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Thread: Zinc vs Brass pipe plugs

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    eemueller's Avatar
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    Zinc vs Brass pipe plugs

    My Pentair Master Temp 400 heater needs a new plug on the header. The parts list indicates a zinc plug, but I was wondering if a brass one could be used instead? This is a salt pool. Thanks.

    Eric
    32K gal rectangular pebble sheen IG salt pool, 1200 gal pebble sheen IG salt spa
    Jandy AquaPure 1400 SWG, Jandy AquaPure 700 SWG
    Sta-Rite 2HP pump, Sta-Rite 1HP pump
    Triton II sand filters on both, Pentair MasterTemp 400K BTU nat gas heater
    CAT 1000 pH controllers w/ Stenner acid pumps on both, Levolor auto-fillers on both

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    JoyfulNoise's Avatar
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    Re: Zinc vs Brass pipe plugs

    No. you'll corrode the copper heat exchanger. Zinc sits higher than copper in the standard galvanic series (more anodic) while marine brass and other brass materials sit low than copper (making copper more anodic than brass).

    Use the zinc plug.
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    eemueller's Avatar
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    Re: Zinc vs Brass pipe plugs

    Got it. Thanks!
    32K gal rectangular pebble sheen IG salt pool, 1200 gal pebble sheen IG salt spa
    Jandy AquaPure 1400 SWG, Jandy AquaPure 700 SWG
    Sta-Rite 2HP pump, Sta-Rite 1HP pump
    Triton II sand filters on both, Pentair MasterTemp 400K BTU nat gas heater
    CAT 1000 pH controllers w/ Stenner acid pumps on both, Levolor auto-fillers on both

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    eemueller's Avatar
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    Re: Zinc vs Brass pipe plugs

    So, I have ordered the zinc plug, but found this whole incident a bit unsettling. Here's what happened.

    I was backwashing my filter, and after returning the slide valve to its "filter" position, I restarted the pump. Immediately, water began pouring out of the heater. I immediately shut off the pump, and opened the bypass valves to divert water away from the heater. I opened the side panel of the heater, and there was the heavily corroded, 3/4" pipe plug sitting in the bottom. The plug had corroded to the point where the threads were barely holding in the hole. They were weakened to the point that the pressure from the pump start-up blew the plug out of its hole in the header. Had I not been present when this happened (i.e., every morning when the pump automatically starts at 7am), 32K gallons of saltwater would have been freely flowing into the basement of my pool house (where the equipment is located). Once things dried out, I inspected the header. There are rust stains below the hole (threads leaking as they rusted), and around the inside threads in the header. I don't think Zinc corrodes with an orange color, so I can only assume that the unit was shipped with a galvanized iron, not zinc, plug in it. Pentair is now calling for a zinc plug in the unit's parts list.

    I am super diligent about my chemistry, keeping my salt level at 3000, my pH between 7.6-7.7, and my TA around 60. Those numbers are very stable.

    This is a 3 year old Pentair MasterTemp 400 heater. Is it normal to have to replace this anode plug every couple of years? My old Jandy/Laars heater gave me 8 years before the heat exchanger started to leak. Frankly, after this episode, I'm thinking of replacing the anode plug EVERY year, since zinc will corrode faster than galvanized iron.

    I'm curious to find out if others have had this issue. Thanks.

    Eric
    32K gal rectangular pebble sheen IG salt pool, 1200 gal pebble sheen IG salt spa
    Jandy AquaPure 1400 SWG, Jandy AquaPure 700 SWG
    Sta-Rite 2HP pump, Sta-Rite 1HP pump
    Triton II sand filters on both, Pentair MasterTemp 400K BTU nat gas heater
    CAT 1000 pH controllers w/ Stenner acid pumps on both, Levolor auto-fillers on both

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    JoyfulNoise's Avatar
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    Re: Zinc vs Brass pipe plugs

    My MasterTemp is about the same age...I'll have to open it up and take look.

    Which p/n is it by the way?
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    eemueller's Avatar
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    Re: Zinc vs Brass pipe plugs

    I've got two: U78-60ZPS and 428-60PS. A Google search will come up with 3/4" zinc plug for MasterTemp heaters.
    32K gal rectangular pebble sheen IG salt pool, 1200 gal pebble sheen IG salt spa
    Jandy AquaPure 1400 SWG, Jandy AquaPure 700 SWG
    Sta-Rite 2HP pump, Sta-Rite 1HP pump
    Triton II sand filters on both, Pentair MasterTemp 400K BTU nat gas heater
    CAT 1000 pH controllers w/ Stenner acid pumps on both, Levolor auto-fillers on both

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    eemueller's Avatar
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    Re: Zinc vs Brass pipe plugs

    Here is the plug that blew out of the header.
    iPhone 10.3.16 001.jpg
    32K gal rectangular pebble sheen IG salt pool, 1200 gal pebble sheen IG salt spa
    Jandy AquaPure 1400 SWG, Jandy AquaPure 700 SWG
    Sta-Rite 2HP pump, Sta-Rite 1HP pump
    Triton II sand filters on both, Pentair MasterTemp 400K BTU nat gas heater
    CAT 1000 pH controllers w/ Stenner acid pumps on both, Levolor auto-fillers on both

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    JoyfulNoise's Avatar
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    Re: Zinc vs Brass pipe plugs

    I just checked mine, it looks like a zinc plug I saw on the part images. There was no corrosion and everything looked clean.

    So was your the original plug?
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Teald024's Avatar
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    Re: Zinc vs Brass pipe plugs

    Quote Originally Posted by eemueller View Post
    Here is the plug that blew out of the header.
    iPhone 10.3.16 001.jpg
    Quote Originally Posted by eemueller View Post
    ...There are rust stains below the hole (threads leaking as they rusted), and around the inside threads in the header. I don't think Zinc corrodes with an orange color, so I can only assume that the unit was shipped with a galvanized iron, not zinc, plug in it. ...


    If I didn't know better, that looks like a steel plug. Iron Oxide is red. Zinc Oxide is white.
    Dave - Aqua Leader Elegance AGP 15'x30'x 54", 12k gallons, vinyl liner ... Hayward/SwimPro Voyager pump SW159412STL, 2hp, 2spd, Hayward/Voyager 175sf element filter SW175MDDVPAKS, Installed August 2016 ... Liquid Chlorine... ...TF-100....CYA/Chlorine Chart...Recommended Levels... Basic Care Schedule...Extended-Test-Kit-Directions

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    eemueller's Avatar
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    Re: Zinc vs Brass pipe plugs

    Yes, this was the plug that was installed in the new heater when it arrived. Pentair tech support couldn't explain the galvanized steel plug, but admitted that that is what was installed 3+ years ago, when the unit was manufactured. Now they spec a zinc plug. Hmmm. Perhaps they realized they had a problem...
    32K gal rectangular pebble sheen IG salt pool, 1200 gal pebble sheen IG salt spa
    Jandy AquaPure 1400 SWG, Jandy AquaPure 700 SWG
    Sta-Rite 2HP pump, Sta-Rite 1HP pump
    Triton II sand filters on both, Pentair MasterTemp 400K BTU nat gas heater
    CAT 1000 pH controllers w/ Stenner acid pumps on both, Levolor auto-fillers on both

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