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Reason You Should Leave the Vents Registers Open of AC

The air conditioner has a lot of important health-related benefits. During hot summer, it helps us by reducing the home’s humidity. Isn’t it comfortable to live in a house that prevents high humidity and creates a less damp home, keeping you healthy? On the other hand, high humidity indicates dust miles, heatstroke, dehydration and mould. 

Nowadays, there is no fixed month or season to turn on the air conditioner. But, we also can’t deny there are a few disadvantages as well. Every appliance you have must be maintained properly so that it runs for a longer period of time. 

In order to save the cost of heating and cooling, many folks keep the vents and the register close. They think that by keeping the vents and the register close, they can save the cost of heating and cooling. Folks think that the heating and the cooling air are redirected somewhere else, particularly in rooms that have open vents. However, the air conditioning does not work like that. 

We will help you to understand –

Reason – You Should not Close the Register of the Air Conditioner

This is the most common question that we come across about whether we should open or close the register. It might be possible that the folk has an entire room that is quite uncomfortable. 

In such a situation, rather than adjusting the thermostat up or down, they control the heating and the cooling supply register. They do this to direct the airflow. 

In most cases, they completely close the register. It is very important to understand the working of the ventilation of the air conditioner. We are quite well aware that air is motionless. There is no external force to move it like a fan. In the case of an air conditioner, the blower fan distributes the air indoors. 

Remember, when you install an air conditioner, the air goes toward the condenser coils for cooling. Or, it is transferred from a heating component and moved to different areas. You may have a fixed or variable motor fan, and it completely depends on the type of air conditioner you have. A fixed motor will maintain a steady rate irrespective of the air pressure you have in your home. 

Basic Idea about Opening and Closing of Registers

We all want a comfortable and safe place where we can relax and get rid of tiredness. Many folks think that the opening and closing register method can help them save energy. This concept is completely wrong. 

This method will lead you to higher energy costs. This can also damage your air conditioner, and it can lead to releasing carbon monoxide poisoning. There are a few points that you must know: 

  1. Daming the AC Conditioner

Folks think that by closing the register, they actually redirect the airflow in another direction. It is just leading the air pressure back into the system. If the register is closed, then it prevents the airflow from moving through the system. Thus, leading to over and under-temperature conditions. 

Henceforth, it leads to overheating damages to blower motors, expands the ductwork leakage, even frozen coil and cracks heat exchange. And, all the exchanges can cost a much higher amount. 

In the case of a big house, around 20 registers, if you close a few, then it won’t harm or damage anything. But, it also won’t help much to make things comfortable. Let us go more deeply into it. 

A zoning system helps by controlling the static pressure at a safe and effective level. Therefore, the temperature sensor and the control panel act as relief valves. 

Henceforth, the system will be able to manage the static pressure and the temperature appropriately. Particularly when the system runs at low temperatures. Thus, you will stay comfortable at any time in any weather.

  1. Wasted Energy and Lost Efficiency 

You might witness closed registers in the unused areas of the house. Now, in those areas, there is already a load due to heat on the roof and in the attic. In case the register is fully closed, you are just adding more load to those areas. It can be even worst – the room must be filled with warm and muggy air, thus spreading to the rest of the house. 

Thus, causing additional strain to the system as it tries to cool and dehumidify air from those rooms. AC was carefully designed so that it can be installed to condition your home. Closing vents does not decrease the airflow coming from the system, rather, it forces the system to work extra.

  1. Bacterial Growth 

Closing the register leads to moisturising the room, thus leading to bacterial growth and mildew. Therefore, if you keep the register and vents open, it will minimise the build-up of bacteria in AC. 

  1. Carbon Monoxide 

Do you have any idea that closing a register will put your family at risk of deadly carbon monoxide poisoning? Well, this is the real fact. This could occur with the heat exchanger. As carbon monoxide is tasteless and odourless, thus there is no warning. Henceforth, it is recommended to install a carbon monoxide detector. 

Why Should You Leave Vents Open?

The reason is quite similar to the register mentioned above. Folks close the vents in the hope of saving money, but actually, they are making things worse. Generally, houses are closed systems, and it is controlled by filtration that keeps the air clean and clear. 

A blower fan circulates the air inside your home. It distributes the heat either by passing it through the condenser coil or picking it up from the furnace. 

You will find two basic types of motors that are used in these fans. One is the variable motor, it adjusts itself based on the amount of pressure. Whereas the other runs at the same rate irrespective of external conditions. The second one is less complicated and slightly cheaper, and it’s quite common in homes. 

Thus, it also means that it will work harder to move the air through a smaller space. We all are well aware that air moves in a cycle. Thus, when it leaves a space, more air replaces it. Therefore, in the home, vents are used to move the air through the window. Henceforth, when you close the air vent, you simply reduce the number of avenues, restricting the flow. 

Drawbacks of Closing Vents

There are certain drawbacks to closing the vents that we will discuss over here. These drawbacks will helps you to have a more clear picture. 

  1. Pressure Problem

Pressure problem is one of the major issues that you might face. Your system has been sized to enhance everything that you need. like from ducts to the climate control unit if it is heating or air conditioning. It is quite similar to the amount of air the blower fan can move with the flow rate of the ventilation system. 

Effective heating reduction in the airflow is quite an issue. The standard motor used in most household blower fans increases the pressure. It means that if the air flows at a lower rate, then it leads to heat transfer problems. Henceforth, the increased pressure means that there is a chance to escape the hot air through the leaks or cause new leaks. 

But, on the other hand, if you have a variable motor, then reduced air flow is not a big deal. It increases the airflow against the additional pressure. It works harder to comprise the decreased airflow, even decreases the lifespan and also costs more energy.

  1. Heat Backup

Heat exchange is another drawback of close vents. If the airflow decreases, proper heat exchange cannot take place. When the hot air moves in the room at a lower rate, it leads to a colder room. For the heating system, the reduced flow rate means the heat exchange temperature increases as the air stays hotter. Moreover, the increase in heat will damage the coil or the exchanger. 


So, this was all about why you should leave the vents and the register open. All the concepts related to this are given. This will help you to deal with the problem. Many people have a lot of misconceptions about whether to close or open the vents and registers. This guide will help you out without much hassle.