I think you could scale or franchise a vent cleaning business, focusing on dryer vents. Who else to trust but a trusted firefighter to clean the dryer vents that cause over 15,000 house fires a year! And for upsells, you could clean the lint from the inside of the dryer where the inside duct is, sell a 30" lint brush, new dryer duct from dryer to wall, dryer balls, Lintgard dryer safety monitor AND have your guys trained to go on the roof if needed to unclog the end cap. All great money makers. But wait..... since your guys are there and it is Firefighter Duct Cleaning..... why not upsell them to paint their house number on the curb. You and I both know every house in the world needs the number painted on the curb.