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What do you think of

Tim McElwain
Tim McElwain Member Posts: 4,622
this unit?

<strong><img src="http://image.bnpmedia-email.com/lib/fefa1670746d0d/m/1/082411RH_EnervexEcoFlex.jpg" width="185" height="120" alt="Enervex EcoFlex 90+" />Flue gas heat recovery: </strong>ENERVEX introduces the EcoFlex 90+ fan-powered flue gas economizer. Manufactured completely in 316L stainless steel, the IPVB-ECO features a patent-pending design and can be installed in any part of the chimney, including horizontally or vertically. It can be used in conjunction with any gas fired heating appliance - condensing or noncondensing. It also allows multiple boilers to share a single economizer. As part of the ENERVEX Chimney Automation System, the EcoFlex 90+ System is controlled by the EBC30 or EBC35 draft control. It features a variable speed and direct drive, as wells as a removable drive unit. Like all ENERVEX products, the EcoFlex 90+ System features a two-year factory warranty. <a href="http://click.bnpmedia-email.com/?ju=fe3117727460027c701478&ls=fde11d76726c037a70117273&m=fefa1670746d0d&l=fe561576726d007b7413&s=fdf115787765017a7d107974&jb=ffcf14&t=">[u][color=#0000ff]www.enervex.com[/color][/u]</a>.


  • JStar
    JStar Member Posts: 2,752
    I wonder

    Does this unit need to be drained? Are they really allowing you to run colder flue gas through non-rated material?
  • chimneydoc
    chimneydoc Member Posts: 1

    I believe they made products under the trade name Exhausto. Something happened in NYC with their controls and chimney design solutions. Due to faulty controls that do not operate safely they were being sued and went bankrupt before changing the name to Enervex. My experience with them has been sketchy at best. All of their devices have issues and alternative devices and controls are available in the US by field controls which uses American designers and engineers installer.
  • icesailor
    icesailor Member Posts: 7,265

    I just did my 6 hours of CE for my license renewal in Massachusetts. The first three hours were on gas. The biggest part of that 3 hours was on venting of gas appliances and how to size vents and chimneys. And venting multiple appliances through common vents.

    I worry, how much restriction does this device add to a vent and who does the calculations on if the flue can handle the additional load on a properly sized vent when it is designed toward the upper end of the scale on a small  sized vent.

    I shudder to think of those things being sold at HD or Lowes and installed by DIY and homeowners. Or some contractors who don't know what they are doing when sizing gas vents.

    How much heat will you recover on a 3" PVC direct vented gas boiler running in condensing mode with 100 degree exhaust?

    Too bad this didn't come up on Friday and I could have asked about this.
  • Jack
    Jack Member Posts: 1,047
    If you wait long enough

    all the old stuff comes around again. I used to make heat reclaimers for wood stove stacks running water thru 3/4" tubing in an 18" length of stove pipe. It was a double wall unit Worked really well, except for the creosote it helped make. The lessons you learn.

    Back in about 78 I went to an Energy Conference and met a guy who ran the maintenance dept for a local college and he was telling us that her was saving a lot of money reclaiming flue gases on the colleges boilers stacks. The following year I was really looking forward to hearing from this fellow on how things had worked out. I found a different person at the conference from the college and asked him how the reclaim project went. The original guy had been let go due to the failure of most of the colleges boilers due to corrosion which was induced by the low stack temps.

    Oh, he also, with military like precision had all the staff synchronize their watches and at precisely noon had everyone of his guys test the big AC equipment around the campus by turning it on at precisely the same time. This spiked the power in a way that put the college into a new, much higher price level with the utility for the following year. I guess they call it "demand shadow".

    Given the history of stack heat reclaiming and my experience with it, and my experience representing Z-Flex, Selkirk and Dura-Vent over the years I am extremely wary of heat reclaiming. I like to use a high efficiency heating appliance and let whatever heat is left over be exhausted.

    What do you think manufacturers of furnaces and boilers would think of an installation equipped with this reclaiming "technology" from a warranty support standpoint ?
  • Tim McElwain
    Tim McElwain Member Posts: 4,622
    Well it took a while for folks

    to hook up with this posting.

    Here is my experience with so called "Heat Reclaimer's" almost everyone I ever encountered was making high levels of CO and creating a soot cleaning nightmare on gas equipment. Those were way back in the days before electronic combustion analyzers and no one tested for CO and of course oil does not ever make CO anyway so they had no problem with them. Then again they did a great job on wood stoves until the creosote plugged the flue.
  • gennady
    gennady Member Posts: 839
    edited March 2012

    I used to work at power plants, and did a lot of services on economizers , which are integral parts of power boilers. I think what needs to be controlled is a dew point, up to chimney outlet, and negative pressure from firing chamber all the way to chimney outlet. This leads to complicated design issues, and with properly set up boiler there is not much heat to recover without damaging chimney and boiler.
  • Al Corelli_2
    Al Corelli_2 Member Posts: 395
    What's that noise?

    I can hear the chimney tiles falling now...
    Al Corelli, NY

  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    Mathematical misconceptions....

    Some people will look at a given stack temperature, say 350 degrees F, and say "WOW, look at all that wasted energy. We really only need 70 degrees F to keep people comfortable. That means there are (350-70 = 280) 280 degrees F of recoverable energy in that flue gas stream... (WRONG!!!)

    Or how about the people who take a 3" magnifying lens, and focus the suns energy on a small thermistor, and see 2,000 degrees F. and think "WOW, LOOK at ALL those degrees F. If I only need 70 degrees F to keep people warm, I could probably generate enough heat to heat my whole neighborhood!!!" (WRONG AGAIN...)

    As a former frequent poster (Copper Head Ken) use to say, "Marketing will overcome engineering every time" .

    With that said, there are some potential waste heat recovery potentials that are out there, but very few are in a residential setting (except drain waste heat recovery, and that is extremely limited based on vertical drain space availability thinking GFX exchangers).

    Great ideas, but most are proposed by people who really have no idea of the issues they can cause in the field. Just because it has a U.L. label on it doesn't means its safe for the application. Proceed with extreme caution. The life you save, may be your own...

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
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