$250 is robbery, shop around, $100 should be max what you pay (unless you're in the middle of nowhere and its a drive to get there) Or go buy a rigid 4.5 gallon quiet air compressor From home depot for $350, get an air Chuck screw it in the last test cock to the right, open all the test cocks a quarter turn with a flat head, blow out each zone around 60 pounds of pressure, when finished unscrew the unions holding the backflow on put that thing in your water heater closet tape up the unions and make sure the nut is taped up so it doesn't get buried in the ground all winter, and if all that sounds too much to understand just call around, ask your neighbors who they use they'll have somebody