I have read all of the info I could find about washing machine drains and vents. We just bought a home with all new appliances and our washing machine backups every time we use it. The previous owner thinks the plumber suggested a vent to solve to problem. My problem is that we cannot even find the existing vents to attempt to snake or any directions on how to install an additional vent. Is it possible that there are no plumbing vents in our 3 bathroom home? Is there another option, such as a compression valve on our washing machine drain hose, that would possibly prevent water overflow in the drain? We are capable of doing some of the work ourselves, but are not sure where to begin!