It works. Pretty damn well, actually. As I recently blogged, there were so many things wrong with the exhaust fan that was here when I bought the previous restaurant that I just went ahead and got a whole new unit. Upgraded it a bit, even.
The difference is huge. Whereas before, the smoke from the char burgers would curl up and under the hood, billowing out into the dining room, the new unit pulls so hard that the smoke literally streams up off the grill and flies right up into the filters and out. It's like night and day. The place already smells less like burgers and fries and I expect that, with time, it will go back to having a fairly neutral smell.
(Not that the smell of burgers is such a bad thing...I just don't want people's clothes to smell like burger grease after eating here.)
I'll resist the urge to share the final cost of the whole operation, but let's just say it was significant and dashed any hopes I might've had about turning a profit this month. The fan I ended up getting was huge--600 lbs--and had to be lifted up onto the roof with a crane. The install was supposed to happen yesterday around 4pm (closing time) but the company doing it called me around noon to ask if they could move it up to 2pm, since the crane would be more expensive at four.
So it all happened while we were open. I was out back, checking out the crane (my cell phone was out of batteries, so I couldn't snap any pictures), running around trying to get people to move their cars out of the parking lot so the crane could maneuver around some electric lines, all while still taking orders, ringing up customers, and making sure that things in the restaurant were happening like they're supposed to.
Except, of course, for the smoke. And the heat. Before the new fan could be installed, the old one had to come out, so we had basically two hours with no exhaust whatsoever, but we were still cooking burgers and fries. So it quickly got pretty hot and smokey. I propped open the front and back doors and warned everyone when they first walked in that it might be somewhat uncomfortable, and everyone was really quite nice and understanding about it.
There were, of course, some issues with the install and so I had to stick around until late into the evening before eventually signing the guy out and writing him a big check. Once it was hooked up and running, I cooked a burger on the char grill just to make sure it was working well, but it was pretty obvious. The draw yanked a piece of wax paper quickly up toward the filter, and it's strong enough to cause the filters to kind of rock back and forth as they get sucked up.
So it's good.
But let's hope not too good. Problems can arise from having too powerful of an exhaust as well. It can create a vacuum by sucking out all the oxygen from a space and cause other gas appliances to get choked off or backdraft, it can pull all the heated air out of the space and require the furnace to run far more than it needs to, and it can sometimes create weird pressure and drafts to move through the space, causing strange problems. This is the kind of stuff that you don't always find out about right away--sometimes these things won't be evident until the weather gets cold, or hot, or humid, or not, or I start running the furnace...or who knows.
We have a passive make-up air system that allows air to flow from outside into the front lip of the hood, which is supposed to prevent the exhaust fan from pulling out all the interior air, and it appeared to be functioning fine today, although there are definitely some new drafts and the door to the kitchen is very difficult to open when the fan is on, so there's certainly some change. Only time will tell if it will be problematic.
Sure hope not. One of the few things that is more costly than an exhaust system is a make-up air system.