What is the purpose of an equalizing loop?
An equalizer or equalizing loop is to have the same pressure on the supply side of the boiler as the return side of the boiler. As pressure builds on the supply side of the boiler the pressure goes through the header and some goes to the system and some goes into the equalizer. In the equalizer there is water as high as the water level in the boiler. The pressure pushes down on the water. With the same pressure on the supply as return sides of the boiler the water stays in the boiler. See a drawing of an equalizer loop.
