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ASHRAE Standard 125-2020 - Method of Testing Thermal Energy Meters for Liquid Streams in HVAC Systems (ANSI Approved), 2020
- ANSI/ASHRAE Standard 125-2020 [Go to Page]
- CONTENTS
- FOREWORD
- 1. PURPOSE
- 2. SCOPE [Go to Page]
- 2.1 The test methods, procedures, and facility descriptions in this standard are intended for use in determining measurement accuracy, pressure losses, service flow rate limits, temperature difference limits, and reliability effects of mounting attitude
- 2.2 This standard is limited to applications in which the fluid remains in a completely liquid state while traversing the thermal energy meter.
- 2.3 The applications of this standard include, but are not limited to, thermal energy meters used for billing or revenue metering for hydronic applications.
- 2.4 This standard does not apply to meters using principles of change-of-state of the fluid, simple elapsed time, or measured indoor or outdoor temperature difference to allocate consumption among various end-use customers.
- 3. DEFINITIONS [Go to Page]
- 3.1 Figure 1 illustrates the elements of a thermal energy meter.
- 3.2 The following definitions apply:
- 4. NOMENCLATURE
- 5. CLASSIFICATIONS [Go to Page]
- 5.1 Basis of Classification. Liquid thermal energy meters shall be classified according to their service. Four classifications of service are domestic hot water, hydronic space heating, hydronic space cooling, and combined heating and cooling. These ...
- 6. REQUIREMENTS [Go to Page]
- 6.1 General. Thermal energy meters shall be tested in accordance with the provisions set forth in this section and in Section 9.
- 6.2 Test Conditions. A meter shall be subject to test conditions according to the service indicated by its manufacturer. If the manufacturer does not state the intended service, then the unit shall be tested for the maximum envelope of conditions des...
- 6.3 Transfer Liquid Properties. The meter shall be tested with water and perhaps one other heat transfer fluid if specified by the manufacturer. Examples include aqueous glycol and brines. Properties of the chosen fluid (specific heat and density) sh...
- 6.4 Voltage Sensitivity. All tests other than the voltage sensitivity test shall be conducted at a stable voltage within 0.5% of the meter’s nominal rated operating voltage. Voltage sensitivity shall be tested at the low-voltage tolerance and high-...
- 6.5 Sensitivity to Flowmeter Attitude. When flow sensor attitudes other than those listed in ASHRAE Standard 41.12 are recommended by the manufacturer as acceptable installation practice, then the appropriate test matrix of Section 9 shall be conduct...
- 7. FACILITY INSTRUMENTS [Go to Page]
- 7.1 Flow Measurements
- 7.2 Temperature Measurements
- 7.3 Integrators and Recorders
- 7.4 Pressure Drop across Flow Sensor. The static pressure drop across the flow sensor shall be measured with an instrument having an accuracy of ±0.04 in. water (±10 Pa, 1 mm w.c.) or better.
- 8. APPARATUS AND METHOD OF TESTING [Go to Page]
- 8.1 Two different types of test facility configurations may be employed to provide a known flow and temperature environment, namely, the closed-loop test configuration and the open-loop test configuration.
- 8.2 Closed-Loop Test Configuration. The suggested closed-loop test facility configuration is described in Figures 2 and 3. The facility consists of two independent closed liquid loops, each capable of being maintained at a desired temperature. This t...
- 8.3 Open-Loop Test Configuration. The suggested open-loop test facility configuration is described in Figure 4. The facility consists of a large open water storage tank that can be heated to a uniform temperature before the start of a test run. The t...
- 9. TEST PROCEDURES AND COMPUTATIONS [Go to Page]
- 9.1 General. A thermal energy meter measures the energy added to or extracted from a liquid fluid loop. Figure 1 illustrates the principal components of the meter. The flow sensor measures the liquid flow and produces a signal that is related to the ...
- 9.2 Standard Test Conditions. To facilitate description of test procedures, standard conditions are described for flow sensor temperature (Tf), temperature difference (DT), flow rate, and system pressure.
- 9.3 Test Conditions. Because of the differing temperature and flow characteristics, experimental test procedures for the four types of service will vary. Therefore, it is convenient to treat each separately.
- 9.4 Test Procedures
- 9.5 Computation of Thermal Energy. The exact amount of energy added to or extracted from the fluid stream for high DT tests is calculated from
- 10. DATA TO BE RECORDED AND TEST REPORT [Go to Page]
- 10.1 Test Data. Table 1 lists the measurements that are to be made for each test point.
- 10.2 Test Report. Table 2 specifies the data and information that shall be reported in testing the thermal energy meter.
- 11. REFERENCES
- INFORMATIVE ANNEX A: BIBLIOGRAPHY OF RELATED STANDARDS [Go to Page]
