Why the fan is the protocol you forget
The exhaust fan is the single component on a commercial kitchen ventilation system that is most likely to be slowly failing without anybody knowing. It sits on the roof, twenty-five feet from the line, and it makes the same noise whether it is pulling 100% of nameplate CFM or 78%. The kitchen does not feel the difference until the hood fails capture-and-containment in the next certification — at which point the failure is six months downstream of when it should have been caught.
What we check
We check the belt for tension and wear, the sheave for grooving, the bearing for temperature (an infrared thermometer reading thirty degrees over ambient is our threshold for replacement-soon), the motor for amperage draw against nameplate, the hinge for free movement, and the curb seal for water intrusion. We also check the inside of the fan housing for grease — which is part of hood + duct cleaning but which we re-check on this protocol because grease accumulates fastest in the fan housing.
What we replace
Belts, on every visit where they show wear. Sheaves, when grooving is visible. Bearings, when over-temp. We do not replace motors on a quarterly visit; motor replacement is a planned service we schedule on a separate ticket so the kitchen can prepare for the downtime.
We carry common belts for Greenheck, CaptiveAire, and Loren Cook centrifugal upblast units. About 95% of our Houston kitchens are on one of these three OEMs. For the remaining 5% — older Penn Ventilation, Aerovent, S&P units — we order the belt and return on a follow-up ticket within five business days.
What we will not do on a fan visit
We will not work on a roof in lightning. We will not work on a roof in sustained winds above 35 mph. We will not work on a roof we cannot access via a fixed ladder or hatch — temporary ladder set-ups are an OSHA fall-protection issue we will not improvise. If the roof access is not safe, we will tell the operator on the walkthrough, the fan service is suspended until access is corrected, and we will not bill for an aborted visit.
The curb seal
The fan curb is the metal collar that connects the fan housing to the rooftop. It is sealed with high-temperature gasket material, and that gasket is the place water gets into a kitchen. We check the seal annually and replace where compressed below 60% of original thickness. A bad curb seal is a $90 fix. The same seal, undetected, is a $9,000 ceiling repair eighteen months later.