How to change the direction of rotation of the hood fan

Fan speed controller: types of devices and connection rules

The fan is one of the little-noticed, but extremely important devices that help to create favorable conditions for work, rest and just a pleasant stay.

Without it, computers, refrigerators, air conditioners and other appliances can not function. To maximize the efficiency of the various devices use the fan speed controller.

From our material you will learn about what regulators are, the peculiarities of their work. Also we will tell you how to assemble the device with your own hands and what you need for this.

Determination of rotation side

Determine the side of the impeller motion is very simple. Often the direction of rotation is marked in the form of an arrow. The arrow shows the side in which the impeller rotates. If, for some reason, there is no directional indication, determining the correct side is not difficult even without it.

Example of a directional sign for a “volute”

To determine the direction of the blades, you must look at the design from the side of the hole through which the air is drawn. If the impeller is rotated clockwise and the volute casing is wound clockwise, the direction of rotation is right. If the rotation of the blades goes counterclockwise. the side is left.

Exhaust unit running in the apartment

Usually to combat ventilation use special plugs, which are engaged in cutting off the flow of air and their subsequent redirection from the house. Below we will consider all aspects relating to the question: why does the hood blows in the opposite direction and how to return its action back to the necessary working direction?


In the main with the failure of the back draft faced in the toilet and bath, but it can happen in the kitchen. One of the main signs of ventilation difficulties is a decrease in temperature in the room. Why is this the case?? The fact that the ventilation system of any apartment designed supply and exhaust design with natural stimulation.

How to change the direction of rotation of the exhaust fan(1)

It says that when a certain part of the air warms up and decreases in density, it is subject to displacement due to the pressure of a denser and cooler wave. Because the inward air has a higher temperature than the outward air, it is characterized by an upward thrust. so it forms a natural draught. Its power and strength depends on the difference in temperature outside the building and in it, as well as the difference in height of exhaust pipes and inlet openings.

To begin to solve the problem, you need to understand the main reasons why the kitchen hood can start blowing backward. There are many reasons for this. The problems with the hood in an apartment or house can be due to:

Fireplace in the kitchen. a more common cause of problems with ventilation

  • sealing the rooms as new windows are inserted;
  • improper selection and installation of the ventilation system on the places of ventilation grilles;
  • Strong gusts of wind, drafts, also if the wind is oriented in one direction;
  • presence of stairs. the least unsafe in this regard is a curved staircase than an ordinary staircase;
  • Kitchen hood installation: when the kitchen is close to the fireplace, you won’t have to wait long for ventilation problems to occur;
  • Faulty position of the chimney (negative position. zone of wind shadow);
  • Large masses of vapor and cool air accumulate in the vent; m
  • contamination by snow;
  • waste accumulation;
  • faulty operation of the hoods.м
change, direction, rotation, hood

How to change the direction of rotation of an exhaust fan(1)

Bravo! The simplest method of rotation configuration!

You could not immediately say that it was necessary to turn the stator and all. I’m tired of listening to this long nonsense!

@Andrey Vostrukhin and you turn the stator upside down??

I have the same fan, thanks for the annotation

Thank you very much! The only thing I think is that the speed of the air flow can be exchanged. ( blade geometry )

But the propeller blades will rake more horribly. the efficiency will fall off

Short and sweet! The rest is a matter of creativity, who has what model. Thanks !

I ended up aligning the walls in my apartment. I didn’t think to film it in action. Put it on the floor near the sanding area on the wall, directing the flow to the side. If you point it upwards, the dust is blown upwards. And later made a holder for the grid with a connection to a vacuum cleaner.

Thank you for you dear man, the video is for dummies, just like us

Determining the direction of rotation

Determining the direction of the impeller is very easy. Often the direction of rotation is marked with an arrow. The arrow indicates the side in which the impeller rotates. If for some reason there is no designation of the direction of movement, it is not difficult to determine the correct side without this.

change, direction, rotation, hood

Example of a “snail” direction indicator

To determine the direction of the blades, you need to look at the design from the side of the hole through which the air is sucked in. If the impeller rotates clockwise and the volute rotates clockwise, the direction of rotation is right. If the rotation of the blades is counter-clockwise, then the side is left.

Conclusions and helpful video

The construction of a ventilation duct for self-contained ventilation of the toilet and bathroom with only one sump is clearly shown here

The connection of a simple fan is described in detail here:

To summarize, it is possible to arrange an effective ventilation system in the apartment on your own, but you must be careful and think carefully in advance. If you are not confident in your abilities, entrust the matter to a specialist, because mistakes in working with electrical wiring can lead to dire consequences.

Have you ever had to install a fan in the bathroom or toilet?? Please tell us which wiring diagram you used and if there were any complications during installation? Leave your Комментарии и мнения владельцев, share your experiences. the block for communication is located under the article.

Ways of reversing the flow

The ways of reversing the flow in axial fans of the K CA circuit are shown schematically in Fig. 2 (scheme K is a special case).

Figure 2 ( more details ) Ways to reverse the flow in the axial fans of the K CA circuit

fan change direction ||ceiling fan direction change || exhaust fan direction change || table fan dir

Method I. reversal of flow by turning the wheel blades by an angle of 180° with a simultaneous change in direction of rotation. As the blades turn, the wheel gets aerodynamic symmetry. If the fan consists of a single wheel (scheme K) and is CS: GO, then the fan will have a degree of reversibility in all modes R = 100%. It is the most effective way, because in reversing the blades are working in exactly the same conditions as in the normal flow.

Method II. reversing by changing rotation direction without turning the wheel blades. This is the simplest and therefore the most commonly used method of reversing.

Method III. reversing by turning the wheel blades by an angle of 180°. 2-θk (θk is the angle of wheel blades installation) without changing the rotation direction. In this case, when reversing the blades, the law of change of angles of blade profiles installation along radius is opposite to that which takes place at normal flow, i.e. blades have reversed twist. Because of this, the peripheral cross-sections of the vanes are streamlined at high angles of attack, which, together with streamlining of sharp (back) edges of the vanes, results in big losses and worsens aerodynamic characteristics of the fan at reversing.

In all cases, except for the losses noted, there are losses due to non-optimal shape of the CA blades, so when reversing the flow, the CA blades must be rotated to the reversed position.

Reversing using method I is mainly used in special fans with high power consumption, where flow reversal is an equal but not an emergency mode (for example, mine fans). In spite of the constructive complexity of this reversing method, its advantages are high efficiency and possibility to create highly loaded reversible fans (ψ ≥ 0.3).

change, direction, rotation, hood

Reversing method II and III is mainly used in fans, when reversing is an emergency mode. The II way is the most interesting since to reverse the current it is enough only to change the direction of rotation of the wheel. Recently, owing to simplicity of its implementation, this method has been widely used in special fans, for example, for ventilation of subway tunnels, where the reversible mode is not an emergency one. However, this method of reversing has a significant disadvantage. low efficiency if the fan is not originally reversible, that is, if it is not used reversible blades.

In the present article the peculiarities of reversing by method II and possibility to improve reversing properties of general industrial fans by means of using special blades are considered.

Conclusions and useful video

How to connect the controller to the fan. The example shows a thyristor controller, but the connection principle will help you to understand the algorithm of the step device:

The features of connecting a duct fan through a speed controller two more ways are discussed in the following video:

Step speed adjustment of fans makes the system less energy consuming, more silent, accurately controllable. The controller ensures the safety of the main equipment, increases its service life. This is facilitated by safe start-up, protection against short circuits, overcurrent, overvoltage, under-phase mode.

The cost of buying the device is paid back by the savings in energy costs. It is only important to choose the parameters of the regulator for the serviced fan. Most manufacturers have model matching tables that you can use when you make your own purchase. It doesn’t hurt to consult with the store manager.

Do you have any questions about the article? Ask our experts and other visitors to the site. the feedback box below. Also here you can share your own experiences and theoretical knowledge, participate in discussions.

What to do if the hood works in reverse

As we promised, now we are going to talk about the most effective and efficient ways to restore proper air draft in ventilation ducts. It should be noted that the correct air distribution in the dwelling is not only a question of comfort, but also of preserving health. It is known that a prolonged shortage of air or breathing stale air can lead to headaches and lung disease.

To find out whether the neighbors have a fan

The first thing to do is “on the surface”, namely to find out. whether neighbors have a fan and in what mode it works. If the fan is constantly used, you can ask your neighbors to use it only if necessary, and if the power of the device is too high. you can recommend another model.

If the fan is used cyclically, that is, turned on only when necessary, then you need to look for another reason. Most likely the whole salt in the clogged ventilation duct.

Clean the ventilation duct

Note once again that the tenants of the house do not have the right to clean the ventilation shaft. To do this, you need to make an application to the HMO or HOA, justify the nature of the problem and seek to implement all measures to clean the ventilation.

Often, HOA or HMO employees refer to the work on schedule and delay the start of cleaning. This sets a precedent for a complaint to the city (village) administration, as cleaning of clogged ducts is performed outside the schedule, but on demand.

Cleaning is carried out by different methods, but most often special long nozzles on a flexible rod are used. they are lowered into the ventilating duct and rotate around their axis. Working with a ramrod is combined with a powerful industrial fan capable of extracting dust, stiffened fat and other particles from the vent duct, which are separated when ramrod penetrating the duct walls.

Is there any dependence on the weather

There is also a direct. In strong gusts of wind can blow air at high velocity directly into the air duct. The top of the ventilating duct is closed by a special mushroom or convection fan, but if the duct is open, the wind may well blow into it. As a result there will be supersaturation of the duct with air, increasing pressure and distribution to the apartment. If the duct and its normal functioning blowing into the apartment will stop as soon as the wind changes direction and intensity.

In this case the problem is solved by installing on the vent-channel mushroom or convection fan. Such fans are movable spiral, which is mounted at the outlet of the channel on the roof and driven by the warm currents from the sump.

Installing the exhaust fan

What could be easier with inefficient natural ventilation than to install a fan and make forced extraction. This activity is very simple and consists of two steps:

  • Installing the fan in the exhaust duct. To do this you need to coat the body of the fan with liquid nails and place it in the hole in the duct. To strengthen the tightness, you can pre-install PVC sleeve to the diameter of the fan, and foam all the joints and gaps with assembly foam. Its surplus is cut off after drying.
  • Connecting the ventilator to the power grid. It is often connected to the electric line of lighting, that is, if the light is on. the exhaust fan turns on. But a more effective way. display a separate switch, for example, in the place where the light switch is mounted. The fan should not be switched on permanently, as this could cause ventilation problems for the neighbors.

How to write an appeal to the Managing Company (Housing and Communal Services) to check the ventilation

This action is extremely simple:

change, direction, rotation, hood
  • You need to find out whose department the house is in, or rather the address of the management company.
  • Contact the management and write a complaint about the poor ventilation. It is necessary to demand that the application is registered. in this case it will be sure to run in the document flow.
  • The application will be reviewed within three days, after which the employees must appear at the address.
  • The staff is explained the essence of the problem, works to identify possible causes and the feasibility of cleaning ventilation ducts.
  • Appointment of the day of work.

We in the most detailed way understood all causes and preconditions of the phenomenon when ventilation does not blow out the used air but on the contrary fills the apartment with it. It is important to remember that we make our living space comfortable. Everyone can make sure the apartment is filled with fresh air and that the ventilation ducts work efficiently.

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