Reverse Contactor - control side help

Discussion in 'The Projects Forum' started by gpfowler, Oct 6, 2008.

  1. gpfowler

    Thread Starter New Member

    Oct 6, 2008
    Evening one and all,

    We have at our location a waterfall with a media filter, UV filter and automated controls for backwashing and rinsing the filter. I'm the new man on the scene and the job is mine and I've found the problem rather easily. Our system during backwash can waste 120gpm. Run it for 2 mins to get the filter clean and that's 240 gallons of water. Simple... The mechanism that replaces water in the feature is about the size of a garden hose and tomorrow I'll check exactly how much water it delivers per minute. The pump has been running dry since installation and I'd bet money that it runs dry after a each and every backwash. A garden hose simply cannot replace 240 gallons of water as fast as it is wasted so there ya go... It has been suggested that I install a reversing contactor on the system feed and control it with the float system used to refill the feature during low water conditions. Basically after a backwash and the water level is low, get a signal from the float system to a relay that will pull the contactor open. The feed for the system in this state will simply be connected to thin air and the system will not run until the water lever is back up, the float system sends it's signal to the relay to fail, close the contactor and turn the feature back on.

    It seems to me that I can use a standard contactor and just turn it on or off based on water-level and that I don't need the "reversing type". I have pictures!

    So what do I use to control the contactor? It's a float system not unlike a toilet and so I need to know what the water level is, and use that information in a meaningful way to control a relay to turn my contactor on or off.

  2. beenthere

    Retired Moderator

    Apr 20, 2004
    A wiring diagram would be helpful.

    It does sound like the float could control a relay with the contacts in series with the contactor coil. If the float dropped low, it would open the relay and pull power off the contactor.