Everything I Need to Know about HVAC Systems I Learned from my Economizer
I’ve been interested in economizers* for more than a decade. While they are one small component of a larger system, I see them as a microcosm of the entire HVAC industry — the issues that affect performance of an HVAC system can be seen in economizers, on a smaller scale. I learned:
“If you don’t know it’s broke, you ain’t gotta fix it.”
One field study found that two-thirds of economizers don’t work, which my surveys with contractors corroborated. Hidden on the rooftop, economizers are neglected, broken, or disabled to fix other air conditioning problems, or weren’t configured or installed correctly — or maybe never even connected.
“If everybody’s comfortable, there’s no problem.”
When an economizer is jammed open it brings in 100% outside air, summer and winter, and an HVAC system uses a lot of energy to condition the hot or cold air. Because comfort isn’t affected, it’s likely that the only way the problem is detected is by carefully and critically looking at energy bills.
“Installers and service providers have control over performance.”
I conducted an informal survey on the “HVAC Fault Detection and Maintenance” Facebook group and many said sometimes it’s necessary to leave the economizer nonfunctional to fix comfort or indoor air quality problems, even though the best solution would be a system-wide upgrade. Rather than troubleshoot and fix a potentially complex problem, it’s easier to jam a two-by-four in the damper and within minutes become the hero of the day!
“Owners have ultimate control over performance.”
Lower-priced economizers can have bad damper seals, inaccurate sensors, simplistic controls, and poor performance. When I co-wrote a mandatory requirement in California’s Title 24 to add diagnostics for all economizers, I was warned that alerting contractors wouldn’t do much: they often know the system isn’t performing and don’t say anything because owners don’t want to pay for a fix.
(right) With unintentional irony, a building operator used this economizer controller itself to jam the fresh-air dampers open to provide immediate comfort, with a disastrous cost to ongoing performance.
The solution to these economizer (and by extension — HVAC) problems is a win-win combination of quality factors:
- Monitoring and diagnostics: to detect if a system is not performing and diagnose specific faults.
- Inherently better (but possibly more expensive) designs: eliminating fragile linkages and adding redundant sensors.
- Provide skills and time for quality work: enabling contractors to understand the entire system and giving them the time to diagnose the system and fix root problems rather than apply a band aid.
- Provide accountability: Fancy controls and diagnostics are nice, but they won’t fix a broken industry. Manufacturers, installers, maintenance contractors, and owners should collaborate to make sure that systems perform well.
* Code-required components on roof-top air-conditioning units that use fresh outside air to cool buildings instead of recirculating warm air.
Originally written by Kristin Heinemeier, Frontier Energy — https://frontierenergy.com/blog/#everything-i-need-to-know-about-hvac-systems-i-learned-from-my-economizer
