NCI Article Library

High-Performance HVAC Resources

Hydronic Balancing: A New Frontier for NCI Contractors

As we are in the process of developing a commercial air and water balancing training and certification program for larger systems, we have been creating hydronic balancing forms and procedures. Water systems have been an integral part of commercial air conditioning...

Adjusting a Ball Valve on Intake of 90% Appliances

Adjusting a Ball Valve on Intake of 90% Appliances by Jim Davis, NCI Senior Instructor In our combustion diagnostics class, we discuss short flues on condensing equipment as causing possible venting problems. We recommend adding a plastic ball valve to the intake of...

How to Use Fan Performance Data in Your Diagnostics

Almost every day we receive requests for additional generic fan performance tables other than .50" table we published previously. Well, you asked for it, you got it. We've just introduced two new generic tables, one for constant speed blowers with up to .80" ESP and...

How to Use Air Density Correction Factors

Air density correction factors have been a part of our air balancing curriculum since the early 1990's. NCI published a small table years ago and encouraged you to make corrections for air density when measuring airflow at higher altitudes. But the accuracy you are...

How to Plot Fan Airflow

How to Plot Fan Airflow by Rob Falke To be well prepared for this new level of diagnostics, begin collecting copies of the fan data found in most installation instructions for the equipment your company installs and services. The most important diagnostic truth about...

How to Maintain Your Combustion Analyzer

The primary goal of combustion testing is to take readings you can trust so you can evaluate the operating condition of the combustion appliance. In order to take readings you can trust you have to be sure your combustion analyzer remains in tip-top shape. The...

How to Get Diagnostic Work

Nearly all systems are in need of air-side and combustion diagnostic, but getting permission to test the systems, and getting the customer to agree to pay for repairs requires more than technical genius. We asked a number of successful NCI Performance-Based...

How to Determine Combustion Air Performance

Combustion air testing is performed using a draft gauge and a CO analyzer. When the draft in the flue of an appliance is low or below -.01" to -.02" W.C. and when CO reading are rising, combustion air problems are present. Carbon Monoxide diagnostics consistently...

How Airflow Affects Heating Efficiency

Airflow is critical to proper heat transfer in heating and air conditioning systems. Most of us know the rule that temperature drop over a cooling coil should be 18 to 22 degrees. If the temperature drop increases, it is evidence that airflow is low. If the...

Home Performance Belongs to the HVAC Industry

There’s more hype and misleading information than ever out there with regards to what constitutes “home performance.” Today, you are faced with several important issues, including what role you should play with regard to home performance. Outside of some basic...