NCI Article Library

High-Performance HVAC Resources

Current Article Library Category: Air Conditioning

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 Size a New Fan Belt

When you spin an adjustable pulley and increase its diameter to squeeze a little more air out of a belt-drive fan, there are times you'll find the old belt no longer fits. The first fix is to loosen the bolts on the motor mount and slide the motor as close to the fan...

How to Redesign an HVAC System – Part I

We've looked, but can't find it. There are mountains of information about how to design a new HVAC system, but nothing much that addresses how to redesign an HVAC system. It would take hundreds of pages to completely detail the process, but let's take a stab at the...

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 Measure Economizer AirFlow and BTUs

Measuring airflow and BTU's through an economizer can be a challenging task. Many have walked away from economizers shaking their heads without the confidence they have taken good readings. The goal of this article, and the related report and procedure, is to give you...

How to Measure Commercial System Efficiency

How to Measure Commercial System Efficiency by Rob "Doc" Falke, President, National Comfort Institute It’s just not fair. Some contractors have a distinct advantage in the marketplace over their competitors; they ruthlessly and knowingly measure the live operating...

How to Implement CoolMaxx for Maxximum Success

Since the heat has settled over most of the country we have had an increasing number of calls reporting a wide range of methods of implementing the CoolMaxx report. While many of the variations are interesting, after a discussion of how we intended CoolMaxx to be...

How to Hire and Train Duct Renovators

Duct renovators can be entry-level employees that don't have any previous HVAC experience. What's needed are a fair driving record, a clean drug test, physical ability, good people skills and the ability to learn and follow instructions. As you consider making this...

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 Much Cooling Can Your Fan Afford?

The quest for higher efficiency cooling equipment is hitting a barrier. Unsuspecting installing contractors are being handed hidden liability that is difficult to identify and resolve. Certain cooling coils are being built for the highest possible SEER rating, but...