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 Yellow CO Tags

Last month we brought you a red tag label that you can attach to an appliance when you disable it due to a safety hazard. This month we bring you its cousin, a yellow tag that is to be attached to equipment when you have made modifications or repairs to improve the...

How to Use Static Pressure Budgets

How to Use Static Pressure Budgets by Rob "Doc" Falke, NCI President Static pressure budgets were originally developed to help new air diagnostic technicians interpret static pressure readings. These budgets provide a set of rules to compare pressure readings so they...

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 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 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 Select a Spill Switch

Spill switches provide additional safety whenever barometric dampers have been installed on equipment by sensing heat that may spill from the flue. If the flue becomes blocked, or if the negative pressure in the room causes the chimney to back draft and begin...