NCI Article Library

High-Performance HVAC Resources

Current Category: Airflow

Finding Heat Pump BTU Output

It's 30 degrees outside and the heat pump is running. Let's say it's a 3 ton unit. What airflow should the equipment deliver through the system and what should the BTU output of that system be under current weather conditions? Last month, NCT included a HeatMaxx...

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...

Estimating Heating Equipment Size and Room CFM

by Rob "Doc" Falke

Many members called our tech support line this last month as you've shifted gears to test in heating mode. A large number of the conversations have been about sizing heating equipment and how to estimate room heating airflow. So let's get back to the basics and review...

Estimating Heating Equipment Size and Airflow

by Rob "Doc" Falke

An essential part of diagnostic testing is communicating your findings to your customers. Your success will be in direct proportion to your ability to help them understand the impact of system performance on their comfort, pocketbook, health and safety. Back when...

Economizer Repair Opportunities Are Everywhere

by Rob "Doc" Falke

Economizer Repair Opportunities Are Everywhere by Rob "Doc" Falke Economizers have stepped into the spotlight recently as one of the prime opportunities for energy savings in the commercial HVAC marketplace. It's said, with little argument from those in the field,...

Duct System Installation Don’ts

by National Comfort Institute, Inc.

"Air doesn't do that!" is a common phrase uttered at NCI during seminars and tech support calls. When it comes to delivering the required airflow there are several field conditions that will cut the airflow short every time. Lonnie Robnett of Nevada Heating has...

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...

Duct Loss Test Methods – Which to Use When?

by Rob "Doc" Falke

Duct Loss Test Methods - Which to Use When? By: Rob "Doc" Falke, NCI President NCI has a number of duct loss test methods that can help identify defects in duct systems. But when it's time to test in the field, you have to quickly determine what test will be most...

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...

Diagnosing Cooling Systems

by Rob "Doc" Falke

Compared to the majority of the service techs in our industry, airheads have a distinct advantage when it comes to diagnosing cooling systems. The general idea that the system is "working" means it's typically only producing 60% or less of the equipment rated BTU...