AC System Commissioning w/ MeasureQuick
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Commissioning is the process of testing a brand-new HVAC installation within a new or existing building to make sure it meets the designer or owner’s specifications. Recommissioning is the process of retesting a previously commissioned piece of equipment to make sure it’s still performing up to standard. Retro-commissioning is the process of testing a piece of old equipment that was upgraded or repaired.
Most systems we work on have at least one fault, which is a challenge AND an opportunity for our industry to improve the lives of customers.
The measureQuick field process requires us to start wide; we have to think about the operation of the entire system, not just the appliance. That is where the visual inspection comes in. MeasureQuick gives flags to indicate when there may be problems, but the technician needs to be able to see the potential causes of those problems.
When it comes to controls, we need to look for poor installation (such as holes in the wall), temperature swings, abnormal runtimes, incorrect temperature and humidity readings, breaker and conductor problems, and bad connections.
We also have to inspect the ductwork, which may contain compressed, poorly strapped, or poorly designed duct runs, especially in cases with poorly installed flex ducts. General duct failure can also happen due to excessive heat exposure and disconnected ducts. Air leakage at the top plate also happens, and a telltale time is discolored insulation. Ducts may also be undersized, especially at the return, and they may have restricted return chases.
During system commissioning, the filter also requires special attention. Make sure the filter slot is sealed (and properly sized) to help the customer significantly! Restricted or restrictive filters can cause significant duct leakage. You will want to make sure that you secure filters in place and that they have enough surface area to do their job without creating too much pressure drop.
Watch your condensate assembly; there should be no dirt in the trap (and avoid double-traps), and the pitch should be appropriate. Condensate issues may indicate filter issues.
Once you have done a solid visual inspection, you may begin using measureQuick. That’s when you gather data and deploy probes while the system is stabilizing. Your outdoor probes would go on the suction line or service valve for the suction line temperature, the service valve for the liquid line temperature, about 6-10 inches from the compressor for the discharge line temperature, and out of direct sun for the outdoor air temperature. Inside the conditioned space, your supply probe would go 6 to 10 feet downstream (to give the air time to mix), and your return probe would go at the inlet or drop. (The duct probe placement is the same outside the conditioned space.) Testing in the correct spots is crucial, as you may miss possible problems by measuring in the wrong place and failing to pick up on abnormalities. When evaluating the ductwork, check for unsealed attic entrances and other possible causes of short cycling.
When checking static pressure, we want to make sure we’re checking TOTAL external static pressure, which includes pressure drops over the filter and indoor coil. When measuring the TESP, we have a static pressure “budget” that we like to consult when checking the static pressure in multiple areas.
All measurements have an acceptable range, which we need to be aware of when making measurements. Out-of-range measurements can indicate minor faults, which can be symptoms of major faults and poor performance. MeasureQuick has all of those targets built-in and is programmed to identify minor faults that aggregate into major faults. MeasureQuick can also do pass/fail tests for subsystems, including electrical and air filtration systems.
Once we get the system operating how we want it, we take those measurements and make a report that we can refer back to in the future. We call that benchmarking. Benchmarking allows you to use non-invasive testing moving forward.
The measureQuick reporting system has always allowed you to save data and use geolocation, but it has recently been upgraded to include a consumer-oriented version that assigns the system a “grade” based on performance.
MeasureQuick’s services include giving an overview of the system status, vitals scoring, and diagnostics. The project’s information updates when you add new readings to the app, and you can then generate a report explaining measureQuick’s findings with access to support. Nowadays, Bluetooth tools also connect to measureQuick automatically.