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Thread: Explain something to me

  1. #1
    DIY Junior Member he8833's Avatar
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    Default Explain something to me

    My pop just received a bid to run a very simple irrigation system with ONLY 2 zones 1 for the grass and 1 for a small bed of flowers. It would be supplied by a small Goulds .75hp pump which draws from the lake....He is used it for years, but now wants the sprinklers lines buried etc vs having to haul hoses around the yard and adjust the sprinkler location

    The irrigation guy came out I believe said all that would be be needed would be 2 solenoid valves and I believe a pump start relay.

    When I asked my pop what safety mechanism (blowoff valve) or something along those lines would he install to prevent the pump from deadheading, he was told one of the valves would always be OPEN. In the event one of the vales didnt open the power would not be supplied to the pump. It sounded like the irrigation guy was saying power is sent to the solenoid valve FIRST. And once the system opens the valve, then and only then would it power up the pump? Thus averting the pump ever turning on without @ least 1 of the valves being open.

    Does this sound right? What I'm having a hard time grasping is do these solenoids valves have a mechnism to shut off the pump, if they dont open? What if they get stuck? How can we prevent the pump from deadheading or overheating if one of the valves got stuck when it was alternating bewteen zones. Or worse if both somehow were closed? Perhaps nothing is needed...Can someone explain?
    Last edited by he8833; 08-10-2010 at 03:02 PM.

  2. #2
    General Engineering Contractor ballvalve's Avatar
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    I believe the pump relay can be actuated with the valve, but if the valve fails the pump might deadhead against a defective valve. Be sure you have a pump with a high temperature cut -out switch that will sense the problem and shut off. You can also install an adjustable pressure release valve just below that pressure. But likely you will not have problems, the solenoid valves are quite reliable.

  3. #3
    DIY Junior Member he8833's Avatar
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    Quote Originally Posted by ballvalve View Post
    I believe the pump relay can be actuated with the valve, but if the valve fails the pump might deadhead against a defective valve. Be sure you have a pump with a high temperature cut -out switch that will sense the problem and shut off. You can also install an adjustable pressure release valve just below that pressure. But likely you will not have problems, the solenoid valves are quite reliable.

    The pump is over 20 years old....My pop has had it serviced in the past...Would the high temperature cut out switch or pressure valve be something he could have added on @ the shop that services this pump? Or is this even neccessary if the pump can be actuated with the valve?

    And what exactly does that mean? The power goes to the valve first and based on whether it succesfully opens, it then and only then would power the pump on?

  4. #4
    In the Trades Wally Hays's Avatar
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    end switch on the valve calls the pump relay. simple wiring. Effective
    Perception is 3/4 of reality

  5. #5
    DIY Junior Member he8833's Avatar
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    Wally

    Can you explain....Is this something the irrigation guy adds...or I need to have added at the shop that services the pump...

    I need more information/details so I can make sure the irrigation guy sets this up so their is no chance of the pump turning on without the @ least one of the valves open.

  6. #6
    Moderator & Master Plumber hj's Avatar
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    The pump circuit on timers turns the pump on about a minute BEFORE any valves open so the pressure has time to build up. The system should have a storage tank, AND a pump pressure switch, so the system has a stable, controlled, pressure to work with at all times. The valves do NOT have a circuit which would activate the pump AFTER they open.

  7. #7
    General Engineering Contractor ballvalve's Avatar
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    I assume he is wiring a relay into the 24 volts at the valve. No delay, and no problem unless the valve does not open. seems a 7$ pressure relief valve is all the insurance he needs. I dont think they want to complicate it with tanks and using a timers pump delay circuit. Perhaps they have a timer with no delay, but it still does not know if the valve is open or plugged.

  8. #8
    DIY Junior Member he8833's Avatar
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    Quote Originally Posted by ballvalve View Post
    I assume he is wiring a relay into the 24 volts at the valve. No delay, and no problem unless the valve does not open. seems a 7$ pressure relief valve is all the insurance he needs. I dont think they want to complicate it with tanks and using a timers pump delay circuit. Perhaps they have a timer with no delay, but it still does not know if the valve is open or plugged.

    Ballvale

    Yes he wants to keep it as simple as possible no pressure tank.

    Are you saying he is safe if the installer uses a pump delay circuit?
    or
    If he doesnt use pump circuit delay that a 7$ pressure relief valve is all the insurance he would need.


    Again I want to make sure the installer puts something in place to prevent the pump from overheating

  9. #9
    General Engineering Contractor ballvalve's Avatar
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    I do not believe the delay talks to the valve about its condition, therefore you should put in a adjustable pressure relief valve - about 7 bucks.

  10. #10
    Porky Cutter,MGWC Porky's Avatar
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    Many irrigators like pump start switches, I don't. Usually the irrigation controller (Zone & Pump Box) controls the zones and activates a pump start switch which then turns on the pump. You're right, if the zone controller turns on the pump but the zone valve or valves don't open, it will deadhead the pump. Or if it turns on the pump and it has lost it's prime (assuming it's a jet or lawn sprinkle pump). This could do damage to the pump or pump pipe system unless there is some kind of protection.
    Personally, I like the pump system pressurized and independant of the irrigation system with a pressure switch with a low pressure cutoff and tank like the Side-Kick switch. This way You can still use a garden hose to do other watering and the irrigation controller will open the irrigation valves and the pump will start and stop when needed. If there is no demand the pump will remain at rest and if there is a break in the system or the pump loses prime the pump will cut off. This is the best setup!
    Porky Cutter, MGWC
    (Master Ground Water Consultant)

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