What Does Timed Dose Mean?

In this article, we’re going to help you understand how your timed dose panel works. First, we’re going to explain what timed dose means. Then we’ll walk you through how simplex and duplex panels work in a typical system. Let’s get started.

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Safety Note: Please use caution while handling your pump control panel. We have designed them with the highest safety standards in mind, however they are complex electronics and can cause death or serious injury if used improperly. Only follow the instructions provided and contact our support team if you are unsure of what to do.

What Does It Do?

timed dose dosing schedule off and on

Timed Dose panels like our Model TD turn pump(s) on and off based on a dosing schedule and the liquid level in the pumping chamber.

A dosing schedule is the combination of the Off and On timer settings.  This allows for a more consistent volume of effluent to be pumped as it does not fully empty the tank in one dose.  A Timed Dose control panel allows effluent to be pumped incrementally throughout the day to prevent over saturating the leach field.

Timed Dose panels can also trigger an audible/visual alarm, letting you know when the liquid level in the pumping chamber reaches a certain level.

How Simplex Timed Dosed Panels Operate

simplex timed dose floats: alarm and timer enable/low level cutout

Simplex Timed Dose panels typically control one pump using 2 control floats:  Timer Enable/Low Level Cutout and Alarm.  When the water rises in the pumping chamber and lifts the Timer Enable/Low Level Cutout float, the control panel calls the dosing schedule to start.

The dosing schedule always starts with the Off cycle.  The Off cycle is the rest period in which the pump is not activated.  It is the minimum amount of time between the On cycles. Once the Off cycle has concluded, the On cycle will commence.  The On cycle is the duration in which the pump is called to run.  If the Timer Enable/Low Level Cutout float is still lifted up after a completed On cycle, the panel will call for another dosing sequence, starting with the Off cycle.

If the liquid level in the tank rises faster than the dosing schedule can accommodate, the alarm float will rise and activate the audible horn and visual beacon. You can press the Silence Test switch to the silence position to deactivate the horn for the current alarm condition. The alarm will remain active until the alarm float lowers down to the off position, clearing the alarm condition. When the panel is not in an alarm condition, pressing the Silence Test switch to the test position will activate the beacon and horn to test functionality.

SJE Rhombus Timed Dose panels are designed for 2, 3, or 4 float operation.  Two float operation consists of Timer Enable/Low Level Cutout and Alarm Floats. Additional floats that can be added are the Redundant Off and Timer Override floats.

The optional Redundant Off float is designed to ensure the pump turns off when the tank does not have enough liquid to warrant a dosing sequence.  This float is mounted below the Timer Enable/Low Level Cutout float, it is the lowest float in the tank.

Timer Override is the other optional float.  It is designed to bypass the dosing schedule and call the pump to run regardless of current Off or On cycle state.  This float is generally installed above the alarm float to provide alarm notification before timer override is activated.  In certain situations, it may be appropriate for the timer override float to be mounted below the alarm float.  Please note using this setup will not provide alarm notification unless the pump is unable to keep up with the liquid level demand.

How Duplex Timed Dose Panels Operate

duplex timed dose system switching to pump 2

SJE Rhombus Duplex Timed Dose panels work with the same Dosing logic as our simplex Timed Dose panels.  The difference is the Duplex panel alternates pumps between the On cycles.

The duplex Timed Dose panel will call pump 1 for the first On dose.  It will call pump 2 for the next On Dose. It alternates between the two pumps every other cycle, equalizing pump wear. It also alternates this way for Timer Override doses.


Now you understand the theory behind how your timed dose panel works! If you have any questions, please contact our customer support team at techsupport@sjeinc.com or at 1-800-746-6287.