1、 AHRI Guideline W (I-P) 2014 Guideline for Selecting, Sizing, or the tilt angle is reversed, effectively stopping heat transfer. 5.1.4.4 Cold Corner Damper or Traversing Defrost. For Plate Heat Exchangers, outdoor air is prevented from entering a portion of the Air-to-Air Heat Exchanger to enable th
2、e exhaust air energy to defrost that section of the component. 5.2 Condensation Removal. Means of removing condensate may be required. If so, observe applicable codes for piping and trapping of condensate drain(s). Section 6. System Balancing 6.1 Equal and Unequal Air Flows. The amount of outside ai
3、r and exhaust air required may be the result of the building design. Many facilities have exhaust air removed from a variety of sources, other than the AAERVE. In order to maintain a proper air balance in the building, this may result in the need to exhaust less air than the outdoor air requirement.
4、 In this case, Effectiveness will be increased by definition (because the percentage of energy extracted from the reduced exhaust airflow is increased), however, the conditions of the supply air will be less favorable and the performance of the building system will be affected (due to induced exfilt
5、ration without benefit of energy recovery). If the exhaust air is greater than the outdoor air intake, then Effectiveness would again be increased by definition; supply air conditions would improve, but again, building system performance would be affected (in this case due to induced infiltration wi
6、thout benefit of energy recovery). 6.1.1 Energy Impacts. Equal (balanced) Supply and Exhaust Airflows provide the maximum energy recovery for a given AAERVE. The system should be balanced as closely as possible as long as other conditions, such as requirements for building pressurization, are met. 6
7、.1.2 Conditions Impact. Unequal airflows will influence the conditions of the supply air. Example: Reducing the Supply Airflow as compared to the exhaust will improve the supply air psychrometric conditions, but reduce the energy recovered from the exhaust air. On the other hand reducing the Exhaust
8、 Airflow as compared to the supply will degrade the supply air psychrometric conditions. Again, energy recovered will be reduced. 6.1.3 Variable Air Flow. On systems that vary total system airflow and/or outdoor air (demand control ventilation, variable air volume, etc.) provisions should be made to
9、 control both supply and exhaust airflows in concert. In no case should the airflows be lower than needed to provide the required outdoor air ventilation rate per ASHRAE standards or local codes. 6.1.4 Building or Zone Pressurization. Requirements for building or zone pressurization should be consid
10、ered when designing and/or balancing the system. If building pressurization requirements would cause the AAERVE to be severely unbalanced, the designer should consider additional methods of building pressurization. 6.2 Balancing Methods. Provisions should be made for adjusting the airflows to requir
11、ed rates. The methods listed below can be used independently or in combination. 6.2.1 Dampers. Dampers may be used to balance airflows to the space to insure proper air distribution to individual Zones or connected air-handling equipment. Dampers may also be used to balance AAERVE Supply and Exhaust
12、 Airflows. However, controlling blower speed is a more energy efficient method of volume control than dampers. 6.2.2 Blower Settings. Methods such as multiple speed motors, adjustments in blower sheaves, etc., may be used to adjust airflows. 6.2.3 Variable Speed. Variable frequency drives, electroni
13、cally commutated motors, and similar variable speed technologies may be used to adjust airflows. 6.2.4 Unitized. Operation of the main unitary blower can impact the AAERVE Supply and Exhaust Airflows. Methods should be provided to balance these flows and unitary airflow. AHRI GUIDELINE W (I-P)-2014_
14、 6 6.2.5 Integrated. Operation of the main unitary blower can impact the AAERVE Supply and Exhaust Airflows. Methods should be included to balance these flows. 6.2.6 Measurement of Flows. Methods should be provided to measure Exhaust and Supply Airflows for the purpose of balancing. Methods can incl
15、ude static pressure across the component, conventional velocity methods in the duct, or other airflow measuring devices. 6.2.7 Outdoor Air Correction Factor (OACF). Consider the impact of OACF to ensure that the correct amount of outside air is introduced to meet the ventilation requirements for the
16、 building. Example: If the outdoor air is being measured at the outside air inlet and the OACF = 1.1, the measured air volume should be 110% of the required (ventilation design) supply airflow. This will ensure that the specified level of outdoor air is being introduced into the building after the O
17、ACF impact from the Air-to-Air Heat Exchanger. Section 7. Economizer Operation 7.1 Economizer Operation. Some applications and standards/codes may require an air economizer be provided for the air-conditioning system. In these cases, provisions should be made to bypass or control the energy recovery
18、 system to permit air economizer operation. The bypass or separate economizer should be sized to handle the maximum outdoor air required during economizer operation. 7.1.1 Economizer Bypass. 7.1.1.1 Unitized and Integrated Systems. Outdoor air is brought into the conditioned space without crossing t
19、he component, thus not recovering energy. This can be accomplished by utilizing dampers, bypass duct and dampers, or by moving the Air-to-Air Heat Exchanger out of the outdoor airstream. 7.1.1.2 Coupled Systems. A system to introduce outdoor air into the conditioned space without crossing the Air-to
20、-Air Heat Exchanger which utilizes the Economizer on the air-conditioning unit. 7.1.2 Wheel Economizer. System to introduce outdoor air into the conditioned space while crossing a Rotary Heat Exchanger without energy recovery. The component is stopped during the Economizer period when energy recover
21、y is not desired. All of the outdoor air crosses the component, thus limiting the outdoor air amount to the components airflow capacity at the application static pressure. Typically, full 100% outside air Economizer function can be provided with this method only for 100% outdoor air systems. 7.2 Mod
22、ulation. All the above methods can be controlled to provide partial or modulated Economizer function. 7.3 Exhaust Air Relief. Barometric relief or power exhaust is often provided in conjunction with Economizers. The exhaust fan in the AAERVE may be able to provide or assist with this function. This
23、should be considered in design. 7.4 AAERVE Shut Down. When a separate air economizer is provided, the control system should shut down the AAERVEs supply air stream at a minimum and typically also the AAERVEs exhaust air stream. Section 8. Design Considerations and Air-Conditioning Equipment Selectio
24、n 8.1 Building Design. The type of building will determine the type of AAERVE required for the application. The design may require that the AAERVE be utilized in a mechanical room application, a rooftop application, a through-the-wall application, or a combination. 8.2 Codes and Standards. The autho
25、rity having jurisdiction will require that the system adhere to all applicable codes and standards. 8.2.1 Building Codes. AAERVE should be designed as applied to meet the effectiveness requirements of local building codes. The definition of effectiveness included in local building codes may be diffe
26、rent than the definition of Effectiveness in this guideline. Building codes may also include additional items, e.g. maximum horsepower, construction details and other requirements. AHRI GUIDELINE W (I-P)-2014 7 8.2.2 Ventilation Standard. The designer is referred to the latest ventilation standard,
27、for information on: 8.2.2.1 Outside air ventilation volumes consistent with good indoor air quality for various building types 8.2.2.2 Consideration of equipment design and construction details which may have an impact on indoor air quality, including removal of standing water, rain entrainment, and
28、 airstream surfaces. 8.2.3 Energy Standard. The designer is referred to the latest energy standard for information on: 8.2.3.1 Guidance on building and climate types for which application of AAERVE has been shown to be both energy-saving and cost-effective. 8.2.3.2 Requirements for minimum effective
29、ness and maximum input fan power consistent with the above guidance. The definition of effectiveness in ASHRAE Standard 90.1 is currently different than the definition of Effectiveness in this guideline. 8.3 Climate. The location of the building may determine the type of AAERVE required. The tempera
30、ture and humidity conditions should be considered when determining the system to be used. 8.4 Building Operation. Controls should be provided to operate the system as required. 8.5 Building Air-conditioning System. The air-conditioning system type utilized in the building structure will influence wh
31、ich AAERVE system will be easiest to install and maintain. 8.6 Building Outdoor Air Requirements. The required amount of outside air will affect the size and design of the AAERVE. 8.7 Building Outdoor Air Intake Location. The location of the outdoor air intake should be considered. Never use outdoor
32、 air from an area that generates contaminated air. Examples of this are (1) areas where idling cars, trucks, or buses are abundant, (2) a processing facility that produces odors, and (3) restaurants kitchen (grease) exhaust areas. 8.8 Building Inside Air Conditions. The quality of the air inside the
33、 building may be important to the selection and design of the AAERVE. If the quality of the exhaust air is objectionable, the EATR should be evaluated. The EATR may be minimized through technology selection, mechanical purge, and/or pressure management. Separate spaces that must remain absolutely se
34、parated due to concerns for smoking odor transfer, for example, should be treated with different systems. When exhaust air presents a safety hazard and is not acceptable for recirculation in any amount, the use of AAERVE may not be advisable. Table 1 provides a summary of classes of air as they are
35、treated in ASHRAE Standard 62.1. AHRI GUIDELINE W (I-P)-2014_ 8 Table 1: Classes of Air and Energy Recovery Ventilation Applications Classification of Exhaust Air (Refer to ASHRAE 62.1) ASHRAE 62.1 Recommendations AHRI Recommendations Class 1 Air - Air with low contaminant concentration, low sensory
36、-irritation intensity, and inoffensive odor. Re-circulation or transfer of Class 1 exhaust air to supply air entering any space is permitted. Use EATR and OACF to calculate adjusted intake rates and insure that proper outside air ventilation is provided. Class 2 Air - Air with moderate contaminant c
37、oncentration, mild sensory-irritation intensity, or mildly offensive odors (Class 2 air also includes air that is not necessarily harmful or objectionable but that is inappropriate for transfer or recirculation to spaces used for different purposes.) When using an ERV, transfer of Class 2 exhaust ai
38、r to supply air entering a Class 1 space is acceptable when no more than 10% is Class 2 air. Class 2 air can be returned to a Class 2 space. Minimize EATR to reduce re-circulation of exhaust air. Most devices will require no special measures to achieve this level of dilution. System design, includin
39、g multiple exhaust points from a variety of spaces can increase dilution performance. Class 3 Air - Air with significant contaminant concentration, significant sensory-irritation intensity, or offensive odor When using an ERV, transfer of Class 3 exhaust air to supply air entering a Class 1 or 2 spa
40、ce is acceptable when no more than 5% is Class 3 air. Class 3 air can be returned to a Class 3 space. Minimize EATR to reduce re-circulation of exhaust air. System design, including separate exhaust air duct systems for Class 3 exhaust, multiple exhaust points including Class 1 and 2 air, purge, etc
41、., will influence dilution performance. Class 4 Air Air with highly objectionable fumes or gases or with potentially dangerous particles, bioaerosols, or gases, at concentrations high enough to be considered harmful Re-circulation or transfer of Class 4 exhaust air to supply air entering any space i
42、s prohibited. AAERVE may not be an acceptable technology. AAERVEs should only be used when the specific and qualified authority having jurisdiction allows. 8.8.1 Fouling. Spaces that generate dust, powder, grease, wax, etc. may require special treatment of the exhaust air or may not be candidates fo
43、r AAERVE. Verify with the AAERVE manufacturer. 8.8.2 Humidity Control. AAERVE in combination with the air-conditioning system may provide adequate humidity control to meet ASHRAE Standard 62.1 requirements. In applications where humidity must be closely controlled (within 5%) additional dehumidifica
44、tion equipment may be required. 8.8.3 Smoking Areas. If smoking is allowed inside the space, additional amounts of outdoor air may be required. Consult local codes for the minimum amount required. Consult the AAERVE manufacturer for appropriate product application. 8.9 Building Structure Installatio
45、n Considerations. Listed below are examples of limitations created due to the structure of a building. This is just a partial list. 8.9.1 The amount of room required for ductwork. 8.9.2 The size of the mechanical room as it relates to the size of the equipment. 8.9.3 The location of exhaust and flue
46、 gas and plumbing vents on a roof. 8.9.4 Maintenance access to the AAERVE. 8.9.5 Electrical requirements. 8.10 Selection of Cooling Design Conditions. Outside air can be a significant source of humidity. ASHRAE Handbook -Fundamentals provides three different sets of cooling design conditions. The dr
47、y-bulb/mean wet-bulb data prioritizes sensible load; the wet-bulb/mean dry-bulb data prioritizes latent load; the dewpoint/mean dry-bulb data prioritizes humidity ratio. The choice of design conditions may impact the efficiency of the system and its ability to control indoor humidity. AHRI GUIDELINE
48、 W (I-P)-2014 9 8.11 Tonnage Reduction Method. The air-conditioning equipment size can be determined by reducing the Total Building Load by the tonnage saved due to the AAERVE. 8.11.1 Total Air-Conditioning Requirement. Determine the total air-conditioning required for the Total Building Load includ
49、ing the amount required for the ventilation. 8.11.2 AAERVE Tonnage Savings. Determine the amount of air-conditioning tonnage that the AAERVE is saving from the manufacturers data. Reduce the total air-conditioning requirement by the savings amount to determine the net air- conditioning requirement. 8.12 Entering Outdoor Air Method. Determine the total air conditi
