NCI Article Library

High-Performance HVAC Resources

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...

Humidity Testing Tips

The primary challenge in effectively measuring humidity is accuracy. The two major elements affecting accuracy are the reliability of your test instrument and the measurement technique that you use. Choose a good quality instrument. Many low cost instruments are...

HSER™ Season is Upon Us

HSER™ Season is Upon Us by Rob "Doc" Falke In May of 2004 we released the CSER ™ and HSER ™ procedures to NCI Members. With the success many members have enjoyed with CSER this summer, several members requested that we address HSER again this fall with additional...

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 Select Your First Water Balancing Gauge

When it's time to take your first try at measuring the performance of a hydronic system, you might want to begin with some starter instruments. A hydro- manometer like the big boys use normally costs over $3000.00 each. Although well worth it, you may not want to part...

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 Does Air Balancing Save Energy?

How Does Air Balancing Save Energy? by Rob "Doc" Falke, President, NCI Air balancing is a relatively small specialty profession with less than 3,000 commercial supervisors certified by four major organizations. There are fewer than 7,000 residential balancing...

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...

Guaranteed Comfort, Memphis, TN

Butch Conway, President of Guaranteed Comfort of Memphis, Tennessee is our choice for August NCT Contractor of the month. Butch and his wife Lynnette started the company in 1992 with Butch saddling his truck until 2001 when he finally began to dedicate all this time...