What You'll Learn

• What the NCI AirMaxx test measures: delivered airflow to each room, total system airflow, and room-by-room balance
• When to use AirMaxx versus a simple static pressure screening
• Equipment needed: DG-1000 or flow capture hood
• How to start and run the test in measureQuick
• How to interpret results: room CFM, percentage of total, and balance scoring
• How measured airflow compares to design CFM (Manual J or equivalent)

What You'll Need

• Device: iPhone (iOS 15+) or Android phone (Android 10+) with measureQuick installed
• Account: measureQuick account with NCI Air Upgrade activated (see NCI Air Upgrade Setup)
• Airflow measurement tool: DG-1000 with TrueFlow plates, powered flow capture hood, or balometer
• Room layout or design data: Manual J load calculation or equivalent design CFM values for each room (optional but recommended)
• Time: 30-45 minutes depending on the number of registers

What NCI AirMaxx Measures

The NCI AirMaxx test measures the actual delivered airflow at every supply register in the building, then compares each room's measured CFM to what it should receive based on its heating and cooling load.

A system may produce adequate total airflow at the equipment but deliver too much to some rooms and too little to others. This imbalance causes hot and cold spots, humidity problems, and comfort complaints that have nothing to do with the equipment itself. AirMaxx identifies exactly where the imbalance exists and how severe it is.

The test produces three key outputs:

• Room-by-room CFM: The measured airflow at each supply register
• Percentage of total: Each room's share of the total system airflow
• Balance score: How closely the actual distribution matches the intended design

When to Use AirMaxx vs Static Pressure Screening

The static pressure screening (H1) tells you whether the duct system has an overall restriction problem. It answers: "Is total airflow adequate?" It does not tell you where the air is going.

AirMaxx answers a different question: "Is the right amount of air getting to each room?"

Use this decision framework:

A system can pass a static pressure screening (TESP within limits) and still have severe distribution problems. If total airflow is 1200 CFM but 500 CFM goes to three rooms and the other seven rooms split the remaining 700 CFM, the system is out of balance even though total airflow is fine.

Step-by-Step Guide

Step 1: Set Up the NCI Air Upgrade

If you have not already activated the NCI Air Upgrade on your measureQuick account, complete NCI Air Upgrade Setup first. AirMaxx is part of the NCI Air integration and requires an active NCI subscription.

Step 2: Open the Quick Test

From the measureQuick home screen, open a project. Navigate to the Quick Tests menu. Select NCI AirMaxx.

measureQuick opens the AirMaxx test interface. The app prompts you to define the rooms and registers you will measure.

measureQuick Quick Tests menu showing AirMaxx with TrueFlow and AirMaxx with Fan Table options

Step 3: Define Rooms and Registers

Enter each room in the building that has supply registers. For each room, specify:

• Room name (e.g., "Master Bedroom," "Kitchen," "Living Room")
• Number of supply registers in that room
• Design CFM for that room, if known from a Manual J calculation or design documentation

If you do not have design CFM values, measureQuick can work with measured values alone. You will still get room-by-room CFM and percentage of total, but the balance score will compare against a proportional distribution rather than a specific design target.

[Visual Reference] AirMaxx room setup screen with a list of rooms entered for the building. Each row shows the room name (e.g., "Master Bedroom," "Kitchen," "Living Room"), the number of supply registers in that room, and an optional design CFM field from Manual J or design documentation. Rooms can be added, edited, or removed before beginning measurements.

Step 4: Measure Total System Airflow

Before measuring individual registers, capture the total system airflow. This establishes the baseline that room-by-room measurements are compared against.

Methods for measuring total system CFM:

• TrueFlow plates with DG-1000: Install TrueFlow plates at the return grille, run the system, and measure pressure drop across the plates. The DG-1000 calculates total airflow from the calibrated plate resistance. This is the most accurate method.
• Flow capture hood at supply trunk: Place the capture hood at the main supply trunk if accessible.
• Sum of individual register measurements: If you cannot access the main trunk, the sum of all register measurements serves as total system CFM. This method has higher cumulative measurement error.

measureQuick records the total system CFM value.

Step 5: Measure Each Register

Move room by room through the building. At each supply register:

1. Place the flow capture hood or measurement device over the register
2. Wait for the reading to stabilize (3-5 seconds)
3. Record the CFM value in measureQuick for that register

If a room has multiple supply registers, measure each one. measureQuick sums them for the room total.

Work systematically. Start at one end of the building and move through every room to avoid missing registers. An unmeasured register means missing airflow in your totals, which will make the balance calculation inaccurate.

Measuring a supply register with a flow capture hood, measureQuick displaying the live CFM reading

Step 6: Review Results

After measuring all registers, measureQuick calculates:

• Room CFM: Total measured airflow to each room
• % of Total: Each room's share of measured system airflow
• Design vs Actual: If design CFM was entered, the difference between what each room should receive and what it actually receives
• Balance Score: An overall score reflecting how closely the actual distribution matches the target

[Visual Reference] AirMaxx results summary after all registers have been measured. The screen lists each room with its total measured CFM, percentage of total system airflow, and (if design CFM was entered) the difference between design and actual. An overall balance score indicates how closely the actual air distribution matches the target. Well-balanced rooms appear near their design percentage; rooms significantly over-served or under-served stand out in the comparison.

Interpreting the Results

Well-Balanced System

Each room receives within 10-15% of its design CFM. The balance score is high. No individual room is severely over-served or under-served.

Common Imbalances

• Master bedroom receiving 150% of design CFM while back bedrooms receive 60%. This usually indicates duct routing favors rooms closer to the equipment. The master suite, often closest to the air handler, gets more airflow because it has shorter, less restrictive duct runs.
• Rooms with long duct runs receiving less than 70% of design CFM. Friction losses in long runs reduce delivered airflow. Solutions include larger duct sizing, additional duct runs, or duct booster fans.
• One room receiving almost no airflow. Check for a disconnected duct, a closed damper, or a crushed flex duct in the attic or crawlspace.

What "Good" Looks Like

For existing residential systems, a room receiving 80-120% of its proportional share of airflow is generally acceptable. For new construction or performance-verified installations, the target is tighter: 90-110% of design CFM per room.

Video Walkthrough

• YouTube (HVAC School): (23,171 views, 1:05). Jim Bergmann on airflow measurement methodology and the relationship between static pressure and delivered airflow

Tips & Common Issues

My room measurements do not add up to the total system CFM

A discrepancy of 5-10% is normal due to measurement tolerances and minor leakage between the equipment and the registers. A discrepancy above 15% suggests either missed registers, significant duct leakage (see Duct Leakage Test), or an error in the total system measurement. Recheck your register count and duct tester setup.

The capture hood does not fit over an oddly shaped register

For registers that do not accommodate a standard capture hood, use a cardboard adapter or transition piece to create a temporary seal between the hood and the register. Some flow hoods include adapter kits for non-standard sizes.

I do not have Manual J design CFM values

You can still run the test. measureQuick will report measured CFM per room and percentage of total. Without design values, the balance score compares each room's share against a proportional distribution based on approximate room size or equal share. The room-by-room data is still valuable for identifying severe imbalances.

Should I run AirMaxx on every service call?

No. AirMaxx is most useful for comfort complaints involving uneven temperatures, new installation commissioning, and post-modification verification. For routine maintenance, a static pressure screening (H1) is faster and sufficient. If the screening passes and the customer has no comfort complaints, there is no need for a full register-by-register measurement.

The balance score is low but the customer has no complaints

Document the findings. Some homeowners tolerate imbalances that others would find unacceptable. The data gives you a documented baseline. If the customer later reports comfort problems, you already know where the distribution issues are.

Related Articles

Prerequisites (complete these first):

• Static Pressure Screening - Quick TESP check and the 140% rule
• NCI Air Upgrade Setup - Activating the NCI Air integration in measureQuick

Follow-up articles (next steps after this one):

• Duct Leakage Test - Quantifying air lost through duct leaks
• Component Pressure Drops - Evaluating individual duct section contributions to pressure loss
• TESP Budget & 140% Rule - Breaking TESP into component pressure drops

Related in the same domain:

• BluVac Evacuation Test - Quick test for vacuum and decay testing
• Static Pressure Screening - When a quick total system check is sufficient

Need Help?

If you get stuck or this article does not answer your question:

• Check the Related Articles section above
• Contact measureQuick support: support@measurequick.com
• Schedule a training session with the measureQuick training team