Merrill-Float
Installation Guide

Existing conventional pressure tanks | PFB / PFC

About the Merrill-Float

Help keep air and water separate.

The Merrill-Float is a foldable floating diaphragm for older pressure tanks. It rides on the water surface to reduce air absorption and help prevent waterlogging.

Before you start

  • For existing, bladder-free, air-over-water pressure tanks only.
  • Verify float size fits the tank inside diameter and an existing access opening.
  • Shut off pump power. Fully drain and relieve pressure before removing fittings.
Opening size
Float diameterOpening
12–20 inches1¼ inches
24 inches1½ inches
30–36 inches2 inches

Four-step installation

  1. Shut off & drain

    Turn off pump power. Drain the tank and verify all pressure is relieved before opening.

  2. Check the opening

    Confirm tank and float fit. Remove a suitable existing fitting; never cut or drill the tank.

  3. Insert the float

    Gently fold the float and feed it through the opening. The float will automatically unfold inside the tank.

  4. Reseal & test

    Reseal the opening. Restore the correct air charge per tank instructions; restart and check for leaks.

ImportantNever open a pressurized tank. Do not modify the pressure vessel or use in bladder tanks.

Technical review — before publishingConfirm float-to-tank sizing, fold method and air-charge procedure.