Activating Pump via low voltage switch input

[Tim Fastle]

So, I started this in the water well forum and am now here. Long story short, I need to move my well pressure tank and pressure switch to accommodate a filter, softener and supply after an addition (about 40 feet). At the new location I do not have 24oAC nor incoming wires from the well (those are both at the old tank location).

I hope to move the pressure switch to the new location and actuate the pump via a contactor (or relay) at the old location. I am thinking I would install a 24vdc transformer at the new pressure switch location and run two wires from it (one through 1 pole of the pressure switch as the switch leg) to a double pole NO contactor at the old tank/pressure switch location (about 40 feet). Then wire it up through the contactor with the 240vac supply on one side and the well pump controller on the load side (as it was wired with the pressure switch there).

I don't know a ton about relays and contactors. I gather they are basically the same but contactors are better for heavy load applications. I believe it's a 1.5 hp submersible pump, 24ovac, single phase. It draws just under 10 amps when it fires up and runs at about 9.5 amps per my meter. Does this sound like a reasonable solution to those in the know and how might I search and sourse the transformer and contactor. Or should I just use a relay (as in this is not a load that needs heavy duty)? I was thinking a contactor would be more heavy duty and reliable but I don't really know that. I looked around at some suppliers online and could not make heads or tails out of the specs with regard to their contactors and relays because I am not remotely familiar with the terminology. I am thinking 24vac because it seems to be somewhat standard but am not married to it if there's a better option. Also, what gauge wire would I need for a 40 feet run in this case. I'm guessing not very heavy.

Any thoughts or input would be appreciated.

Thanks!

 

[Jadnashua]

The pressure in the line at the current location is likely the same it would be at the new location of the pressure storage tank. IOW, you probably can leave the switch where it is, or tap it into a line near where it currently is. There's typically only one check valve in the system, so sensing the pressure would be the same anywhere after that. Maybe I'm all wet, but I'd not want to deal with moving more than you have to.

 

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[Tim Fastle]

That was my original thinking and I'm not sure if it's off by a lot so I appreciate where you are coming from. I did some reading and the consensus of the well experts seemed to be that the closer to the pressure tank the better. The thinking seemed to be that being far away there could be brief drops when a valve is opened near the pressure switch or between the pressure switch and the tank and cause frequent and quick cycling of the pump which, for obvious reasons, you don't want. Moving the pressure switch in the manner I am thinking will not be overly difficult, I just don't have enough experience at this time to source out exactly what I need. Last night while laying in bed I had another thought. I would have to guess they make 240vac connectors (and relays) that have a 24vac power source built in which would also simply it a bit.

 

[Jadnashua]

What gauge wire is being used now to run your pump? Why couldn't you essentially just extend those wires to the location of the new tank?

You could use a new pressure switch to switch a low voltage circuit that in turn operates a power contactor if you don't want to extend the current power lines to the new switch location. You need to ensure that the relay or power contactor has contacts rated to support the size motor in your pump. The larger the contactor power it can handle, often, requires a bit more current, so use large enough wires so there isn't a big power loss and a transformer that can provide enough current to adequately hold the coil tight.

 

[Tim Fastle]

It's wired with 12 gauge wire. I thought about running the wires to the new location and back but it will add 80' to 100' which is probably an increase of 1/3 over again and I didn't want to risk the voltage drop. Also, would rather use a much smaller wire. And yes, my plan is to just use the existing (or one like it) pressure switch as the switch to actuate the relay. Having looked at quite a few relays and contactors I think I am leaning towards one that has the transformer built in but am not sure which is best.

 

[Jadnashua]

You might be able to do this with a wireless control, no wiring between things required. check out www.smarthome.com for some ideas.