How Does a Boiler Condensate Tank Work?

A boiler condensate tank holds water produced by the boiler heating process until it reaches a preset level and is discharged from the tank via a condensate pump. This system of water discharge is used on steam heating systems as well as on air conditioners.

The condensate tank receives the water from the boiler via a discharge line that runs from the bottom of the boiler. Inside the tank is a float, which triggers the condensate pump to start discharging the excess water. The pump will run until the water level in the tank no longer activates the float.

The water line from the condensate tank is either attached to the plumbing under a sink or basin or to an inside or outside drain. The line is placed in back of the waste trap to prevent it from running back up inside the basin. For this to work, the waste trap, or the "U" section, must measure at least 75 millimeters, or roughly 3 inches in length.

Some boiler and air conditioning systems have condensate tanks that have two pumps. One acts as a back-up for the other. These are two-stage systems. If the first pump doesn't start expelling the water when the first stage is reached, the second pump is triggered. During normal operations, the pumps will alternate being first and second pump to make sure both are operational.