Armstrong Armflo E Series circulators are balanced internally so they will operate quietly. They are also engimeered to be up to 74% more efficient than competing pumps operating at the same flro conditions as well as being up to 30% smaller. This series is designed with ball bearing mtor instead of sleeve bearings and never need lubrication.
Click here for link to technical specs for Armstrong Armflo E.2 Series circulators