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Thread: need to replace Burned up heating element

  1. #1
    Join Date
    Mar 2011
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    Nashville, TN
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    127

    need to replace Burned up heating element

    Our brewery uses an electric heating element for the hot liquor tank.

    We've burned up two of the Mcmaster Carr stainless steel units...about $280 / each. I don't know if it's salts, acids or what that's causing the corrosion and ultimate failure of these elements, but I would like to get a recommendation on a similar unit.

    we sometimes put lactic acid, calcium chloride and / or calcium sulfate in the HLT.


    Our wiring is 3 phase, 208V, i believe max amperage of 25V for 10kw unit.

    thanks for any input.

    McMaster Carr: model 3656K162 Screw-Plug Mount Immersion Heater, 304 Stainless Steel, 240V AC, Three Phase, 10500W, 28" Long
    Last edited by Swags; 07-24-2018 at 06:41 PM.
    Scott Swygert
    Founder - Honky Tonk Brewing Co.

  2. #2
    Join Date
    Aug 2010
    Location
    Enterprise, Oregon
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    I don't have time to look up that part right now, but the important thing is: Is it an ultra-low density unit? If not, then it's likely that scale--even transient scale that will be seen as little tube-ish bits on the bottom of the HLT--may be causing your element to burn out prematurely. The fastest way to kill an element is to let it get buried in scale, or, worse yet, let it run dry. You do have a low-water cut-off to prevent this, right?

    Since you're running a 240V element on 208 power, it's drawing ~50 Amps, not the 44 Amps it's rated at. This can also cause premature failure.
    Last edited by TGTimm; 07-25-2018 at 10:19 AM.
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

  3. #3
    Join Date
    Oct 2014
    Location
    Kent, WA
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    Quote Originally Posted by TGTimm View Post
    Since you're running a 240V element on 208 power, it's drawing ~50 Amps, not the 44 Amps it's rated at. This can also cause premature failure.
    Actually, it's the other way around. An element rated for 240 Volts will draw less current when powered at 208 Volts. Instead of using the power equation, use Ohm's law. An element rated at 10KW at 240V doesn't have the same power at 208V. Probably the resistance isn't the same either, but it's close enough for this:

    Find Current of 10.5KW at 240V
    P=IV
    P/V = I
    10,500 W / 240 V ~= 44 A

    V=IR
    V/I = R

    So,

    V1/I1 = V2/I2

    I2 = V2 / ( V1/I1 )

    I2 = 208 V / (240 V / 44 A )

    I2 = 38 Amps

    So, the actual power of that element at 208 V is:

    P = IV
    P = 38 * 208 ~= 8 KW

    EDIT: Sorry, those calcs are for single phase, but when I look up the element, it's actually 3 phase. So the equations are similar, but with a constant for correction. In other words, Ohms law for three phase systems is V = Sqrt(3) * I * R

    Find Current of 10.5KW at 240V 3ph
    P=1.73 * I * V
    P/(V * 1.73) = I
    10,500 W / (1.73 * 240 V ~= 25 A

    And then Ohms law looks like this.
    V=1.73*I*R
    V/(I*1.73) = R

    So,

    V1/(I1*1.73) = V2/(I2*1.73)


    To the OP: If you're adding calcium chloride, you might be getting chloride stress or chloride pitting corrosion. This can happen very quickly, especially with 304 SS. There are alloys that are resistant to it...Inconel is one, if I recall correctly.
    https://en.wikipedia.org/wiki/Inconel

    Maybe you should use the Incoloy element instead? https://www.mcmaster.com/#3656K93

    Regards,
    Mike Sharp
    Last edited by rdcpro; 07-25-2018 at 12:34 PM.

  4. #4
    Join Date
    Aug 2010
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    How did I get those numbers backwards? Must not have had enough coffee this AM. And, indeed, I forgot the correction for 3-phase.
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

  5. #5
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    I'll also mention that SS is a very poor conductor of heat, which might be contributing to your problem. We used to heat our HLT with electric element, and simply used 6 kW low-density home-water heater elements. They lasted for a few months to a few years, and were cheap and easy to replace.
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

  6. #6
    Join Date
    Jun 2011
    Location
    Richmond, VA.
    Posts
    431
    Quote Originally Posted by TGTimm View Post
    I'll also mention that SS is a very poor conductor of heat, which might be contributing to your problem. We used to heat our HLT with electric element, and simply used 6 kW low-density home-water heater elements. They lasted for a few months to a few years, and were cheap and easy to replace.
    i got a quick question about this subject. If you added lactic acid to the water like in an electric boiler using ss element, would that help prevent scale build up on the element?

  7. #7
    Join Date
    Oct 2014
    Location
    Kent, WA
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    312
    Quote Originally Posted by TGTimm View Post
    Must not have had enough coffee this AM.
    Lucky for you, the US Military has your back:

    https://qz.com/1296394/the-us-armys-...k-performance/

    :)

    Regards,
    Mike

  8. #8
    Join Date
    Oct 2012
    Location
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    Ive had very good luck with these....
    http://www.brewmation.com/Components...g_Elements.cfm

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