Recently had bathroom renovation by the pros. Involved moving bath to other end of room. Plumber has used one of those shallow seal traps and no room under bath for deeper seal. Waste goes to stack so this isn't right. Basin waste also tees into it. Bath trap now getting siphoned. Need pragmatic solution not involving ripping all out. He is suggesting air admittance valve on bath waste and anti vac trap on basin. Is this likely to work. Very angry 
