Airflow Heat Recovery Ventilators

When and how a fan and motor are installed can make a gargantuan difference in how well a fan or set of ventilation fans perform. An improperly located or installed fan can even result in contaminants being ultimately blown back into a workplace, rather than being removed or contaminants diluted.

The first and most important decision when it comes to making decisions about fan ventilation systems is the decision as to what type of fan system you actually need when it comes time for ventilation on your premises. The fan setup may be for cooling or air conditioning purposes. They may be permanently installed within a system or they may be stand alone solitary units which you may of purchased at your local retailer , big box store or hardware outlet. Just as various and different types of ventilation hoods suit widely varying different applications across the waterfront so do various types of fans have different specific and indeed widely varying applications.

The basic parts and setup of a centrifugal fan are the housing , shaft with bearings, the impeller wheel or what some call "the rotor", an outlet discharge along with fan pulley (sheave) and lastly of course the motor. The most commonly used axial fan variety is the "propeller" fan type. Propeller fans successfully provide cooling and dilution ventilation. They are good air movers because they carry large volumes of air all the while using a minimum of electrical current and power. However they are rarely used in local exhaust ventilation systems since they can withstand only very little resistance. In an axial fan setup the air-streams will flow straight through the fan itself and the centrifugal fan. Propeller fans as used in a household window fan , a double window fan, or a large panel fan can be used in a studio or shop to exhaust hot air or for dilution ventilation of solvent vapors. For example if you operate a small electric enameling kiln in a room, a household! window fan eighteen inches in diameter , will give you some relief from heat and will dilute the metal fumes.

A second and radically different type of centrifugal fan is the backward inclined or "BI " fan. A backwards inclined fan has its blades arranged in a configuration opposite the direction of rotation. These are mostly used with clean air. However they also can be used for light dust loads, although the blades can no doubt become clogged with solid material reducing air flow. Centrifugal fans themselves then again are divided into several different types and formats. Forward curved centrifugal fans overall have low space requirements coupled with a disadvantage of low top speeds. Yet this apparent disadvantage works in a contrary fashion to provide for relatively silent and quiet operation. Their mechanical efficiency and sets of efficiencies are relatively good and basic. It can be said and summarized that for a given set of air capacities that their rotation speeds are usually less and slower than other comparable sets of fans. It can be said that basically the assort! ed types and varieties of centrifugal fan system types vary in the way and means by which their blades are arranged and set forth on the fan wheel or wheels. The FC or forward curve fan is also called a squirrel-cage fan. The squirrel cage fan has many blades . All are cupped in a single direction of rotation. This type of fan is best used for exhausting heat, for dilution ventilation and for "clean air" ( that is no particulate matter) local exhaust ventilation.

Many factors determine the "right" or "best" choice of fan type , model or brand. Keep in mind that that overall what you most likely want and prefer is the fan that uses the least amount of energy to move the most air and air flows. Indeed there are many situations and events by which any of the fan types of varieties available would be more than adequate or even sufficient. This is even more so if all you want to do is to move or circulate clean fresh air. Yet given heating and air conditioning engineers and mechanics the discussion and debate can go on almost to no end or definite single choice. It can be summarized as "different strokes for different types of folks". There are the different fan types for different applications or setups. Still in many circumstances it comes down to personal preferences and vendor stocking and availability. Parts and service support is yet another consideration in the marketing and support mix. To the greatest degree it usually comes d! own to personal and professional individual choices and preference.

What may be one contractor's best and wisest choice may be to the disdain of the next builder or heating trades person giving you or your family their best considered professional advice and workup estimate. The apparatus may be for cooling ,heating or ventilating purposes and work. Yet in the end it comes down to matching design benefits and performance to needs. In economics it is supply and demand. In the heating and ventilating trade its reliability, air movement and final operating costs. The fan setup may involve considerations other than simple ventilation only . Take for example the case when explosiveness or flammability works itself as a basic design parameter and risk consideration set of factors. Explosiveness or flammability of materials that require non-sparking construction will involve non-ferrous blades and an explosive proof motor and housing. One other consideration that may well come into play into the choice of which and what type of fans are chosen may! be space limitations and concerns about noise and ambient noise levels. In the end it's all a matter of personal preference and choices.