I got a call today that was just a little different than most. When it comes to restaurant hood cleaning you never know what kind of call you will get. My customer said that the kitchen hood didn't have much suction. It was sucking out the smoke, but not as strongly as before. I knew that I had just cleaned this account about a month and a half ago so it wasn't that dirty (quarterly account).
There are only a few things to check when it is a problem with smoke in the kitchen. My first thought is usually a belt. Either the belt has broken or it is just loose and is slipping too badly to draw enough air. The customer told me that they had went on the roof to check that and air was blowing out of the top of the upblast fan really strong. Not the belt.
Next, I had him check the filters; they were clean. Not the filters.
Then, I had him check the make-up air. He said both vents in front of the hood were blowing like crazy. Not the make-up air.
By this time, I'm a little confused. What else is there? Well, this particular kitchen exhaust system has duct work snaking through the attic, I remembered. ACCESS PANELS! The customer went into the walk-in attic and checked the access panels. Nope, both were tight, he said. Ah-ha. "There is a third access panel hidden on the other side of the duct in one of the bends", I told him, "did you check that one?" It wasn't easy to get to and harder than heck to get pressure washing equipment back in there to clean, but he got back there and checked.
He said that it had slid down and the access hole was wide open. He finally got the access door put back on and it started working like a champ. What happened was I didn't get it tightened down completely and it took it a month and a half to slide down enough to leave the hole open and affect the ventilation of the hood system. My bad. Lesson learned.