We sell a brand new check valve for your Little Giant condensate pump. The CV-10 Little Giant Condensate Pump Check Valve is brand new and comes in a sealed Little Giant factory bag. If your little giant pump is allowing water to flow back into the condensate pump after the pump shuts off then you might need to either clean the check valve or install a new valve. We sell the new valve. The Little Giant CV-10 (599065) check valve is used in Little Giant Condensate Pumps VCC, VCM, VCMA and VCL-14/24. The valve specifications are 1/4″ MNPT (male national pipe thread) to 3/8″ ID vinyl tubing.