Well pump control circuit problems


Old 07-10-15, 09:11 PM
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Join Date: Jul 2015
Location: United States
Posts: 2
Well pump control circuit problems

I am working on a semi complex water system. There is a Mercoid switch at the tank house as the pressure switch. There is approx. 1100 ft of switch wire run down the mtn. to the pump house. The pump is controlled by a Franklin 5hp deluxe control box and has a soda ash pump tied into it. There is also a second pressure switch that is supposed to be a safety (I don't think it does much) tied into the switch wires at the pump house. We are having an intermittent problem where the contacts in the Franklin control box are sticking and keeping the pump on. It's not the box, as we have tried 3 as they keep backups around. There is a blow-off valve to protect tanks and pipes, but we are afraid it will burn up the pump. This is a vacation home area, so it is not watched close enough to catch a malfunction for hours or longer at times. I was told you could rewire the mercoid switch with 220v to where it will not allow this to happen, but it will be a several days before he can explain. Does anyone have any ideas? Here is a couple really rough drawings of the system. Right now there are 3 occopuied homes with no water as we just had to shut the pump off again for the second time today, but it worked perfect frome Sunday evening until last night. No one in my area wants to touch this system, so calling in electrician or plumber is out of the question.
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Old 07-11-15, 12:29 AM
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Location: Northern NJ - USA
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Welcome to the forums.

The circuit is very basic. I have the switch line highlighted in pink. When they are shorted the pump runs. These are the two wires you have going to the Mercoid switch. You also show a second pressure switch as a safety. Right now.... either pressure switch will start the pump. That is incorrect. You have the Mercoid one shown wired correctly. The safety pressure switch needs to be wired in series so that when it's activated the pump stops. That means that the safety pressure switch needs to be a normally closed switch until the pressure rises and then it opens breaking the switch line.

First things first..... disconnect that safety pressure switch.
If you still have problems..... your Mercoid switch is sticking closed or you have a short in your 1100' of switch wiring.

In the bottom of your diagram.... what is light switch for pump ????
There shouldn't be any switch in the control line unless it's there to OPEN the line to stop the pump.

Your Mercoid pressure switch is already switching 240v


Last edited by PJmax; 07-11-15 at 12:48 AM.
Old 07-11-15, 11:55 AM
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Join Date: Jul 2015
Location: United States
Posts: 2
Thanks for the help so far. I have disconnected the second switch and we are still having the same issue. The Mercoid switch is not sticking because it has flipped every time the pump has been stuck on. The issue is very intermitent. Sometimes it hangs 2-3 times a day and sometimes it runs for a week or 2. The switch at the bottom is to cut the pump off from the tank house when servicing the system.

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