Lowest cost way to circulate water within water heater tank?

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Melissa2007B

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I've mentioned in these forums before, the stacking problem we're getting with our Aprilaire 360 whole house humidifier, and how it appears to be super heating the water at the top of the tank because it takes a trickle of hot water from the top and there's cold coming in the bottom and triggering the burner. I also mentioned the black water coming out, because of this, after it goes on every day for awhile.

So I'd like to find the least expensive way to circulate water within the tank, from top to bottom, and keep the temperature uniformly at the set temperature.

I'm not a plumber and will need to find the stuff to do this, and probably hire a handyman from Craig's List to do it for me ( shudder ).

But I need to know how to describe it, and find the parts ( pump ) so that people don't get the wrong impression that I'm trying to do a whole-house circulation system, when I'm not.

I just need a decent low cost pump for circulating the water WITHIN the tank.

I'm not even sure how to do this ( photos below ). UBC modular house ( on a foundation with crawl space ). The mixer shown here is where the line goes out to the humidifier. The humidifier is actually spec'd at 140 degree water temp input but we want to operate the hot water at the temp spec'd for the tank. Not sure how to do that, without adding an expensive "instant" hot water heater in between them? ( I say "expensive" because I've heard a special electric line has to be run for them - they cant just be plugged into a wall. )

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Cacher_Chick

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I am trying to better understand the problem.... normal operation is taking the hot water from the top of the tank, and at the same time the tank is being refilled with cold water, which enters through the dip tube which drops down to the lower 1/3 of the tank. The cold water will naturally stay at the bottom of the tank until it is heated by the burner.
Circulation in the tank is only going to make the heater run more to maintain the desired hot temperature.
 

Melissa2007B

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I am trying to better understand the problem.... normal operation is taking the hot water from the top of the tank, and at the same time the tank is being refilled with cold water, which enters through the dip tube which drops down to the lower 1/3 of the tank. The cold water will naturally stay at the bottom of the tank until it is heated by the burner.
Circulation in the tank is only going to make the heater run more to maintain the desired hot temperature.

Yes, which apparently raises the temp of the tank when the humidifier runs. For example if I set the temp setting to A ( lowest of A, B and C ), the temp is around 120 normally. But if the humidifier runs awhile, it shoots up to around 135.

If someone tries to take a shower at the far ends of the house ( 80 feet ) it's too cold unless the humidifier has been running on and off all day. BUT if the humidifier has been running, then when we run hot water to get a shower started, it comes out BLACK at first.
 
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Jadnashua

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Some of the flexible supply hoses can have their waterproof layer degrade (some are rubber verses plastic), and that can produce black. Solution is to change the flexible sections to new, quality ones. That happens faster when the water gets hotter.
 

Melissa2007B

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Sooo.. what do you attribute the black water to?

I haven't had it tested, but it may be iron being burned from the inside of the tank bottom.

I mean, we've been here 11 years now and have already had to replace the first gas water heater after about 7 years, when it developed a hole in the bottom.
 
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Melissa2007B

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Some of the flexible supply hoses can have their waterproof layer degrade (some are rubber verses plastic), and that can produce black. Solution is to change the flexible sections to new, quality ones. That happens faster when the water gets hotter.

Whoa! You mean those red PEX hoses? That's a scary thought - that both of us and our pet cockatoo may be bathing in that!

And that we might have to spend a lot to have them all replaced?
 

Reach4

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BUT if the humidifier has been running, then when we run hot water to get a shower started, it comes out BLACK at first.
I would flush the water heater. That does not just meant to drain and refill it.

Also, do you have a sulfur smell? I know that is not the question that you asked.
 

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PEX is not the cause of your black water. Hoses like those used on a fixture or washer can break down and leech into the water.
A proper chemical analysis of the water would be a good place to start. Dark color often comes from magnesium. Your water could have an effect on the anode rod it the tank, which would be easy to check.
The average lifespan of today's water heaters is less than 10 years, so having one that lasted 7 should not be too surprising.
Your goal should be to make the heater fire less often, and ciculation is not going to accomplish that.
 

Melissa2007B

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I would flush the water heater. That does not just meant to drain and refill it.

Also, do you have a sulfur smell? I know that is not the question that you asked.

No, this is city of Denver mountain water, not underground - snow melt.
 

Melissa2007B

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PEX is not the cause of your black water. Hoses like those used on a fixture or washer can break down and leech into the water.
A proper chemical analysis of the water would be a good place to start. Dark color often comes from magnesium. Your water could have an effect on the anode rod it the tank, which would be easy to check.
The average lifespan of today's water heaters is less than 10 years, so having one that lasted 7 should not be too surprising.
Your goal should be to make the heater fire less often, and ciculation is not going to accomplish that.

This is a gas water heater. What anode or rod?

Yeah, I need to have it analyzed, and a recent visit from a guy from an energy company - he suggested that I also ask Rheem what it might be.

But as far as analysis, are there people who will do that for free? I should start with the water company, I suppose...
 

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If you have not already, do a little reading on water heater anode rods. They make tanks last longer, but with some water chemistry, you might benefit by switching the rod to a different type.
 

Jadnashua

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Pex doesn't have a lining, but some of those flex copper lines you have do. If that starts to break down, some of them can give a black output.
 

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All of those pumps will circulate water in the tank, if hooked up correctly. Some are designed to push water a lot further or higher but you do not need anything that big and powerful to just keep the tank stirred up. You did not state what the problem is or what you are trying to accomplish by circulating the water in the tank. If the reason you want to circulate and blend hot and cold in the tank is to avoid being scalded there are several other ways to do that, and most of those methods have been mentioned in your other threads.
 

Melissa2007B

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Pex doesn't have a lining, but some of those flex copper lines you have do. If that starts to break down, some of them can give a black output.

Those flex lines shown on the top, with the copper outsides? So if the water temp gets too high, that can cause the black water? Wow.

I think they were put in because it's a modular home and was shipped, but maybe they can be replaced with rigid copper lines now.

I lowered the water temp to half way between A and B and haven't seen any black in 2 days ( it was at B before ), but now I'm wondering how toxic that might have been, and if such flex lines were even meant to be used on hot water, at all?
 

Melissa2007B

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All of those pumps will circulate water in the tank, if hooked up correctly. Some are designed to push water a lot further or higher but you do not need anything that big and powerful to just keep the tank stirred up. You did not state what the problem is or what you are trying to accomplish by circulating the water in the tank. If the reason you want to circulate and blend hot and cold in the tank is to avoid being scalded there are several other ways to do that, and most of those methods have been mentioned in your other threads.

The reason I was thinking about it, was to prevent that temp stacking effect being caused by the humidifier. I think I said that originally. If a pump was circulating the water all the time, the temp would be uniform all the time?
 

Jadnashua

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Some places REQUIRE flexible lines (earthquake country, mostly), some places REQUIRE rigid lines. Some places allow either.

Yes, some of those flex copper lines have a coating on their inside (not all). Especially if the water gets quite hot, that can cause issues. Note, the same thing could apply to some valves that may have their own supply lines, but most don't have that problem. Really, though, if there is any rubber component in the system, under the right conditions (water chemistry, excessive heat), could start to degrade and give you a black spurt. Don't remember if I saw heat traps on the WH, but they, too, could have that issue. Not all that common, but possible.

Pulling the hottest water off of the top and putting it into the bottom of the WH would also diminish the amount of hot water available during use. I suppose you could put a flow sensor in there, and only run the pump when there is no hot water usage. ANother failure point, and expense.

IN reality, though, I've not seen any significant problem with using cold water for my humidifier, which would solve that problem, and save you money constantly.
 

Melissa2007B

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Some places REQUIRE flexible lines (earthquake country, mostly), some places REQUIRE rigid lines. Some places allow either.

Yes, some of those flex copper lines have a coating on their inside (not all). Especially if the water gets quite hot, that can cause issues. Note, the same thing could apply to some valves that may have their own supply lines, but most don't have that problem. Really, though, if there is any rubber component in the system, under the right conditions (water chemistry, excessive heat), could start to degrade and give you a black spurt. Don't remember if I saw heat traps on the WH, but they, too, could have that issue. Not all that common, but possible.

Pulling the hottest water off of the top and putting it into the bottom of the WH would also diminish the amount of hot water available during use. I suppose you could put a flow sensor in there, and only run the pump when there is no hot water usage. ANother failure point, and expense.

IN reality, though, I've not seen any significant problem with using cold water for my humidifier, which would solve that problem, and save you money constantly.

You have an Aprilaire 360?

Because they specify 140 degree water.
 
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