Corrosion on water heater pipe

Discussion in 'General Plumbing Help' started by shobuddy, Nov 23, 2017.

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  1. Nov 23, 2017 #1

    shobuddy

    shobuddy

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    I have two water heaters setup as series. I have turned of the first heater in the series since we don't need it. I've noticed corrosion on the pipe where hot water exits the second heater that is turned on. These heaters were installed about a year ago and this is the only pipe that is showing corrosion. I'd like to find out what is causing the corrosion just one this one pipe. Picture attached.

    IMG.jpg
     
  2. Nov 24, 2017 #2

    frodo

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    it is because of a leak.

    those water heaters are not hooked up correctly

    water travels path of least resistance, all piping must be the same so that the water will enter the tanks at the same time and leave at the same time

    what you have is a water heater and a storage tank

    aa.gif
     
    Last edited: Nov 24, 2017
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  3. Nov 24, 2017 #3

    shobuddy

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    frodo, what you're describing is a parallel setup. This one is a series setup.
     
  4. Nov 24, 2017 #4

    frodo

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    Series installation uses heaters that are not identical in both BTU input and storage capacity. An example might be when an expansion or addition is made in an application that will require additional hot water. For example, you add a new bathroom to your home. The existing system will not handle the demand and a new water heater must be installed. The new heater is not identical to the existing heater. In this example, series installation may be appropriate. When installing water heaters in series, the heater with the largest input (BTU or KW) should be the first heater in the series, at the cold-water inlet side of the system. Series installation draws hot water from one tank at a time. As hot water is drawn, it is taken from the last heater in the series. For every gallon of hot water drawn, preheated water is introduced into the last heater in the series and cold water is introduced into the first heater in the series. In a series configuration, the first heater, piped to the cold-water inlet, will do the majority of the work. The second (or remaining) heater will not work as hard because it receives preheated water, not cold water. The last heater in the series will do very little wor



    Parallel installation uses heaters that are identical in both BTU input and storage capacity. Normally, parallel installation is used when there is a demand for large quantities of hot water over a short period of time, such as filling a large garden tub or back to back showers. Equipment being equal, two or more heaters connected in parallel will deliver more hot water than the same heaters connected in series. In a parallel configuration, the hot water demand is taken equally from each unit. For every gallon of hot water drawn from each unit, one gallon of cold water is introduced into the water heater. Each heater will then perform the same amount of work to heat the cold water


    two or more heaters connected in parallel will deliver more hot water than the same heaters connected in series
    This is why I only pipe then in parallel,
     
    Last edited: Nov 24, 2017
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  5. Nov 24, 2017 #5

    shobuddy

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    Frodo, I agree with you and would have much rather preferred parallel. This is a new construction home that we moved into about a year and half ago and unfortunately this is how the builders piped the water heaters. Another benefit to the parallel is if one goes bad, the other one can easily be used where in a series, if the second heater goes bad, you cannot just switch to the first heater. I've thought about having this redone as a parallel but it has not been a priority.
     
  6. Nov 24, 2017 #6

    frodo

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    that's cool, I just pointed out what i saw,
     
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  7. Nov 25, 2017 #7

    journeyman

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    You don't ever thread metal into plastic that is why it leaked do it right and no problems
     
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  8. Nov 25, 2017 #8

    frodo

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    and 18'' away from that heater
     
  9. Nov 26, 2017 #9

    voletl

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    Those look like cpvc to metal adapters so the plastic is not threaded onto the metal. Also its and electric waterheater theres no flue so plastic can go right to the unit.
     
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  10. Nov 26, 2017 #10

    journeyman

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    It is called electrolisys you have to metals eating each other
     
  11. Nov 26, 2017 #11

    voletl

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    Water heaters come with two standard dielectric nipples installed from Factory to prevent that the leak was caused because whoever tightened it on to the water heater failed which caused the leak
     
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  12. Nov 26, 2017 #12

    frodo

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    if you have seen in the code where it says ok on electric but not on gas
    please share that with me, i have looked and looked for that loop hole
    it escapes me.
    It is common sense, I agree with you
    but all i can find is plastic pipe 18'' from water heater
     
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  13. Nov 26, 2017 #13

    frodo

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    this is leaking at the adapter to nipple connection
    wh222.jpg
     
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  14. Nov 26, 2017 #14

    voletl

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    Thanks for the blown up picture but I think we established that.

    If it's an electric water heater I don't see any reason why not to put the piping right to the heater if there is no flue

    View attachment 1511686252469.jpg
     
    Last edited: Nov 26, 2017
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  15. Dec 17, 2017 #15

    WyrTwister

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    First of all , I would run a bond / jumper wire between the 2 WH's . Than might ot might not cut down on electrolysis .

    This is plastic pipe , just re-do it correctly & add any needed valves . If you wish to change it to a parallel setup , you can do it at that time .

    With only 1 WH turned on , have you ever run out of WH ? If not , sounds like you are OK as is .

    Really , plastic plumbing is not that difficult . Be sure to use CPVC ( hot water ) plastic , fittings , primer & appropriate glue / cement .

    Or , buy the flexible fittings . Or use PEX .

    Best of luck , :)
    Wyr
    God bless
     
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