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Old 18-10-2021, 13:20   #1
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Is this zinc still ok to use

Hi All ... was going to replace my heat exchanger zinc. See the attached pic. I expected it to be much worse give that it has been over a year. Can I continue to use this or does one suggest to replace .. tx ... Dennis
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Old 18-10-2021, 13:23   #2
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Re: Is this zinc still ok to use

Before I even clicked on this thread, by simply reading the title I knew what was coming.


My answer, since I've also had this question, has always been: Heck, I got in there and removed it already, why not go with new.
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Old 18-10-2021, 13:28   #3
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Re: Is this zinc still ok to use

I figured that would be the answer !!! Thanks Stu ...
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Old 18-10-2021, 13:32   #4
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Re: Is this zinc still ok to use

It's hard to tell just from the pic, but it looks like you have 80-90% of the zinc remaining. I would wire-brush it to expose clean zinc and re-install it. Waste not want not.
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Old 18-10-2021, 13:35   #5
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Re: Is this zinc still ok to use

It's what, 5% depleted?
Me? I'd scrape it clean and put it back in.......tho I *do* carry spares!
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Old 18-10-2021, 13:48   #6
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Re: Is this zinc still ok to use

replace it.

Zincs aren't like break pads. A break pad does 100% of the work whether it's at 99% or 5%. This is not the same for a sacrificial anode.

The zinc should be replaced when 50% has been lost to corrosion. With zinc's it's the loss of mass, not necessary surface area, so you would really need to weigh it. At this point, even if it weighed in at 70%....how long will it take to go from 70% to 50%?? Now you're on a weird zinc maintenance schedule.

It's out, replace it.
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Old 18-10-2021, 13:52   #7
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Re: Is this zinc still ok to use

Following the reuse and my first post: shave it, clean it, save it for a backup.
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Old 18-10-2021, 15:34   #8
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Re: Is this zinc still ok to use

Yes buy a new one & I'll take the old one off your hands & dispose of it slowly.
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Old 19-10-2021, 06:20   #9
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Re: Is this zinc still ok to use

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replace it.

Zincs aren't like break pads. A break pad does 100% of the work whether it's at 99% or 5%. This is not the same for a sacrificial anode.

The zinc should be replaced when 50% has been lost to corrosion. With zinc's it's the loss of mass, not necessary surface area, so you would really need to weigh it. At this point, even if it weighed in at 70%....how long will it take to go from 70% to 50%?? Now you're on a weird zinc maintenance schedule.

It's out, replace it.
The reason you replace it at 50% is because presumably you've used more than 1/2 the zinc in that maintenance interval, so there is insufficient zinc remaining for the next maintenance interval. The zinc itself continues to offer protection until it completely disappears, although the diminishing surface area reduces the maximum current. The weight determines the longevity of the zinc.

Much like brake pads, you check the wear and replace when there's not enough 'life' left in them to get you to the next inspection.
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Old 19-10-2021, 09:37   #10
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Re: Is this zinc still ok to use

Slap some antifouling paint on it and you’ll get another couple thousand hours from it! /wink
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Old 19-10-2021, 09:46   #11
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Re: Is this zinc still ok to use

Let's see: $5 for new zinc (maybe $10 if u don't reuse the brass holder) or you can have extra fun picking broken bits of zinc out of the heat exchanger later. Easy choice for me.
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Old 19-10-2021, 09:55   #12
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Re: Is this zinc still ok to use

I'd be more concerned as to why it has not corroded more than that in 12 months................
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Old 19-10-2021, 10:53   #13
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Re: Is this zinc still ok to use

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Originally Posted by Shrew View Post
replace it.

Zincs aren't like break pads. A break pad does 100% of the work whether it's at 99% or 5%. This is not the same for a sacrificial anode.

The zinc should be replaced when 50% has been lost to corrosion. With zinc's it's the loss of mass, not necessary surface area, so you would really need to weigh it. At this point, even if it weighed in at 70%....how long will it take to go from 70% to 50%?? Now you're on a weird zinc maintenance schedule.

It's out, replace it.
great info. Thanks for the teaching moment.
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Old 19-10-2021, 11:05   #14
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Re: Is this zinc still ok to use

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I'd be more concerned as to why it has not corroded more than that in 12 months................

Not necessarily. When I moved from SF to BC in 2016, I kept checking on my California timetable of 3 months. After 2 years it expanded to every six months. Colder water? I dunno, but it DID change with downsides.
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Old 19-10-2021, 11:28   #15
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Re: Is this zinc still ok to use

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Originally Posted by kingofcary View Post
Hi All ... was going to replace my heat exchanger zinc. See the attached pic. I expected it to be much worse give that it has been over a year. Can I continue to use this or does one suggest to replace .. tx ... Dennis
Rule of Thumb is 2/3s missing replace.
But anytime you remove it. Replace it!
They're cheap and it's out to inspect.
Be sure to reseal it, no Teflon tape!
Yellow, blue, no white tape.
Or pipe dope.SV Cloud Duster
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