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Aquapex in radiant system

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Andruid_2
Andruid_2 Member Posts: 42
Aquapex is cheaper than HePEX.  Even when you account for the more expensive components that can withstand oxygen in the system (stainless heat exchanger, stainless pumps, proper expansion tank, etc), it's a cheaper system that uses Aquapex instead of HePEX in most cases it seems.  The only concern I can think of is high points where the oxygen that gets in can collect and cause problems.  If one has good air elimination and a proper flow rate to get the entrained oxygen to it, it seems that would not even be a problem.  Am I missing something here?

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  • Alan (California Radiant) Forbes
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    Missing

    As I understand it, oxygen in the air can pass through non-barrier tubing and be absorbed by the water in the radiant system. This oxygen is not air and no matter how good your air elimination (hmmmm), you can't get this oxygen out since it has been absorbed by the water.



    Stick with barrier tubing. 
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • EricAune
    EricAune Member Posts: 432
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    Missing, definitely

    If you factor the cost of cleaning agents and the labor needed to maintain a system without the proper tubing you will have spent any amount saved the first time around.



    Don't even let me start in on the heat exchanger issues we are so very used to seeing when this method of value engineering is ensued.

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  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
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    Key word...

    Cheaper...



    ME

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  • Not so fast...

    Oxygen barrier tubing is the thing for most hydronic heating systems, more especially those with ferrous emitters such as Euro-panels etc.



    However, I started many years ago with polybutylene (a nearly perfect pipe for radiant floor heating) and found that simple precautions made for very sound (and cheap) radiant floor heating systems.



    Oxygen diffusion is directly related to temperature, so many of our Ag buildings - never seeing design water temperatures above 90°F - were perfectly ignorant of the hard and fast "heat exchanger rule".



    I am generally with you on the barrier PEX, but on low temperature in-slab commercial applications it makes big dollars and sense to forgo the barrier (and the sub-slab insulation in all but the perimeter).



    It should be noted that the heat exchanger is necessary if barrier tube is not used, as most boiler manufacturers require a barrier or heat exchanger in its stead.
  • Dave Yates (GrandPAH)
    Dave Yates (GrandPAH) Member Posts: 281
    edited April 2010
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    amazing!

    So you're saying ferrous components don't continue to be degraded in the presence of O2 and water because your non-barrier cheap systems stay below 90F? When's the last time you actually measured the percentage of O2 in one of those systems? The degradation rate would continue unabated as the O2 levels will equalize across the tubing. I could agree the rate might be slower at lower temps, but not halted. And unless you can quantify what that lower slower rate might be, I'd be wary of this advice that striving to dumb down any system based on price-driven efforts is worth the risk.  
  • Andruid_2
    Andruid_2 Member Posts: 42
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    What will the oxygen hurt?

    I'm talking about using Aquapex in a system that has NO ferrous materials.  I'm talking about a system with all Aquapex, copper, brass, and stainless steel.  What in this system will be degraded by oxygen?
  • Dave Yates (GrandPAH)
    Dave Yates (GrandPAH) Member Posts: 281
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    nothing

    Devoid of ferrous = no ferrous corrosion. From my own personal perspective and seeing, first hand, the durability of PEX and PB, I'd spend the extra $ for PEX. Barrier or not. Especially if I planned on burying it in a concrete tomb. I've seen PB hydronic & snow-melt systems that failed. Your money = your call. Might raise an eyebrow or two via a home inspection when/if you sell because home inspectors look for PB. Red flag for them from an unrelated class-action lawsuit that had to do with potable-system fittings & not the actual tubing. 
  • Slimpickins
    Slimpickins Member Posts: 340
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    cheaper?

    I think the difference Aquapex and barrier tubing is 60 to 80 bucks for a 1000' roll. A small price to pay for doing the right thing for your customers and besides, they're the ones paying for it. 
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
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    You just have to ask yourself....

    IF this is such a GREAT way to do hydronic radiant heating, why doesn't EVERYONE do it that way?



    As for oxygen diffusion through the walls of tubing, operating temperature affects the amount of time for 02 to get through the wall and into the water and bring the levels to their maximums. Non barrier tube WILL allow more O2 to pass through and into the water faster than barrier tube, even with room temperature water.



    The presence of a high quantity of 02 has a major detrimental affect on rubber components (diaphragms on expansion tanks, pump gaskets, packing glands etc) and it isn't pretty.



    And then there is the contingent that uses "non ferrous" copper fin tube boilers to satisfy their need to be cheap, thinking they're giving the consumer a "good deal", only to have to replace the appliance within 5 to 7 years because the mild steel tube sheet rots out due to the O2 in the system...



    And don't even get me started on the Onix issues, another alledged O2 barrier tube that has a lot of issues.



    Ya just have to ask yourself, if the DIY internet peddlers say it's a good idea, is it really?



    And again, IF this is such a GREAT way to do hydronic radiant heating, why doesn't EVERYONE do it that way? Why isn't it an industry standard?



    Oxidation never sleeps...



    ME

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  • NRT_Rob
    NRT_Rob Member Posts: 1,013
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    bad reasoning mark

    "everyone" designs cookie cutter, energy hog systems. following the crowd is no path to excellence.



    The munchkin VWH can handle open systems. As can triangle tube prestige boilers, according to the MFG. I'm sure there are others. for the prestige solo or excellence, all you have to do is switch out in the internal pump... nothing else in them is ferrous.



    However much more typically I would use non barrier pipe with a heat exchanger to a high output water heater like a phoenix evolution. I have designed such systems myself in the past. with open expansion tanks and pumps in use, no big deal. audetat is completely correct on this matter. Concrete slows down o2 diffusion as well, I believe, so with low temps and concrete it's not *necessariy* a big deal even if someone forgot a detail like to switch out the expansion tank.



    I had a client running such a system on a cast iron boiler for over a year before I, horrified, got him to put in a heat exchanger. But you know what? his water and boiler were just fine when it was cut open. a heat exchanger was used anyway as a long term safety measure, but I think it's pretty safe to say low temp water in concrete is not a huge oxygen issue.



    I do have problems with dry systems and no barrier if they run any "real" water temps. If for no other reason than glycol longevity. Even if they don't use it now, they might someday, and oxygen will reduce the lifespan of the inhibitors in glycol solutions.



    but it is definitely possible to responsibly forgo oxygen barrier piping. Saying otherwise is dogma, not fact. Whether the cost savings is worth it or not probably depends on the product line and system configuration. but if it encouraged system pump and zone valve design, I'd call it a Good Thing(tm).
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • jp_2
    jp_2 Member Posts: 1,935
    edited April 2010
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    backwards maybe?

    more O2 can dissolve in cooler  water than hot .  we have all seen this, just in the opposite direction , open a cold beer then a warm one, which ends up on the floor?  so cooler water will can hold more O2.



    of course warmer temperatures speed reactions, and rusting is a reaction.......





    jp
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
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    Tell you what Rob....

    When you get thirty five years worth of experience under your belt, and have seen as many crap O2 barrierless systems as I have, well sit down and have a serious talk.



    I say again, why aren't people with more experience (Europeans) with this than the U.S. doing it? Where do we look to for guidance and experience? Europe.



    Will TT warrant their tank in a tank design on a system without barrier? I didn't think so.



    Why don't they offer a boiler with all non ferrous components?



    Are there warning signs notifying the first year service technicians that there is non 02 barrier tubing in the system to keep them from throwing the wrong pump into the mix?

    I didn't think so.



    BTW, when I was involved with the GY case, the tubing experts said that concrete does not stop the migration of oxygen. This from PhD's who study these processes for a living.



    Speaking of energy hogs, aren't you the one who says the use of water heaters as a space heating heat source is OK? Having lived with one I can tell you that they are serious energy hogs.



    Proper design is only part of the problem. Proper installation and maintenance play a large role in the longevity of the system as well. What say we agree to disagree.



    You do your systems the way you want, and I will do mine the way must customers want it done. Right the first time.



    ME

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  • CMadatMe
    CMadatMe Member Posts: 3,086
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    Come On

    I read each post and I'm sitting here shaking my head in disbelief. The price difference between Aquapex and HEPEX is so small that if that if this is a deal breaker from getting a job then you need to find a new line of work.



    Aquapex is mfg for plbg and HEpex for heating. Could you get away with using AquaPex in a completely non-ferrous application and I haven't see too many of them over the years. Sure you could. The pumps would cost you more than the difference in the tubing price though.



    I would think that a pro would use the product he is suppose to use no matter the cost versus cutting corners to put a couple of bucks in his pocket because in the end it's not your house it's in. Its the consumers. Your customer. The person that recommends you to his neighbor and friends. Do it right and stop hacking.

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  • NRT_Rob
    NRT_Rob Member Posts: 1,013
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    come on mark

    I don't blame mod/cons for being installed improperly, as they often are, and I don't blame non barrier pipe for bad system design either. I also don't appreciate your tone, or the attempt at an ad hominem attack. Maybe you could stay on topic and defend your point of view on merit alone, instead of trying to attack my credibility?



    The fact is I have been in contact with many systems that followed that design methodology for 30 years or more and, properly executed, they do not die early. And putting a note on a control panel about pump replacement is not that hard. I'll note again that I do not design such systems anymore... mostly because of the glycol question. But there are times that I have had to work around tubing already installed, and my previous work experience was with a company that did use non barrier pipe, for a long time. I know it can be done properly. There are thousands of systems out there proving it right now. The fact that some are done improperly is not really relevant.



    Triangle tube DOES offer boilers with all non-ferrous components, I guess you didn't read my last post very closely, since I already mentioned that. Talk to their engineers, I have. They have indicated all you have to do is, if the boiler has an internal pump, replace it. nothing else in the TT prestige series is ferrous. I know this because of a non-barrier system I was involved with finishing with a TT. no heat exchanger necessary.



    I never said concrete stops anything. I said it slows it down. As does having cooler water. After a year on a cast iron boiler, no excessive oxidation was found on my client's system. You figure out what that means, then. I assume it meant that in that particular circumstance the boiler wasn't going to die early, you know, since it wasn't rusting. But if your 35 years experience tells you something else, I'll all ears.



    As for water heaters, all I have ever said is that on *low load systems*, they can make sense. When a 20% jump in efficiency will not ever pay back the cost differential between a water heater and a mod/con, that is. Those situations exist. Not typically in colorado (though I wager there are such homes there as well, especially with passive solar design), but this is the internet, and people in all kinds of climate zones read our words. You cannot defend your point of view with math, because you're quite simply wrong to say that there are no situations where a water heater makes sense. but if you care to run some numbers on low loads or mild climates and justify your point of view... like I have in previous posts on the matter, and I can do again in another thread if you like... then again I'm all ears.



    I'm not really interested in knee-jerk generalities though. and I expect better than that from you.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
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    You're right.... My appologies. I'm just tired.

    Tired of being called in as an expert witness to system that are powered with water heaters and use non barrier PEX because the consumer did their homework and determined through the internet experts, that it was OK to do it that way. And then when it doesn't work, and most of them don't, the people who sold it to them are told that it is THEIR problem, not the suppliers.



    By all means, I have seen your handy work and you do not fit this profile. But just the same, you are condoning the practices, which is your option. If all of the people I have consulted had hired you to do their design, I probably wouldn't have been called in in the first place.



    But I have been, and I am tired of seeing the results, and want to make sure that any DIY'er who reads this understands my position, and their potential problems.



    Peace



    ME

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  • NRT_Rob
    NRT_Rob Member Posts: 1,013
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    accepted

    I am not condoning their practices. Their practices are, in my mind, unethical preying on uninformed consumers.



    What I am doing is not throwing out every product they use simply because they use them inappropriately, that's all.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • Lar_2
    Lar_2 Member Posts: 3
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    I have read with great interest.....

    I have searched and read and maybe missed it but now that someone else has done a staple up job with pb and a heat exchanger is out of the question due to the 7 zone pumps, what is the most logical way to maintain  a system such as this to keep it operating.  The boiler was recently replaced to an ultra.  Is there a treatment that will be safe with copper, aluminum, pb, pex, iron?  I appreciate your feedback.

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  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
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    Gonna be tough....

    My recommendation would be to contact Rhomar Water (Dwight Hedgpeth) and seek his qualified advice. Aluminum and ferrous components have differing pH needs.



    ME

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  • Big Will
    Big Will Member Posts: 396
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    Good thread

    I did use non barrier once. It made me nervous and with the cost of the pumps It really didn't save me much in the end. That was quite a few years ago. Today went through a house with a system that is in the owners home for our biggest costumer . He had it built by my competition before we were working together. The system has been running for a few years now and is fairly well installed. However they used aqua-pex and non-ferrous pumps. So in my report to the customer I was just going to point out that it is imperative that any components replaced be non-ferrous. I read some things in here about rubber deterioration. Is this ligament. I have never heard this but if its a real problem I need to let him know. Thanks for the good read all. 
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
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    Ultra 3 and water treatment.

    I have an ultra 3 (that has an aluminum heat exchanger), in a system with steel and copper pipe and cast iron Taco 007 circulators and a Taco brass air eliminator. This seems typical of Ultra boiler systems.



    W-M now recommend putting in Sentinel X-100 water treatment, although they used to say tap water was OK if the pH was between 7 and 8.5; hardness less than 7 grains; Chlorine concentration less than 200 ppm. But for their stainless indirects, they say pH should be between 6 and 8 and chloride less than 80mg/l. Note that chlorine and chloride are not quite the same thing.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
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    You can have ferrous components in a non oxygen tube environment...

    But you MUST maintain a high pH on the fluid, of around 8.5 for iron based systems. If it's aluminum in the picture, it is completely different, and the reequired pH's for the two metals is tough to control. Real fine band of acceptable pH. If you don't maintain the proper pH, the ferrous components WILL go away.



    The trick becomes gaining access every year to buffer the inhibitors.



    And we all know how well annual maintenance works with the busy homeowners of today....



    ME

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  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
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    If you don't maintain the proper pH

    the ferrous components WILL go away.



    Trouble is, if you do not maintain the proper pH, the aluminum will go away too, and the proper pH differs for these two.



    Where I used to work, we chemically treated aluminum in a sodium hydroxide bath for a brief time before we applied other treatments. One busy Friday late afternoon, someone put an assembly in the caustic bath and forgot to remove it when the time was up. By morning, it had been dissolved to shim stock, where it was 0.062 the night before. This bath was more basic than you would run in a heating system, but gives an accelerated view as to the consequences of incorrect pH.
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