Stainless tank concerns?

Dan_15

Crown provides up to lifetime warranty on its Megastor stainless tanks, although labor costs are not covered.

tim smith

Stainless tank concern

I was talking with one of the storage tank engineers from one of the largest commercial potable hot water storage tank/ residential hot water tank mfrs last week. I asked why they don't make a stainless storage tank for domestic hot water. He said that stainless tanks will not hold up well to the flouride and chlorine in the water that is present in cities today. They have studied this quite a bit and other type of lined tanks will probably hold up much better to these chemicals is what I got out of the conversation. This concerns me to the longevity of stainless tanks. What do y all think, just looking for opinions. Tim. PS Anyone have any 20 year old stainless potable tanks out there, just a question.

Brad White_172

Interesting....

Part of me says, "all the water going in is the same; Indirects are not made just for the clear, rural, non-chorinated/fluoridated well water market."

The other part of me says, "Yes, but direct-fired heaters take more thermal abuse, with combustion products directly opposite the water". Then I wonder why that might be an issue as the combustion side is not seeing the chlorides at least directly. I also have to think that chlorides are going to affect all metals, stainless too, but less so than mild steel or aluminized steel.

My realistic if not cynical side says, "A stainless heater will cost more in a competitive market and have less of a replacement potential, thus fewer new sales down the road. Planned obsolescence is required for long-term company survival."

However short-sighted, last thought rings most true to me.

My $0.02

Brad

tim smith

reply to brad

Brad, this is not just for indirects, this was regarding just hot water storage tanks also. I was very interested in what he said because I was looking for a custom built asme tank for a job and thats how the conversation struck up. In my mind I always think stainless will hold up better in this application but he has been doing this a long time and he knows quite a bit about tanks as that is all he does.

Brad White_172

HTP SuperStor

makes a decent line among others, so I have no idea why it would be an issue compared to less noble materials. Nothing wrong with cement lined of course, they have lasted for years but for the integrity issue of the lining itself. It tells you of failure by the failure, absent eddy-current testing. I took the liberty of injecting about direct-fired too, thinking that would be the most abusive application. I would presume that the proper alloys (316L or 316Ti) would be used in any case as is standard for all lines that I have seen.

Not sure of the volume you need, Tim. I can see the cost associated with getting not only ASME VIII stamping but also NSF certification in a custom tank. Wondering if an array of smaller off the shelf tanks would work as well for less cost and more modular installation through common doorways.

Yes, it is interesting, the observations. Must be something to them and I would love to see the data.

Where my antennae go up (yes, I do have those is when I often hear, "It should not/could not/cannot be done", I also hear, "I cannot". With an abundance of alternate SS tank manufacturers (HTP, TT, Viessmann, MPI, etc. etc.), I would ask why it would be an issue.

Larry Weingarten

I'd add...

... that there are a variety of stainlesses and some don't work in hot water. Type 304 is an example. Yet 316 has worked for solar applications for over twenty years. Also, Monel, a copper / nickel mix works quite well for gas fired and electric heaters. Cost is the thing. The main stream buying public buys what's the least up front cost. They don't get the concept of life cycle cost. Manufacturers make what sells. High quality, high price units don't sell. Perhaps a start-up company is needed to grow the niche of really good heaters so that the major players feel the need to enter that market too. The technology does exist.

And that's my Mother's Day rant ;~)

Yours, Larry

hot_rod

Maybe addressing the high chlorides

would be better, both for the tank and your body.

Instead of finding a tank that can handle excessive levels of ... whatever attacks stainless.

There must be a filter or a method to handle whatever water condition the utility can throw at you.

Excessive chlorine (a posion) is not good for your system either. I have also heard concerns about water that is excessivly flourinated? it's always wise to know what you are injesting.

hot rod

D107

May depend on chloride levels in a particular area

Had a make-up water test done by Rhomar. They advise that for stainless steel, chloride concentration should be no more than 20ppm, but for other metals--presumably copper,aluminum, iron/steel--under 100pm is OK. Since my chloride level is 28ppm, I have also been concerned about both indirects and boilers with stainless steel HXs or tanks. So filtering and annual cleaning may be the Rx.

Glenn Sossin_2

drinking

making me nervous about drinking the water

ALH_4

Alloys and concentrations

Higher chloride concentrations also increase the possibility of galvanic corrosion problems. I would recommend using dielectric fittings if this is to be connected to copper plumbing. I believe 250ppm is the taste threshold for chloride.

The grade of stainless steel is very important when considering chloride resistance. The chloride ions can prevent the formation of the passivation layer on the stainless steel and lead to pitting. One of the engineers at Viessmann once told us of an application where sea water had been heated in their stainless steel water heaters for many years without problems.

I wish I knew more about this sort of thing.

Brad White_172

Not as nervous about

typhoid then? That was the motive behind chlorination in the first place. Not saying one should go overboard on PPM, but it beats getting typhoid...

Unknown

Galvanic corrosion

I've seen 3/16" stainless angle eaten away to nothing in 3 months due to being exposed to sulfuric acid and electric current flow. I'm not familiar with the grades anymore but this was the good stuff. It would hold up to the acid but there was current running it it for some reason and the results had to be seen to be believed.

I too believe it is more a cost thing than anything else. Some mfgs/installers will only produce what sells the most while there are a few that will address the specialty market. I like both SuperStore and Crown's Megastor. I've installed plenty of them and haven't had a problem yet.

Paul Pollets

Even Viessmann....

excludes high chlorides for their tanks. I'd treat the water and use a 316Ti tank. Water chemistry is key to longevity.

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Larry C_5

Where is Perry?

I thought this was up his alley? SS heat exchangers and water chemistry.

Paul Fredricks_3

We won't install a stainless unit for our customers in Stamford, CT. The chlorides eat them up in 2-3 years.

Metro Man

current.

Ditto MPF - current is our major concern when fabing our stainless tanks. These tanks are non-pressurized and made of #304 stainless. We will test and treat (if necessary) water used in tanks. Usually not a problem since we fill with tap. Grounding pumps and controls correctly is essential. But..... stainless are our tanks of choice. Tanks installed 25 years ago still holding fine. Again these are non-pressurized and non-potable so a little different than the indirects.

Stainless prices have risen several times this year alone so not surprised more manufactures are not jumping in.

Warranty on superstore is only good for 150* or below, not sure about
Megastor

D107

How about whole house filtration

Just saw a site http://www.aquasourcewater.com/howitworks.php

Seems that as long as the water is not softened too much it might be a solution for chlorides, hardness etc. and better tasting water.

Anyone recommend this approach?

Dwight (Rhomar Water Mgt.)

Chlorides & Stainless

Water softeners only remove calcium and magnesium along with some iron that may stick to the resin. They may actually add chlorides to the water from the salt brine that is used to regenerate the tanks.

Chlorides / chlorine are very corrosive to some grades of stainless. As little as 10ppm chloride can rapidly corrode some grades, especially if heated. There are some grades that are more resistant but I am not sure which ones they are. I have seen bleach eat holes through stainless steel sinks in several days when soaking parts in bleach water.

All natural and municipal water supplies contain some level of chloride. The only way to know how much is to have it tested. It is fairly easy to test for and we can do it if needed. You can get a "Water Test Request Form" on our website, www.rhomarwater.com. High levels, usually over 50ppm can beging to attack other metals also. The rate of corrosion increases rapidly as water temperature rises. Added chlorine in municipal water supplies can also add to this but are supposed to be only around .5-1.0ppm.

Fluoride can also be corrosive and it is a very toxic poison. I personally wouldn't drink water with fluoride or chlorine added to it. Long-term ingestion can create all kinds of health issues.

Carbon/charcoal filters will remove most chlorine and fluoride but you would need R.O. filtration to remove everything completely. This would also include the good stuff like calcium and magnesium though.

Dwight

Tom Hopkins

Plagiarized from the Buderus Site

Buderus manufactures domestic hot water tanks for practically every application - from residential on up to large commercial applications. Water capacities range from 32 to 258 gallons.

The average household spends up to 30% of its energy dollars producing domestic hot water. That is why Buderus pioneered a method of producing and storing domestic hot water that is incredibly efficient. The super insulated design of the Buderus tanks protect against heat loss.

Only Buderus hot water tanks are equipped with the thermal glaze DUOCLEAN™. DUOCLEAN™ is a ceramic that is thermally bonded to the internal components of our hot water tanks. The smooth glass-like coating provides added protection against the corrosive affects of minerals which are naturally present in water.

Buderus hot water tanks provide clean, pure, and reliable hot water comfort for many years.

*This will eliminate your concerns regarding steel tanks*

Rick

hot_rod

water softeners that don't backwash

properly or completly are a major source of excessive chlorides in the water. According to a local water treatment fellow in my area that does water treatment for many food processors.

Stainless is the metal of choice in the food industry so water quality is critical. When stainless tanks and vessels fail, it is often due to water softener issues, so he tells me.

hot rod

Bob Gagnon plumbing and heating

Chlorine

A metallurgist told me the harmful effects of chlorine would be stopped with an anode rod. Does anyone know if that is true? Thanks, Bob Gagnon

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