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Adding a vent through a crawl space

Post in 'DIY and General non-hearth advice' started by abrucerd, Aug 10, 2011.

  1. abrucerd

    abrucerd Member

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    EDIT: Crap, meant to post this in DIY... my bad.

    Hi,

    I originally posted this in the pellet forum (since I have a pellet stove), but thought I might get some good advice here too.

    My house is a old new england colonial with an addition on one side, which is where my stove happens to be. The addition has vaulted ceilings, with one wall running up along side where the master bedroom is on the 2nd floor (see photo).

    I’m considering putting a vent in the top of the wall of the addition, through a small crawlspace and into the bedroom wall (close to the floor) to help the warm air from the pellet stove get to the bedroom upstairs. I don’t have any existing ductwork in the house, and I've never done any type of ductwork myself.

    Originally I looked at thru wall fans that seem ideal for this (http://www.suncourt.com/Suncourt ThruWall Fans.html), but those are not long enough to make it through my crawlspace (about 2.5 feet).

    After researching, I'm thinking that flexible duct with a fan might work, but I'm not sure how wide the duct should be or how the duct fan would be hooked up to a switch (I'm not electrically inclined either :) )

    Any advice or suggestions would be appreciated... Thanks in advance!

    Attached Files:

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  2. smokinj

    smokinj Minister of Fire

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    Looks like a great spot to collect some warm air. Any ceiling fans in place?
  3. abrucerd

    abrucerd Member

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    Yes... one right above the stove. You can actually see it, but the blades are running full speed so it's hard to tell
  4. semipro

    semipro Minister of Fire

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    I just completed similar work in our house. I found a fan was not really needed. Natural convection due to the density differences of the air will move the air.

    You could put a wall register in each area with a duct boot and flexible ductwork to transfer the hot air. Its really pretty simple work if you're willing to cut holes in your walls/ceilings.

    One note though, consider effects on fire propagation. There are fire vents (called fire dampers) available that will close automatically if temps get too high.
  5. Don2222

    Don2222 Minister of Fire

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    Hello

    If you go with 6" duct then Home Depot has a nice 6" InLine Fan real cheap.

    That's is what I use to get the heat upstairs from my basement pellet stove. Works Great!

    Also here is a nice wiring diagram I made for auto or manual fan operation.
    With the switch in Auto mode the fan turns on the Line Voltage Thermostat if the Temp goes above 75 degrees to blow the heat upstairs. The fan is connected to the cooling contacts to work this way!!

    If you click on the wire diagram to enlarge it, you should be able to see it ok. :)

    On the wall control panel
    The Top Switch is Auto Fan On/Off
    The bottom switch is Manual Fan On/Off
    The round knob is the speed control of the Fan. Too fast and the air will not be very warm.

    Attached Files:

  6. semipro

    semipro Minister of Fire

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    Don, is that fan running on 115 VAC? If so, aren't thermostats of that type rated for 18-24 VAC? Maybe I've misidentified the thermostat.
  7. Don2222

    Don2222 Minister of Fire

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    Yes, that fan is 120 VAC and the Thermostat is a Honeywell Heat/Cool 120 VAC Line Voltage thermostat T651A1269
    The thermostat pic is below.

    From Amazon I believe this is the new model see link
    http://www.amazon.com/Honeywell-T60...ref=sr_1_1?ie=UTF8&s=hi&qid=1250214207&sr=8-1

    Here are some on e-bay. Nice Price!!
    http://cgi.ebay.com/Honeywell-Super-Tradeline-T6051A-1016-HD-Thermostat-NEW-/250814820118

    Attached Files:

  8. abrucerd

    abrucerd Member

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    Can I use that type of fan with flex duct, or does it need to be rigid?
  9. Don2222

    Don2222 Minister of Fire

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    I prefer the rigid but the flexible should work also.
  10. nate379

    nate379 Guest

    Line Volt T Stat. Used for electric heat/turning on/off a fan. Can buy at Lowe's for $20 on up depending on fancy of a model you want.
  11. Don2222

    Don2222 Minister of Fire

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    Yes Nate but those T-Stats only have Heating Contacts. It depends upon what you want to do with the fan.

    In my case I want the FAN to turn on when the air temp is ABOVE 75 Degrees, so I connect the fan to the Cooling contacts.

    If you use a T-Stat at lowe's with only the heating contacts, then the FAN will turn on when the temp drops BELOW 75 Degrees.
  12. nate379

    nate379 Guest

    10-4, wasn't thinking of it that way.

    I put a water to air heater in my garage recently so that's where I knew about the T Stat.
  13. begreen

    begreen Mooderator Staff Member

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    Agreed. If the bedroom door is left ajar so that the cool air can descend back downstairs this should convect naturally without a fan. You might even consider putting a small window up there. The reason being that it will allow you to regulate the air flow, it will bring in more light to both rooms and when not heating you can close it off for noise reduction.
  14. semipro

    semipro Minister of Fire

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    Good to know. I've used a very quiet ceiling-mounted bathroom fan to do something similar before. I used an attic ventilation fan control as the thermostat but its not quite as presentable as the one you used.

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