Old house with old air ducts...

Discussion in 'HVAC Heating & Cooling' started by bbsux, Oct 6, 2008.

  1. bbsux

    bbsux Custodian

    Messages:
    23
    Location:
    Lincoln NE
    I have a 2 story house built around 1910 that was changed to a duplex sometime in the 1960's or 1950's. The furnace is a unit that was put it in the 1970's and uses new(er) flat and round ducts. However some of the returns are not even ducts. They put a flat metal sheet across 2 joists and stapled it on and ran that back to the furnace. They are the old ones with a floor grate. Could I just take the metal off and basically make a false duct (basically install a duct in the floor and run it in the joist for a foot and let it open into the basement with a mouse proof cover) a for a foot or so in the basement and allow the furnace to pull its air from the basement? Or do I need to duct all the way back to it? (remember its just the return)

    I hate these things because every single winter the mice get into these returns and I have to clean them out, plus they look ugly...
  2. Mikebarone

    Mikebarone DIY Senior Member

    Messages:
    206
    Location:
    Phoenix, AZ
    Question...

    Is your basement a, “finished basement†and is it heated / cooled? My parents had a house back East, and the basement was cold and damp, and not really finished, (drywall, carpeted etc.).

    Mike
  3. Southern Man

    Southern Man DIY Hillbilly

    Messages:
    530
    Location:
    North Carolina
    Code requires a return from each floor directly to a plenum on the furnace. Its a fire safety issue.

    You have to get rid of the mice. Find out where they get in and bait them, making sure that the bait is inaccessible to kids and pets. Depending on how many mouse that you have, they can eat a lot of bait before you get rid of them.
  4. bbsux

    bbsux Custodian

    Messages:
    23
    Location:
    Lincoln NE
    Its un-finished with a concrete floor (just crudely put over dirt and uneven)

    its a decent temp down there and not too damp unless something is leaking...
  5. bbsux

    bbsux Custodian

    Messages:
    23
    Location:
    Lincoln NE
    I can't bait them, my darn cat catches the things and eats them (good for it catching them but poison is bad for cats!)

    I've been using peanut butter with a combination of a live trap and a whole bunch of snap traps. But they often eat the peanut butter off the traps without it snapping... smart things!

    I don't like killing them necessarily, because I used to have a few mice as pets. they are really nice pets as long as they are social and you keep the cage cleaned, and just have females...

    I guess maybe I gotta suck it up and buy some ducts for them...
  6. Southern Man

    Southern Man DIY Hillbilly

    Messages:
    530
    Location:
    North Carolina
    Oops yes the cat would get quite ill. I use the bait at my weekend cabin and leave the cat at home. My dog doesn't eat what she kills- she offers her victims to me whole in exchange for a dry biscuit.

    I also use the electronic repellents, $30 at the big box stores. These emit a high frequency sound that doesn't effect pets but drives the pests crazy. I had "roof rats" in the peak of a cathedral ceiling. One problem was that the noise does not pass through the ceiling, so its not a simple matter of leaving the unit inside the living space. I had to remove some ceiling boards and aim the speakers straight down the peak of the roof, and opening in the framing about 3" wide and 12" tall. I dismantled the electronic unit, attached the speakers to a light gauge steel strap, fastened the strap to a rafter and bent the strap to aim the speakers straight down the opening. I then extended the speaker wires, which of course are low voltage, through a small hole in the ceiling then to a surface mounted box at the top of the wall. I then put the electronics in the box and ran line voltage to the box through a surface raceway to a point near the floor. I used an extension cord from a nearby outlet to a strain relief the bottom of the raceway, then stripped off the cord outer jacket and let the insulated wires run up the raceway to the box.

    I had been using the bait for weeks and noticed a gradual decline in activity (stools falling though the ceiling boards onto the floor below) but after I installed the electronics that way the mice left for good.

    I suspect that there are openings in your joist-ducts, like at knots or framing joints, where the critters can get in. With an all metal system you should have much less of a problem.
    Last edited: Oct 6, 2008
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