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What makes it ventless?

Post in 'It's a Gas!' started by brogsie, Oct 24, 2008.

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  1. brogsie

    brogsie Feeling the Heat

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    What makes a ventless unit ventless?
    I understand the different methods of venting, but what makes these suposedly safe?
    Is there less emissions or is it the same output just let into the room?
    If so couldn't you just let a vented style unit vent into the room?

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  2. tubbster

    tubbster Member

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    Having used ventless, (and now just ordering a real stove) for a couple of years, all I can say is DON'T.

    It puts WAY to much water in the air, enough after three years of (what I considered careful) use - to cause significant mold problems.
    If you can stand to only use it two to three hours a day max, and stick with that, it MAY work.

    I feel it damaged my cinder block foundation in my raised ranch. I painted the outside of it, and anywhere that was an exterior wall to a heated area had many pits where the water vapor went through the blocks, froze, and made nasty "zits".

    A 20K btu unit puts roughly 20 ozs of water an hour into the house. That adds up quick.
  3. Redox

    Redox Minister of Fire

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    I would also add that they are against code in some jurisdictions. If you do get one, make sure you have a good CO detector. They can make CO long before they trip the O2 sensor...

    Chris
  4. R&D Guy

    R&D Guy New Member

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    Agreed!
  5. dave11

    dave11 Minister of Fire

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    I have both vented and unvented heaters in my house at present, and have found certain criticisms true, and others not to be, at least for me. Yes, they create moisture and carbon dioxide, and lower the oxygen level in the room, but if you follow the sizing recs of the manufacturer and the National Fuel Gas Code (which does allow them), these changes should not be significant. Also, many people who have problems with them do not allow the proper amount of fresh air to enter the heated space, which is clearly spelled out by the manufacturer.

    On the other hand, they are 99+% efficient, and the extra moisture in the Winter, for me, is beneficial. They should not be giving off significant levels of any toxin if they are working properly.

    My only complaint about them is that, even when they're working properly, to me they have a slight combustion smell. Apparently most people can't smell it, but I can. So I heat my basement and garage with them, to allow compliance with the air change requirements.

    My sister heats her living room though with an unvented gas fireplace though, and would never give it up.

    You can't vent ordinary gas appliances into a room though because they are not designed as stringently for complete combustion, and so they give off carbon monoxide, etc.

    So, though people have strong opinions, I've never seen convincing evidence that unvented gas appliances cause any health problem, if they are properly installed and used. And if you have a real worry about excessive moisture, keep a simple hygrometer in the room to keep track of it. Again, if the unit sized properly and the air exchange rules are followed, moisture should not be a problem.
  6. tubbster

    tubbster Member

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    I do know, beyond any shred of a doubt, that a vent free heater did damage to my house.

    When it's -10 out, are you going to open up a couple windows to get the cross flow?

    When you do, the heater is no longer 99% efficient also. I'm sure vent free would be perfect somewhere, like maybe an ice fishing hut on the lake or something.
  7. webbie

    webbie Seasoned Moderator Staff Member

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    Sort of a catch-22 since most vent frees warn not to use unattended....and they are certainly not for real heating purposes.

    My experience is this - it only takes ONE instance to do away with all the perceived savings...I have had people who later discover that they have to repaint large portions of their home, replace window or wall coverings, etc.

    As to them being "legal", keep in mind that this is due to lobbying....they are not legal, for instance, in Canada.

    All in all, a bad idea IMHO. Way back when, I used to sell them...a lot of them. Then I learned better. Sure, there might be a rare case where it would do OK if used a couple hours a week - or for emergency backup in power failures - or as a fireplace gas log where the damper could be partially opened. But not as an actual long term source of heat.
  8. thechimneysweep

    thechimneysweep Minister of Fire

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  9. tubbster

    tubbster Member

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    Tom, I sure wish I saw that before I put mine in!
  10. dave11

    dave11 Minister of Fire

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    I'm well aware of the information posted on chimneysweeponline.com, and I'll say again: I've seen no reliable evidence that ventless heaters, when sized, installed, and used properly, cause any significant health problems. It seems the men and women who write the building codes have reached the same conclusion.

    Though I'm curious about the comments regarding the lobbying by the manufacturers of ventless heaters. Are you implying that the engineers and other pros who write the National Fuel Gas Code are being influenced? I'd like to see some back-up for that.

    The flip side then can be the accusation that the reason Canada has banned them is purely because of lobbying by the makers of vented heaters.

    Seems fair to me.
  11. RedRanger

    RedRanger New Member

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    Or maybe it is just because us Canucks are a little too clever to allow ourselves to be poisoned eh??
  12. tubbster

    tubbster Member

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    Well, when I installed the ventless in my house, I thought pretty much the same. I inquired, some cautioned, some said no problem - but I learned (not) soon enough. The gov't coldn't be wrong -right? I've got reliable evidence all around the foundation of my house, and in some sheet rock.
  13. Redox

    Redox Minister of Fire

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    It really gets down to the cost/benefit ratio and the risk that you want to take to save money. Unless it were an emergency, I wouldn't use a vent free. I've stood next to enough gas vents to realize that it is downright unpleasant in concentration. I don't want it diluted all around my house, especially 24/7.

    Anyone know if these things will pass the canary test?

    Chris
  14. dave11

    dave11 Minister of Fire

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    I don't deny that there are many reports of people having trouble with them. I do deny though that there's any evidence showing that ventless heaters are unsafe or destructive in any way if they are sized, installed, and operated properly.

    The Code is very specific about these details, and when I installed mine (workshop/basement and garage), I followed the Code. Not that hard. And in the 3 years since then, I've had no problems.

    For the record, I have no affiliation with the makers of any ventless technology, and frankly, I'm not that fond of the odor the heaters emit (though apparently not many people can smell it). I do however know some folks that are involved in writing the codes, and I'd be curious to hear their reaction to being told that either:

    A) They are incompetent, or

    B) They're being bought off.

    Otherwise, how else are we to explain this mass "poisoning" of the US population?
  15. tubbster

    tubbster Member

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    I don't know about the poison, only that my house could not handle that much water, even with the window cracked.
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