Wiring relays with Flow sensors

Discussion in 'The Projects Forum' started by TMASCO, Jan 29, 2010.

  1. TMASCO

    Thread Starter New Member

    Jan 27, 2010
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    Hello, I am hoping someone can assist me in determine the correct way to wire a project that I am currently working on. I have totally confused myself on how to wire each control.

    My Goal: To install a flow switch/sensor into the main hot water line coming from the heater, this will turn on when it senses the draw for hot water. - Then the output from the sensor will activate the 10sec “delay-on” relay. Once the ten seconds has elapsed the relay will turn the pump that circulates the water throughout the system. – Once the draw for the main flow of hot water is stopped, the flow sensor will not recognize this because the pump will generate the flow over the sensor and therefore the pump will continue to run (this is ok). – On the hot water return pipe that the water continues to flow through there is an aquastat which is set to 130 degrees, once the aquastat senses that the water has reached 130 degrees it will break the current to the pump and therefore there will won’t be any flow of water over the flow sensor. Then the system will reset itself till the next time there is a demand for hot water. In theory this should work.


    Electric Flow Chart.jpg





    Parts list:
    Since I have 110v ac at the location I plan on operating all controls by 110v ac. Due to the large number of wires and connection I have managed to completely confuse myself and would hate to damage any of these devices. Therefore any help would be greatly appreciated.

    I should mention that all of the items are installed in the system and that the aquastat has been installed and set to cut out at 130 degress. The problem I am having is how the flow meter and relay should be energized also where the pump leads and aquastat should be tied into the circut. I have tried to map the connections out on paper but I get confused with the purpose of each wire on the relay and flow meter.
    Doug
     
    Last edited: Jan 29, 2010
  2. BillB3857

    Senior Member

    Feb 28, 2009
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  3. TMASCO

    Thread Starter New Member

    Jan 27, 2010
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    BillB3857-
    Thank you for the responce, I have scoured the web extensivly and have been told that since my heating unit is tankless with check valves installed on the various lines, I need a recirculation set-up like the one shown in my diagram.

    Tankless water heaters only turn on when they sence water flow. The problem I am having is with the wiring of the relay and flow meter and where to tie in the electrical feed to the pump and aquastat. I have the plumbing done it's just the wiring I I can't figure out.
    Thanks again for the quick responce
     
  4. BillB3857

    Senior Member

    Feb 28, 2009
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    Your simplest solution may be to simply place the pump on a programmable timer. If you typically use the hot water about the same time each day, you could set a timer to start the pump a few minutes before the anticipated usage. Multiple set-point timers are available. If you Google Watts Hot Water Recirculate, you will see a very pricey commercial unit that uses a timer.
     
  5. TMASCO

    Thread Starter New Member

    Jan 27, 2010
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    We wanted to avoid using a timer (we had one in place previously) since the unit could be turning on and off more frequently than needed. The water usage is not consistent.
    I have spoken to several plumbers and they like my idea - they just don't have any idea how to wire a configuration like this.
    Once I get this figured out and if it works as we think it will the plumbers said they would be all over this type of circulation layout.
    I just need help in the wiring process.

    Thanks
     
  6. BillB3857

    Senior Member

    Feb 28, 2009
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    I think I understand what you are wanting to do, but I fail to see how that will help get hot water to the usage point instantly. If you wait to have water flow before starting the pump, wouldn't the standing water be cold in the pipes? Wouldn't it take the same volume of water to reach the usage point as it would without the pump?
     
  7. TMASCO

    Thread Starter New Member

    Jan 27, 2010
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    The ten second delay relay (adjustable) is if someone turns the hot water on then off immediately the pump won't be activated. Once the pump is triggered then with the help of the pump hot water will arrive much quicker than without the pump. I realize it won't be instantaneously but the time frame will be much shorter with less water being wasted. Also the reason for the aquastat is to bring the temp in the recirculating line (insulated) up do 130 degrees then turn off the pump until the next cycle is started.
     
  8. williamj

    Active Member

    Sep 3, 2009
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    Tmasco,

    To wire as described would be something like this…

    Aquastat contact---Timer contact---pump motor

    Flow meter contact-------------------Timer coil

    However, if I interpret what it is that you are trying to do correctly, you might want to rethink. By increasing the flow of water to the tap you decrease the amount of time a given amount of water is in the heating chamber of the water heater, therefore decreasing the amount of temperature rise of the water.

    The pump specified is rated at 19GPM, if the water heater used is set to heat water at, say, 1GPM, then the heat gain could be reduced by as much as a factor of 19, something to consider.

    If all you are trying to accomplish is hot water faster at the tap then you may want to consider BillB3857’s suggestion of a hot water recirculation loop. If that is the case then all that would be needed is the Aquastat and the pump. Having the Aquastat and then the pump located at the end of the loop just prier to the water reentering the water heater would insure hot water within just a second or two of the tap. This active loop system would use more energy than just the tank less water heater alone but would still use less energy than a tanked water heater.

    williamj
     
  9. TMASCO

    Thread Starter New Member

    Jan 27, 2010
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    Thanks for the reply williamj

    Your point about the increase of water flow at the tap won't be effected because of the extremely high BTU output of the heater. If I had a faucet on the main line next to the water heater the temp of water coming out would be 140 degrees (thats what makes these tankless hot water heaters great).

    The water pressure in the system is set to 80lbs, we installed a water pump to generate this amount of pressure plus some. I believe the water heater is rated at 24+ gpm so we are ok here.

    I have done various tests to determine how quick the pump would get hot water to the faucets by turning on the water then activating the pump and we get hot water at all of the faucets extremely quick, so we know this system will function correctly.

    The idea BillB3857 is a great idea, but would cause the system to run more frequently than needed. That is why we incorporated the flow switch and "delay on" relay.

    My goal is to determine the correct way to wire the system using the various components noted in my first post. I spent the day drawing a wiring diagram and would like to get any input on my best guess on how to wire this system. Most importantly I want to make sure I have the wires at the correct spot on each of the components. (SEE ATTACHED).

    Thanks for all of the great input!
     
  10. williamj

    Active Member

    Sep 3, 2009
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    TMASCO,

    I may be wrong in my interpetation of the purpose of your project.
    Based on previous posts and attachments I interpet your purpose to be;

    1, maintain a set temperature within a loop (as shown in Attachment 15727)

    2, increase water pressure and flow at tap as described in your post of January 30,2010 @ 04:17 PM

    In the ladder diagram attachment below is a circuit that 'I believe' will allow you to achieved the goals stated. The 'sequence of operation" attachment will walk you through the circuit.

    Now, I have been retired for some time and I am not fully current on today's timer and flow sensor technology. So if I am in error I hope someone, who is more up to date on these technologies, will step forward and make corrections where needed.

    If you have any questions feel free.

    williamj
     
  11. BillB3857

    Senior Member

    Feb 28, 2009
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    After another look at the hydraulic diagram in post #1, I have a question. If the pump is running, wouldn't the flow sensor indicate flow even though the tap has been closed?

    Edit: The fix would be to put the flow sensor outside the recirculate loop.
     
  12. TMASCO

    Thread Starter New Member

    Jan 27, 2010
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    Yes, you are correct that is what we want - for the water to continue to recirculate until the loop reaches 130 degrees at which point the aqustat will break the connection to the pump therefore causing the flow to stop causing the system to reset until the next call for water.

    Now I think you will see why we need to keep the sensor in the loop.

    Thanks
     
  13. BillB3857

    Senior Member

    Feb 28, 2009
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    Will this circuit do what you want? With the flow sensor in the loop, how would the motor shut off??
     
    Last edited: Jan 31, 2010
  14. TMASCO

    Thread Starter New Member

    Jan 27, 2010
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    If I am thinking correctly.

    Once temp in the loop reaches the high mark - the aquastat will break the connection to the pump causing it to shut off. - If call for hot water has been terminated pump will remain off until a new call for hot water and aquastat has fallen below temp differential

    In the event there is another call for hot water it will cause the flow sensor to make again - relay goes into the 10 sec delay-on then power is sent to aquastat. - If aquastat is still open it will block the power to the pump - pump will stay off until aquastat drops below the differential point (which should not be that long if there is still a call for water) - If call for hot water has stopped and pump is inactive the flow sensor circuit to the relay will break and the system will reset until there is a new call for hot water.

    Flow switch needs to stay in the path of hot water exiting hot water heater for the above process to work. The return line of circulation loop dumps into the cold water feed of hot water heater causing flow over flow sensor unless pump or call is not needed.
     
  15. TMASCO

    Thread Starter New Member

    Jan 27, 2010
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    williamj, I made a few comments above regarding the thought process.

    Thanks for the great feedback!
     
    Last edited: Jan 31, 2010
  16. williamj

    Active Member

    Sep 3, 2009
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    TMASCO,

    The ladder diagram illustrates electrical connections (current flow) not component placement. 'Rung a' was shown seperate from the rest of the ladder to show that the electrical connection came from timer relay pin 5 and went back through timer relay pin 6 and are not directly connected to L1 or N.

    Where you place the individual components is entirely up to you.

    In order to try and make the ladder diagram a little more clear I took the connection points from the ladder diagram and placed them in a wiring diagram. Some (myself included) believe that most wiring diagrams can become really confusing when there are large numbers of wires involved. I believe that (for me) ladder diagrams are a little more clear in meaning and are easier to read. It's simply a matter of personal prefference.

    I hope the wiring diagram makes it a little easier for you.

    williamj
     
  17. TMASCO

    Thread Starter New Member

    Jan 27, 2010
    13
    0
    Williamj’
    Thanks for the break down, I will try and explain what I see happening in this diagram so you can correct me if I am wrong.

    • The A.C. (Black) will feed Flow sensor 1, Relay 2 + 1 and red on aquastat.

    Result = when water moves through the flow sensor - FS 5 will close and make contact with FS 4 therefore FS 5 will send current into RLY 5 (**What does FS 4 and RLY 6 do because 110 passes through FS 5 with FS 4 acting as a neutral “A.C. White wire”**) It looks like the box between FS 4 and RLY 7 is supposed to have a fuse therefore I would assume FS 4 is + A.C. Black power.

    Next timer starts count down in RLY – once timer has lapsed RLY circuit will close RLY 3 with RLY 1 - **(why is RLY 1 also getting A.C. Black in or is there supposed to be a line break between RLY 2 and RLY 1 because with A.C. Black power going to AQ Red when AQ Blue makes contact with RLY 3 won’t the line AQ Blue and RLY 1 short?

    I understand all of the connections on the A.C. Neutral White line.
    Now you can see how I confuse my self!

    The attachment is what I think is supposed to happen. HELP!
     
  18. williamj

    Active Member

    Sep 3, 2009
    180
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    TMASCO,

    It appears to me, that your last attachment show one large overly complicated circuit and I'm having a difficult time following the wiring. In drawing it looks like the flow sensor is driving the Aquastat, and the only time that the pump comes on is when the Aquastat calls for heated water. Just opening the tap wouldn't tell the pump to come on, the Aquastat would need to be calling for heated water in order to energize the pump.

    Back to the beginning, project objectives...

    1, maintain heated water within loop
    2, start pump after 10 sec. delay when tap is opened

    Both objectives require that the pump be running and circulating water. All that is needed to reached both objectives is two independent and relatively simple circuits (running in parallel) controlling the pump.

    Circuit 1, maintain heated water in loop
    components required... Aquastat wired to pump (see first attachment)

    Circuit 2,start pump after 10 sec. delay when tap is opened
    components required... Flow Sensor, Timing Relay, Pump (see second attachment)

    Either circuit can operate one at a time, or both at the same time, makes no difference.

    If both objectives are what you want then combine both simple circuits as shown in earlier attachment, if objective 2 is all that is desire then wire as shown in simple circuit 2

    One suggestion, if components are not already mounted, construct a simple test board and test all the different wiring arrangements and find which one works best for your desired outcome.

    williamj
     
  19. TMASCO

    Thread Starter New Member

    Jan 27, 2010
    13
    0
    williamj - Thanks for all of your hard work. I appreciate the time you have spent of this project.

    I will try my best to explain what my goal is -

    When water is turned on FS will activate time relay - after time has elapsed power is then sent to the AQ - If AQ is is closed power will then flow to pump - pump will start and continue to run even after the water is turned off. (pump is pushing water over sensor to keep circut running) - Circut to pump will break once temp has reached 130 deg at AQ - Once pump has stopped FS will reset until next call for water.

    Now when water is turned on FS will activate time relay - after time has elapsed power is then sent to AQ - if AQ is open (which means circ temp is at 130 deg or above) power will not be allowed to pump - current will remain active up to AQ until temp has fallen below 130 deg or water has been turned off. - Once water has stopped AQ will remain open until water in circ system has fallen below 130 deg at which time AQ will close and entire circut will reset until next call for water. - If circ temp falls below 130 deg while the tap was open the power will start the pump and continue to run until AQ hits 130 deg even if tap has closed after pump has started.

    I don't want the circ loop to cycle on and off while faucet water flow is idle.

    My fault for not explaining my goal in a simplefied way, so please bear with me.
     
  20. williamj

    Active Member

    Sep 3, 2009
    180
    32
    TMASCO,

    Communication has never been one of my strengths so misunderstanding is probably a guilt best shared.

    You have stated quite well how it is that you believe that your objective would be/should be accomplished. It is, however, your ultimate objective that I am still not quite sure of...

    Is it that you are attempting to regulate water temperature once the tap has been openend? (If so, doesn't your water heater have a variable temperature adjustment? Just set it to 130 degrees and forget it?)

    If you could just state the objsective...

    I want hot water faster or I want more hot water pressure at the tap... etc.

    In an earlier post you wrote...

    Result = when water moves through the flow sensor - FS 5 will close and make contact with FS 4 therefore FS 5 will send current into RLY 5 (**What does FS 4 and RLY 6 do because 110 passes through FS 5 with FS 4 acting as a neutral “A.C. White wire”**) It looks like the box between FS 4 and RLY 7 is supposed to have a fuse therefore I would assume FS 4 is + A.C. Black power.

    "Initiation" voltage (RLY pin 5 to RLY pin 6) is provided internally from the Timing Relay. (it may or may not be the same as line voltage (110V A.C.)) By routing through FS pin 4 and FS pin 5 you connect RLY pin 5 to RLY pin 6 intiating timer sequence, neither FS pin 4 nor FS pin 5 is routed to Line (110V A.C.) or Neutral.

    I took the liberty of translating your last attachment to a ladder diagram format. (see attached)

    I beleive it would function as described except for one thing... there was no connection from Line to TR pin 1. (I made the connection in the ladder diagram) TR pin 1 feeds voltage to TR pin 3 once timing sequence is complete and the normally open contact closes. Without that connection AQ would never have any voltage to run the pump.

    As shown, the pump will only run when FS senses there is flow 'and' AQ senses that water temperatur is below 130 degrees.

    Hope this helps.

    wiliamj
     
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