Last week, the HVAC community engaged in some diverse and thoughtful discussions. Members explored the origins and implications of the Friday startup superstition, offering insights into industry traditions. There was also a lively exchange on common challenges faced by new technicians when handling large HVAC systems. Additionally, the debate over whether closing vents can actually save energy sparked significant interest and varied opinions.
This Week’s Hot Topics
Origin of the Friday startup superstition
This discussion delves into the history behind why many in the industry avoid starting new projects on a Friday. It’s intriguing to see how such beliefs can shape work schedules and project timelines. Read more here
Where new techs stumble on big systems
Here, experienced professionals share insights into the typical pitfalls that new technicians encounter when working with larger systems. It’s a valuable thread for anyone mentoring juniors or looking to avoid common mistakes. Read more here
Closing vents: energy saver or myth
There’s an ongoing debate about whether shutting vents in unused rooms really conserves energy. This topic is a must-read for those looking to optimize system efficiency while balancing energy costs. Read more here
Looking forward to another week of engaging discussions. As always, your contributions make this community a valuable resource for all.
On the Friday startup superstition, I treat it like a scheduling rule: baselines on Thu, power-up early Fri only if I’ve got someone on-call to babysit alarms, otherwise Monday. For new techs on big air handlers, grab a quick baseline of total external static with a Magnehelic and note the fan curve — closing vents “to save energy” drives me nuts and will spike static. @kevinH, ever tried dropping a $30 temp/RH logger in the return for the first weekend to catch creep without a site visit?
But got burned on a Friday AHU power-up once, so now I use a ‘soft open’ — cap VFDs around 40 Hz, stagger compressor/boiler enables, and widen the DAT deadband for 60 minutes so the BMS doesn’t chase alarms, then tighten back up; like easing a cold engine. @miller33 your on-call rule tracks, but for critical spaces I push to Monday unless the client signs off on risk.
And i’ve had better luck doing a 20–30 minute “vent-only” run with economizer wide open and heating/cooling interlocks held off while trending CHW delta-T, SAT, and return DP — it lets the BAS have its coffee before taking real load. If it has to be Friday, I also set a temporary alarm throttle and route critical faults to @LeahK so one ping gets eyes, not a fire drill. On the vent-closing debate, I’ve seen static creep and rooms go wonky; if you must, crack the door and confirm there’s a real relief path.