When I visited the HVLS fan factory in Italy, I was surprised to find that it was a warm day. Opening the door of the tiny rental car felt like stepping into a preheated oven as I walked out of the factory and into the hot, humid air. We’d been driving for about 20 minutes when we finally reached a temperature where we were comfortable and the interior surfaces were no longer melting.
Nevertheless, there’s a catch. It had been refreshingly cool all day in the factory. Outside it’s sweltering, but inside it’s pleasantly cosy.
As I drove back to the airport, I realised that, despite nearly three decades in the air-conditioning business, I had never given much thought to the concept of apparent temperature. An enjoyable day of learning about HVLS fans and discovering the nitty gritty of apparent temperature was just what the doctor ordered!
Do you know what it means to be an HVLS fan?
A high volume low speed fan, or HVLS for short. The machines to use in order to reduce the apparent temperature in large buildings are HVLS fans in any case.
First and foremost, HVLS Fan Singapore is known for their high volume, or the “HV” part of their name. For example, the smallest Evel HVLS fan moves 41,000m3/hr of air, while the largest has 7m blades and moves 850,000m3/hr. To put it another way, that’s a lot of air moving in that direction.
The LS bit, or Low Speed, is the next component. Both the fan’s blade speed and the air discharge velocity are considered. At 50 revolutions per minute, one of the largest in the range moves 850,000 m3/hr. To put it another way, a full rotation takes over a second when going at top speed. It took me a while to get used to how slow these fans were compared to the 960 rpm direct drive fans I was used to. However, their sluggishness is a good thing. Slowly sweeping blades create a gentle wash of air over you, rather than a flurry of air that would blow your socks off.
It’s hard to put into words how it feels. One HVLS fan’s airflow covers a large area, and while you can feel the movement of fresh air wherever you go, it doesn’t bother you in the slightest. Refreshing and calming, this gentle air movement is a great way to relax and unwind.
What Is the Appearance of the Temperature To Be?
The temperature can reach 35 degrees Celsius on a still hot day, which is unbearably hot, especially if it is humid. In the event of a light breeze, the temperature will remain at 35°C but will be noticeably less humid. Our skin is kept cool by the evaporation of moisture from our skin, which cools our skin and makes us feel cooler. In other words, our body’s natural cooling mechanism works better when there is movement in the air.
Thus, the following changes in apparent temperature can be explained using a simple linear relationship:
- Rises as the relative humidity rises, and vice versa.
- Slows down as air speed increases and vice versa.
Perceived temperature differs from dry bulb temperature because it is affected by both air flow rate and humidity.
An unusual experience occurs when you know that it is a hot day outside and you’re inside a large building that’s neither cold nor hot. Having an enjoyable work environment is a major plus.
27°C and 50% RH is outside of the comfort zone when there is no air movement.
What is it about Evel HVLS fans that sets them apart?
The mounting, the blades, and the controls are the four main parts of a motor.
Fans with Evel HVLS Motors. European regulations on energy efficiency have resulted in the use of EC (electronically commutated) motors in a large number of machines in recent years. They are unquestionably more efficient and easier to control than the old AC induction motors. The Evel HVLS Fan Supplier In Singapore motors are all brushless EC type, but they are cleverly direct driven. Just a direct shaft from the motor to the fan hub assembly without any belts or gearboxes.
You have to scratch your head a little when you are used to 4 pole induction motors whirring at 1450 rpm under load, and the biggest fan in this line can be spinning at the same speed as the fan blades, i.e. at 50 rpm, because of this. A 0-10v control signal can be used to control it to spin at much lower speeds than its maximum speed, making this even more daunting to consider. When these motors first get going, they sound and feel like something out of a Rolls Royce. At a brisk pace, it packs a powerful punch.
Since the motors are only available in two sizes—large and small—it follows that larger fans get the larger motor. It’s all in the programming, and each motor is customised for the fan and blade profile it’s going to be attached to. In order to get the most out of each fan model, the motor must be programmed with a long list of parameters. Using a controller, each fan can be linked to the internet. In the event that the HVLS fans brushless motor goes awry, this is a useful tool because it can be remotely inspected and its operating parameters compared to design values; even the temperature of the casing and shaft can be seen.
Evel HVLS Fan Supplier Singapore Installation. The mounting system consists of several components, none of which are particularly light.
The structure is built to withstand a wide range of failures.
Two inverted U-shaped brackets support a base plate to which the motor’s base is bolted, cradling the motor. A number of bolts hold the impeller hub to the shaft. Normally, the weight is supported by the two tightest bolts, but if either of them fails, the weight is distributed among the remaining bolts. Brackets bolted to the base of the motor cradle the rotating shaft, but do not touch it. This is another layer of failsafe design. These cradle plates will keep the blades attached to the hub if all three bolts fail, preventing them from falling off.
Two plates, each with five spurs, make up the “spider” assembly found on the hub. In the event of a single spur cracking, the other plate will be strong enough to support the blade on its own.
Several optional fittings make it easier to install the entire fan assembly, and these can be chosen based on the design of the roof structure.
Designed aerofoil profile with moulded wing tip to prevent air leakage from the blades’ termini.
Blades made of HVLS (High Velocity Low Speed) material. As you can see, Commercial Ceiling Fan come in a variety of blade counts. Early models had ten blades, while more recent models have eight or six. There are five blades in the Evel HVLS fan range. The number of blades is the subject of a great deal of study. Overcrowding the fan blades causes the blades to try and bite into the turbulent air that was created by the previous blade. With only one blade, the fan cannot move the air as effectively as it could if there were two. To put it another way, the goal here is to determine the maximum value on the bell curve for the parameter you’re designing. Aerofoil blades are designed with an upturned wing tip on each one to keep air from leaving as they sweep across the surface of the air. This upturned wing tip is the result of careful engineering to strike the right balance between minimal turbulence and maximum effectiveness at this high speed.
The Evel HVLS fans have a variety of control options. A 0-10v speed control signal is used for all, but various modbus options are available for additional control and system monitoring.
What’s Up With All This Hype?
It’s a legitimate concern. It’s a given that moving 850,000 cubic feet of air per hour is going to make a lot of noise. At the very least, that was my preconceived notion prior to my trip to the Italian factory. Because I’m used to the sound of blades slapping air and motors humming, I was prepared for something else to fill my ears.
I’ll be the first to admit that, having served in the military, where there was the occasional bang, I’m not the best at hearing pins drop. I listened, felt the movement of the air, and I believe I heard a faint hum. This was not the Industrial Ventilation Fan Singapore, according to my host, but the factory next door. Having my doubts confirmed, I made my way across the factory floor to the back wall next to the next-door property and sure enough, the hum increased in volume – it was the factory next door! I didn’t notice anything unusual about the softly sweeping Industrial Ceiling Fan Singapore directly above my head.
The effect on the senses was awe-inspiring because of the absence of noise, the slow rotation of the motor and blades, and the gentle, even breeze they produced.