Static Pressure for HVAC: 5 Tips Before Testing

Static Pressure for HVAC (Blog Cover)

Testing for static pressure in the ductwork of any HVAC system is a basic, yet important part of your job as an HVAC contractor. The static pressure in ductwork is indicative of what condition the ducts are in and can help you diagnose common problems and inform you on what services need to be suggested to the client.

In fact, static pressure testing is such an important part of the job that it becomes routine. Everyone knows that static pressure for HVAC systems should be tested every time you do an inspection. The problem with things we take as a given is that we often slip into auto-pilot mode when doing them. 

One of the most common causes of inaccurate HVAC inspections is a faulty static pressure reading. Faulty readings can happen for a number of reasons but if you aren’t paying close attention or lack the experience, they can be quite puzzling. But fret not. Today we are going to be covering 5 helpful tips for static pressure testing to help you avoid faulty readings and misdiagnosis of HVAC problems. If at any time you would like to read other helpful blog posts or peruse our list of contractor resources, check us out here at Plumbing Heating & Air Alliance. But for now, let’s review some tips on measuring static pressure for HVAC.

1) Check the Blower Wheel

Remember that static pressure needs to be lower than the push of air for the HVAC system to be working properly. And remember that a dirty blower wheel can significantly lower airflow. In fact, just having an eighth of an inch of dust or debris on a blower wheel can reduce airflow in ductwork by up to 30%. So when you are getting a low static pressure reading that looks great, you may not be getting the whole story. Before you do any static pressure for HVAC testing, be sure to check and/or clean the blower wheel.

2) Take your Time

Rushing through a service call is never a good idea. It can lead to some very rudimentary mistakes. With any HVAC system you are testing, you should always take the time to let it warm up and put it through its paces. Static pressure readings may look good when you first switch a system on, but they can change as the system reaches its highest load capacity. So calling the job done too early can once again, cause you to miss out on the whole story. Always make sure to test the first and second stage of 2-stage equipment and take the time to let the coil get completely wet when you are testing cooling capacity. Taking your time and letting the system run through all its stages will help you get the most accurate static pressure readings.

3) Test the Right Spots

Testing the external components of and HVAC system will often lead to inaccurate static pressure readings. The most important places to test a gas furnace are areas prior to the coil, areas built just after the coil, areas prior to the filter, and areas built directly after air leaves the filter. Having a conglomeration of readings from these key areas will help you correct any mistakes and have a clearer idea of what is going on with the static pressure.

4) Install Test Ports Correctly

Drilling test portholes should always be done with a drill bit sheath. If you don’t use a sheath, you could puncture a hole in a refrigerant line or cause a leak in the ductwork which will throw off your static pressure readings 100% of the time. Pushing the drill too hard can also cause problems. You should practice drilling test ports on sheet metal before you do the real thing and make sure you have the proper equipment on hand at all times.

5) Avoid Meter Problems

Remember that if you are using an analog manometer, you can’t simply hold it in your hand. It has to be leveled and zeroed out to give an accurate reading. This happens a lot when HVAC contractors forget that the methods used for testing with an analog manometer and a digital manometer are different. Holding a digital manometer in the hand is fine but you have to make sure that it is set to the right unit of measurement which can change when the batteries are switched out. Be sure your digital manometer is set to inches of water for the most accurate readings.

This may all seem like a lot to remember but impressing these points into your mind will save you much more time and hassle. For more information or to become a member, contact us here at Plumbing Heating & Air Alliance.