Don't waste your money. Get a good capillary tube flow restrictor from Spectrapure or Buckeye, trim it to fit acccording to your exact water conditions and forget the "flush valve". It does nothing but lighten your wallet and give you a warm fuzzy feeling, it has no proven documented value. If you want to flush something get a DI bypass valve and flush the TDS creep out before t hits your DI resin, that does have proven value.