kW) with an identical indirectly heated storage tank to determine their Combined Annual Efficiency (CAE) as specified in ASHRAE Standard 124. To this end, tests for the Energy Factor (EF) for water heating and the Annual Fuel Utilization Efficiency (AFUE) for space heating were conducted. For the domestic water heating test, daily hot water draw volume of 243.4 L (64.3 gal) was used. The results showed that for the three boilers, the AFUE for space heating differed by approximately 2.5 percentage points, with the smaller size boiler having a higher AFUE. On the other hand, the EF for water heating depended more strongly (differed by near 5 percentage points from the smallest (22 kW) to the largest (44 kW) capacity boilers tested on the size of the boilers for the same daily hot water drawn. However, the EF was an approximate linear function of the boiler size. The results also showed that the CAE varied by slightly over 1.6 percentage points among the three boilers. Thus a simple linear interpolation appears adequate for determining the Combined Annual Efficiency (CAE) within a family series.