Glass Lined versus Stainless Steel - Indirect HW Heater

rsc92

I am replacing my water heater (Rheem 75 gallon power vent nat gas) with an indirect HW heater.  My plumber is insisting that the Glass Lined Superstor Contender is the way to go.  Reading the documentation available on the web leads me to believe that the Stainless (Superstor Ultra) is a better option.  The documentation reports a much higher first hour rating for the stainless versus the glass lined and the stainless is much lighter which should make installation much easier.  My plumber told me that the Stainless fails more frequently than the glass lined units, yet HTP offers a limited lifetime warranty on the stainless and only 7 years on the glass lined.

I would welcome any opinions or experiences with both.

The indirect will be paired with a Power Vent Burnham Boiler (PVG6NI and, will be set on priority. 

lchmb

I have

the contender in my cellar and installed the ultra at my Father in law's. Both unit's seem solid. I would go with what make's you more comfortable. Life time warranty is a nice thing...;)

CMadatMe

Chlorides

In certain areas Stainless Tanks tend to fail more rapidly then glass lined tanks due to chlorides in the water. Whether lifetime or limited doesn't cover the labor to replace it. The minimal increased gph is trival when comparing a SSU45 over a SSC50 in my opinion. Your installer may know that your area is not a good fit for a stainless tank.



The better fit in my opinion would be the Burnham Alliance Stone Lined Tank. Out of the box is a 10yr warranty but you can send a small check in with the warranty card and turn it into a lifetime heater. Weight has no bearing as to how easy the install will go.

rsc92

Burnham Alliance

Thank you for the suggestion.  I will ask my plumber about that tank. 

SpeyFitter

400 series vs 300 series

Stainless steel tanks SHOULD last significantly longer than a lined steel tank. The issues of chlorides and stress corrossion cracking is an issue but only with 300 series stainless steels and only in areas where they put a lot of chlorine for disinfection in the water. 

Having said this - this is something I am really curious about. A LOT of manufacturers of the various stainless steel tanks use 316 L stainless steel (many manufacturers), in some cases an even higher/more expensive grade - 316 Ti (Viessmann). 316L and 316 Ti has very high chemical resistance, but they are not immune to chloride attack.  300 series stainless steels cost significantly more than 400 series stainless steels due to the nickel content and nickel prices are through the roof. Yet look at the Bradford White RTV stainless steel tank - made out of 444 stainless steel.  400 series stainless steel is generally immune to chloride attack according to some metallurgical reading I've done and so I wonder why we don't see more manufactuers looking that way?

The other really interesting thing is if you find fact sheets with metallurgical data on various stainless steels, you'll note that when you look at many of the different 400 series stainless steel fact sheets- 409, 439, 444, etc they talk about one of their primary uses as being used for hot water tanks.  But I don't think they are neccessarily talking about building them today with the exception of the Bradford White tank. I think they are talking about them having used these grades in the past.

Here is some more interesting info - I frequent some plumbing sites, and I seem to recall some threads about guys finding 40 and 50 year old hot water tanks during hot water tank retrofits by certain manufacturers that back in the day were made out of stainless steel (before they starting building hot water tanks as a commodity). I have a gut feeling that many of these tanks were probably made using a 400 series stainless steel but don't quote me or consider it fact and I haven't done some research to confirm it. Just a suspiscion right now anyways. 

meplumber

400 series stainless.

Not to hijack the OP's thread, but a note for Scott.



400 series tanks are extremely common in industrial and institutional hot water tanks. They are the standard for industrial process water heating applications. Hence the claim that the primary use is for water heating tanks. It is true, just not for residential and light commercial DHW tanks.



To the OP.



The previous posts are correct. Chlorides are a factor in stainless steel tank life. Your plumber may have that piece of inside knowledge of the water conditions in your area that make the glass lined tank more reliable.



Discuss your concerns with him and give him a chance to explain it.

kcopp

Interesting...

I came to this DHW forum to ask about chlorides. I have a customer who has a real issue w/ them in his well water.... damages a lot of stuff. And yes he has a stainless indirect. How does one fix that/ filter that? Bock claims their water heater (similar to the SS Contender) can handle chlorides better.  Thoughts?  I presume that if you added an extra anode to the water heater that may help you. The only issue I had a few years back were pinholes in the coil on a few SSC50 that leaked into the boiler and caused the t&p to pop/ weep. They covered them under warranty.

PickyPro

Use RO to filter out chlorides

From the info I've gathered reverse osmosis would be the correct filter for chloride removal.



Sorry to jump into this post. I came to this forum to get opinions on choosing between a stainless steel and a glass lined indirect HW heater. Please let me know if it would be better to start a new post.



To the OP : what did you end up going with?



I am a general contractor and am doing research for my customer. The plumber I use and my customer's plumber have given us a few options. We are all set on sizing. My customer is wary because he had a glass lined storage tank in the past, it failed and flooded his finished basement and he's been living with a poor quantity of hot water from the existing (probably scaled fouled) tankless coil in his oil burner. I explained that it probably failed because he never maintained the anode. He wants my opinion, on ss versus lined, because I have more knowledge about water treatment in general and his water quality specifically. I recently had his well water tested before and after his water conditioner (softener). I wanted to find out if the system was doing its job and if it was properly sized for his home and his water quality, before I considered what type of hot water storage I would advise he choose. Both plumbers gave us similar options of going with a storage tank or an indirect and options for stainless or lined with anode(s).



The water tests showed 7 gpg hardness a pH of 6.7 and 16.5 mg/L of chloride before and after the .75 cubic foot (24,000 grain) conditioner. This proved my theory that the 16 year old conditioner was not doing its job. After analyzing their water consumption and usage patterns, checking the performance of the well and pressure tank, measuring the static pressure and gpm flow at the tank and various fixtures throughout the home we concluded that a new water softening system would be the first priority. We will be upgrading to a 1.0 cubic foot system which I will purchase, install and program.  I will have to retest for chloride once the system is online.



Since the water will still contain chlorides ( I don't know how much yet), both plumbers agreed with my opinion that stainless may not be the best route.

I researched different manufacturers warranties on their stainless versions and as I recall chlorides were acceptable up to a certain limit, but just because they would replace the unit doesn't mean I would jeopardize my customer having to experience another flooded basement. Does anyone know if a stainless tank can be protected by adding an anode? This is the only link I could find when doing a search for "stainless steel hot water tank with anode" I will be speaking with one of their reps today.  http://alliedboilers.com/indirect_fired_water_heater.php



We will probably be choosing a lined steel tank with one (and I'll add another, if possible, prior to install) or 2 anode(s). We have decided to go with an indirect instead of just a storage tank because we will be bypassing and/or removing (any suggestions?) the boiler's tankless coil. Then we still have to decide on a tank in tank design or one with a coil. Would a stainless steel circulator be ok or is bronze preferred?



Any suggestions or opinions will be greatly appreciated

CMadatMe

Vitocell 300

Want the mack daddy of all stainless tanks?



http://www.viessmann.ca/etc/medialib/internet-ca/pdfs/tanks.Par.84646.File.tmp/Vitocell-V_300_TDM.pdf



You will pay top dollar but be assured its the last tank your customer will ever purchase. Max chloride acceptance before the warranty wouldbe void is 500 mg/ltr. See warranty.



http://www.viessmann.ca/etc/medialib/internet-ca/pdfs/doc/war.Par.86762.File.tmp/Vitocell_300_Warranty.pdf

PickyPro

Viessmann versus Allied

Thanks for the link Chris.  That is a beauty. I like the access, the layout, the specs and the warranty but not the price. 



Did you check out the link I had posted for the Allied? Pretty similar but no access. Ten year warranty versus lifetime, 1" coil versus 1-1/4", possibly better grade of stainless,  less insulation, half the price and has a magnesium anode. Only ss unit I've seen with an anode. I don't  understand recovery rates, yet, so I can't compare them.



Here's a cool link to compare 316L and 316Ti stainless :

http://www.bssa.org.uk/topics.php?article=71



I'm pretty sure my customer will look at me like I'm crazy if I suggest the Viessmann.

I've looked at the Mega-Stor and have heard that others really like it and it is competitively priced.



I still have to compare the lined indirects as an option for my customer.

Any opinions on favorite lined indirects?

Zman

Recovery Rates

Pickypro,

Thanks for the info on chlorides. It makes for good "brain food". I think we need more GC's with your interest in the details.

Have you looked at heatflo stainless indirects?

I think State makes a lined model with a non stainless coil.



As for the recovery rate subject. Most of the indirects that are coming out today have a bigger exchanger than the boiler powering them. If you take the input BTU rating of the boiler and derate it for efficiency you will get your output BTU's. If you divide that number by 500 and then divide that by your delta t you will get the max gpm the boiler can produce. 

For example, A 100,000 btu 80% efficient boiler  (at sea level) heating water from 60 degrees to 120 degrees would look like this 100,000x80%=80,000  80,000/500= 160    160/60=2.6 GPM



2.6 GPM is the max this boiler can produce no matter what exchanger you hook it to. One problem that arises when using an oversized indirect is that if the boiler is not piped correctly it can drag the boiler temps down and cause condensation. This great for condensing boiler and horrible for non condensing.



Beyond that the only variable is how much water does the indirect store.

PickyPro

Recovery Rates and Add Anode to Stainless Indirect

Zman,



Thanks for the recovery rate info.

Also, I'll make sure that the plumber who installs it understands the info in your last paragraph.



I'm learning more about chlorides because I'm really interested in water conditioning

and will be purchasing and installing equipment for my customers. Many of my customers here in southern Ct. use well water. With all the high end products I use in remodeling their kitchen and baths, I need to test their water and also make sure their softeners, well pumps,  etc. are doing their jobs to protect the fixtures including the water heating equipment. I also try to give them optimum flow rates.



Thanks for the suggestion about looking at the Heat-Flo products. I like what I see from their website. But, I was hoping to be able to add an anode. I'm going to give them a call to ask their opinion. I've had a really difficult time  researching whether or not adding an anode would extend the life of a stainless steel tank and its exchanger. I've even emailed the folks at Allied Engineering ( the only manufacturer of stainless indirects, that I could find, with an anode) to ask them how the anode assists in the longevity of the stainless, but no reply. I've also emailed the techs at Triangle Tube to ask if adding an anode, using the "aux" connection on top,  would affect their warranty and whether it would benefit the stainless's tolerance to chlorides. But, no reply. I can't figure it out? Why wouldn't companies who have engineers on staff answer a relatively simple question? Sorry to inundate you with my concerns.



I'll take a look at the State products soon.



Thanks for the compliment on caring about the details. I really appreciate it. My customers really like my attention to choosing the best products for their situation. I am the architect and the designer for all of my projects...and the master carpenter working on the job every day. It gets overwhelming at times, but it keeps me off the streets.



Have a good day.

PickyPro

Zman and Recovery Rates

Zman,



Thanks for the lesson on Recovery Rates. I appreciate your assistance.

I did not intend to hijack this thread, but didn't know if I should start a new one.



The existing boiler is a Burnham. The label on the jacket says "V8 Series low pressure boiler",  Model 85WFH.  D.O.E. heating cap 164,    196 MBH



I contacted Burnham asking for a manual. They emailed me the pdf version for the V7 Series, stating that the 85WFH is a warranty replacement block, jacket , and canopy for the V7 boiler. So, I am assuming the rating label on the jacket refers to the new block.



Using your lesson in calculating the max. gpm this boiler can produce I came up with 5.46 gpm (using a delta T of 60) and 4.68 gpm (using a delta T of 70, well water in CT at 50?).



To do the calculation I used 164,000/500= 328/60= 5.46 gpm for 60 degree water

and 328/70= 4.68 gpm for 50 degree feed water. Did I do this correctly based on the ratings of the boiler?



So, for example, if I chose to go with an indirect like the Triangle Tube Smart 50, its specs state a boiler output of 140,000 BTU and Peak/Flow (gal/10 min.) : 65 (6.5 gpm?), the boiler would still only be able to produce 4.68 gpm with a 50 degree water supply and the max. the Smart 50 could produce would be 6.5 gpm if my supply water was 70 degrees?

 

You stated that an oversized indirect can drag the boiler temps down and cause condensation if the boiler is not piped correctly. I don't know if this is a condensing boiler or not and would appreciate any input on how you would set up an indirect with this boiler. I assume my plumber will have this knowledge. I'm just trying to learn from others prior to choosing an indirect and also want to know how best to hook one up.



I am guessing that we will be bypassing the existing tankless coil in the boiler and that we will add a zone for the indirect. Do you pull the existing tankless coil and replace it with a cover plate with access ports and hook the indirect up there? Or, do you just cap the the existing tankless ports and add a zone valve or an additional circulator? BTW, the Burnham rep I contacted did state that I would need to call their inside tech. dept. to ask them these questions.



Right now the existing boiler has one circulator and 6 zone valves. I've read some articles about making the indirect a priority, but don't really understand how this is done. Any advice or insights are really appreciated.