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Air sealing satisfaction.

Post in 'The Green Room' started by TradEddie, Jan 23, 2013.

  1. GaryGary

    GaryGary Feeling the Heat

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  2. milleo

    milleo Feeling the Heat

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    Wow nicely written, that should help lots of people out, right now I walk around in my bare feeties to find my air leaks Lol.
  3. woodgeek

    woodgeek Minister of Fire

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    Very nice explanation....I like the ^0.65 power law! Coincidentally....I scheduled my first energy audit today for March 14th.
  4. TradEddie

    TradEddie Minister of Fire

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    I never really thought about the numbers before, but now I suppose my plan to use my old insert blower (200cfm?) to depressurize and look for leaks isn't going to work as well as I thought.
    One thing to watch, those magnahelic gauges are only as accurate as their calibration, and I wouldn't trust the accuracy of one I bought online without verifying it against something else first.

    Thanks for the ideas.

    TE
  5. semipro

    semipro Minister of Fire

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    One relatively simple way to get strictly relative readings of air tightness might be to use a fan like the one Gary used and monitoring the change in amperage as improvements are made. Centrifugal fans (squirrel cage) actually pull less current as flow decreases.

    Gary, could you try opening a window and measuring amperage while yours is running to validate?
  6. TradEddie

    TradEddie Minister of Fire

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    Another way to gauge relative tightness, and which wouldn't depend on calibration accuracy would be to record the ultimate pressure reached by the fan at any given speed setting, more tightness, lower pressure. You could close doors in the house sequentially, block the bottom with a towel and see which rooms made the biggest difference, focus on those first.

    TE
  7. GaryGary

    GaryGary Feeling the Heat

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    Hi,
    I'll try to remember to include measuring the amperage when I get to doing the house with the blower door, but its going to be a couple weeks as we are away for a while.

    I just found out about the less current at lower flows today, and along with it that furnace blowers are actually designed work into some pressure load (the back pressure from the duct system), and that some of them may draw too much power if they have no pressure load on them at all. I measured the amperage on mine and it was indeed somewhat above the motor nameplate amperage, and if I added a little resistance it dropped down to the nameplate value. I'll probably just add a little resistance to keep the amperage down toward the nameplate value. Added a note to the writeup alerting people to this.

    Eddie: That is one thing I like about the old fashioned water or oil manometers is that they really can't go out of calibration (unless gravity changes). I think that Dwyer oil manometer that only costs $34 new from Dwyer would do a good job.

    Gary
  8. semipro

    semipro Minister of Fire

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    I and others have been using these fans for shop ventilation as they're quiet and usually free since you can get them from old air handlers. You can restrict either the inlet or outlet to get the proper amperage.
    We use one for a whole house fan and I built that restriction into the fan enclosure.
  9. RustyShackleford

    RustyShackleford Minister of Fire

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    What about using foil duct tape ? I wonder if it can withstand the heat of chimney pipe ? I doubt it'd melt, but maybe the adhesive drys out and it becomes brittle and falls off ?
  10. kingquad

    kingquad Minister of Fire

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    You're correct. The adhesive wouldn't hold up.
  11. woodgeek

    woodgeek Minister of Fire

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  12. kingquad

    kingquad Minister of Fire

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    In my old house, I secured the flashing to the chimney with tapcons. Then, I ran a large bead of silicon around the edges. I never had any problems.
  13. RustyShackleford

    RustyShackleford Minister of Fire

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    That looks like the shizzle, but remarkably similar to the foil duct tape; please let us know !

    What is "black silicon" ? The high temp silicon caulk that I got is red - from the auto parts store, to install a BK thermostat to replace mine with the reverse-wound coil.

    I have sheet metal around mine now, but maybe a 1/4" gap. I'm afraid the silicon would droop through (I'd apply it from the attic). So something temporary while it cures - maybe that tape that woodgeek found.
  14. semipro

    semipro Minister of Fire

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    How about using the orange high temp spray foam?
  15. woodgeek

    woodgeek Minister of Fire

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    Yeah...just hi temp silicone...various colors I guess. I left a smaller gap at my chimney and the silicone just sat there.
  16. jebatty

    jebatty Minister of Fire

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    Perhaps I'm a little old school. Between the living room wood stove that heats our entire 1500 sq ft house, a large wood fireplace (which has a chimney damper), 2 bathroom and 1 kitchen exhaust fans, and 1 electric dryer, all of which move inside air to the outside, my house can't be too tight on air leaks. Maybe small leaks scattered around are better than a tight house and a heat recovery unit with variable fresh air supply based on air exhaust levels. A '56 house on which I have done a lot to make it tighter than it was, but I tend to measure "tightness" by how much wood we have to burn in the winter to keep the house warm and whether or not I need to crack a window to get good stove draft. For our cold climate, 4 cords of aspen/pine for the wood stove during a typical northern MN winter seem a pretty good measure of both fairly low heat loss and acceptable air infiltration for fresh air supply. The only time a window needs to be cracked for the wood stove to draft well is when outside temps get into the high 20's and above, and then only sometimes, probably when other exhaust fans are operating, although I don't pay too much attention to exactly when I need to crack a window. We don't notice drafts in our house, so I would guess that air leaks are small and scattered.
  17. woodgeek

    woodgeek Minister of Fire

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    Indeed. There are a lot of indications of air infiltration to those who pay attention. Myself, I use a humidifier index....I can keep my house at 30%RH in the dead of winter (not MN cold, 20s) using a 2-3 gallons of water per day. Before I tightened up, couldn't bump the humidity at all.

    I just keep thinking about the guy who owned my 1960 house previously....he clearly must have known that his house was an 'energy hog' (i.e. >1000 gallons oil/yr) and went berserk weatherstripping all the doors and windows to get them airtight, all the while with huge openings in his attic sucking all the heat out of the house.

    By the same token....why mess around with indoor air quality? You can prob get a pro to come out and blower door your house for free from your utility...and (s)he will tell you whether you still have room for improvement, and where that might be, or alternatively, that you might want to add some ventilation for health.
  18. EatenByLimestone

    EatenByLimestone Minister of Fire

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    I finally got upstairs into the knee wall to get a look at the canyons around the chimney so I could figure out what to do. I'm not crazy about cutting flashing and screwing it to the framing, but without getting up there to look at it I don't know what I might do to seal it. One of the things that bothers me about the idea is that Al flashing really doesn't retard heat loss.

    After getting up there I think I've figured out a way to do it without the flashing. All of the talk about the foil tape above helped me get there.

    I was looking at the cracks thinking if I had something that I could stuff in the cracks that was fire safe I'd only have to lay a thick bead of caulk over it and it would be sealed without dealing with tin snips. I remembered that I had some kaowool blanket left over from a few stove insulations and tweaking sessions. That will insulate, but not stop the air flow. The caulk should lay on top of it to stop air flow. Now for the foam tape stuff. I also have foil backed kaowool blanket that is still wrapped around about 4 feet of extra chimney liner I have. I can stuff that along the roof with the radiant barrier down so it will reflect the heat back into the house. It also gives a nice spot for me to seal around with the fireproof caulk. The 3M stuff I picked up also says it expands a bit.

    While at Lowes I walked past the insulation section and Roxul had a representative there. I decided to pick his mind and asked about chimneys. He had only been working there for 3 weeks so he didn't have any ideas to help. *rolls eyes* At least he was honest and gave me the customer service number to call. He seemed like a pretty good kid, just new on the job. My 3 year old was making him nervous by grabbing for his display rocks. Yes, he had rocks for props. Maybe he thought she was going to break them. I had her sit on the floor where she wouldn't make the guy nervous. He said his other job was doing birthday parties for kids. *shrug*


    Matt
  19. EatenByLimestone

    EatenByLimestone Minister of Fire

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    I finally got upstairs into the knee wall to get a look at the canyons around the chimney so I could figure out what to do. I'm not crazy about cutting flashing and screwing it to the framing, but without getting up there to look at it I don't know what I might do to seal it. One of the things that bothers me about the idea is that Al flashing really doesn't retard heat loss.

    After getting up there I think I've figured out a way to do it without the flashing. All of the talk about the foil tape above helped me get there.

    I was looking at the cracks thinking if I had something that I could stuff in the cracks that was fire safe I'd only have to lay a thick bead of caulk over it and it would be sealed without dealing with tin snips. I remembered that I had some kaowool blanket left over from a few stove insulations and tweaking sessions. That will insulate, but not stop the air flow. The caulk should lay on top of it to stop air flow. Now for the foam tape stuff. I also have foil backed kaowool blanket that is still wrapped around about 4 feet of extra chimney liner I have. I can stuff that along the roof with the radiant barrier down so it will reflect the heat back into the house. It also gives a nice spot for me to seal around with the fireproof caulk. The 3M stuff I picked up also says it expands a bit.

    While at Lowes I walked past the insulation section and Roxul had a representative there. I decided to pick his mind and asked about chimneys. He had only been working there for 3 weeks so he didn't have any ideas to help. *rolls eyes* At least he was honest and gave me the customer service number to call. He seemed like a pretty good kid, just new on the job. My 3 year old was making him nervous by grabbing for his display rocks. Yes, he had rocks for props. Maybe he thought she was going to break them. I had her sit on the floor where she wouldn't make the guy nervous. He said his other job was doing birthday parties for kids. *shrug*


    Matt
  20. EatenByLimestone

    EatenByLimestone Minister of Fire

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    One side is caulked at the top and bottom. I have KW stuffed vertically between the chimney and framing but it isn't caulked yet. Either the wind stopped blowing or I got a leak. Now to do the easy side.


    Update: The chimney is done. 5 tubes of firecaulk were used. That stuff is expensive! I did 2 seals. One at the roof/ceiling of the kneewall and one at the floor to stop air from coming up from below. 2 more cans of foam were used sealing additional cracks and crevices in the front kneewall. I noticed that it was a bit cool by the chimney when I went in there this morning compared to the rest of the floor. It was much warmer in there when I put the insulation back in the framing when I got done. I haven't stapled it back up though. The staple gun jammed and my kneed hurt a bit from kneeling so long. I'll get everything finished tomorrow.

    By the way, does anybody know a tape that sticks well to kraft faced insulation seam?

    Mat
  21. EatenByLimestone

    EatenByLimestone Minister of Fire

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    Update:

    The 2 areas that lost the most heat were the chimney and the interior wall area that was drafting into a small unheated space above a room. We had about 6 inches of snow Friday, followed by a sunny ~50F day today and both areas are still showing lots of snow. SUCCESS!

    There is a small area that is snowless about the size of a basketball a little further down. I'm pretty sure this is a spot where the kraft paper is all ripped up. I'll be fixing that tomorrow.

    Matt
  22. TradEddie

    TradEddie Minister of Fire

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    Untitled.jpg
    So here's the end result, 10 years of effort to reduce my bills.:)
    Gallons of propane and btu/hdd/sqft, based on actual season hdd.
    It's hard to sort out the various factors which can affect consumption, certainly there is variation in our use pattern from year to year depending on babies, sick days, snow days, vacations, unemployment etc., but the trend is clear and none of the improvements below are from sacrificing comfort. Wood use is not shown, but was probably steady with the old slammer and significantly reduced now.
    Improvements made:

    • Replacing most 1970's sashes with identical or High Perf/Low E.
    • Air sealing and insulating rim joist where accessible.
    • Air sealing - utility penetrations, receptacles, kneewalls.
    • Installing exterior door at basement Bilco door entrance
    • Insulating floor of crawlspace behind cape kneewalls.
    • Sealing access doors of knee walls.
    • Insulating supply ducts in basement, sealing boots at duct, and at registers
    • Insulating behind brick wall to garage
    The only expensive part of this was the windows, these were replaced as necessary for rot and damage, and on a priority basis. The rest was barely $50 at a time, one or two projects each year. Problem now is that all the easy jobs are done.
    woodgeek likes this.
  23. RustyShackleford

    RustyShackleford Minister of Fire

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    How are people sealing electrical boxes ? There's two sources of leakage: between the edge of the box and the drywall, and through the knockouts (especially the ones knocked-out for wires to pass) into the box and thence into the house.

    The first is easily dealt with by caulking. The second is typically addressed by the little foam gaskets, but these don't seem like they seal very well to me, and I've read they're next to worthless. In a small addition, I am trying to get ahead of the game by caulking around the knockouts before the insulation and drywall go up. This can't be done later, because it's a no-no to put caulk inside the box, although I suppose a little discretely applied would be fine if it doesn't use up appreciable volume in the box and if you can figure out how to actually do it.

    So I'm caulking the heck out of the wires on the outside, but I'm worried that when the outlets and switches go in, all that tugging and pushing on the wires will cause the caulk to fail. I thought of installing the fixtures BEFORE the drywall, but apparently that's considered a pretty bad idea. I've heard of something called "putty pads", but I don't know if they'd work any better or not.
  24. TradEddie

    TradEddie Minister of Fire

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    Those foam pads are useless, most receptacles allow air through the body and out the pin holes, so you'd have to plug unused outlets with those child safety covers. I used caulk rope on the knock outs where I could, would love better ideas. Wherever I could access the wire penetrations from the basement, I plugged those too.

    TE
    woodgeek likes this.
  25. DickRussell

    DickRussell Member

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    Rusty, if this is new construction you are describing, you can do one of two things to address box leakage. Lessco makes a flanged polypan that goes onto the framing first, with the electrical box mounted inside that. Airfoil makes a nice box with a wide flange all around and with two narrow pockets outside the main box volume for wire sealing with a squirt of can foam after wire is run. There may be a similar product out there now; I seem to recall reading about it. With either product, the drywall is sealed to the flange with either acoustical sealant or gaskets. This seals the box and its contents on the room side of the air barrier.

    I used the Airfoil boxes on exterior walls in my house, with Certainteed MemBrain as the vapor retarder. I tape-sealed the MemBrain to the Airfoil box flanges. There is NO air leakage through that assembly, for all practical purposes.

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