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Under Pressure

static pressure
Reading Time: 2 minutes

Let’s start with a bold statement; air conditioning in your home should never be seen, felt, or heard. You should just walk in and every room in the house should be very close to the thermostat set point. My air conditioner is too loud. My master bedroom is too warm. My office is too cold. This room is too humid. I can’t even begin to count the number times I’ve heard those complaints and more. There are many different reasons; from poor design, to lack of return air, to disconnected ducts and more that can cause these types of issues. Today I want to focus on the problem of incorrect static pressures.

Static what? Static pressure is to an air conditioner what blood pressure is to you and I. Either too high or too low and you are going to have issues. We define the static pressure by measuring inches of water column. Huh? I can hear you right now saying what in the wide world of sports is that? In H2O or in Aq is how static pressure is often abbreviated and it is defined as the amount of pressure exerted by a column of water 1” tall under certain conditions. As with most things, the world of modern technology has taken away the need to use tubes and water to takes these measurements. Today we have digital manometers to do the measuring for us.

If you have a split air conditioning system and you go to the label of the indoor unit known as the air handler, you will see in the very fine print something to the effect that this unit has been tested to perform at .1 to 1” of external static pressure, or this unit is rated to .5” of water column. The manufacturers of the equipment put this on the units to let you know that static pressure is something that impacts the performance of a system. They test the units in sterile laboratory environments and often times some of the things that impact static pressure the most aren’t in play under those conditions. Here it comes, what can I do?

First and foremost, change your AC filter on a regular basis! An impacted filter can raise the static pressure on your system dramatically and make the unit use more energy, work harder, burn out motors sooner, etc. The other major thing that causes huge static pressure issues is the design of the duct system especially in homes built before 1990. These duct systems are often undersized for today’s air conditioners and can really cause problems. As they say at NCI (National Comfort Institute), if you don’t test you guess, and testing static pressure is crucial whenever there is work being done and even more crucial when you are considering purchasing a new comfort control system for your home. We can take the best AC on the planet, and if the ductwork isn’t right that system is not going to work any better than the old one and in some cases the new equipment will perform even worse.

As always, Art Plumbing, Air Conditioning & Electric will be more than happy to come to your home and check the static pressure on your system and help you solve some of the issues I brought up at the beginning of this article. Schedule a visit by calling 1-800-475-1504 or schedule online at today!

House Whisperer out!


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