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  1. #1
    Jonathan Goad's Avatar
    Jonathan Goad Guest

    Default Unusual Direct Venting Configuration for Crawlspace Furnace

    See the attached photo. I would like to get some comments about this venting configuration. I have never seen it done this way and I suspect one portion of the pvc piping may violate manufacturers installation guidelines.

    Please note the bottom of the vertical section of PVC piping is acting as a condensation trap that is connected to a condensation pump (pump not visible in photo).

    Thanks in advance for the comments!

    Jonathan

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  2. #2
    Join Date
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    Default Re: Unusual Direct Venting Configuration for Crawlspace Furnace

    Remember Dom Deluise in Blazing Saddles? - "WRONG!".

    Eric Barker, ACI
    Lake Barrington, IL

  3. #3
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    Default Re: Unusual Direct Venting Configuration for Crawlspace Furnace

    Wow! Configuration heck! Is that the outside vent pipe for a gas fuel furnace?


  4. #4
    Jonathan Goad's Avatar
    Jonathan Goad Guest

    Default Re: Unusual Direct Venting Configuration for Crawlspace Furnace

    forgot to mention this is high efficiency furnace. Anyone else have any thoughts?


  5. #5
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    Stamford, CT
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    Default Re: Unusual Direct Venting Configuration for Crawlspace Furnace

    It is my understanding that a condensing furnace can be either horizontally or vertically vented, but not inverted. Also, if hozontally vented, the vent should slope toward the furnace so that condensate and can drain through the drain tube and does not have the potential to freeze and block the vent. I recommend to look up the installation instructions for that model of furnace to confirm manufacture's requirements.


  6. #6
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    Default Re: Unusual Direct Venting Configuration for Crawlspace Furnace

    I am not a HVA/C guy, but my understanding agrees with Harold.

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  7. #7
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    Default Re: Unusual Direct Venting Configuration for Crawlspace Furnace

    There's 4 elbows visible in the pic. 4-6 is typically the max on a pipe run depending on length. They may be at or exceeded the number of elbows allowed. You can download the install guide to see the vent chart.
    The addition of a drain tee is good considering the configuration. Early model 90+ units pretty much all needed a drain tee. Crapping and goofy overall but may be Ok if there aren't more 90's in the vent run.
    Gas and electric lines aren't secured
    Is that sand under the unit, is the return fully sealed
    Is the space damp, if so tell the client the unit may not last as long or need more servicing

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  8. #8
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    Near Philly, Pa.
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    Cool more questions

    As always, it falls back on the listed instructions. However, he could have re-configured it for less ells and better flow. If he came out of the appliance collar with a broad radius ell out laterally and down towards the camera where he could have put the condesate tee then angled out, it would have left room to access the front of the unit, had less flow restriction and used less fittings and pipe.

    BTW, that pipe should have been supported.

    Nice trap on the CSST

    Looks like the condensate drain to the pump really rises up a lot-could back up.

    Do your AHJs allow condensing units in unconditioned spaces such as this crawl space? No problems with condensate freezing?

    I'd double check with Am. Std. to verify this unit is approved for multi-poise mounting.

    Is there a switched service light for the space? 120 GFCI outlet within 25 ft?

    Do ya'll recommend crawlspace remediation including heavy mil poly, sealing and dehumidification?

    Keep the fire in the fireplace.

  9. #9
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    Default Re: Unusual Direct Venting Configuration for Crawlspace Furnace

    The condensate trap in the PVC vent is on the positive pressure side of the induction fan. I think the trap built into the unit is located in a neutral or negative position of the fan housing not to mention it is also on the up stream side of combustion! Doesn't look right to me.

    Last edited by Vern Heiler; 05-15-2012 at 09:50 AM. Reason: up stream
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