When doing a blower door test, do you ever use long term average? Why or why not?

Digital pressure and flow gauges have an option for time averaging, such as 1, 5 or 10 seconds, long term or a manual time average option.

Under what circumstances would you use the long term average and why?

Views: 264

Reply to This

Replies to This Discussion

When the wind is breezy, I use long term averaging. The more the pressure jumps around due to breezes, the longer the term that I use. Even then, I mentally average the readings. This is after I have taken steps to shield the end of the outside hose from the wind.

Wind is caused by a difference in air pressure so the change in air pressure from the wind, or a passing truck, is reflected in the change in the readings of a digital pressure gauge. Keep in mind that 1 pascal is a tiny change of pressure. I find that the best way to get a stable baseline is to insert a "T" fitting into the reference tube and connect 2 reference tubes. Place 1 tube on 1 side of the house and the other tube on the opposite side of the house. Be sure that the tube nearest the blower door is at least 5' (preferably more) from the fan. If the fan needs to be installed where it is blowing into an enclosed porch or mud room (not a good choice unless there is no better alternative) make sure the tube is outside of the porch.

Hi Kim,

Wind is probably the most frequent reason for using the time averaging with our manometers, but there is another that we need to be careful with.  Manometers are unique in that they ignore barometric pressures.  Place your refer tube out the front door and walk your manometer (long tube) upstairs or into the basement and even though the top to bottom pressure may vary (on a cold day) by 50 pascals or more our manometers will register very little.  When the temperature of our tubes and the air inside is the same as in the house, any changes in elevation are canceled out.  However, if those tubes just came out of an ice cold vehicle, or a hot one, and have not fully acclimated, our readings will drift.  In this case, before we start averaging we need to allow those tubes to become room temperature.  The section of tube that goes outside needs to acclimate as well.

Bud

I never use any setting but "long term" average. Any other setting will always give you a less accurate average reading. Under the "long term" setting the manometer automatically calculates a mathematically continuous average. That means that you can "hold " the reading after "any" length of time and it will give the average for all of the seconds that you had the meter running.

RSS

Videos

  • Add Videos
  • View All

Twitter

Latest Activity

Profile IconBarbara Smith and Carl Johnson joined Tom White's group
Thumbnail

Weatherization

Share your concerns and successes as a weatherization professional, or information for this…See More
7 hours ago
Carl Johnson replied to Joel Greenberg's discussion The Truth About Windows? in the group Weatherization
"I think the appeal of replacing windows is largely on the aesthetics for most homeowners. Nobody…"
7 hours ago
Carl Johnson commented on Amber Vignieri's blog post Chicago Winter No Match for Retrofitted Logan Square Building
"Beautiful home! Did Josh replace the windows as well or no? Living in Chicago myself, I know about…"
7 hours ago
Carl Johnson commented on Diane Jackson's blog post Two Addison Projects Win Housing Innovation Awards
"These homes look great! Congrats!"
7 hours ago
Carl Johnson is now a member of Home Energy Pros
8 hours ago
Paul Scheckel posted a blog post

Renewable Rant: Traditional Energy!

Why, when I open up a newsletter or market evaluation report about “traditional energy” markets, do…See More
yesterday
Rob Madden, Solar Home Broker's discussion was featured

Indoor Air Quality Monitors and Meters

I'm considering purchasing the AirAdvice for Homes indoor air quality monitor but it seems to have…See More
yesterday
Luis Hernandez's discussion was featured

ERV Configuration

Greetings everyone,     I did an energy audit on this new home that is too tight and needs…See More
yesterday

© 2016   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service