The mechanical float valve that EVAPCO uses operates with a makeup water pressure between 20 and 50 psi. When the makeup water pressure exceeds the 50-psi limit, the makeup valve will not close. The reason for this is that the buoyant force of the float ball and arm mechanism cannot overcome the force that the water pressure exerts on the valve. Therefore, when the water pressure force is greater than the buoyant force, the float ball is forced down and the valve stays open flooding the cold water basin. In addition, the excessively high water pressure will wear out the valve seat.
The solution to this problem is to simply add a pressure reducing valve (PRV) to lower the makeup water pressure to below 50 psi. Keeping the makeup water pressure to the cooling tower between 20 and 50 psi will ensure adequate operation of the mechanical float valve.
For additional troubleshooting assistance, please contact your local EVAPCO sales representative.