NCI Article Library

High-Performance HVAC Resources

Current Category: Measurements

Five Airflow Rules You Need to Know

To understand airflow, you need to have a firm grasp of the rules driving airflow characteristics and behaviors. What you’ll find is many of the most complicated issues you encounter often tie to an airflow problem. Let’s look at five airflow rules that can help you master the airside of your profession.

FisherAir Heating & Air Conditioning Services, Brea, CA

by National Comfort Institute, Inc.

Alan Fisher, President of FisherAir Heating and Air Conditioning Services in Brea, California, was one of the first technicians certified by the National Balancing Institute (now National Comfort Institute) in the early 1990’s. His company has kept the flame burning ever since.

Find CFM By Measuring Coil Drop on New Installs

by National Comfort Institute, Inc.

There's a fast test for a new installation that is highly accurate and takes just a few minutes. You can get system CFM by measuring pressure drop over a new coil. You simply plot the pressure drop on the coil engineering data sheet and read the airflow passing...

Do You Know How External Filter Racks Impact Total External Static Pressure?

by David Richardson

Do You Know How External Filter Racks Impact Total External Static Pressure? A few weeks ago I was asked a question about finding the proper location to obtain the entering static pressure reading on an upflow gas furnace using an external filter rack. This is one of...

Duct Sizing Made Easy

by Rob "Doc" Falke

ACCA manual D and other similar programs are the industry standards for duct sizing. But from hundreds of unofficial polls conducted in our seminars, we have learned that in the "real world" these programs are used for designing less than 1% of the residential and...

Diagnostic Tests That Teach and Sell

by Rob "Doc" Falke

Since the mid 1980's most contractors have been selling air conditioning and heating using methods like slick calculations that promised return on investment and energy savings. Times have changed and so have our customers. Today's buyers are better equipped to make...

Design Vs. Redesign

by Rob "Doc" Falke

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 one. It would take hundreds of pages to completely detail the process, but let’s take a stab at the basic ideas....

CSER Enters Its Second Year

by Rob "Doc" Falke

CSER Enters Its Second Year by Rob "Doc" Falke Since the introduction of CSER™ (NCI's Cooling System Efficiency Rating), last year, the number of contractors that measure their system's total BTU delivery has skyrocketed. Many have enjoyed the benefits of measuring...

Cool Weather Testing in Cooling Mode

by National Comfort Institute, Inc.

Measuring wetbulb temperatures on a cooling system under a low or no load situation is a whole new ballgame. What happens is that a system operating in cool weather in a building with no load on it generates extremely rapid temperature changes. If you take the...

Commercial Boiler Combustion Testing

by Jim Davis

Commercial burners may appear to be intimidating and you might feel they're too big to for you to work on. But when you gather the nerve to get your hands on one you'll find they are not that complicated and are quite simple to combustion test and adjust. Commercial...