Sump and Sewage Pump Float Settings

Norm Hall
May 10, 2010
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There are basically four float control schemes used in sump and sewage pump applications. Simple one pump sumps normally have a single float attached to the pump, which is off when the float is down and turns the pump on when the level raises to a level of 7” to 10”. When the amp draw of the motor is less than 15 amps and the pump is single phase, you could use a “piggyback” switch available in various lengths. ITT Bell and Gossett Centripro series A2E float switch can be used on pumps up to ¾ HP at 115 volt and 2HP at 230 volt.

diagram showing piggyback switch Alarm and Pump Control

Simplex, single phase applications, with very little storage of the effluent, can be handled with a two float system. One float operates the pump, as above, and a second float operates the alarm. B&G offers weatherproof alarm panels, with and without battery backup, for these applications. The elevator sump we discussed in the MMM a few weeks back is an example of this control.

Most commercial duplex applications use three or four of the B&G Centripro A2D switches with bare leads to be wired to a control panel. In the four float system, the low level float turns the pumps off, the next float up turns on the lead pump, the next float turns on the lag or standby pump, and the highest float turns on the alarm. In a three float system, the third float turns on the lag or standby pump AND the alarm.

Many representatives recommend the four float system, but R. L. Deppmann Company recommends using a three float system. In a four float system, the lead pump could fail. The system would continue to operate off the lag pump. You would not know about the failure until the lag or standby pump also failed, allowing the level to rise to the alarm condition. Call the R.L. Deppmann Company to discuss the best float system for your application.

…R. L. Deppmann Company recommends the use of a three float system…

3 Float System

Disclaimer: R. L. Deppmann and it’s affiliates can not be held liable for issues caused by use of the information on this page. While the information comes from many years of experience and can be a valuable tool, it may not take into account special circumstances in your system and we therefore can not take responsibility for actions that result from this information. Please feel free to contact us if you do have any questions.

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