Taking advantage of my boyfriend’s skills

My boyfriend Marcus is really handy. Marcus can fix wiring, hang a door or install drywall like a champ. Basically, any of those manly type of jobs he can do. I told Marcus to hide his skills from my family. My family is very quick to ask for free favors and not really appreciate it. Marcus is such a nice guy thought, he couldn’t help it. The worst is that my family has realized my boyfriend is good with HVAC. It is like him and the HVAC equipment are one. He totally understands how the heater works and how an AC system might break down. Using things around the house, he can do the necessary HVAC repair. Now word has spread around my family that I am basically dating a HVAC contractor. My mother has gotten him over to the house multiple times checking the inside of her gas furnace. My father has him cleaning out the condensate drain on his air conditioner once a week. My brother’s boiler system is basically on life support and needs constant attention. My sister is trying to get Marcus to install her heat pump for her. I think what I am going to do is sit my family down and propose a deal. They either pay Marcus everytime he does something HVAC related, or they are banned from getting his skills. Marcus is just too nice to ask for money or say no to them. So I need to step in and take care of this. My boyfriend should not be my family’s free HVAC contractor.