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I have a chlorine feeder (120v Stenner 45) that is supposed to run at the same time my well pump (240v) is running.

Currently they are set up on separate pressure switches, with the chlorine feeder set to switch on (40.x psi) slightly before the well pump (40 psi) is triggered and off slightly before (59.x psi) the well pump (60 psi) shuts off. Obviously this isn't ideal because A) it is hard to keep configured and working properly, and B) there is a chance that the chlorine feeder could be triggered, yet the well pump not get triggered (there is at least quart difference between the 2 trigger pressures), leaving it to run longer than needed.

As I see it, I have a few options:

  • Buy a 240v chlorine pump and run them off the same pressure switch ($$$).
  • Find a different type of switch for the chlorine feeder - e.g. flow switch.
  • Find another way to run the chlorine feeder off the same pressure switch as the well pump. If it's possible, this seems like the easiest approach. The 240 well pump line has 3 wires, I presume black and white are both hot and the ground. Is it possible to wire this switch to a 120 device (and leave it on the 240 well pump)?

  • Other?

  • If you're going to do anything that is remotely expensive (eg, more than the relay) you might want to consider ditching chlorine and going to a UV system. Aside from being quite nasty and dangerous to deal with and adding smell/taste to the water, chlorine treatment byproducts can include trihalomethanes (THMs), some of which are classified as a potential carcinogen. UV systems have no byproducts and are much simpler to deal with (replace filters as needed, replace bulb yearly). – gregmac Mar 7 '17 at 16:49
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    This is a bad idea because all uses of the well water might not need chlorination. Irrigation for instance, during an irrigation cycle (assuming the irrigation bypasses all the water conditioning systems you have), the chlorinator is injecting chlorine into the holding tank but there's not water coming out the other side, so the chlorine concentration rises until the irrigation cycle is off. Now run some water at the faucet and you get a high concentration of chlorine water. Better to use a flow switch. – enorl76 Mar 7 '17 at 17:16
  • gregmac - agreed, this is a short-to-medium term solution until we replace our water treatment set-up. enorl76 - good point. We don't do much irrigation, so I don't think this will be a big problem for us, but definitely something to keep in mind. Thank you. – Josh Mar 7 '17 at 17:19
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Use a relay with a 240 coil (connected to the well pump circuit) and 120V contacts (connected to the feeder.)

Use the pressure switch only to switch relays (at any convenient coil voltage) and use (suitably rated for the power) relays to switch both devices. But the first option will be cheaper - only one relay, and that for the low-power feeder.

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    The first option (240V relay in parallel with the pump control box/power) is the common way to do this. For the second option, you'd need a contactor (rather than a relay) to control the well pump, the wiring is more complicated, and there's really no benefit at all. – gregmac Mar 7 '17 at 16:42
  • Thanks for the response. I agree the first option you mentioned looks easiest/best. I've done some basic electrical work, but relays would be new to me - is this (amazon.com/…) the type of product that would help me do what I need to do? Then I'd pigtail the power coming out of the well pump pressure switch, leaving it connected to the well pump and connecting it to the relay? Then connect the other side of the relay to the chlorine feeder? – Josh Mar 7 '17 at 16:53
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    I actually use a relay to run my pump - it's a 3/4 hp pump and the relay is rated 240V 2 Hp - but I do it because the electrical supply and the water inlet are far apart, so rather than run pump power across the building and back, I run a control wire across the building, and save about 100 feet of pump wire. The relay you post is of the right general sort, if probably overkill (don't know the ratings on your chlorine pump.) If it's 1/3 HP or less, mouser.com/ProductDetail/Altech/RUC-2013-26-5230/… will do for under $5 – Ecnerwal Mar 7 '17 at 17:51
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(Note I do not endorse this setup of 'always running the chlorine injector with the well pump if theres any irrigation running from the same well pump, see my comments in the other answer.)

It is possible to run the 110v injector off one of the 220v legs. The well pump is running 220v already and the injector pump is 110v, simply run an additional line off of either of the pressure switch contacts.

I can take a picture of doing this sometime this weekend.

  • Thanks, enorl76 - so, clarifying question - do I not need a neutral wire from the well pressure switch to the chlorine injector? Thanks, a picture would help a lot. – Josh Mar 7 '17 at 17:30
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    Hi! Just checking that you intended to post two distinct answers (instead of one that covers both options). – Niall C. Mar 8 '17 at 2:02
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The best answer is flow switches for a reasonable cost and solves the irrigation problem http://www.pool-spa-supplies.com/grid-controls-flow-switch-model-225-2in-spg-25amp-57-f1-2225-00w

Install the flow switch inline to the conditioned water flow, and run the irrigation on a separate line so as not to trigger flow in the conditioned water side.

Some of these switches have additionally a 110v receptacle installed that would enable you to simply plug in your injector pump into the flow switch and the flow switch will automatically turn on and turn off the injector pump as conditioned water is demanded into the house.

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