I thought I would start a thread with ideas on adding profits to a hood cleaning stop and maybe some other ideas would follow. Somehow it ended up with NFPA/filter selection and construction. My point was was just this, sell filters, make money. Here is another one. Offer fan belt service. If you carry a pail of belts from 4L200-4L400 in size you should be able to match justa bout any size belt. New England are has, for the most part, upblast type fans. Most common size 4L340-4L370. You can charge $30-$45 for a two minute job with belt cost avr.$8.00. If a customer has to get an electrician in to fix a broken belt they would charge $125-$200 in this market area. Just trying to offer up some info from 20 years in the trade.