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  1. #14
    Join Date
    Jun 2011
    Location
    Severna Park, MD
    Posts
    19
    OK,
    Here's where I was going when I mentioned the thermo-couple sensing the drop in temp....
    "A thermo-couple sensor detects when the temperature of the water drops and sends an electrical impulse to the thermostat control. The thermostat causes the burner to light and bring the temperature of the water back up to the temperature setting on the thermostat."
    The "piezo" switch needs mechanical input in some way, that is, if we're dealing with a piezo SW per-se. However, it's quit possible, there is an electronic ckt that triggers the ignition or lighting of the gas, instead of a piezo, upon receiving the call for heat?
    After giving this more though, I'm just trying to rationalize the process.

  2. #15
    Join Date
    May 2012
    Location
    Upper Michigan
    Posts
    3,589
    Pilot stays on constantly, temperature probe on gas valve controls call for heat, the piezo is just like an electric spark lighter, you push button to send a spark to pilot.


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  3. #16
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,900
    the way they work is the pilot generates 30 milivolts of electricity
    We really need change now

  4. #17
    Join Date
    Jun 2011
    Location
    Severna Park, MD
    Posts
    19
    Quote Originally Posted by catmanacman View Post
    the way they work is the pilot generates 30 milivolts of electricity
    Hi,
    Can you expand on this? Thanks.

  5. #18
    Join Date
    Dec 2007
    Posts
    4,770
    You do not understand the operation of you unit.

    Do a search for your manual online, or read it if you have it.

    Your gas valve is the control over complete operation of the fire on that unit; on, off or pilot only operation.

    The piezo is strictly an ignition(spark) just like on a barbeque.

    The thermocouple is the safety, along with an over temp safety on this unit, that provides a millivoltage to hold open a magnet in the gas valve. This voltage is created by the heat of the pilot flame burning on the thermocouple.

    If you read the lighting instructions, you must hold the control valve down for 30-60 seconds while lighting the pilot. This is to allow enough time for the heat to generate the voltage to hold that magnet.

    You are making things way to complicated. You unit works without the need for house power. You have what you wanted, unless you are on a well and then you need power to deliver the water.
    The Food Stamp Program, administered by the U.S. Department of Agriculture, is proud to be distributing the greatest amount of free meals and stamps EVER.
    Meanwhile, the National Park Service, administered by the U.S. Department of the Interior, asks us to "Please Do Not Feed the Animals". Their stated reason for this policy "... the animals become dependent on handouts and will not learn to take care of themselves."
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  6. #19
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,791
    Quote Originally Posted by Abuello View Post
    Hi,
    Can you expand on this? Thanks.
    Your thermocouple is is the pilot flame. Your water heater's thermostat is a mechanical switch. As long as the pilot is lite. The thermocouple generates voltage.
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  7. #20
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Quote Originally Posted by Abuello View Post
    Hi,
    Can you expand on this? Thanks.
    I don't remember the exact physics, but the energy from the flame when run across a thermocouple, generates a very small voltage (30 millivolts) to ground. This very small amount of power can be used for very simple controls like opening a gas valve when a mecahnical thermastat closes. ITs' also used as a simple flame detection system. if the flame goes out, the controls lose power and the gas valve shuts.

    SO the water heater generates it's own electricity. The downside is that you have the continous gas useage and the need for a open draft vent where you are constantly losing heat to the flue. That's why the eneryg factor is about 0.56, when the burner istself is around 75% efficient. You have big standby loses from the flue as well as the insulated tank.

  8. #21
    Join Date
    Jun 2011
    Location
    Severna Park, MD
    Posts
    19
    Hi Guys,
    Thanks for all of your replies. I think I have it figured out. As "beenthere" has mentioned, the Piezo is there to re-ignite the pilot at such time, it is needed. This unit still has a pilot flame and thermo-couple to control the gas valve. As another respondent mentioned, had I some type of full auto-light system , it would have required a dedicated electrical connection. A power outage would have put me without hot water. I think this is how it goes.

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