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: 254

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

Photos

Loading…
  • Add Photos
  • View All

Latest Activity

Profile IconCharlie Ouellette, Karin Haerter and Juan joined Home Energy Pros
6 hours ago
Juan added a discussion to the group Energy Auditing Equipment for Sale, Trade or to Purchase
Thumbnail

Need Energy conservatory Blower door 3 + DG-700

Hello thanks for taking the time to read this post. I am currently looking for a blower door…See More
7 hours ago
Juan joined allen p tanner's group
Thumbnail

Energy Auditing Equipment for Sale, Trade or to Purchase

Discuss the pros and cons of the equipment you are interested in prior to purchase. Post equipment…See More
7 hours ago
Caoimhin P Connell replied to Rodney Fox's discussion Radon: Truth vs. Myth
"Good morning, Mr. Cullen – As I mentioned in another post – for the purposes under…"
8 hours ago
tedkidd replied to Rodney Fox's discussion Radon: Truth vs. Myth
"If putting the house under positive pressure using fresh air helps mitigate not just radon, but…"
9 hours ago
Rich Manning replied to Rodney Fox's discussion Radon: Truth vs. Myth
"Tell them the truth as you know it, and back it up with the facts!!"
10 hours ago
Rich Manning replied to Charles Ryan Weitzel's discussion Oil Fired Boiler Being Used as the Heating Source in Two Air Handlers of a Historic Home
"Yes, its a Hydro-air system. It uses one boiler to supply hot water to the coil in the supply side…"
10 hours ago
tedkidd replied to Rodney Fox's discussion Radon: Truth vs. Myth
";) I love uncovering absuedities... Funny how creatively and vehemently people will argue against…"
10 hours ago

© 2016   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service