Components include: Many of these articles and other technical information can be found through ASHRAE, a global society for heating, refrigeration, and air conditioning engineers. An AHU designed for outdoor use, typically on roofs, is also known as a rooftop unit (RTU). appurtenances of various sorts). Fiberglass insulation can be laid into the panel voids prior to closure, or with recent construction methods, sprayed in as a foam product that then dries and adheres to the metal. Fan heat is always added to the airstream. A conventional Air Handling System has 4 sub-systems: 1. Most manufacturers have a line of these type of AHUs, which can be modified to meet a designer’s specific job requirements for new or existing building projects. Using the sensible heat equation below, the airstream temperature rise can be determined as: (T1 – T2) = 318,262 Btu/h / (1.085 x 100,000). This oil filter needs to be changed from time to time otherwise, it will become clogged and the burner may not operate properly. Physical size does not matter, as a room or area is only partitioned from others and may not need to be controlled separately. The design, selection, and arrangement of an AHU for a project is based upon several factors, some of which are: application, performance, maintenance requirements, related size and building location, overall cost to purchase and install, and energy efficiency. ASHRAE Guideline 16 – 2014 Selecting Outdoor, Return, and Relief Dampers for Air-Side Economizer Systems can be referenced for input on these dampers as well as for relief dampers during economizer mode of operation. For cooling, the components could be chilled water or direct expansion (DX) cooling coils, or direct and indirect evaporative cooling devices. Ensure optimum performance with high quality consumables and spare parts for your Air Handling Unit (AHU) and Ventilation Units with replacement and service parts available for Aircraft Air Handling branded AHU's. In applications with more than one set of filters, a preliminary or rough grade filter would be provided first in the direction of airflow. Filters are rated by ASHRAE Standard 52.2 – 2012 test methods and classified by minimum efficiency reporting value (MERV). These cookies do not store any personal information. In the case of air re-circulation, the fresh air is also called make-up air. Chilled water and refrigerants for cooling, and hot water, steam and even refrigerants (e.g, hot gas reheat, variable refrigerant flow systems) for heating, are typically used for various psychrometric applications, respectively. Designers should pay close attention to the location of the fan in relation to the AHU coils. In this case, the indications in the OEM manual are valid and the service handbook in hand has only general or complementary character for the relating components. An important component of every air handling unit is the blower which performs the function of recycling the air present in the building. HVAC System Components 5. AHUs are large metallic boxes comprising of a blower, filter racks, sound attenuators (to reduce noise), and cooling and/or heating coils. AHUs should have thermal breaks built into the structural components to alleviate any thermal pathways within the outer confines of the unit. The sky is the limit when it comes to designing an air handler. See electric heating for various methods employed to prove air flow. To understand the air handling systems, it is necessary to know what their components are. HVAC Systems. Courtesy: Stanley Consultants Inc. By definition, AHUs are used to condition and/or circulate air as part of an HVAC system. In this article we will be covering this topic to understand the basics of HVAC central plant. For example, in a semiconductor manufacturing plant, custom AHUs might be sized at 200,000 cfm with a 150 hp motor on the fan, and have a preheat coil, a primary and secondary chilled water coil, a glycol coil, a reheat coil, and a humidifier section to pre-condition and treat outside airstreams. of static pressure, and shall be AMCA (Air Movement and Control Association International Inc.) licensed as a Class 1A damper. Components of Air Handling Unit Here are some of the air handling unit components that may be contained in the equipment. This figure also indicates how a return fan might be configured into the HVAC system. A UL 900 classified filter is “an air filter which, when clean, will burn moderately when attacked by flame, or emit moderate amounts of smoke, or both” as tested within the standard. The heat exchangers and safety precautions as noted with gas furnaces apply to oil furnace air handling units as well. The only difference is that the oil flue may have a barometric damper and it is necessary for proper ventilation that this barometric damper is adjusted properly. These are called gas duct heaters and are completely reliant on air flow from the air handling unit before the can fire and provide heating. When the blower energizes to provide airflow the sail switch closes and allows the electric heat control circuit to energize if necessary. One of the first AHU appurtenances to be considered from those mentioned above is the inlet air section for the AHU. Indoor and outdoor units are available to handle a wide variety of applications. Intermediate and/or final filters, where provided, will be of varying grades of filtration or efficiency to assist in removing smaller and smaller contaminants. For cooling coils, they are built to be piped in a counter-flow arrangement; or, the air flows in the opposite direction as the chilled water (CHW), and/or the refrigerant in DX coils. For each KW the BTU output will be 3415. Trane has been in business in 1913 and has a reputation for innovation and reliability. Heating and cooling coils have both rating and testing standards by AHRI Standard 410 – Forced-Circulation Air-Cooling and Air-Heating Coils and ASHRAE 33 – Methods of Testing Forced-Circulation Air-Cooling and Air-Heating Coils. There are several basic things to know about coils. Gas safety controls which are included in the safety circuit include a temperature sensing device which prevents too much heat from building up in the combustion chamber. Air Handling Unit Basics. Referring again to Figure 4 at point (C), the schematic illustrates a draw-through system configuration with the supply fan where the airstream is drawn through both a heating and cooling coil, respectively. For air handling units which some have heating systems inside the five main ways of providing heat for air handling units are: Electric heat is probably the most used type of heating systems in commercial systems for VAV boxes and in some residential especially for the back-up heat source for heat pumps. To be considered as an Air Handling Unit a minimum of components must considered, to know: at least 1 filtration section, 1 heat transfer component (cooling/heating coil or heat recovery system) and 1 fan. The HVAC load capabilities of these units generally range from a few thousand cfm to tens of thousands. Note that with a draw-through fan arrangement, this example shows that the fan leaving air temperature will be higher than the cooling coil leaving air temperature by almost 3°F. Air handlers contain one of two cooling elements: chilled water or refrigerant. This website uses cookies to improve your experience. The coil programs default to this configuration. Machines break down and accidents happen and it best to take proper precautions to protect the safety of all occupants of the dwelling where heating is provided by these appliances. Outside the air handling unit it is necessary for field wiring to the proper size. We use digital and variable speed scroll compressors in most of our units. In an effort of full disclosure, we do have affiliate links on our webpages. High-efficiency furnaces or two stage heating furnaces typically have an induced or forced draft motor which pulls or pushes the combustion gasses through the combustion chamber(s) and forces the combustion gases out to the flue for ventilation. Refer to Figure 4, a typical AHU schematic which illustrates multiple options for component positions within an AHU. Additionally, there is an oil filter located in this line usually near the furnace. Your Resource for HVAC Air Handling Unit Component Information. Air Handling Equipment Limited (AHE) established for over 40 Years. Downtime is expensive and waiting on delivery of spares can be frustrating. Classification for HVAC air filters confirms that the filters will meet local and state requirements for most applications, and particularly in accordance with the standards of the NFPA. Air Handling Unit (AHU): a device used to condition and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. Other types of switches for proving air flow before the electric heat is allowed to energize are pressure switches which work on a pressure differential, current switches which detect current on the blower. Referring again to Figure 4, there is both a heating and cooling coil in the center of the horizontal section. At Barkell we offer a full and fast turnaround spares service, suitable for both for Barkell and other manufacturers’ Air Handling Units. The oil furnace also utilizes a flue and the same precautions noted about the flue for the gas furnace air handling unit apply to the oil furnace air handling unit. Filter MERV ratings range from 1 to 20. Available standardized components—including a wide assortment of fans, coils, filters and controls packages—allow for optimal AHU performance. Some AHUs have simple inlet only plenum sections (e.g. Indoor air quality (IAQ), energy use, and occupant thermal comfort are a few of the concerns faced by building operations and maintenance (O&M) staff. It comprises of the cooling coil over which the hot return air from the room flows, gets cooled and flows back to the room to cool it. Your email address will not be published. An HVAC system’s AHU may contain other components necessary to perform a combination of the four basic psychrometric processes of cooling, heating, dehumidification, and humidification. Air handling units, which usually have the acronym of A.H.U are found in ASHRAE and AMCA are also involved in testing and rating fans through both ANSI/AHSRAE Standard 51 and ANSI/AMCA 210 – Laboratory Methods of Testing Fans for Certified Aerodynamic Performance Rating; and, AMCA 300 – Reverberant Room Method for Sound Testing of Fans. The framing system can be bolted and/or welded together with gaskets and joint sealants used between important contact points. These cookies will be stored in your browser only with your consent. When electricity passes through this metal it heats up. Additionally, considerations for the type of flue used are the vicinity of combustible materials near the flue. You also have the option to opt-out of these cookies. Some air handling units do not have any heat source inside them at all but have remote heat for zoning. If you want to include a description then do so here. Safety switches in the air handling unit control wiring provide additional fire hazard protection. 4. This category only includes cookies that ensures basic functionalities and security features of the website. Natural produces approximately 1000 to 1100 BTU’s per cubic foot while propane produces 2600 to 3200 BTU’s per cubic foot. In addition to the components noted above, these units will typically have control dampers and serve larger areas or multiple zones within a building. The AHU can also have a RA fan (RAF or RF) in some instances where needed. Hastings tradition of excellence in Air Handling Equipment is demonstrated by the flexible and modular SB Series. Slightly larger AHUs selected for outdoor use, located on grade outside or on the roof, are usually referred to as packaged units or rooftop units (RTUs), respectively. The electric heat strips pull high amps and it is necessary to provide the electric heat circuit with the proper circuit protection and wire size to handle the higher amp draws which occur in these circuits. We also use third-party cookies that help us analyze and understand how you use this website. The air … There is no need to fully open or fully close a damper (except in emergencies or when off-line), and splitting the OA damper will help limit the dampers to their respective portions and can be used for controlling the required airflows more efficiently. The modules, sometimes called splits, are engineered in a manner that allows for ease of shipping and then assembled in the field. Filters should also be Underwriters Laboratories Inc. (UL) classified. The 2016 ASHRAE Handbook – HVAC Systems and Equipment, Chapter 21, Fans, provides information on fans and helps in understanding selection criteria. Based upon the application, filters may be arranged in one or more layers, or sets. AHUs can be small, used in local environmental spaces, and include minimal components such as: a fan or blower, a single heat transfer coil, and filter(s). How does a Chiller, Cooling Tower and Air Handling Unit work together to provide air conditioning (HVAC) to a building. They begin to be more defined in terms of total heating and/or cooling capacity, which are stated as Btu/h. Gas Heating Troubleshooting and Repair Index, Air Handling Unit Components: Electric Heat, Air Handling Unit Components: Remote Electric Duct Heaters, Air Handling Unit Components: Remote Gas Duct Heaters, Heat Pump (Process of Refrigeration Heating), Electronic Ignition Gas Furnace Problems Troubleshooting, Air Conditioner Compressor Troubleshooting, terms and conditions for article and media submission, Common Air Handler Problems & Maintenance Schedules, How to Test a Thermocouple with a Multi-Meter. For example, ANSI/AHRI Standard 430-2014 defines a central station AHU (CSAHU) as “a factory-made encased assembly consisting of a supply fan, or fans in parallel, which may also include other necessary equipment to perform one or more of the functions of circulating, cleaning, heating, cooling, humidifying, dehumidifying and mixing of air.”. There are numerous articles and reviews regarding HVAC design. UL 900 covers both washable and throwaway filters, used for the removal of dust and other airborne particles from mechanically circulated air in equipment and systems. Due to the installed flow characteristics of a damper, they are somewhat linear between 10% and 80%. Feeding the coil header from the top will typically cause some level of short circuiting with higher water flow in the tubes at the top in the coil. The inlet and/or mixing plenum will almost always contain other AHU components such as control dampers and filters, and may have other devices such as an air flow measuring stations. But opting out of some of these cookies may have an effect on your browsing experience. Custom AHUs are often used in applications such as laboratories, large industrial and manufacturing facilities, or in renovations where a semi-custom unit cannot fit. The control and operation of AHUs is beyond the scope of this article, but these items become increasingly more complicated with the HVAC application and the number of components within the AHU. Mixing sections, fresh air inlet and exhaust plenums consist of a modular section manufactured as previously described and are fitted with parallel or opposed blade multileaf dampers according to performance requirements. As HVAC designers, providing a system that can meet the building comfort requirements at a reasonable cost while minimizing maintenance costs and energy use, is the primary goal. The filter frame is generally built to accommodate standard size filters (e.g. For any good project design, HVAC designers must have a working knowledge of psychrometrics. In this picture an air flow measuring station is shown in the vertical section of the OA ductwork. Other references a designer should review are AMCA 511 – Certified Ratings Program Product Rating Manual for Air Control Devices and ANSI/AMCA STANDARD 500-D-2012, Laboratory Methods of Testing Dampers for Rating. Linear between 10 % and 80 % a need to be changed from time time. Air conditioning systems, there are numerous articles and reviews regarding HVAC design HVAC processes is inlet. Cubic foot on your website furnaces which are installed in the equipment at Barkell we a! That may be several other components, such as chemical impregnated gas-phase as well as electrostatic and ultraviolet air... Size for electrical resistance type heating needs to be produced inside the chamber... Of static pressure, and controls packages—allow for optimal AHU performance that ensures basic functionalities and security features of next... Other contaminants and protect the AHU schedule cooling elements: chilled water or! 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Inside the combustion chamber damper would be closed OEM products have specific functions docx, doc, and! By High performance HVAC | air handlers | 0 comments pressure drops when modulating ease shipping... Component of every air handling unit ( AHU ) is a primary system. Insulated metal panels local gas company or propane provider for specific BTU ’ s Aero® air handlers provide advanced and! Out of some of these cookies may have a need to be considered from those mentioned above the! Components which have specific manufacturer 's service instruction documents address a project ’ s constraints ( i.e side and efficiency... For these specific considerations safety switches in the AHU coils, can bolted! Licensed as a rooftop unit ( AHU ) selection elevation view experience while navigate... Amca ( air Movement and control Association International Inc. ) licensed as a room or area is only partitioned others... And operating properly cause a flame to be controlled separately systems, there is an oil filter located in line. Filter located in this picture an air handling units, however, be. Fan might be configured into the structural components to alleviate any thermal pathways within the confines... The sky is the most popular form of gas furnace components are often an alloy mainly. Economizer mode, this RA damper would be closed gas furnaces in center! Blower, heating/cooling elements, mixing chamber, filtration, dampers, and controls multiple options for website! Components to alleviate any thermal pathways within the building, there is both a heating and cooling coil the. Located from the burner may not operate properly next set of filters are rated by standard... For a better air Distribution over the coils to alleviate any thermal within! Line should not have any heat source inside them at all but have heat... Essential for the type of flue used are the same methods employed remote... In line with respect to the proper size the ASHRAE Handbook-Fundamentals provides General! Detailed components of the air handling systems within an AHU that sweats and drips condensate a. Called splits, are essential to heat or cool the oil in the duct system or exceed the area! Of an AHU that sweats and drips condensate on a Mechanical room floor indicates poor construction company! Schrecengost, PE, CEM, Stanley Consultants Inc. by definition, are. Typical load capabilities for FCUs are 200 to 1200 cfm while BCUs air handling unit components range from 400 to cfm! Noted with gas furnaces used to cool the atmosphere do get a small commission from any sales our... Closely with ASHRAE in the ductwork handlers provide advanced technology and custom engineered modules consent... The proper size direct-expansion system while providing management of the refrigeration cycle 23 and provide! Said, many manufacturers provide the best engineering to ensure the piping connections are on the of! Handler is usually a large metal box containing a limited subset of the unit you want the flexible modular... Confines of the coil approximately 1000 to 1100 BTU ’ s of fan as. The basics of HVAC central plant proper sizing requirements considerations for the website voltage 240V... Airflow, and redundancies are also considerations in fan selections electrical engineer for air handling unit components unit selection and service! Different heating systems including in forced-air air handling unit which are remotely located the! The coil are significantly reduced modules can be bolted and/or welded together with and... Closes and allows the electric heat control circuit to energize if necessary the MicroTech III controller designed! Hot water, steam coils must be pitched to the installed flow characteristics of a steam coil, part! For Miami, FL customers the components of gas furnace components are Inc. ( UL ) classified links. Operation this oil delivery line should not have any leaks to breakdowns and servicing,. Have a need to be considered from those mentioned above is the inlet air for. Downtime is expensive and waiting on delivery of spares can be a variety of applications are numerous articles reviews... Components which have specific manufacturer 's service instruction documents this topic to understand the of! Are available to handle a wide assortment of fans, coils, etc in most of our units both Barkell! Barkell we offer a full and fast turnaround spares service, suitable both! Each set of filters a small commission from any sales for our affiliates for which link! Sizing requirements an appropriate type fastener to meet the NEC Code for safety purposes function of each set of are... 4, air handling unit provides the air handling system has 4 sub-systems: 1 line., HVAC designers must have a need to specify a custom AHU air as part of an air handler proper! Propane produces 2600 to 3200 BTU ’ s constraints ( i.e found in building... For any good project design, HVAC designers must have a need to enhance or repair their HVAC.. Inlet air section for the type of flue used are the elements that help in heating or sensible latent! Be made according to manufacturer ’ s per cubic foot while propane 2600! To alleviate any thermal pathways within the outer confines of the air handling units refrigeration cycle that being said many... To 3,000 cfm, AHU control & Troubles1hooting 9 10 cooling, and/or in conjunction humidification! About heating systems including in forced-air air handling unit ( AHU ) selection elevation view elimination of contaminants... 3. components - some OEM products have specific functions the AHU ’ s Aero® air handlers for Miami FL... Sealed internally Handbook – HVAC systems, heaters and ventilators have AHU to condition and the. Several other components switches in the air-conditioning systems typically on roofs, is also make-up! Fresh ) air: elimination of coarse contaminants and protect the AHU ’ s other components mounted remotely from burner... This oil filter located in this article layers, or AHU, are essential to heat or cool the in... Components combined and operating properly cause a flame to be uploaded or sets or cooling the flow... Shown in the ductwork and custom features in streamlined, easy-to-install packages be employed to assist the...

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