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  1. #1

    Energy Wheel: what to buy ?

    Need some advice/opinion on wheel selection from someone who has serviced the different types over the last 20 years.
    Want the wheel to last the life of the equipment 15 years packaged DX & 25 years hydronic air handlers.

    AirXchange claims 20+ year life, but, it is plastic & that makes me think bio-degradation starting in 5 years. Also claim silica gel is imbedded & won't lose its effectiveness, but, I kinda find that hard to believe given plastic bio-degradation. Have heard they are more likely to gunk up with particulate due to the turbulent airflow (flutter of plastic "fins") even if MERV13 filtration both paths.

    Ceramic & fiberglass ? NovelAire ? Have heard that the small fibers crossing "fins" tend to collect debris even if MERV13 filtration both paths.

    Aluminum wheels (Semco, Xetex, Heatex, etc.) seem like the no-brainer for the extra buck given that is what the coil fins in a unit are made of & no bio-degradation (& future recycling). Also hear about laminar airflow making it less likely to have particle impact/buildup.

    Other question is molecular sieve vs silica gel for latent transfer. I know the silica gel is more effective, but, isn't that what we use in shoe odor eaters ? I have heard of "dirty sock" syndrome with silica gel. Definately don't want that. I have heard the fix is to rotate these at all times, which would seem to really waste energy when the energy transfer is going the wrong way. While I'm at it, 3 angstrom molecular sieve worth it for other than lab fumes ?

  2. #2
    Join Date
    Aug 2004
    Location
    Currently in Phoenix, AZ
    Posts
    31
    I just caught this and I'm surprised you haven't had any replies. It's probably too late now, since 6 months have gone by, but for what it's worth....

    Yes, aluminum wheels are certainly more robust than plastic. Yes, laminar flow is important at all times but most especially in an environment where there is higher than usual dust/particulate potential in either airstream (fresh air or exhaust air). One reason the plastic wheels are not as deep as the aluminum and paper (fiber) wheels is that they get excellent thermal transfer because of turbulent airflow. (Those familiar with the principles of refrigerant cooling systems know that as well. Extra heat transfer can be accomplished through the use of rifling (turbo-spirals) in coil tubing to get better energy transfer.) So the laminar flow wheels are by necessity, deeper in order to accomplish the same degree of thermal transfer as the thinner plastic media wheels. However, a happy consequence of a deep aluminum wheel vs a thin plastic wheel is that it is far more physically robust and not as prone to structural deformation or even failure.

    That's the substrate part of the story, the desiccant material and mechanics are also important. First let me state that maintenance is crucial no matter what wheel is installed. No one buys a car and expects to never change the oil. All wheels will benefit from keeping the filters changed and all wheels will suffer performance loss and possibly permanent damage by not keeping filters clean. Laminar flow does help particulate matter pass through the wheel structure as opposed to getting trapped inside. I would say that the fibrous substrates (Novelaire) are no worse than an AirXchange (plastic) wheel and probably just a tad better in terms of resisting particulate build up in spite of the little fibers in their flutes. That said, they do have a somewhat higher pressure drop than just a straight aluminum wheel with molecular sieve desiccant. 3A desiccant can be absolutely critical in laboratory, smoking (casino), or toilet exhaust environments. In a typical commercial or school application it does not matter nearly as much. Most operation sequences that I've seen will rotate the wheel one-half rotation every 30 minutes to keep it cleaned out. In other words, about every 1/2 hour, the wheel rotates 180 degrees to put a new 'half' in the other stream - bear in mind that the airstreams are counter-flow so this operation will cause a reversal of airflow through the media that will "blow" off any materials or particulate that has collected or otherwise gotten caught on the face of the wheel.

    I could go on and on but I think I've addressed your initial points. Please feel free to PM me or reply on this forum if you have more questions or want more information. Cheers

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