21887U Beckett Precision Delay Timer Kit (PD Timer) For 120V CleanCut Pumps
PD stands for “Precision Delay”. The PD timer is used with the CleanCut pump in retrofit applications when the pump is installed on a burner that does not have a pre-purge control. One end of the PD timer is wired in with the burner motor, and the other end is plugged into the built-in valve on the CleanCut pump. When current is applied to the PD timer, the timer has a built in 4-second delay before it allows the current to flow through to the valve. When the motor and PD timer are powered at burner start-up, the motor begins spinning, but the timer holds the valve off for 4 seconds. At the end of the 4 second delay, it opens the valve and allows oil to flow.
The PD timer should be used because it allows the burner motor to get up to full speed before opening the valve. This is important because the motor is what creates the air pressure and pump pressure in the burner. If oil is allowed to flow BEFORE the burner reaches the rated air and pump pressures, the result is a slow, potentially dirty light-off. The PD timer ensures a clean, crisp light-off.
The PD timer is NOT needed when the CleanCut is wired to controls with pre-purge because the control already has a built in 15 second delay before opening the oil valve, which ensures that the motor is up to full speed.
Because most new controls already have pre-purge, the PD timer is primarily intended for use when a technician is upgrading a pump without a valve to a CleanCut with a built in valve. In these cases, the controls usually do not have pre-purge, which is why we included the PD timer in every CleanCut pump kit.Beckett 21887U Precision Delay Timer Kit (PD Timer) For 120V CleanCut Pumps