Rust or Sediment Stains and Hydronic Water Tank Draining


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Old 06-10-20, 12:34 PM
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Rust or Sediment Stains and Hydronic Water Tank Draining

I was away from home for a few months this spring. When I returned a hose bib was leaking and these stains were present on the stamped concrete. Thinking it was sediment from my well, I used a 3100psi pressure washer, but it couldn't remove the stain as you can see in the photo. Even though this is obviously a cold water line, I then began to think it's a rust stain, but I have no idea what would have caused the rust. Any ideas>

Secondly, I read the sticky post warning not to periodically drain a hydronic water tank, but my Viessmann CVA450 tank manual recommends draining and inspection of the tank and anode every two years. So, what is the recommendation for this tank? The closest Viessmann certified tech is a $450 trip charge away, so I don't want to have the tank serviced unless it's really necessary.
Thanks.
 
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Old 06-10-20, 12:45 PM
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So what is different about this post that you did a few days ago for the same topic?
 
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Old 06-10-20, 01:02 PM
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No problem draining this hydronic storage tank other than consuming time and water.

Usually draining between two and 5 gallons of water every 6 mongths should keep it clean. Every other time do the draining with the cold water supply turned off and an upstairs hot faucet open. Check the anode on the times when u drained it this way with the supply water turned off.
oy

There is a separate procedure for flushing the heat exchanger coil that connects to the boiler next to or near the tank. This is comparable to servicing a tankless water heater.
 
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Old 06-10-20, 01:10 PM
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The first post, Marq1, was in a concrete forum not plumbing and requested stain removal advice, not rust causation. Further, the first post didn't address tank draining, so the difference is obvious. I ordered a gallon of GoofOff rust remover and will try that on the stain. If you can help me understand how a dripping faucet generates rust, I'd appreciate it.
 
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Old 06-10-20, 01:15 PM
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Thanks AlanJ. So, is it recommended to drain and flush the tank, or optional? I've owned the tank for 4 years.
 
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Old 06-10-20, 01:46 PM
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If you can help me understand how a dripping faucet generates rust, I'd appreciate it.
I did in the first post, you have well water, you said it was leaking for a long time, exposure to hard water over a long period of time leaves rust stains! Just like I stated in your original post!
 
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Old 06-10-20, 03:07 PM
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zich -

(just saw Marq1 post - but since I went through the trouble of typing all of that below ...lol)

If your well has a lot of iron then wouldnít the iron rich water dripping on your concrete, and then exposed to oxygen, eventually rust? It seems like it would to me Ė but Iím no expert.
 
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Old 06-10-20, 03:49 PM
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I've had my water tested recently and it isn't hard and doesn't contain above normal ppm of iron. More likely after talking to my well driller is a galvanized pipe that has lost it's galvanization after being exposed to air during my two month absence.
So, any ideas on the 2nd part of my post that didn't appear in the concrete section. Marq1?
 
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Old 06-10-20, 05:38 PM
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So, what is the recommendation for this tank?
I always opt for what the manufacture recommends for maintenance than somebody on a forum that has no real stake in the outcome!
 
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Old 06-11-20, 10:10 AM
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I was away from home for a few months this spring. When I returned a hose bib was leaking and these stains were present on the stamped concrete.
It does look like rust. It seems like more rust than would be coming from your plumbing system. Even if the valve was rusty or something, you wouldn't see that much staining in such a short amount of time. I've heard of iron bacteria too causing staining. Have you tried CLR to clean it?

Secondly, I read the sticky post warning not to periodically drain a hydronic water tank, but my Viessmann CVA450 tank manual recommends draining and inspection of the tank and anode every two years.
Hydronic systems usually refer to home heating systems. You're not supposed to drain those systems as the addition of 'new' water causes more corrosion to the piping systems. You're talking about a water heater, which are usually recommended to drain some water out every year or so. There's some disagreement on how much draining a water tank really helps, but if it's recommended by the manufacturer, it probably should be done.
 
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Old 06-11-20, 01:40 PM
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I haven't had good luck with CLR on other rust stains, so I ordered a gallon of the highly rated GoofOff rust stain remover. I'll post how it went. I was gone for 81 days and the faucet was dripping at least two drops a second, so that could be a lot of water. About 144 square ft. were stained and wet when I returned. We also had high winds as you can see from the wall stains on the left side of the faucet.

The Viessmann 119 gal. water storage tank has a heat exchanger fed by a Slantfin boiler. The factory rep called and gave me the procedure to check the anode for corrosion which I'll do soon. Upon further inspect the manual requires inspection every two years and only draining "if necessary." So, I don't plan to drain unless there are anode problems.
 
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Old 06-11-20, 03:42 PM
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You got the rust stain on the concrete because the faucet dripped on the same spot day after day, month after month, and the water evaporated leaving the mineral content behind on the concrete. Included in the mineral content was a minute amount of dissolved rust from water mains, house plumbing, etc. No additional rusting or corrosion took place in the water after it left the faucet.
 
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Old 06-11-20, 03:46 PM
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Agree, no question. I'm waiting for the stain remover to arrive.
 
 

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