NCI Article Library

High-Performance HVAC Resources

Current Article Library Category: Air Conditioning

How to Measure Economizer AirFlow and BTUs

Measuring airflow and BTU's through an economizer can be a challenging task. Many have walked away from economizers shaking their heads without the confidence they have taken good readings. The goal of this article, and the related report and procedure, is to give you...

How Much Cooling Can Your Fan Afford?

The quest for higher efficiency cooling equipment is hitting a barrier. Unsuspecting installing contractors are being handed hidden liability that is difficult to identify and resolve. Certain cooling coils are being built for the highest possible SEER rating, but...

HeatMaxx and CoolMaxx Testing a Huge Success!

We're not quite sure what's driving it, but it appears the HeatMaxx and CoolMaxx service programs are becoming the newest shining stars among NCI-certified contractors. Perhaps it's the change to 13 SEER minimum efficiency equipment that has flipped a switch in...

Gas Pressure Adjustments Done Right

Whether starting up new equipment or servicing existing equipment you should never assume that the recommended gas pressure of an appliance will assure safe or adequate operation. Performance cannot be determined until combustion testing has been completed. There 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 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 to Determine Combustion Air Performance

Combustion air testing is performed using a draft gauge and a CO analyzer. When the draft in the flue of an appliance is low or below -.01" to -.02" W.C. and when CO reading are rising, combustion air problems are present. Carbon Monoxide diagnostics consistently...

How Much Cooling Can Your Fan Afford?

The quest for higher efficiency cooling equipment is hitting a barrier. Unsuspecting installing contractors are being handed hidden liability that is difficult to identify and resolve. Certain cooling coils are being built for the highest possible SEER rating, but...

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...

Heat Pumps Can Handle More Filter Pressure Drop?

It's true: heat pump air handlers can normally afford more filter pressure drop than furnaces with the same fan capacity. As filters continue to increase in efficiency, one parallel fact is that usually the pressure drop over the filter also increases as well....