Hot Water Control Circuit

Discussion in 'General Electronics Chat' started by JOESEWI, Oct 11, 2009.

  1. JOESEWI

    Thread Starter New Member

    Oct 11, 2009
    1
    0
    I am looking to build an accurate hot water system that will allow me to control hot water in a vessel to within +/- 1C. This is a home project and I have most of the components, I believe, to build a proof of concept system.
    What I have on hand:
    1. A Watlow 988 PID Contoller
    2. A 100 ohm RTD device
    3. A simple on off heater with a potentiometer for temperature control.

    I plan to possibly add an SSR as a switch between the controller and the heating element. It seems pretty basic but I am not sure what components I need to get this all working together or how to tie them all together. Also, I am not sure if I have the controller output set up correctly to trigger the SSR. Any Help would be appreciated.
     
  2. markosillypig

    Active Member

    Jul 21, 2008
    184
    0
    how big is the vessel you want to heat the water in ???
    gallons or litres
     
  3. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    #3. You only need a heater...no pot. The 988 with the RTD will control the temp set in the 988's display. You didn't say what the heater voltage and current is. The 988 has a built in SSR for currents up to 0.5A and voltages between 24 and 265VAC. It has an electomechanical relay for currents up to 5A. It has a DC output that can drive a bigger, external SSR for higher currents.

    I would suggest that you read over the 988's manual. Then come back with questions. You may have all you need.

    Ken
     
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