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AIR CONDITIONING & HEAT PUMP SYSTEMS
A/C - HEAT PUMP CONTROLS & SWITCHES
AIR CONDITIONER COMPONENT PARTS
AIR CONDITIONER TYPES, ENERGY SOURCES
AIR FILTER EFFICIENCY
AIR FILTERS, FIBERGLASS PARTICLES
AIR FLOW MEASUREMENT CFM
APPLIANCE DIAGNOSIS & REPAIR
APPLIANCE EFFICIENCY RATINGS
BLOWER DOORS & AIR INFILTRATION
BLOWER FAN CONTINUOUS OPERATION
BLOWER FAN OPERATION & TESTING
BOOKSTORE - Air Conditioning "How To" Books
CAPACITORS for HARD STARTING MOTORS
CLEANING & Legionella BACTERIA
CHINESE DRYWALL HAZARDS
CONDENSATION or SWEATING PIPES, TANKS
DEFINITION of HEATING & COOLING TERMS
DEW POINT CALCULATION for WALLS
DEW POINT TABLE - CONDENSATION POINT GUIDE
DIAGNOSTIC GUIDES A/C / HEAT PUMP
DIAGNOSE & FIX HEATING PROBLEMS-BOILER
DIAGNOSE & FIX HEATING PROBLEMS-FURNACE
DUCTS - Asbestos
DUCT INSULATION, Asbestos Paper
DUCT INSULATION for SOUNDPROOFING
DUCT SYSTEM & DUCT DEFECTS
DUCT SYSTEM NOISES
DUCTS, Asbestos Transite Pipe
DUST, HVAC CONTAMINATION STUDY
ELECTRIC MOTOR OVERLOAD RESET SWITCH
EVAPORATIVE COOLING SYSTEMS
FAN LIMIT SWITCH
GAS EXPOSURE EFFECTS, TOXIC
GAS DETECTION INSTRUMENTS
HEAT LOSS (or GAIN) in buildings
HEAT LOSS (or GAIN) INDICATORS
HEAT LOSS R U & K VALUE CALCULATION
HEATING SMALL LOADS
INSPECTION CHECKLIST - OUTDOOR UNIT
INSPECTION LIMITATIONS, A/C SYSTEMS
LEED GREEN BUILDING CERTIFICATION
LOST COOLING CAPACITY
LOW VOLTAGE TRANSFORMER TEST
MOTOR OVERLOAD RESET SWITCH
MOLD in AIR HANDLERS & DUCT WORK
OPERATING COST, AIR CONDITIONER
OPERATING DEFECTS, AIR CONDITIONING
REPAIR GUIDES A/C / HEAT PUMP
REPAIR & DIAGNOSTIC FAQs for A/C
THERMOSTATS, HEATING / COOLING
THERMOSTATIC EXPANSION VALVES
WATER COOLED AIR CONDITIONERS
WINDOW / WALL AIR CONDITIONERS
WINDOW / WALL A/C SUPPORTS
How to optimize indoor air filtration: this article explains how to select and install air filters on heating and air conditioning systems to obtain the best indoor air quality by superior air filtration.
We describe the design of a cascade or series of air filter types and how they are placed to provide very high levels of indoor dust or airborne particle removal.
Naturally if there is an IAQ problem source in the building it is essential to also find and correct that condition. In these articles we are referring to filters installed on central air conditioning or central heating systems that move air through air handlers and duct systems. Standalone or portable "air cleaners" are generally ineffective in buildings and are not capable of removing an indoor air quality problem.
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This website article series almost any question you might ask about air filters for heating or air conditioning systems. We explain how an air conditioning service technician will diagnose certain common air conditioning system failures or defects.
We include photographs to assist readers in recognizing cooling system defects. Readers should also see Air Filter Effectiveness and Real-World Effectiveness of Air Cleaners in our INDOOR AIR QUALITY IMPROVEMENT GUIDE article series.
Selecting Air Conditioning System Filter Types & Air Conditioner Filter Cascading for Optimum Indoor Air Quality and maximum reduction in airborne particles involves selection of high efficiency filters and other filtration equipment and placing them in the correct order and in the most effective location within the air conditioning system air handler and duct work.
Highly efficient air conditioning or heating air handler or duct air filters which trap smaller particles are available, right down to HEPA filters. We recommend improved filtration installed particularly in buildings where occupants have mold, allergy, or other respiratory concerns.
For the front-end air filter described in the cascaded air filter system outlined below, we selected a Filtrete Filter - the Micro Allergen 1000TM reduction filter made by the 3M Corporation. This filter is described as also resisting microbial growth.
Air filter effectiveness and MERV ratings are described in detail at AIR FILTER EFFICIENCY.
Cascaded Air Filter Designs: Optimum Air Filtering Can be Obtained by Air Filter Selection, a Combination of Air Filters, & Air Filter Placement
At our forensic microscopy lab where it is important to keep the dust and airborne debris to a minimum, when we replaced our heating/cooling system we specified the following filters in the order shown, moving from the building air return to the air handler itself.
Cascades of filters will significantly reduce airborne particulate debris, mold, pet allergens, dust mite allergens, and similar particles.
But as we discuss below, cascaded air filters may also cause an un-wanted reduction in total air flow unless the heater or air conditioner blower fan is of adequate capacity.
It may be possible to regain some of this lost air flow by making sure that the blower assembly is clean and that the duct system is not leaky or blocked anywhere.
The use of a variable speed fan with high output capacity combined with a discussion with our installer provided a heating system that was able to provide excellent air filtration without suffering from airflow restriction or air starvation.
We discuss the detection of duct system defects such as blockages and leaks at DUCT SYSTEM DEFECTS.
Below we describe a series of filters that might be placed in a cascaded HVAC air filter design, in the order of installation beginning at the front-end at the air return.
1. First cascaded air filter: the Front End Filter
Front end air filter: shown at left and represented by arrow #1 in the photo above, at the central air return we installed a typical inexpensive 1" disposable filter which protects the return ducts from
high levels of debris. This filter is changed monthly. Our first photo just above in this article shows the installation of a front-end filter at the return air register in our lab.
Effectiveness of the front-end air filter: In our experience, the front-end air filter has been doing a great job of keeping the dirt and debris level very low in our air handler, as you can see in our photo at left where we've removed the filter to show the interior of the sheet metal return air plenum chamber after three years of system operation.
2. Second cascaded filter: a washable metal air filter in the HVAC Return Air Plenum
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