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Cast Aluminum Heat Exchanger - Chemical Treatment

Steve Ebels_3
Steve Ebels_3 Member Posts: 1,291
For me, the jury is still out and I won't put any in until my conservative/stubborn Dutch head is convinced there are no issues like you describe. That being said, I'd contact the folks at Rhomar and/or Noble Chemical regarding inhibitors for AL containing systems. IIRC, both companies have products that they recommend. My gut feeling is that when you get into older systems which contain A: large amounts of fluid, B: a pre existing combination of steel, iron, and copper and C: water chemistry that is ancient and carrying who knows what, you have recipe for a meltdown. All bets would be off in my book unless you could start with a spotless system along with known water chemistry and quality.

Comments

  • Chris_91
    Chris_91 Member Posts: 5


    Our office specifies a lot of condensing boilers and lately the newest boilers (PK, AERCO, Weil) seem to be using Cast-Aluminum heat exchangers.

    My problem is glycol, and chemical treatment. Our chem treatment contractor's are saying that they don't have anything in their batches of chemicals that will provide adequate protection of an aluminum component in a boiler loop.

    I'm also getting mixed messages about what glycol can be used: prop, ethylene, specially-inhibited prop only, none...

    To top it all off we just had a HX failure on a new installation ~2 years old... looks like a glycol/chemical problem.

    Now... to finally ask a question: has anyone encountered a chem treatment program suitable for AL HX? Has anyone else had problems with glycol in these systems? I'm tempted to back to SS only... expensive, but less liability.
  • hot_rod
    hot_rod Member Posts: 22,121
    Only one that I know

    that has been tested and accepted by several of the boiler manufacturers is Rhomar. www.rhomarwater.com.

    They have cleaners, inhibitors and now aluminum blended glycols.

    Proper cleaning with al friendly products is a big often ignored step.

    Nobel NoBurst AL is another glycol I have used without a problem in aluminum boilers.

    Most aluminum boiler manufacturers are very clear in their installation instructions about the use and care of aluminum. Weil lists a ph of 7- 8.5. installers are responsible for testing and correcting any fluids they use. It's probably not the boilers fault it failed :(

    Certain conditions will effect stainless hx also. And the stainless have a lot less wall thickness to "give" up. I have pictures of leaking stainless heat exchangers.

    Did you test the fluid on the failed system? What was the ph? It would be good to have that info to see what the tolerance level indeed is.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Chris_91
    Chris_91 Member Posts: 5
    Thanks Hot Rod,

    We're still waiting to see the 'post-mortem' but it sounds like a batch of non-AL friendly glycol was mixed in with the specified glycol.

    Not the boiler's fault, but the fact is that a cast-iron or SS HX would still be running...
  • Chris_91
    Chris_91 Member Posts: 5
    That's what scares me...

    Is that all systems become 'old' with a water chemistry that is ancient and carrying God knows what.

    If all it takes is one batch of 'discount' glycol to tank the boiler we're going to see a lot of failures.
  • Brad White
    Brad White Member Posts: 2,398
    Chris

    You mentioned Aerco among aluminum HEX boilers- do you mean the Benchmark model? That is the only condensing boiler to my mind that Aerco makes unless they have a new one. The Benchmark is 316L stainless.

    Here is another view of pH and aluminum that I have not had yet "explained away"- With all of this talk regarding how close one has to maintain the pH of the water side (above or more alkaline than neutral by a bit) why is the combustion side, with much hotter conditions and much lower pH somehow immune?
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • Dan Foley
    Dan Foley Member Posts: 1,258
    Aerco

    Brad,

    The new Modulex condensing boiler line has an aluminum block. It looks very similar to PK's aluminum block. I recently ran across this boiler when they were spec'd for a large residential project we just started. I was able to get the spec changed to Vertomats. I too am wary of aluminum blocks until I get more information on longevity. -DF

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • Brad White
    Brad White Member Posts: 2,398
    Thanks, Dan!

    I did not know that they had a more residential grade boiler. Interesting that they departed from their current manufacturing material stream, unless it is an OEM product made by others and them putting their name on it.

    Thanks DF!

    Brad
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • hot_rod
    hot_rod Member Posts: 22,121
    That Aerco boiler

    has been around for some time across the pond. I can't recall the manufacturers name. Here are some in a large project in Brescia, Italy. The dealer and installer has been happy with the product.

    As we know not all the Euro technology behaves the same in our country.

    I'd suspect more often then not it is an installer error problem. We all need to learn the best way to install, commission, and maintain this high efficiency equipment. Or else someone will pay down the road. The contractor is often the first to get the blackened eye.

    The training needs to start at the manufacturer, rep and dealer level, in my opinion.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Drew_2
    Drew_2 Member Posts: 158
    Aluminum & Antifreeze

    Chris
    Give me a call if you'd like the condensed version of "Why the Antifreeze Differs". 800-678-6625, Ext. 108

    Drew
    Noble Company
    Home of Noburst AL
  • WM Technical Services Bulletin SB0603,

    Here's the service bulletin from Weil-Mclain:
    http://www.weil-mclain.com/professionals/services/Bulletins/SB0603.pdf

    Cleaning Weil-McLain's Boilers!
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