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  1. #1
    mathew stouffer's Avatar
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    Default Induced draft water heater vent

    Does an induced draft water heater vent still require the 1/4 inch per foot slope?

    Thanks

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  2. #2
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    Default Re: Induced draft water heater vent

    Matthew,

    Since moisture can condense on the interior of the pipe, then I would say yes. So the water can drain out.

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  3. #3

    Default Re: Induced draft water heater vent

    Here's the installation instructions for an AO Smith power vent water heater. They don't require the 1/4" per foot.......http://www.hotwater.com/lit/im/res_gas/185363-001.pdf
    It really depends on the manufacturers installation instructions. I have found it pretty easy to take a pic of the data / info sticker on the appliance and look up the instructions on- line.


  4. #4
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    Default Re: Induced draft water heater vent

    Quote Originally Posted by Brandon Whitmore View Post
    Here's the installation instructions for an AO Smith power vent water heater. They don't require the 1/4" per foot.......http://www.hotwater.com/lit/im/res_gas/185363-001.pdf

    Actually, they do, kinda sorta ... but the slope is not that much.

    *IF* condensation can occur, then, yes, it must be protected against, and condensation *can* occur under various conditions, therefore, unless one *can prove that condensation will not occur, the vent must be sloped to protect against that condensation when it occurs*:

    From page 15 in your link: (underlining is mine)
    - CONDENSATE
    - - Condensate formation does not occur in all installations of power vented water heaters, but should be protected against on installations where it can form in the venting system. Condensation in the venting system of power vented water heaters is dependent upon installation conditions including, but not limited to ambient temperature and humidity of installation location, ambient temperature and humidity of venting space, vent discharge and slope, and product usage. In certain conditions, installations in unconditioned space or having long horizontal or vertical vent runs may accumulate condensate. In these conditions, the vent pipe should be sloped downward away from the blower assembly 1/4" (6.4 mm) per five feet (1.5 m) of pipe but not more than 1 1/2" (3.8 cm) in the total vent length. If the vent piping is vented level or sloped upwards away from the blower assembly, then adequate means for draining and disposing of the condensate needs to be made by the installer (if condensate is detected). If you have condensate, then a 3/8" drain hose can be connected to the built-in drain port of the rubber boot on the blower assembly. For your convenience, the rubber boot is supplied with a removable cap on the built-in drain port. Prior to operating the water heater, make sure the removable cap is installed on the drain port (if a drain hose is not needed).


    Last edited by Jerry Peck; 02-26-2009 at 11:32 AM. Reason: changed small font size to correct font size
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  5. #5

    Default Re: Induced draft water heater vent

    This sentence: If the vent piping is vented level or sloped upwards away from the blower assembly, then adequate means for draining and disposing of the condensate needs to be made by the installer (if condensate is detected).

    ...tells me that they can run it level-- they just must take care of any condensate issues. I don't like these instructions because it leaves it up to the "installer" to decide what can work. So basically, they can slope it any which way they want to , or just run it level.............


  6. #6
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    Default Re: Induced draft water heater vent

    Quote Originally Posted by Brandon Whitmore View Post
    This sentence: If the vent piping is vented level or sloped upwards away from the blower assembly, then adequate means for draining and disposing of the condensate needs to be made by the installer (if condensate is detected).


    Except that it then goes on to say that the vent potential for condensation is there, and thus, when that potential exists, the slope needs to be addressed.

    Which is why I said "therefore, unless one *can prove that condensation will not occur, the vent must be sloped to protect against that condensation when it occurs*".

    ...tells me that they can run it level--
    Yes, except that they must firs verify that it *WILL NOT* collect condensation, and if they cannot, or do not, then ...

    they just must take care of any condensate issues.
    I don't like these instructions because it leaves it up to the "installer" to decide what can work.
    I don't like them much either, too wishy-washy, until you realize what it is saying and then, if they cannot or do not prove no condensation will form, they need to slope it - but, yes, those instruction are very poorly written.

    So basically, they can slope it any which way they want to , or just run it level.............
    No, there are minimum and maximum limits on the slope ... or just run it level - if they prove no condensation will occur.

    Jerry Peck, Construction / Litigation Consultant
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  7. #7
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    Default Re: Induced draft water heater vent

    Hope that drain tubing has a trap loop formed in it.

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