My hot water tank for my high pressure soap and wax keeps overflowing. I thought it was the inlet float/fill valve. I changed it but it still fills up when im not there and overflows. So I thought maybe it was coming back up from the outlet in the bottom of the tank. I drained the tank and had someone go to each bay and use high pressure rinse as I watched the tank but no water backed up in it. Im not sure if it only backs up when using high pressure soap or wax? Didn't want to try those functions while the tank was empty. Any help is appreciated.