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Under house fans

Discussion in 'Repairs & Maintenance' started by neK, 11th Jan, 2016.

  1. neK

    neK Well-Known Member

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    I have an Victorian style house built in in the 1900's. Unfortunately being an older house, i do tend to get moisture problems and the only way the house gets a breeze is through these tiny 10cm x 20cm floor vents (everything is blocked up, not like other homes on stumps where a breeze can run freely across).

    I've installed underfloor vent fans Quad Fans - Envirofan Sub-Floor Ventilation Solutions, Sydney - Reduce Mould - Prevent Termites several years ago and that hasn't done much, the ground is still constantly damp.

    I'm thinking of going out to bunnings and buying the following Dynabreeze 30cm Yellow Extraction Fan with a hose Dynabreeze 5m Extraction Fan Hose.

    Very much aware that these things aren't going to be quiet, however I only intend to run this every so often (while I am out at work etc).

    I'm either going to:
    1. Put the entire thing under floor and run it for several hours at a time (I'll use a timer or something to give it a break)
    2. Connect it to the house and feed that under the house. The fan itself will then remain above the floor.

    Is there anything i can potential break? Surely during up the ground is better than having it damp. Thoughts?
     
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  2. Scott No Mates

    Scott No Mates Well-Known Member

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    Injection of silicon into brickwork to create a damp proof course wherever you have rising damp.

    Improve subfloor ventilation by replacing the vents with larger wire vents.
     
  3. neK

    neK Well-Known Member

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    This is the hard part... i can't. Don't have the room.

    The previous owner cemented around the house, as a result the some of the vents are actually on the same ground level as the cement driveway. I can't go higher either due to the height of the existing floor. The vents are already wire vents.

    On the side where i do have the height, I already have 3 ventilation fans installed that suck air out of the subfloor and out.
     
  4. dabbler

    dabbler Well-Known Member

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    Are the fans really extracting, or maybe they do next to nothing unless all the floor etc is sealed up as well.

    Just a thought, I lived in a place that was like this, it was a mouldy old hole, the problem really laid in the land itself, the location, the surrounds and that basically it had about 6-12 inches of dirt on top of rock, so rock acted like a pool and dirt retained moisture.
     
  5. neK

    neK Well-Known Member

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    Revisiting this thread after a year.
    Haven't done anything, so the problem is still there.
    I want to make sure the kids don't have health problems in the future due to poor ventilation.

    Your comment makes a lot of sense, its extracting air.... but from where? There are cracks everywhere, so its probably quite ineffective at its job.

    I've also looked at those subfloor "specialists" and looked at their "solutions" which involve ducting that "extracts moisture" and moves it out. I can't see how that is really effective anyway.

    [​IMG]

    I'm now thinking of getting Expol subfloor insulation done - my theory is that this will block the cold air coming up and create a better seal so that air can actually get extracted out.

    Then coupling this with 1 of these fans per bedroom (placed next to the vent)
    Ezi Air Inline Axial Booster Fan - 10 to push air around and out towards the current Enivronfan extraction fans.

    Aim is to create the draft that would flow naturally on better ventilated houses.

    Thoughts?
     
  6. Propertunity

    Propertunity Exclusive Real Estate Buyers Agent Business Member

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  7. neK

    neK Well-Known Member

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    @Propertunity - The subfloor in my house hasn't dried up since i bought it 7 years ago. :(
    Damn thing has always been a bit moist. There's bugger airflow underneath, and the extraction fans do a bit, but not a lot. Hence why i want to get fans just to blow air around in the subfloor so it makes it way to the extraction point.

    That said, how does that positive ventilation system work?
    It sucks air in from the outside, filters the air and pushes it out into the room.
    In theory, that would create the positive pressure, but then where does the excess air pressure go?

    That site (like many others, don't really explain it).

    Expelling heat and humidity where?

    So they are saying don't open the windows.... so where does that dirty heat and humidity go?

    Also, have you used (or know people who have used it) before ?
     
  8. Marg4000

    Marg4000 Well-Known Member

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    Is this a drainage issue?
    Do you have a cracked or broken water pipe under the house?
    Is rainwater diverted away from the foundations?
    Marg
     
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  9. Propertunity

    Propertunity Exclusive Real Estate Buyers Agent Business Member

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    Should have used a BA for the purchase :)

    Positive air pressure inside forces air outside thru leaky windows, doors and floor boards etc so damp can't enter the house.
     
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  10. neK

    neK Well-Known Member

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    I don't think its a drainage issue.
    I think its simply due to the levels of the house.
    Its not wet, just not dry. No large areas of wet, just consistent not quite dry areas.
    House smells musty if no windows are open.

    I've drawn a cross section of my house.
    Unfortunately the previous owner decided to concrete the side of the house, but instead of ripping out the old concrete, he concreted on top.

    As a result, the side air vents are the same level as the concrete, which i don't believe helps the cause.

    That said, it probably don't get much air flowing through
     

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  11. neK

    neK Well-Known Member

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    Yes that does make sense.
    Which means putting some subfloor insulation would actually be a bad thing if i used Positive Air Pressure.
    Any idea how much these systems cost - as a ball park?
     
  12. Marg4000

    Marg4000 Well-Known Member

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    Can you have the concrete removed and relaid to a better level?
    Enlarge and/or increase air vents?

    Treat the cause of the problem rather than try to deal with the consequences?
    Marg
     
  13. neK

    neK Well-Known Member

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    I believe the gap between the top of the vent and the floor is 5cm at best.

    As for the concrete removed, its a very large area that would need to be redone. About 2.4m x 20m for the side section. I would then need to redo the front (at least $3k for me and $3k for the neighbour as we share the driveway) otherwise when it rains all the water will pool up on the side section and make the situation worse.

    If i did redo the concrete, it would end up costing close to $20k.
     
  14. Marg4000

    Marg4000 Well-Known Member

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    Ouch!!
    Marg