The house you live in has a network of air ducts hidden behind the walls of your home that make up its ventilation system. The air ducts are in every room where the air in your home comes in and out from, and the HVAC (i.e., Heating, Ventilation, and Air Condition) system is more significant than just a compressor in your home background or the furnace in your basement.
The ducts permit airflow for heating and cooling; you might not have also known the vents serve different purposes. There are two types of vents which are supply vents and air vents; you will learn about the difference between these two in this article.
What supply vent and return air vent are
What a supply vent is
Your mind probably goes to the supply air vent when you think of an air vent, but they are pretty different from the return air vent. The primary job of a supply vent is to provide the rooms in your house with conditioned air. To differentiate vents between each other, you can try putting your hand in front of them; whichever one blows cool and conditioned air is the supply vent. You can adjust the airflow and the direction to suit your taste by using the adjustable slats.
What the return air vent is
The return air vent sends the air into a direction opposite that of the supply air vent, and they are usually more extensive than the supply air vent. The return air vent takes the excess air in the room and returns it to the heating and conditioning system to condition the air and pump it back into the home through the supply vent. You can carry out a paper test to identify a return vent; simply do this by placing the paper on the front of the vent; if the piece moves towards the vent, the vent is a return air vents.
Unlike the supply air vent, they don’t have adjustable slats because the air isn’t going into your rooms. They are usually located in the ceilings, on the floor, or on the base of the wall. There should be at least one return air vent in the room, but one isn’t good enough; two to three return vents are the standard.
The critical differences between supply and return air vent are
- The supply vent supplies the room with conditioned air, while the return vent takes out excess air, conditions it, and sends it back through the supply air vent.
- You can have at least one return vent, but there must be up to 3 supply vents in a room.
- The return vent is larger than the supply vent.
- To recognize a supply vent, you can put your hands in front of it while you should use paper to identify a return air vent.
- You can adjust the airflow for a supply vent in the adjustable slat, but you can’t change the airflow for the return air vent because the flow of air direction is towards the heating and cooling system.
The difference in temperature between supply vents and return air vents
Although we have mentioned some noticeable differences between supply and return air vents, we highlighted the ideal temperature differences below. For both supply air and return air vent, there is no standard temperature you should set the HVAC system to, but a perfect temperature difference must exist between the supply and return vent.
The temperature difference ranges between 16 to 22 degrees Celsius, which means your HVAC system works well. If it is not within the range stated above, you should consider checking the vent for fault. When it comes to air conditioning, the evaporator Delta T will inform you about the AC’s evaporator coil performance which is highly responsible for cooling the warm air in your home. Find out how to determine the delta T for your system below.
Find the temperature probe.
The temperature probe is the ultimate device you will use to measure accurately and quickly the surrounding air temperature.
Take note of the return vent temperature.
In this step, you should measure and record the temperature of the return vent.
Take note of the supply vents’ temperature.
You should measure and record the temperature of each supply vent in this step.
Calculate the average temperature of the supply vent
Sum up the temperature of each supply vent and divide by three to get their mean temperature.
Determine Delta T
Delta T is the result of subtracting the return air temperature from the mean temperature of the supply vent, and it must be within the range of 16 to 22 degrees.
What happens when Delta T is too high?
When you calculate the difference between the temperature of the return vent and supply vent and the temperature difference doesn’t fall in the range of 16 to 22 degrees Celsius, your AC system might not be working correctly. The temperature difference that doesn’t fall in between this range may result from the airflow through the coil. This could result from:
- Your air filter is dirty, or it could be the evaporator that needs cleaning.
- The size of your ductwork isn’t big enough.
- The fan set speed is wrong.
To correct the temperature difference of an AC system with a high Delta T value, you can try any of these:
Replacement of the air filter
It could be that the air filters are overheated as a result of constant use, so you can replace them to reduce the temperature.
Hire an expert
You should hire a professional if you don’t see changes after replacing your air filter. The professional would find the correct issue with your HVAC system.
What happens when Delta T Is Too Low?
When the Delta T temperature is less than 16 degrees, the temperature difference between the incoming and outgoing air temperature is not high enough. Here are highlighted reasons why Delta T is lower than 16 degrees:
- Not enough refrigerant levels
- Leakage of reverse valves
- The return air ducts leak
- If the compressor valves become weak.
In this case, hire an expert to check the system, identify the problem, and proffer a solution where necessary.
You now know what a supply vent and return vent is and the importance of each. What step would you take to recognize?
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