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  1. #1
    Join Date
    Apr 2005
    Location
    Finksburg, MD
    Posts
    193
    I'm just moved into a new house and I would like to plug up all the air leaks. The house was built in 97 so it's modern construction. I have read that you can use an infrared imaging sensor to see which walls are colder and possibly windows also. I've also read that using smoke sticks to see if the smoke gets blown around by the drafts can he helpful. Can one of these infrared sensors be purchased at a resonable price? I have not found one on the internet.

    Should I just have someone come in and do a real test using a blower door and such? If so what kind of company does this? None of the HVAC contractors I've called really even know what I'm talking about. I get the idea that they would solve my air infiltration problem simply by installing a larger unit.

    As a result of plugging up all my leaks I hope to cut down on the number of spiders and crickets that find there way into my basement. How do these bugs get in anyway? In my old house I thought I had everything plugged up but even the largest of crickets still found a way in. I want to do this one right.

    Thanks in advance

    Rob'


  2. #2
    Join Date
    Jul 2002
    Posts
    962

    Air inflitration problem

    What symtoms do you have that show you have an infiltration problem? Measuring the temp of the walls and windows sounds more like a heat loss problem. I think an exterminating co. would be more help, for the cricket problem in the basement.

  3. #3
    If you have average construction or better your air infiltration should be minimal.
    It really appears as though you have "modern" construction as you noted, but not "average to tight" construction.
    It should be fairly easy to assess. What type of insulation do you have? Orientation of windows? Windows facing? Size of house?...etc.
    Upsizing your equipment won't change the CFM of infiltrated air in your home but you can check for tightness throughout your duct system to minimize leakage there and have a number of other checks performed including
    a load calculation ,which in your case, should be done
    You don't need an imager or anything like that.
    Shop around for a company that knows heating & air and knows what should be going on with the structure and the system.

  4. #4
    Join Date
    Aug 2003
    Posts
    626
    You need a blower door test. Ask your local utility or go on the net and look for energy raters in your state. The most important holes are the attic holes. Any time you have wires, pipes, chimneys, canned lights ect. , you can seal these4 and help.

  5. #5
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    instead of spending the $ on a test, start sealing holes -- pop off the trim around windows, fill that gap with minimum expanding foam. take off elec box covers [ look for insulation behind these in outside walls ] fill gap between boxes & wall with spackling or silicone caulking, same for HVAC registers & grills. seal ALL seams, holes, joints & cracks of HVAC ductwork & equip (NOT around the covers).

    My house had NO insulation on exterior fam rm wall, big hole under dbl window, around door, etc.

    BUT, do not seal up the small weep holes near the bottom of brick siding! brick is pouous & the water needs to get out --

    now get a blower door test, maybe.

  6. #6
    Before you start checking the system capacity, you need to verify that the load considerations on the envelope are accurate.
    A blower door test may not be needed at all and certainly won't be needed until you figure out what system requirements are needed to satisfy the load on the house.

  7. #7
    Join Date
    Apr 2005
    Location
    Finksburg, MD
    Posts
    193

    I'm told the unit is a bit over sized right now so i have no doubt that it can heat and cool the house but I just want to make sure everything is air tight. Maybe I just like my stuff tight, I don't really know what motivates me sometimes. I do plan to touch up the caulk around the windows, wires, pipes, outlets etc.,but I figured if there was a way to detect what areas are a bit cooler in the winter or actually be able to see air movement and direction I could be find all of the holes. In my old house I obsessed over plugging every hole I could find, but there was still a slight draft comming from the utility room that I never found.

    Thanks for all the advice and I will seal all the holes to the attic also. In my old house I could tell that the air was entering in from the basement and heading out through holes to the attic and I seem to feel this slight draft in the new house. I would to lick it for good.

  8. #8
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,642
    Most homes infiltrate a little excess fresh air during cold windy weather. MY bet is that you are not getting the necessary air change rate for good air quality during the mild seasons when not windy. Best to setup proper ventilation before stopping infiltration. All homes need 50-100 cfm of fresh air to purge pollutants and provide oxygen when occupied. How much are you getting now?
    If the windows are dry during the heating season and you do not need a humidifier, you are ok during the winter. But need make-up air during the spring, summer, and fall. Suggest proper amount of make-up air first. Than have a ball and tighten everything possible. Also remmeber clean air and <50%RH.

  9. #9
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,981
    Before making your home more tight, first rid it of all pollutants. Anything that has a chemically induced odor is a severe pollutant.

    This reminds me a bit of the thinking during the Black Plague of the Dark Ages. The royalty all shut themselves up in their castle compounds which actually caused the disease to spread more quickly due to lack of dilution by fresh air.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  10. #10
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
    Posts
    3,304

    Effect of fresh air inlet

    Here is an idea which might draw some criticism from the professionals here. If you do not already have a fresh air inlet, and add one, then you will change the air dynamics so it will have a greater tendency to flow outward rather than inward. It would seem this would reduce the air infiltration via ceiling-attic penetrations (e.g. typical cannister lamps) which is one of your more "harmful" infiltration sources -- at least in my area.

    It very well could be that you seal a lot of openings, thus causing an increased need for a fresh air inlet. While this is ironic, the inlet air will always have the chance to go through your filtration and conditioning. That's gotta beat random attic air every time<g>. The motto of many experts is "Build it tight and ventilate right".

    I have trouble with the argument that you should seal attic and other penetrations "instead" of having a blower door test. The sealing process will be labor intensive if it uses a lot of caulk, you can DIY but cannot buy a lot of labor for that price. And if you go the route of buying new airtight cannister lamps, again it's either DIY or spend a lot of money. Usually a blower door test will tell you do seal more, anyway. Just that with the testing you will understand where you started out and where you ended up.

    House leakage is likely to be measured as a surprising number of square inches total leakage. Since a cricket only needs a tiny fraction to crawl through, I would think you could seal very well and still not get all the holes bugs come through. I agree an exterminator would be the method unless you can find and fix some obvious bug holes.


    Best of luck -- P.Student

  11. #11
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,915

    Re: Effect of fresh air inlet

    Originally posted by perpetual_student
    House leakage is likely to be measured as a surprising number of square inches total leakage.
    Boy thats an understatement!

    A company I used to work for did blower door testing. I was in a few houses while they were being tested, that looked well constructed, that I thought wouldn't be to bad, but in reality were leaking so bad it was almost like having a 10'x8' section of the outside wall knocked out!
    If more government is the answer, then it's a really stupid question.

  12. #12
    Join Date
    Nov 2000
    Location
    Indiana
    Posts
    318
    My two cents. I also think it is a good idea to know where you are starting from and where you end up as far as infiltration goes. A blower door test in conjunction with an infrared camera is a cool way to get an idea of infiltration rates and leakage paths. IMO, a blower door test can give you a better idea of infiltration when it comes to doing your load calcs on the building rather than taking a guess for infiltration load. You can also operate the blower door and then "see" where air is coming from. There could be huge by-passes in wall cavities, through structural return systems on forced air units, and in bulkhead areas. I agree that sealing high and low are the best places to start and not on the neutral pressure plane of the home. You have to seal around a lot of windows to equal the open wall cavities into an attic from typical bulkhead construction. Knowing where you are starting can give you a better idea of when to stop so you don't get it too tight and start messing with IAQ. Like Teddy Bear said, ventilation is important, but you may be able to cut infiltration in half - and, in turn, reduce comfort conditioning costs and still be fine.


  13. #13
    Join Date
    Apr 2004
    Location
    Niantic, Illinois
    Posts
    545
    Originally posted by 7X
    My two cents. I also think it is a good idea to know where you are starting from and where you end up as far as infiltration goes. A blower door test in conjunction with an infrared camera is a cool way to get an idea of infiltration rates and leakage paths. IMO, a blower door test can give you a better idea of infiltration when it comes to doing your load calcs on the building rather than taking a guess for infiltration load. You can also operate the blower door and then "see" where air is coming from. There could be huge by-passes in wall cavities, through structural return systems on forced air units, and in bulkhead areas. I agree that sealing high and low are the best places to start and not on the neutral pressure plane of the home. You have to seal around a lot of windows to equal the open wall cavities into an attic from typical bulkhead construction. Knowing where you are starting can give you a better idea of when to stop so you don't get it too tight and start messing with IAQ. Like Teddy Bear said, ventilation is important, but you may be able to cut infiltration in half - and, in turn, reduce comfort conditioning costs and still be fine.

    Another point is in your duct system but not related to leakage. If you don't have a return in each room that can be closed off using a door ( except for bathrooms) then you have an infiltration problem when the doors are closed to those rooms. If you are putting 160 cfm supply into a room and the door is closed and it has no return that room is now in a positive pressure and pushing air to the outside any where it can. The main area where the return is now missing that 160 cfm and goes into a vacuum pulling in air anywhere it can. Multiply that by four bedrooms. Most of your home is in a vacuum. This only relates if you have that type of return duct system.

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