Hot Water Circulation Point-of-Use Control

Discussion in 'The Projects Forum' started by LambdaEnt, May 8, 2015.

  1. LambdaEnt

    Thread Starter New Member

    May 8, 2015
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    I have a flash water heater with a circulation pump. I need to place 3 RF control switches, 1 in each bathroom and kitchen, which will operate the motor, then stop when the desired temperature reaches that location.

    I have designed this circuit for one control. But I’m having trouble figuring out how to get 3 separate controls and sensors in the circuit.

    Situation: What if two switches were pressed at the same time?

    [​IMG]
     
    Last edited: May 8, 2015
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Is there just one hot water loop for the whole house?

    Where is the temperature sensor located? Or are there three temp. sensors?

    Do the radio switches have a relay contact output?

    The radio switches are momentary, so you have to latch a relay to remember that the button was pushed, and then that relay is unlatched when the return water reaches 110degF?
     
  3. LambdaEnt

    Thread Starter New Member

    May 8, 2015
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    Yes, one loop. 3 sensors, surface mounted on the pipe at each point-of-use. Please see the schematic, there are 2 relays.

    The point is to stop the motor when the temp gets to 110° at that specific location.

    The Mini remote switch sends a signal to the In-Line Linc, which closes relay 1, and then the temp sensor closes relay 2. When the temp sensor reaches 110° it opens the circuit.

    Did I connect them properly?
     
    Last edited: May 8, 2015
  4. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    I am doing this with only one temperature sensor, so I never shut off the heater until the water gets hot at the third station on the loop, but you want to stop the heater when the water reaches the station that called for the heat. That means you will have to have a latching relay for each station. The heater will run when any (one or more) of the relays are latched. Each relay will be unlatched when the hot water reaches that station...
     
  5. LambdaEnt

    Thread Starter New Member

    May 8, 2015
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    Yes, I stated that in my initial question. I am having trouble figuring out how to connect all 3 of them in the same circuit!
     
  6. LambdaEnt

    Thread Starter New Member

    May 8, 2015
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    Sorry if that was unclear. Yes, I know I need 3 separate sensors and relays. But how to get all 3 sets connected to the pump at the same time?
     
  7. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Here is how I would do it. Kn are the three DPDT station relays, where n is 1 to 3. Kna and Knb are two sets of NO contacts on each relay. Tempn are the three NC temp sensors. PBn are the radio link outputs (equiv. to NO pushbutton). It doesn't matter in what order, or how many of the pushbuttons are asserted.
     
  8. LambdaEnt

    Thread Starter New Member

    May 8, 2015
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    Awesome. Sometimes you're brain hits a roadblock, and it takes a fresh look to find the answer. Thank you!
     
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