1、 2015 Guideline for Selection, Installation and Servicing of Residential Humidifiers AHRI Guideline F (I-P) Price $10.00 (M) $20.00 (NM) Copyright 2015, by Air-Conditioning, Heating, and Refrigeration Institute Printed in U.S.A. Registered United States Patent and Trademark Office IMPORTANT SAFETY D
2、ISCLAIMER AHRI does not set safety standards and does not certify or guarantee the safety of any products, components or systems designed, tested, rated, installed or operated in accordance with this standard/guideline. It is strongly recommended that products be designed, constructed, assembled, in
3、stalled and operated in accordance with nationally recognized safety standards and code requirements appropriate for products covered by this standard/guideline. AHRI uses its best efforts to develop standards/guidelines employing state-of-the-art and accepted industry practices. AHRI does not certi
4、fy or guarantee that any tests conducted under its standards/guidelines will be non-hazardous or free from risk. Note: This guideline supersedes AHRI Guideline F-2008. For SI ratings, see AHRI Guideline F (SI) 2015. TABLE OF CONTENTS SECTION PAGE Section 1. Purpose 1 Section 2. Scope .1 Section 3. D
5、efinitions.1 Section 4. Factors Affecting Humidification Load 2 Section 5. Humidification Load Determination .3 Section 6. Residential Humidifier Selection 6 Section 7. Installation Best Practices .8 Section 8. Servicing Best Practices 10 TABLES Table 1. Humidification Load Required, gal/day .4 Tabl
6、e 2. Correction Factor for Other Indoor Temperatures and RH Conditions 4 Table 3. Selection Based on Water Types and Hardness 6 APPENDICES Appendix A. References Normative 11 Appendix B. References Informative 11 Appendix C. Periodic Maintenance Checklist Informative .12 AHRI GUIDELINE F-2015 (I-P)
7、1 SELECTION, INSTALLATION AND SERVICING OF RESIDENTIAL HUMIDIFIERS Section 1. Purpose 1.1 Purpose. The purpose of this guideline is to establish, for residential Humidifiers: definitions; factors affecting Humidification Loads; determination of Humidification Load; equipment selection; installation
8、practices; and servicing practices. 1.1.1 Intent. This guideline is intended for the guidance of the industry, including manufacturers, engineers, installers, contractors and users. 1.1.2 Review and Amendment. This guideline is subject to review and amendment as technology advances. Section 2. Scope
9、 2.1 Scope. This guideline applies to Central System and Self-contained Humidifiers, as defined in AHRI Standards 610 (I-P) and 620 (I-P), installed in residential and small commercial applications. Section 3. Definitions All terms in this document will follow the standard industry definitions in th
10、e ASHRAE Terminology Site (https:/www.ashrae.org/resources-publications/free-resources/ashrae-terminology) unless otherwise defined in this section. 3.1 Humidifier. A device used to add moisture to the air. 3.1.1 Central System Humidifier. A type of Humidifier that adds moisture to the air stream of
11、 a central air system. It may be mounted in or on the following: 3.1.1.1 Return air duct 3.1.1.2 Return air plenum 3.1.1.3 Supply air duct 3.1.1.4 Supply air plenum 3.1.1.5 By-pass (supply to return) 3.1.1.6 Heating or cooling central air system 3.1.2 Self-contained Humidifier. A type of Humidifier
12、intended for installation independent of a central air system. Self-contained humidifiers may or may not be installed directly within the humidified space. Note this may also be referred to as Self-contained Humidifier for Residential Application. 3.2 Humidification Capacity. The maximum amount of h
13、umidity that a humidifier can add to the air, expressed in gal/day or lbs/hr. 3.3 Humidification Load. The amount of water that needs to be added to the air by the humidifier in order to satisfy the conditions desired in the space expressed in gal/day, or lb/hr. 3.4 Humidifier Types. Different kinds
14、 of Self-contained Humidifiers for Residential Application. 3.4.1 Atomizing Humidifier. Humidifiers which disperse or spray a fine mist of liquid water directly into the air. Some examples of Atomizing Humidifiers are centrifugal, nozzle, and ultrasonic. 3.4.2 Heated Tank Humidifier. Humidifiers whi
15、ch use electricity, gas, or another energy source to boil water into steam. The steam is then dispersed directly into the conditioned space or into a ducted airstream. Some examples of Heat Tank Humidifiers include electric and electrode. AHRI GUIDELINE F-2015 (I-P) 2 3.4.3 Wetted Media Humidifier.
16、A type of Humidifier intended for duct applications in which water passes over media placed in the air stream. As the air passes through the wetted media, water evaporates increasing the moisture content of the air stream. The water not evaporated is drained, retained in the reservoir, or returned t
17、o a tank for recirculation. Some examples of Wetted Media Humidifiers are wetted pad and rotating drum. 3.5 Rating Conditions. A fixed set of environmental conditions which lead to a given level of performance. Varying these conditions will result in varying humidifier performance 3.5.1 Standard Rat
18、ing Conditions. A set of Rating Conditions that are standardized and used as the basis of comparison for performance characteristics. 3.6 Should. “Should” is used to indicate provisions which are not mandatory but which are desirable as good practice. 3.7 Water Characteristics. 3.7.1 Water Types. 3.
19、7.1.1 Potable Water. Domestic water from a municipal or well source that meets standards for consumption. May also be referred to as tap water or municipal water. 3.7.1.2 Softened Water. Water that has been conditioned by the ion exchange process (commonly referred to as a water softener) to exchang
20、e calcium and magnesium ions with sodium or potassium ions. 3.7.1.3 Demineralized Water. Water which is largely free from particles and dissolved substances having a conductivity below 0.2 micro-Siemens per centimeter (S/cm). This includes deionized (DI) and reverse osmosis (RO) water, and distilled
21、 water. 3.7.1.4 Untreated Water. Water from a rainfall, river, or lake source that has not been treated. Untreated water is not suitable for use in most humidifiers. 3.7.2 Water Hardness. The amount of dissolved minerals (e.g., calcium, iron, magnesium, and sodium) that are naturally present in the
22、water and are expressed in grains/gal or ppm. Hardness in water contributes to the formation of mineral scaling inside of humidifiers and may affect the performance of the humidifier. 3.7.2.1 Naturally Soft Water. Water with a dissolved solid content usually below 3.5 grains/gal or 60 ppm. 3.7.2.2 M
23、oderate Hard Water. Water with a dissolved solid content of 3.5 to less than 7.0 grains/gal or 60 to less than 120 ppm. 3.7.2.3 Hard Water. Water with a dissolved solid content of 7.0 to 10.5 grains/gal or 120 to 180 ppm. 3.7.2.4 Very Hard Water. Water with a solid content of more than 10.5 grains/g
24、al or 180 ppm. Section 4. Factors Affecting Humidification Load 4.1 General. The following should be used as a basis for estimating the Humidification Load required: 4.1.1 Outdoor design conditions 4.1.2 Indoor design conditions 4.1.3 Size and physical characteristics of residence 4.1.3.1 Conditione
25、d space volume 4.1.3.2 Tightness of structure, insulation, storm windows and doors or equivalent, etc. AHRI GUIDELINE F-2015 (I-P) 3 Note: Some older structures may have inadequate protection against water vapor transmission through walls, which may result in damage from excessive moisture. 4.1.4 Qu
26、antity of outdoor air entering the conditioned space. 4.1.4.1 Mechanical and Natural Ventilation. 4.1.4.1.1 Mechanical ventilation may include fans, blowers, energy recovery ventilators (ERVs), and heat recovery ventilators (HRVs) 4.1.4.1.2 Natural ventilation may include operable windows and doors
27、4.1.4.2 Open fireplace dampers greatly increase the amount of outdoor air added to the heated volume of the structure. Satisfactory performance of a Humidifier, as applied to a given structure, is often based upon these dampers being closed. 4.1.5 Internal Load Generated. 4.1.5.1 In calculating humi
28、dity load requirements in residential applications, internal load factors are normally not included because of the variation in living habits, e.g., bathing and laundry habits, cooking, number of occupants, etc. However, these may be included at your discretion. 4.2 Outdoor Design Conditions. The ou
29、tdoor design conditions to be used for calculating humidity requirements are 20F and 70% RH, or local design conditions may be used. 4.3 Indoor Design Conditions. The indoor design conditions to be used for the calculation of humidity requirements are 70F and 35% RH. 4.4 Ventilation and infiltration
30、. Ventilation in a residence is in most current practices handled by natural or mechanical ventilation. Air leakage or infiltration is air flow from open doors or windows, as well as unintentional openings in the home, such as cracks in walls, or door leakage. For ventilation, some installations use
31、 a positive inlet duct or a mechanical air recovery exchanger. Since there is a large stock of housing that has been constructed over decades and governed by different or minimal code requirements, the load estimates should add both the infiltration and ventilation rates. 4.4.1 Infiltration. Infiltr
32、ation is variable. For humidifier sizing, the infiltration may be estimated as follows: 4.4.1.1 For tight construction, use air change per hour. 4.4.1.2 For average construction, use 1 air change per hour. 4.4.1.3 For loose construction and/or maximum ventilation factor, use 1.5 air changes per hour
33、. The ASHRAE Handbook HVAC Systems and Equipment defines a tight house as one “.assumed to be well insulated and to have vapor retarders, tight storm doors, windows with weather-stripping, and a dampered fireplace. An average house is insulated and has vapor retarders, loose storm doors and windows,
34、 and a dampered fireplace. A loose house is generally one constructed before 1930 with little or no insulation, no storm doors, no insulated windows, no weather-stripping, no vapor retarders, and often a fireplace without an effective damper.” Any air exhausted from or fresh outdoor air being introd
35、uced into the home will increase the Humidification Load. Section 5. Humidification Load Determination 5.1 There are 2 methods of load calculations presented in this section. The first method, described in Section 5.2 is the simplest and uses several assumptions to generate a humidification load for
36、 the home. A more detailed method is presented in Section 5.3, and it allows the user to specify conditions for weather and indoor design humidity levels beyond that of the simplified method. Regardless of what method is chosen, homes that include fresh air ventilators, specialized exhaust systems,
37、or loose fitting fireplace dampers should also follow the calculation in Section 5.4 to account for these devices. AHRI GUIDELINE F-2015 (I-P) 4 5.2 A simple method for estimating the humidification load is presented below. 5.2.1 Step 1. Begin by determining the volume of the home in cubic feet. A s
38、imple way to achieve this involves multiplying the floor area by the average ceiling height. Be sure to include the basement in the calculations. For more accurate calculations, consider calculating the volume for each individual room and summing the results. 5.2.2 Step 2. Match the result to Table
39、1 below. Refer to Section 4.1.3.2 for home construction tightness. Note that Table 1 assumes an indoor condition of 70F and 35% RH. 5.2.3 Step 3. If your indoor condition varies from the result, multiply it by one of the correction factors in Table 2 that reflects your actual design condition. Ideal
40、 humidity levels for human health are between 40 and 60% RH, however it is good practice to limit the relative humidity to around 35% during very cold months. This is to protect the home structure from moisture migration, particularly in average and loosely constructed homes. Please note that some m
41、odern controls feature automatic setbacks to reduce the risk of condensation. 5.2.4 Step 4. A single occupant can generate up to 0.5 gallons per day (gal/day) of humidity through activities such as cooking, cleaning, showering, and laundry. You can choose to reduce the load by 0.5 gal/day per occupa
42、nt. Due to the variability of these activities it is common practice to leave the load uncorrected from step 3, as this also provides a safety factor for equipment sizing. Table 1. Humidification Load Required, gal/day1,2Type of Construction Volume of Building, ft3 8,000 10,000 12,000 16,000 20,000
43、24,000 32,000 40,000 Tight 3.3 4.2 5.0 6.7 8.3 10.0 13.4 16.7 Average 6.7 8.3 10.0 13.4 16.7 20.0 26.7 33.4 Loose 10.0 12.5 15.0 20.0 25.0 30.1 40.1 50.1 Notes: 1. Loads shown in the table are based on indoor conditions of 70F and 35% RH with 20F and 70% RH outdoors. 2. An amount of 2.0 gallons per
44、day may be deducted from these figures if it is desired to take credit for internal sources of moisture (based on a family of four). Table 2. Correction Factor for Other Indoor Temperatures and RH Conditions Temperature Indoors 70.0F 75.0F Indoor % RH 30% 35% 40% 30% 35% 40% Correction Factor 0.8 1.
45、0 1.3 1.0 1.2 1.4 Note: This table provides the correction factor to use for other indoor temperatures and RH conditions. Multiply Humidification Load Required from Table 1 by the appropriate correction factor in Table 2. 5.3 A more exact humidification load can be calculated using the formulas pres
46、ented below: 5.3.1 Step 1. Begin by determining the volume of the home in cubic feet. A simple way to achieve this involves multiplying the floor area by the average ceiling height. Be sure to include the basement in the calculations. For more accurate calculations, consider calculating the volume f
47、or each individual room and summing the results using Equation 1. V = hlw 1 AHRI GUIDELINE F-2015 (I-P) 5 Where: h = Height, ft l = Length, ft V = Volume, ft3w = Width, ft 5.3.2 Step 2. Apply Equation 2 or Equation 3 to determine the humidification load. =() + 2 or = ()33,082 + 3 Where: a = Conversi
48、on factor, 7,000 grains/lb D = 24 hours/day H = Humidification Load requirement, gal/day L = Other moisture losses, gal/ day R = Calculated air changes per hour S = Contribution of internal moisture sources, gal/day V = Total indoor conditioned volume of space being humidified, ft3Wi = Moisture cont
49、ent of air at indoor design conditions, grains/lb Wo = Moisture content of air at outdoor design conditions, grains/lb = Density of water, 8.34 lb/gal of water = Specific volume of moist air at indoor design conditions, 13.6 ft3per lb of dry air 5.3.3 Example. 5.3.3.1 Space being humidified (volume of the building): V = 40.0 ft wide50.0 ft long8.0 ft high = 16,000 ft35.3.3.2 Air changes per hour (tight construction) = 1/2 (See Section 4.1.3.1) 5.3.3.3 Assume S=L=0 5.3.3.4 Wi(indoor) a
