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Discussion Starter #1
Ok so my uncle just bought a used boat, it has 2 billig(spelling?) pumps to pump the water out of the boat.

One is on a switch and once you power it, goes on and off every 10 seconds or so. Now, he wants to wire the other pump so that if this pump fails, the power will be directed to the backup pump.

Is this possible? And what is needed?

Thanks guys
 

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Doc here, :pimp:

It's pretty simple actually, You need a pressure sender on the outflow side of pump 1..when the flow fails, it provides a ground to a Relay Coil that fires and turns on Pump 2.

To do that, get a relay and wire it thus:
  • RELAY COIL + #85 = To Pump power Switch presently for pump 1.

  • RELAY COIL - #86 = To outflow pressure sender.

  • RELAY CONTACT # 30 = To #2 Pump.

  • RELAY CONTACT # 87 = To a properly gauged, Fused , Power source. (like the battery with a fuse link.)

  • RELAY CONTACT # 87a = Is not used in this application.




That's it, be sure the other end of the pressure sender has a good ground, and it will turn on pump 2 whenever the flow is not present in pump 1..This is also good for mechanical failures as well as electrical, since it relies on Flow not power.

Doc :pimp:
 

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boatbob2
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BILGE pump

hi,an easier way to run the pump would be to wire directly to the battery,use an inline fuze,and an off on switch. (of course use a second overboard dump fitting) and second hose, that way, when the first bilge pump quits you flip the switch. CHECK BOTH PUMPS FOR ACTIVATION, every time you use the boat. im boatbob2
 

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Discussion Starter #4
docvette said:
Doc here, :pimp:

It's pretty simple actually, You need a pressure sender on the outflow side of pump 1..when the flow fails, it provides a ground to a Relay Coil that fires and turns on Pump 2.

To do that, get a relay and wire it thus:
  • RELAY COIL + #85 = To Pump power Switch presently for pump 1.

  • RELAY COIL - #86 = To outflow pressure sender.

  • RELAY CONTACT # 30 = To #2 Pump.

  • RELAY CONTACT # 87 = To a properly gauged, Fused , Power source. (like the battery with a fuse link.)

  • RELAY CONTACT # 87a = Is not used in this application.




That's it, be sure the other end of the pressure sender has a good ground, and it will turn on pump 2 whenever the flow is not present in pump 1..This is also good for mechanical failures as well as electrical, since it relies on Flow not power.

Doc :pimp:
Wow, thanks Doc. So the pressure switch isnt hooked up directly to the pump one right? Its hooked into the relay thats hooked up to pump one?

And this might be a silly question but im not electrically inclined, what kind of relay is that? Is that the generic breakdown of all relays? So I can tell him what to buy, thanks a ton.
 

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Artemis Entreri said:
Wow, thanks Doc. So the pressure switch isnt hooked up directly to the pump one right? Its hooked into the relay thats hooked up to pump one?

And this might be a silly question but im not electrically inclined, what kind of relay is that? Is that the generic breakdown of all relays? So I can tell him what to buy, thanks a ton.

Doc here, :pimp:

I'm actually glad you asked that..

I forgot to mention, that relay Should be a TIME DELAY RELAY, (TDR) On Delay, (10 seconds "Turn On Delay") Or just slightly greater than the time it takes the first pump to Cycle..(or it will start when pump 1 Shuts down) . This way, When pump 1 is off (or the outflow switch is detected longer than normal) the pump will only start after that time. So both aren't running at the same time.

The pin-out above is for a standard automotive Bosh relay (can be had at any auto parts store). For an ON Delay Relay, you can try Potter Bloomfield, AMF, Or any Electrical Supplier, just be sure the Coil Voltage is 12 Volts.

If you don't wish the time delay, you can hook it up the same way as in the first post, and pump 2 will run anytime the flow is off..(pump 1 cycling)..which means you will have positive flow all the time, with pump 1 and pump 2 cycling..between each other.

The outflow sender is just a "Gated Switch" that hooks into the flow of media, when it opens the gate, it switches a switch to ground, that fires the relay, and that provides power to the pump.

Doc :pimp:
 
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