ACH - Stands for "air changes per hour" and is a unit of measurement that indicates how many times per hour a particular space's volume of air is extracted and replaced.  Like CFM, ACH is a volumetric unit.  ACH can be calculated by: (CFM * 60) / (Cubic Feet of the space).  Air Changes Per Hour provides a metric for the selection of a heat or energy recovery ventilator as defined by a local jurisdiction's requirement for minimum outside air delivery.  It is also a critical design factor in residential forced-air systems.  Each space requires a certain range of ACH depending on usage and occupancy.  For example, most residential living spaces require between 3 and 8 air changes per hour since the occupancy is less dense and indoor environmental pollutants are minimal.  Commercial kitchens and auditoriums can require as many as 18 air changes per hour.  When designing a forced air system for a residence, the heating or cooling capacity (in BTU's) is dependent on the construction of the building (insulation ratings of walls and ceilings, number of windows, proximity of each room to unconditioned or outdoor space, etc.).  But it is the ACH requirement that will ultimately determine the required total CFM for the residence.  It is also important to note that CFM alone is not enough information to determine the selection of the appropriate room-to-room transfer fan for a particular space.  Suncourt includes reference ACH charts plotted against square footage of the room in our Thruwall Fan instructions to help you select the best fan for your application.

Centrasense® - Suncourt's exclusive and patented technology for measuring the static pressure of a duct system by measuring an inline duct fan's electrical motor attributes.  Our technique eliminates the need for pressure sensors or RPM sensors in critical applications that require monitoring the duct system performance. 

Centrax® Centrifugal Fan- A centrifugal fan will have a centrally mounted motor with blades that radiate out from the center motor or hub. The Centrax® Centrifugal Fan is an in-line centrifugal fan with backwardly inclined fan blades. These blades accelerate the air outward where the air is moved down to the output end of the fan. Centrifugal fans are useful in applications requiring larger airflows or pressure. 120v AC Current

CFM- Stands for cubic feet per minute and is a unit of measurement that indicates how many cubic feet of air pass by a stationary point in one minute.

Dba or Decibel- For our purposes a decibel is a numerical expression of the relative loudness of a sound. A whisper is 30 decibels and a normal conversation is 60 decibels. Most of the Suncourt fans fall in the 50-55 dB range. Please go here for more information on Fan Noise

DEDPV - "Dryer Exhaust Duct Power Ventilator:" a term used by Underwriter's Laboratory (UL) to describe a specific category of clothes dryer booster fans.  UL standard 705 describes unique and detailed safety features required for a product marked "DEDPV" on the product label.  UL705 also describes additional testing specific to DEDPV's verifying the manufacturer's claims about airflow performance and confirming the additional safety features of a DEDPV.  Features unique to DEDPV's include: all-metal housings, provisions to access the interior of the fan for cleaning without un-mounting the fan, remote indication status panel to warn the end-user of problematic conditions with the exhaust duct and/or ventilator during or after the dryer cycle, suitability for only 4" duct and only for residential clothes dryers.  The UL705 standard applies universally to use of a DEDPV with electric clothes dryers.  If a DEDPV is marketed as suitable for gas clothes dryers, UL requires that the specific gas clothes dryer model and DEDPV are tested for fire containment and the product will bear a marking indicating which gas clothes dryer make and model was tested and approved for use with the DEDPV by the certifying agency.  Currently the International Residential Code (IRC) version 2015 requires a DEDPV for a clothes dryer boosting application.  If your jurisdiction is using IRC2015, then a Home Inspector will be looking for this "DEDPV" acronym on the product label.

Duct- The tube that provides the pathway for the air in your home. Usually rigid metal or flexible plastic tubes.

Duct Muffler- Duct Mufflers are used in duct runs that are transmitting noise. The Duct Muffler has sound absorbing material inside the body of the muffler. This material can attenuate (reduce) any noise moving through the duct.

Duct Run- This term refers to the distance the air must flow to reach the output end of the duct.

FPM - Stands for "feet per minute" and is a unit of measurement that indicates air velocity.  Since CFM is a volumetric measurement, conversion from FPM to CFM and vice versa are dependent on the duct's cross-sectional area.  While CFM's are typically what is specified for required air delivery, air velocity can also be a critical factor.  For instance, too low of an air velocity from a supply register will not provide the adequate "throw" of conditioned air into the space while too high of an air velocity may result in turbulent noise created by the exhaust register grille.  A good 'rule of thumb' for a standard residential air delivery system that maximizes air delivery while minimizing the noise of the air delivery device is to keep the FPM at the between 600-650 as measured at the device.  For clothes dryer applications, air velocities below 1200FPM are too low to effectively deliver the entrained lint in the airstream to the exterior.

HVAC Duct- The ductwork used by your furnace and air conditioning system to distribute air.

In-Line Duct Fan- Any style of fan that is installed in the HVAC duct.  In-Line Duct Fans must be certified to UL Standard 1995, which is the safety standard for Heating and cooling Equipment.  (see below for additional information regarding various standards). 

Inductor In-Line Booster Fan - Single speed axial flow fan in a galvanized metal housing that uses a polymeric or metal fan blade attached to a shaft and motor.  The booster fan runs on household 120V power using the attached cord or attached electrical wiring box (depending on model).  Unlike a stand-alone ventilation fan (in-line centrifugal or mixed-flow fan), a booster fan is purpose-built to boost an existing airflow from an underperforming branch duct to a level required for maintaining comfort.  Centrifugal and mixed-flow fans of equivalent duct diameter are often too powerful for a booster application and can 'over boost' a duct run leading to excessive noise and to imbalance the static pressures / branch airflow delivery in an otherwise well apportioned duct system.  The Inductor In-Line Booster Fans utilize our custom molded fan blade designs to deliver high-velocity laminar airflow at the perimeter of the duct.  This creates a low-pressure zone in the center of the duct which induces an increased flow of the existing air stream, and does so with minimal turbulence where the two air streams converge.  This approach provides the most efficient and least noisy method of boosting branch duct airflow while minimizing the booster fan's influence on the remainder of the duct system.   The Inductor In-Line Booster Fan can also be used as a stand-alone ventilator for applications with low static pressure / friction losses in the attached duct system (short duct runs, open-patterned grilles, etc...)

Inductor 2-speed fan- Similar to the single speed Inductor fans but they will have the ability to be wired either HI or LOW. A 3 position ON-OFF-ON switch can be wired to switch between the two speeds. The 3-position switch is field supplied.

Static Pressure- Static pressure is the resistance to the flow of air, usually measured in water column inches of pressure. A 5’ duct run would have less static pressure than a 10’ duct run. Static pressure is also influenced by elbows and other restrictions in the duct or by the temperature of the air traveling through the duct.

Sones- A Sone is a subjective unit of loudness, as perceived by a person with normal hearing, equal to the loudness of a pure tone having a frequency of 1,000 hertz at 40 decibels.

Radon – Radon is a cancer-causing, radioactive gas that you cannot see, smell or taste.  The Surgeon General has warned that radon is the second leading cause of lung cancer in the United States today, second only to smoking.  The Environmental Protection Agency (EPA) attributes 20,000 deaths annually as a result of exposure to dangerous radon. It comes from the natural decay of uranium that is found in nearly all soils.  Radon can enter your home through cracks in foundations, concrete walls and floors as well as floor drains, sump holes and pipes or wires that penetrate foundation walls.  Because air pressure inside your home is often lower than pressure in the soil around your home’s foundation, your house acts like a vacuum, drawing radon in through cracks and other openings.  It is estimated that 1 in every 15 homes in the US has high levels of radon and it is found in all 50 states.  All types of homes can have elevated levels of radon, whether you have a new, newer or older home, full or partial basement, crawl space, or cement slab.  Sub-slab depressurization is a recommended solution to reduce radon levels in homes.  Suncourt® Radon Mitigation Fans have proprietary impeller design that builds high suction and force suitable for sub-slab depressurization. 

ThruWall™ Room to Room Transfer Fan- The ThruWall™ Room to Room Transfer fan is installed in the wall of adjoining rooms, allowing air to be moved from one room to another. They are often used in conjunction with PTAC units, mini-splits, fireplaces, wood stoves, window air conditioning units, and other heating and cooling systems. Suncourt has three ThruWall fan models. The TW108, TW208, and TW408.

UL Standard 507 - Safety standard for Electric Fans.  The scope covers fans and blowers such as desk fans, ceiling fans, thru-the-wall fans, ducted exhaust fans, and rangehoods.  The scope does not cover fans incorporating heaters or refrigeration, commercial kitchen ventilators, fans in corrosive environments or those used to ventilate corrosive or flammable vapors.  Most notably, the scope does not cover fans intended to move heated or conditioned air.  Any inline duct fan (axial, mixed-flow, centrifugal, or otherwise) with a UL507 certification cannot be used as a duct booster for a forced-air heating/cooling system.

Suncourt products listed to UL507:

Entreeair® Doorframe Fan models RR100, RR100-B

Equalizer® EQ2 Register Booster fan model HC300

Flush-Fit Register Booster fan models HC500-W, HC500-B

Thruwall™ fan models TW108, TW208, TW408


UL Standard 705 - Safety standard for Power Ventilators.  The scope covers roof and wall-mounted ventilators, and ducted inline fans for commercial or residential use.  Power Ventilators listed to UL705 must use totally enclosed motors.  The standard has a specific section dedicated to DEDPV's (dryer exhaust duct power ventilators.)  The scope does not cover those fans mentioned in the scope of UL507, and also has similar limitations of scope as named in UL507.  Although the scope does allow duct-connected fans intended to move heated or conditioned air, it does not allow shaded pole motors inside the airstream for any application.  Though they are wrong for the application, mixed-flow and centrifugal fans listed to UL705 may be used as duct boosters since their external rotor motors are considered 'totally enclosed'.  Any axial inline duct fan with a shaded pole (skeleton) motor listed to UL705 also cannot be used as a duct booster for a forced-air heating/cooling system.

Suncourt products listed to UL705:

Centrasense® DEDPV Kit model DRM04

Centrasense® Inline Fan with Monitor model TFM04 (OEM applications)

Centrax® Inline Fan models TF104 (4") thru TF112 (12")

Clothes Dryer Booster Fan Kit model DRY04

Radon Fan Mitigation Kit models RDK04, RDK04-3, RDN04, RDN04-3


UL Standard 873 - Safety standard for Temperature Indicating and Regulating Equipment.  UL873 is superseded by UL60730-1/UL60730-2-9 for all new designs of temperature indicators/regulators.

Suncourt products listed to UL873:

DuctStat® Temperature Sensitive Switch model: DS100


UL Standard 1310 - Safety standard for Class 2 Power Units.  This standard covers direct plug-in or hardwired power supplies with output ratings not to exceed 42.4V AC or 60V DC.  Class 2 power supplies offer additional safety features such as circuit isolation and overheating protection that are not found in "ITE" power supplies or "LED Driver" supplies.  UL1310 is the only acceptable type of power supply suitable for low-voltage ventilation equipment.

Suncourt products listed to UL1310:

Included power supply for Equalizer® EZ8 Register Booster model HC600

Included power supply for Flush-Fit Register Booster models HC500-B, HC500-W

Included transformer for ZoneMaster™ Adjustable Motorized Damper models ZC206, ZC208, ZC210, ZC212, ZO206, ZO208, ZO210, ZO212

UL Standard 1995 - Safety standard for Heating and Cooling Equipment.  Though this safety standard is normally associated with heating and air conditioning equipment, it does also cover fans intended to be connected to a duct system that supplies conditioned air for heating and cooling.  Since UL705 places limitations on some of the standard construction features of an appropriately designed in-line duct booster and UL507 restricts the application completely, UL1995 is the only option for an axial in-line duct booster fan.  UL1995 is superseded by UL60335-1/UL60335-2-40 for all new designs of in-line duct fans.

Suncourt products listed to UL1995:

Inductor® Register Booster Fan models: DB100C, DB200C, DB204C, DB205C, DB206C, DB208C, DB210C, DB212C, DB306E, DB308E, DB310E, DB412E, DB414E, DB416E, DB6GTC

ZoneMaster™ Adjustable Airflow Control Motorized Damper- An electrically powered mechanical device for controlling airflow in an HVAC system. They are commonly used to shut off or open airflow to seldom used rooms or sections of living space.  This allows home owners to customize airflow throughout the home for improved comfort and energy savings.  Suncourt offers motorized dampers that are fully adjustable (0°- 90°adjustment capabilities) for both powered on and powered off positions.  This technology is perfect for use in fresh air intake applications.  Suncourt has normally open and normally closed dampers sized to fit the most common duct sizes.