NCI Article Library

High-Performance HVAC Resources

Current Category: Measurements

Combustion Air – a Grimm Fairy Tale

Combustion Air - a Grimm Fairy Tale by Jim Davis When it comes to combustion air, safety truths created by someone's imagination -- based on little or no factual data whatsoever -- nothing but fairy tales. This article not only addresses the need to provide combustion...

“Air Free” CO or “As Measured” Carbon Monoxide?

by National Comfort Institute, Inc.

Jim Davis, Senior Instructor, National Comfort Institute "Air Free" CO or "As Measured" Carbon Monoxide? by Jim Davis The subject of carbon monoxide (CO) Air Free and As Measured is not new, but still causes confusion due to many conflicting protocols. ANSI standard...

Closing More Sales The Performance-Based Way

by David Holt

Closing More Sales The Performance-Based Way by David Holt, NCI Director Sales & Service Leadership The rapid pace of technological development means that no manufacturer can maintain a competitive edge for very long. Manufacturers develop a hot new box and,...

Changing Fan Speed with an Adjustable Pulley

by Rob "Doc" Falke

Changing Fan Speed with an Adjustable Pulley by Rob "Doc" Falke Adjustable pulleys are the most commonly used method for changing fan speed in commercial balancing. Let’s take a look at how adjustable pulleys work and learn how to adjust them. We’ll also learn how to...

Can Your Fan Really Afford That Filter?

by Rob "Doc" Falke

The air filters we use in our heating and cooling systems are becoming more and more efficient every year. Filter marketing brochures compete to raise our awareness of the legions of dreaded unseen airborne enemies that threaten the peace and security of our homes....

Calculating Heating Energy Savings

by Jim Davis

Calculating Heating Energy Savings It is safe to say 98% of equipment in the field is underfired at factory settings, making that equipment quite inefficient. It can also be said that two-stage equipment can be even worse, especially in "low-fire" mode. To tune this...

Calculate CFM With the Air Changes Method

by National Comfort Institute, Inc.

Some rooms present a real challenge when it comes to determining how much air to deliver. The problem is that heating or cooling load airflow requirements are sometimes very different from ventilation airflow needs. When you find yourself wrestling with this scenario,...

Building Surface Temperature and Your Customer’s Comfort

by David Richardson

Building Surface Temperature and Your Customer's Comfort by David Richardson One of the primary goals of an HVAC professional is to ensure the comfort of their customers. Let's say that you have designed and installed an HVAC system that is absolutely perfect. The...

Airside vs. Refrigerant Performance Measurement

by Rob "Doc" Falke

When it comes to performance measurement of air conditioning systems, most master technicians gravitate to one of two measurement approaches: the airside or the refrigerant side. On one hand, refrigeration experts will challenge anyone who questions pressure and...

A Simple Way to Set Outside Air CFM

by David Richardson

It's often tricky to measure the volume of airflow through an economizer or fresh air intake on a windy day or when a good place for an airflow traverse isn't available. Here's a test method using temperature that will get the job done when the chips are down. This is...