Selecting Your Switch
The sump pump switch turns the pump on and off. The on-off cycling of the sump pump depends on the water level within the sump pump pit/basin. Choosing the right switch for your sump pump setup can have a big impact on how long your pump will last. You should choose a switch that will allow as much water as possible to be removed but also let the pump be off long enough to cool down.
Pump down (Normally Open NO)
- PUMP DOWN is normally open contacts for emptying Normally Open Model (high level) The control switch turns on (closes) when the float tips slightly above horizontal signaling a high level, and turns off (opens) when the float drops slightly below horizontal.
Pump up (Normally Closed NC)
- PUMP UP is normally closed contacts for filling Normally Closed Model (low level)The control switch turns on (closes) when the float drops slightly below horizontal signaling a low level, and turns off (opens) when the float tips slightly above horizontal.
The first step in deciding what type of float switch is right for you is to know the size of your your basin. It is important that the switch can move freely without touching the sides. If it does touch the side it could get stuck, causing the switch to function improperly.
14" minimum diameter
Advantages: Provides a longer run time, and a longer 'rest' time for the pump. This means the pump can cool off more completely between cycles. Also, the amount of cord between the attachment (pivot) point and the float can be adjusted. This is great if you have an unusually large sump pit. You can "fine-tune" your pump's on and off points
Disadvantages: Requires a larger sump pit so that it does not get stuck on the walls of the pit.
10" minimum diameter
Advantages: Since the float only moves straight up-and-down, this switch can operate in a very narrow sump pit. There is a bit of adjustability to the switch's "off" point.
Disadvantages: The narrow range of operation makes the pump run more often, and provides less "rest" time between cycles for the pump to cool off.
10" minimum diameter
Advantages: No moving parts means there is nothing that can get stuck. This means the pump is very unlikely to fail to start or stop because of obstructions in the basin.
Disadvantages: If your ground water contains a lot of lime, calcium, or other contaminants, it is possible for those to collect on the probes and coat them. This could mean the probes will not "feel" the water and turn on. You may have to clean off the electronic probes periodically.