Welcome my friends and in the usual tradition I am opening today’s post with a bold statement. A properly designed HVAC system should never be seen, felt or heard. You should just walk into your home or office and whatever the thermostat is set at is what it should feel like within the space. The humidity should be around fifty five percent and the space should just feel great to you, whatever your preferred temperature is.
Okay, so why is my air conditioner so noisy? The first and most prevalent cause of air conditioning noise is when we have duct work that is improperly sized. If the supply or return ducts in the home are undersized for the unit you will get air noise. The more undersized the duct work the higher the velocity of the air becomes, thus raising the decibel level, sometimes to the point that you can’t even hear yourself think when the air conditioner comes on. Of course in the category of stating the obvious, a jet engine is much louder than a car motor and the same principle applies to the velocity, the faster something goes the louder it gets. Unfortunately, in most homes built before the year 2000 we find ducts that just can’t handle the volume of air today’s systems deliver. So, what’s the fix?
We first need to begin with running some diagnostic testing of the system to determine whether or not the ducts are causing the noise. In some cases, for example, if the blower motor of the air handler is located in the base of the cabinet vs. the center of the cabinet, that can cause a huge noise problem. Other examples of noise issues can be improper wiring in the air handler, any type of restriction in the ducts, and sometimes it’s just the system is aging and needs to be updated.
Now back to our testing. We’re going to check the air speed and the static pressures. If my FPM (feet per minute) of the air is over 400, we are definitely creating a noise problem with the speed of the air. Next up, we check the static pressure to confirm the reading on the FPM. Faster air is always equal to higher pressures and more noise.
The good news is that we can oftentimes correct a noise issue rather easily. It can be as simple as adding supply or return air ductwork to the existing system, thus slowing the air down and decreasing the static pressure. In other cases, the fix may end up being full duct system replacement depending on the style of duct work and the age of the system. Of course, as usual this House Whisperer suggests you enlist the aid of a certified HVAC tech to help you address any noise concerns you have and get the peace and quiet you so richly deserve.
Speaking of velocity can someone please email me the airspeed velocity of an African swallow laden with a coconut? My Monty Python fans shall certainly understand. Until next week, I strongly believe a good pun is its own “reword”.
House Whisperer out!!
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