Pump unions in the 4 main sizes, 2" being the most common. NONE of the dimensions relate to ANY measurement on the union. Sizing help, union outside diameters : 1" union = 2-2/8" - 57mm 1-1/2" union = 2-13/16" - 71mm 2" union = 3-3/8" - 81mm 2-1/2" union = 4-1/4" - 105mm

Unions There are no products in this category.


  • Step-up unions
  • Unions 1"
    1" Pump unions are only used, in Europe, with the Waterway Tiny Might. The diameter of the union is 57mm.
  • Unions 1-1/2"
    Pump unions 1-1/2 inch. This size on union can be found mostly on Circulation Pumps and also, more rarely, main pumps using wet ends such as Aqua Flo. The diameter of the union is 71mm.
  • Unions 2"
    Pump unions 2 inch. The most common pump union used on Waterway and Aqua main pumps. The diameter of the union is 81mm
  • Unions 2-1/2"
    Pump unions 2-1/2". This size of union will ONLY be found on the suction (face) of Waterway pumps when they have a 2-1/2" wet end. The diameter of the union is 105mm.