Decorative Grilles, Return Air Filter Grilles
The Truth About White Louvered Return Grilles
Is the venerable “White Louvered Return Air Grille” the best for all Heating and Air Conditioning Systems (HVAC)? They must be, since you see them in 97% of all homes, stores, hotels and restaurants. Why would all major manufactures of HVAC vents make them, if they were not the best?
The truth is they have several problems; they are louvered, white, noisy and exceedingly unattractive. The reason the big manufacturers make louvered returns is because they are cheap and inexpensive to make, especially when out-sourced to foreign countries, such as Vietnam, China, and Mexico.
Since the 1970’s they have been The HVAC Industries’ only available option. In a world where the consumer typically has dozens of different options available, the HVAC grille makers mainly offer just the “White Louvered Return Grille”. Their marketing philosophy is reminiscent of Henry Ford when he stated “Any customer can have a Ford in any color he wants, so long as it is black.”
Therefore, there is no color chart to select from multiple finishes, like floor tile or wallpaper. Even toilet makers offer multiple finish selections, but not HVAC grille producers. The white finish is strong and durable, since it is powder coated. However, the powder coating makes it difficult to paint over if a discerning homeowner wants to change the color to match their interior. White also gets dirty quickly on return grilles, since their function is to clean the dirty air via the filter in the HVAC system.
Why are the louvers necessary on return grilles anyway? Understandably louvers can help direct the air flow on supply grilles, but what is the advantage of designing return grilles with louvers? It can’t be performance, because louvers are angled by 30% to 50%, which forces the air to bend around the angled louver, thereby decreasing air flow and increasing static pressure. So in truth, louvers reduce the overall performance of supply grilles.
When quizzed as to why return grilles are designed with the same louvers used on supply grille, the common answer is they block your view into the duct behind the supply grille. If pressed, the major grille manufacturers admit, that they are also easy and cheap to fabricate quickly. In short their sole function is to block the view of the ugly duct with louvers which in turn reduces your HVAC system’s performance.
Heating and Air Conditioning systems can also be noisy. In many cases the noise may come from the fan or blower, squeaky bearings or a vibrating refrigerant line, but most often it comes directly from the louvers. If you hear a high pitched irritating sound your return grille’s louvers is the most likely culprit. Louvered return grilles are made from thin sheet metal usually 24 to 28 gauge, which is very thin. If too much air is forced through all those louvers, the thin gauge metal vibrates creating that high pitched irritating sound.
One major Manufacturer of HVAC grilles even includes a foot note in it’s performance data warning that “Recommended face velocity is 300-450 FPM, higher velocities will possibly be of noise concern”. Ironically, they do provide engineering data on 500 and 600 FPM, but do not recommend air speeds that high, because of noise problems.
In conclusion, louvered return grilles are just quick and inexpensive to make, which to HVAC grille manufacturers outweighs the fact that the louvers are ugly, noisy and only available in white.
Comments are closed