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ASHRAE Standard 164.1-2025 -- Method of Test for Residential Central-System Humidifiers, 2025
- ASHRAE Online Bookstore
- Addenda
- Errata
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- ANSI/ASHRAE Standard 164.1-2025 [Go to Page]
- Contents
- Foreword
- 1. Purpose
- 2. Scope [Go to Page]
- 2.1 The scope of this standard covers a method of test for measuring the humidification rate of central-system residential humidifiers intended for use with forced-warm-air heating/cooling systems.
- 2.2 This method of test describes the test apparatus, mode of test conduction, and information to be recorded.
- 2.3 Tests covered include methods for measuring electrical power input, water flow rate, water temperature, and water pressure to the test humidifier. Included are airflow rate, static pressure, temperature, and relative humidity entering and maintai...
- 2.4 Information resulting from the application of this test method is intended for use by manufacturers, specifiers, installers, and users of central-system residential humidifiers.
- 2.5 This test method does not apply to self-contained humidifiers, portable humidifiers, or humidifiers for commercial and industrial applications.
- 3. Definitions
- 4. Symbols and Subscripts [Go to Page]
- 4.1 Symbols
- 4.2 Subscripts
- 5. Instruments and Measurement Methods [Go to Page]
- 5.1 Instrument Calibrations. Measurements from the instruments must be traceable to primary or secondary standards calibrated by the National Institute of Standards and Technology (NIST) or to the Bureau International des Poids et Mesures (BIPM) if a...
- 5.2 Instrument Accuracy Requirements and Measurement Methods. Measuring instruments must be selected to meet or exceed the instrument accuracy listed in Table 1 for each type of measurement. Instruments and measurement methods must comply with the AS...
- 5.3 Airflow Measurement. For humidifiers to be installed within an air duct, apply ASHRAE Standard 41.26 to measure volumetric airflow and standard volumetric airflow using a single- or multiple-nozzle test chamber.
- 5.4 Static Pressure Measurement in Ducts or Chambers. Static pressure in ducts or chambers must be measured in accordance with the static pressure tap geometry and the piezometer ring specifications in Section 8 of ASHRAE Standard 41.2.6
- 5.5 Air Temperature. Both wet- and dry-bulb air temperatures must be measured in accordance with ASHRAE Standard 41.6.3 An air sampling apparatus and a wet-bulb psychrometer are illustrated in Figure 1.
- 5.6 Water Temperature. Methods of measuring water temperature include a submerged well, an insulated wrap of the supply line, or other methods.
- 5.7 Air Density. Air density must be calculated from measurements of wet-bulb temperature, dry-bulb temperature, and atmospheric pressure or other parameters for air density calculation if the maximum error in the calculated density does not exceed ...
- 5.8 Wattmeters. Power must be measured using a wattmeter connected to the humidifier over the duration of the test in accordance with ASHRAE Standard 41.11.5
- 5.9 Water Flow
- 6. Equipment and Setup [Go to Page]
- 6.1 Setup. The setup of the testing equipment must be defined by Table 2 and illustrated in Figures 3 through 7.
- 6.2 Air-Volume Measuring Apparatus for Air Distribution. Apply ASHRAE Standard 41.2 6 to measure volumetric airflow and standard volumetric airflow using a single- or multiple-nozzle test chamber.
- 6.3 Connections to Other Sections of Apparatus. Ductwork must be used to connect the air measuring section with other sections of the apparatus. All joints and seams in the connecting ducts and between the connecting ducts and adjoining sections of a...
- 6.4 Air-Treatment Apparatus. Each test apparatus must be provided with air treating equipment to maintain the prescribed conditions of temperature, humidity, and pressure of the air entering the humidifier test section.
- 6.5 Temperature Measuring Apparatus. Air temperature measurements in ducts and fluid temperature measurements within conduits must be made in accordance with the applicable provisions of ASHRAE Standards 41.1,2 or 41.6,3 except where the specific req...
- 6.6 Water Measuring Apparatus. Means must be provided to measure the amount of water evaporated by the humidifier under test, as prescribed in Section 5.9.
- 6.7 Humidifier Test Sections
- 7. Observations and Conduct of Test [Go to Page]
- 7.1 Test Methods. The test methods described are as listed below:
- 7.2 Test Requirements. See Figure 3 for the location of planes.
- 7.3 Performance of Test. The humidifier to be tested must be installed in the appropriate test section as described in Sections 7 and 8.
- 8. Calculations [Go to Page]
- 8.1 Calibration Correction. Calibration corrections, when required, must be applied to individual readings before averaging or other calculations. Calibration corrections are not required if the correction is smaller than one half the maximum allowab...
- 8.2 Standard Airflow Rate. Apply ASHRAE Standard 41.2 6 to calculate the standard volumetric airflow rate Qstd, m3/s (cfm).
- 8.3 Power Input at Test Conditions. The total power input to the test unit is the sum of fan and pump or rotary device power and appurtenance device power.
- 8.4 Humidification Rate
- 9. Report Results of Test [Go to Page]
- 9.1 Report. The report of a laboratory test must include the following:
- 10. References
- Informative Appendix A: Informative References and Bibliography [Go to Page]
