Setting pre-charged tank pressure

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Reach4

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Is that 24 volt powering pump the pump AC or DC? Is that a solar- or wind-charged battery? Most pressure switches are not rated for DC, although you are probably fine. How many amps does the pump draw... just curious.

I am thinking that you would be more interested in minimizing power consumption than somebody plugged into $0.12/KWH electricity. You would use less power if your pressure switch was set to 30/50 PSI compared to using 40/60. So if 30/50 does the job, I would tend to get a pressure switch that is preset to that. If you use the search feature on the Grainger website, I remember seeing a selection criterion that lets you select that. I chose that for the Grainger link that I put into post #15.

Using only one side of a 2-pole switch is not wrong. But paralleling sides will give it a little more capacity to carry the amps.

I'll be going to Grainger's..
Grainger does not have a showroom. They are aimed at the professional and industrial crowd. I think it used to be that they would not even sell to DIYers. They may not have everything in stock. I suggest placing your order through the web, and just picking up your stuff at "will call". That will save time for you too, including not having to make a return trip.
 
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UPDATE..
things are normal now..the Parts2/0 press. switch from HD is working fine, it needed some coaxing.
Here's why. It states in the instructions that differential is factory set and not adjustable. Ok, it also states nothing about the smaller adjusting nut.
However, looking at the inside of the switch cover you'll find something different.. instructions that say the smaller nut will RAISE cut-out pressure! So, a few turns and now I'm at 36-56, about where I wanted, and the pump takes about 3 min. 45 seconds to fill the tank. (We're using propane water heaters that require above average water pressure.)
Reach4, the pump is 24V, powered by two large 8D batts. and two solar panels @60 watts each, going to the switch DC, and re-wired as you suggested (per pump instructions, in series, to extinguish the arc that forms when contacts break).
The pump draws a max. of 15 amps. I hope I've got enough solar wattage..so far so good.
I powered it via solar not to save electrical power but to use when the power is out here, as happens frequently.
After the last major hurricane there was no water and no power in this area for 3 months..it's what you get when you're at the "end of the road". You wanna stay married, no? Got to be a boy scout. (hotels are expensive ;)
Thanks for all your input..
Will pick up another press. switch next trip to town at Grainger's. Their store here is pretty well stocked..I remember when they didn't sell to DIY'ers, glad that's changed.
 

LLigetfa

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On Square-D pressure switches you can completely remove the small spring and still have 20 PSI differential. The small nut/spring can only increase the minimum differential, not decrease it.
 

DonL

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I'll do as you suggest...it is how the pump diagram shows it. I wired it this way on the advice of a friend with a similar setup, although with house current. He's knowledgeable in electric wiring but not a pro. It's probably not correct.


AC is not the same as DC.

For DC you leave the ground connected and put the switch contacts in parallel on positive, that doubles the current the switch can handle.

I think you are asking a lot from that pump and batteries. Cutoff at 50 would be more better, I think.

Good Luck on your project.
 
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