Most of my posts on this site are HVAC related. But as a hobby, I sometimes tinker with Microcontrollers. Microcontroller ADC’s have a “resolution” formula that is often stated incorrectly.
Hopefully, this post can clarify some confusion for beginners.
The original talk on this topic was a Power Point presentation. The PDF attached does not have the benefit of the verbal commentary along with the slides.But it still conveys some key concepts and should prove useful. (There is some “inside” humor sprinkled around, as the original was intended for my own Company Project Engineers – please ignore.)
I wrote this booklet in the middle 80’s when pneumatic controls ruled in the HVAC Industry and DDC was just beginning to appear. (We were all fascinated with what can be done with a microprocessor based control with 16k bytes of memory!) Although the content is a little dated, I still think it should serve very useful for people trying to figure out just what a PID controller does and how it is different from a straight Proportional only controller.
I will post this booklet in 3 parts: Part-1 Introduction and Proportional. Part-2 Integral. Part-3 Derivative.
I hope you find it useful. Please click on the PDF link below and then come back here for your comments.
Many HVAC engineers work their entire careers and retire without realizing that what they always thought of as Fan Static Pressure is not how ASHRAE, AMCA or the fan manufacturer’s define Fan Static Pressure (FSP). The concept of Fan Static Pressure is a purely “defined” one – there is no direct measurement in the field that corresponds to “Fan Static Pressure”. FSP is commonly confused by Engineers with the Fan Static Pressure Rise or Duct Static Pressure Rise.
Confusion in the use of the terms STATIC PRESSURE and TOTAL PRESSURE is widely prevalent among HVAC Engineers and Contractors. There are serious consequences of not distinguishing clearly between the two, and one example would be that you make troubleshooting more difficult and in some cases impossible.
This article clarifies the distinction between Static Pressure and Total Pressure.
The art of peddling Boilers has shifted from the realms of Logic and Thermodynamics to sheer magic and out-of-context truths. It is becoming imperative for Engineers like myself, who get involved with selecting Boilers maybe four or five times a year, to educate ourselves about the basic facts of boiler efficiency. In this series of posts we will take a closer look at the work-horse of our industry – the common commercial gas fired hot water boiler in the 2 million BTU input range. The posts will attempt to investigate the realistic level of efficiencies that might be expected from these boilers. We will assume that no special “heat recovery” contraptions are in use.