24 volt pressure tank switch?

phredophredo Registered Users Posts: 11
I'm installing a pressure tank for my well pump and am looking for one that can be set for 30-50 or 40-60. I'm unclear on the concept: do such pressure switches require electricity or do they just use the water pressure (or lack of it) to open and close the contacts on the switch?

If they do use electricity, does anyone know who makes/sells 24 volt dc ones?

Comments

  • solarvicsolarvic Solar Expert Posts: 1,053 ✭✭✭✭
    Re: 24 volt pressure tank switch?
    phredo wrote: »
    I'm installing a pressure tank for my well pump and am looking for one that can be set for 30-50 or 40-60. I'm unclear on the concept: do such pressure switches require electricity or do they just use the water pressure (or lack of it) to open and close the contacts on the switch?

    If they do use electricity, does anyone know who makes/sells 24 volt dc ones?
    The water pressure turns the switch on and off.
  • BB.BB. Super Moderators, Administrators Posts: 30,642 admin
    Re: 24 volt pressure tank switch?

    And you need to check the power rating (voltage/current) of the switch... AC switches tend to be smaller than DC switches of the same rating because AC is much easier to turn off... DC tends to sustain arcs better and need larger contacts and different design to help stop the arcs from causing damage to the switch.

    Most times, you will find switches with both a DC and an AC rating--you will need to make sure that it exceeds your voltage/current rating of your pump.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • phredophredo Registered Users Posts: 11
    Re: 24 volt pressure tank switch?

    Thanks. So the answer is: they don't use electricity themselves, but since they are part of the circuit they need to made to support the electricity that will pass through. My motor is 24 volt, 15 amp. I would think that a switch that would work with a typical 3/4 hp 220 volt ac submersible would probably work with my situation, but maybe not. Do you know where I can find such switches? Solar energy websites? Or where? And thank you again.
  • solarvicsolarvic Solar Expert Posts: 1,053 ✭✭✭✭
    Re: 24 volt pressure tank switch?

    Square d pressure switchs are for sale everywhere. Home depot, Lowes, any pump dealers and just about any good hardware store. Amazon even has them.
    Shouldn,t cost over $20. S:Dlarvic
  • phredophredo Registered Users Posts: 11
    Re: 24 volt pressure tank switch?

    Thanks. This is a great forum!
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: 24 volt pressure tank switch?

    Square D P switches work quite well, but they are not specifically dc rated. It was suggested to me that if you down rate them to ~25% of the amperage rating of the switch it should be fine.

    I use a conventional Square D with a Shurflo 9300 submersible pump, drawing ~9 amps @12 vdc. Has worked fine for several years.

    Your 24 vdc, 15 amp load should do just fine with a switch rated ~30-50 amps.

    Tony

    The difference between DC and AC is that when you switch DC, especially at higher currents, the power has a tendency to "jump" the gap when the switch is opened much greater than AC, therefore inducing arcing. The risk is that switch contacts can become pitted over time, and could possibly weld themselves shut.

    (Bill, did I explain that right?)
  • solarvicsolarvic Solar Expert Posts: 1,053 ✭✭✭✭
    Re: 24 volt pressure tank switch?
    solarvic wrote: »
    Square d pressure switchs are for sale everywhere. Home depot, Lowes, any pump dealers and just about any good hardware store. Amazon even has them.
    Shouldn,t cost over $20. S:Dlarvic

    I was on conenergy website and they mentioned not to run real high pressure as your dc pump will use twice as much energy. If you have a larger dia, pipe running to your water tank, less pressure is needed. Also the surges from your pump wont effect the switch as much. Because people use a smaller dia pipe is the reason you have to have higher pressure. So I would either get a 20/40 switch or a 30/50 switch. If you use about 1 1/2 inch pipe from the pump to pressure tank the 20/50 is probably ok. You can still kick it up or down about 5 lb. pressure on the on and the off. S:Dlarvic
  • BB.BB. Super Moderators, Administrators Posts: 30,642 admin
    Re: 24 volt pressure tank switch?

    Tony--You are correct as I understand it...

    And regarding the "plumbing"--listen to those around you that have the experience... I am not a plumber--but as I understand you don't want a huge pipe either--You can get sediment build up with slow moving water.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: 24 volt pressure tank switch?

    In the real world, go with the minimum pressure that you are comfortable with. Every PSI above what you really need comes at some pumping cost. That said, I went with a higher pressure just to have more litres worth of drawdown without the pump having to kick on.

    In my case, I try to pump water only during the day, so during the evening, the pump doesn't have to run even if the P-switch calls for water at 30psi, and I can still get a good shower down to ~15 psi. I have to be careful however, because once it drops much below 20 psi, the tank runs dry very fast,, it is not a gradual draw down!

    (I have mine set 30/50)

    Tony
  • phredophredo Registered Users Posts: 11
    Re: 24 volt pressure tank switch?

    It sounds like you are partly addressing my questions at my other recent post about pressure tank and switch considerations with my SimplePump because you mention "surges". The type of pump I'll be using is similar to an electric motor powered "windmill pump" so it will produce surges of water, and, I suppose, pressure. The idea of making a larger gap than the usual 20 psi difference of a 30-50 or 40-60 spread, that is a 20-50 spread, might help me solve the problem I asked about there. The "surge" of pressure might temporarily raise the pressure to 50 even though the average pressure might be less, so when the pump shuts off I might still be realizing something like a real 20-40. Is that a bit of what you are suggesting? I confess I didn't understand everything you said, especially about the effect of the larger pipe size.
    solarvic wrote: »
    I was on conenergy website and they mentioned not to run real high pressure as your dc pump will use twice as much energy. If you have a larger dia, pipe running to your water tank, less pressure is needed. Also the surges from your pump wont effect the switch as much. Because people use a smaller dia pipe is the reason you have to have higher pressure. So I would either get a 20/40 switch or a 30/50 switch. If you use about 1 1/2 inch pipe from the pump to pressure tank the 20/50 is probably ok. You can still kick it up or down about 5 lb. pressure on the on and the off. S:Dlarvic
  • solarvicsolarvic Solar Expert Posts: 1,053 ✭✭✭✭
    Re: 24 volt pressure tank switch?
    BB. wrote: »
    Tony--You are correct as I understand it...

    And regarding the "plumbing"--listen to those around you that have the experience... I am not a plumber--but as I understand you don't want a huge pipe either--You can get sediment build up with slow moving water.

    -Bill
    I have had a sediment filter for a long time. I had problems with the water shutoff valves sticking on my washing machine causing the water to overflow. After I put the sediment filter on it that stopped the problem. I have 1 inch from pump to tank and 3/4 inch from there. S:Dlarvic
  • phredophredo Registered Users Posts: 11
    Re: 24 volt pressure tank switch?
    icarus wrote: »

    Your 24 vdc, 15 amp load should do just fine with a switch rated ~30-50 amps.

    Thank you, sounds like what I need to know.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: 24 volt pressure tank switch?

    I don't know about the new ones but my pressure switch (110v) has adjustment on both the hi and low pressure, so I can set it to 20 psi for on and 80 psi for off if I want to, but use 35 / 60 psi for household use and yes we have 1/2 inch pipe for the most part ...

    HTH
    Eric
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • Chuck46Chuck46 Solar Expert Posts: 95
    Re: 24 volt pressure tank switch?

    here is a link to the pump I use it works fine. Give them a call and see if they have a pressure sensor that might work

    http://www.theresourcestore.ca/proddetail.php?prod=R4515-743

    Have fun
    Chuck
  • BigwoooBigwooo Solar Expert Posts: 60 ✭✭
    Re: 24 volt pressure tank switch?

    When you buy the pressure switch, buy two of them. They're inexpensive and do tend to go out. It's nice to have a backup and not have to wait until you can get a new one before you have water flowing again.

    While we're on the subject, my Square D switches corrode fairly rapidly. I get about 3 years out of the switch before it's kaput. We live on the coast, and no matter how sealed the utility room is, the switch is prone to corrosion. Are there any other brands that provide a sealed compartment for the contacts?
  • solarvicsolarvic Solar Expert Posts: 1,053 ✭✭✭✭
    Re: 24 volt pressure tank switch?
    Bigwooo wrote: »
    When you buy the pressure switch, buy two of them. They're inexpensive and do tend to go out. It's nice to have a backup and not have to wait until you can get a new one before you have water flowing again.

    While we're on the subject, my Square D switches corrode fairly rapidly. I get about 3 years out of the switch before it's kaput. We live on the coast, and no matter how sealed the utility room is, the switch is prone to corrosion. Are there any other brands that provide a sealed compartment for the contacts?

    I don,t know if this is good thing to do or not. In my old mobile hame I had the storage tank buryed by the well and kept the pressure switch inside the furnace compartment where the entry lines connected on the plumbing and never had a problem. Then when I updated to a manufactured home I got a crawl space basement that has water tank and switch and I started replaceing switches because it sweats in my basement and the points get caroded. The last one I connected the wires and put a light coating of vaseline type grease you put on aluminum wire and this one has lasted twice as long so far as the previous ones did. S:Dlarvic
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: 24 volt pressure tank switch?

    Sv makes a good point. Within reason, the Pressure switch need not be at the tank. Since the switch only sense pressure in the pipe, the pressure will drop off (relatively) equally through out the plumbed system. So instead of putting the switch in a damp well house, there is no reason that you can't install it under the kitchen sink for example. Of course that leads to some more complicated wiring, but there is no real reason you can't do it.

    Tony

    (Same with pump controllers)
Sign In or Register to comment.