You need to consider that there is a fundamental issue of uncertainty with using 4 Pa as a reference pressure. Just imagine, if there is even a 1 Pa fluctuation, due to so many possible sources that can cause pressure fluctuations as you know, the pressure measurement already has an uncertainty of +/- 25% error. Consider that for almost all airtightness testing standards across the world, the reference pressure for Flow results are either 50 Pa or 75 Pa.
The main disadvantage to positive duct test pressure is that it blows off register seals or makes them leak. An LBL study showed a wide dispersion of results when the same duct test was repeated many times. Depressurizing will allow the use of lower sticking masking materials that are less likely to pull off the paint. In some cases plastic food wrap will work.
The main advantage to positive duct test pressure is that the flex duct doesn't contract as much. In cases where the flex runs to the ceiling this contraction effect might cause problems.
Testing using depressurization will usually result in less leakage because gaps and seams will be pulled closed”
Whether it’s for a building code, third-party home performance program, HERS rating or quality control, testing ducts on new construction homes before the drywall is installed is a good idea to easily fix issues. Once the drywall is installed, it can be difficult to access certain parts of the duct system that need air sealing, especially if there are ducts in chases or between floors. Sometimes it can be tricky to set up your duct tester at rough-in since you typically don’t have a grille to tape the flange to, especially if the return is in the ceiling. Unfortunately, duct mask doesn’t stick to wood and mastic ver
A comprehensive guide to getting the most out of your blower door system
Authored By: Sam Myers
A blower door system can do much more than tell you how much your building is leaking. It can also help you determine the location and severity of the leaks in different zones. There are also cases where you can use your blower door to determine if some ventilation systems are working properly. Knowing the tightness of a home and finding leaks is helpful to HERS Raters, BPI analysts, insulators and HVAC contractors. In this article we’ll introduce the blower door system and ho
When it comes to home energy performance, comfort, durability and health, the United States falls short in the ranks compared to other developed countries. This is based on the 35 years of experience that Colin Genge has in testing houses from coast to coast and from selling diagnostic tools to over 10,000 technicians who have tested millions more.
Duct leakage in existing homes can range from 12% to 35%.
Most American houses have poor quality flex duct running outside of the envelope into attics and/or crawlspaces and typically leak an average of about 20%. Some as high as 50%! Code for new
Posted: June 07, 2018|Categories: Air Leakage Testing|
In 1980 I calibrated the fledgling Retrotec Energy Innovations Ltd.’s blower door at the National Research Council (NRC) in Ottawa, Canada. It used RPM and pressure drop to crudely measure flow. Little did I know that what I learned from the head air flow scientist at NRC would result in a 38-year long career making Retrotec the largest calibrated door fan manufacturer in the World.
Retrotec stands for retrofit technology, which means fixing houses after they’re built. Our first blower doors were designed to perform energy audits on these houses using their in-house energy analysis software based on HOT2000. It ran on a 32k pocket computer. Currently known as Home Performance (HP), this application was promoted by Retro
As you may have heard, the RESNET 380 standard will replace RESNET Ch. 8 which dictates how raters test homes for envelope leakage, duct leakage, mechanical ventilation, and duct system air flows. Any home permitted on or after July, 1 2018 must be tested in accordance to the 380 Standard. The standard currently applies to all single-family homes as well as multifamily projects that are three stories or less. There are more updates coming for multifamily so make sure you are signed up to receive email updates from RESNET.
One goal of the 380 standard is to improve consistency throughout the HERS process and to reduce the need for Raters to make judgement calls when taking measurements in the field. To help achieve this, the standard includes definitions for:
- Conditioned Space Volume
- Unconditioned Space Volume
Posted: October 18, 2017
Leakage to Outdoors and Advanced DucTesting Methods
- When is it required?
- Setup options
- Complex setups
- Additional leakage to the outdoors tests
Major Enhancements Are Right Around the Corner
- Feature 1: Completion of the ATTMA (Air Tightness Testing & Measurement Association) standard. This standard is primarily used in the United Kingdom but also used or referenced in 90 other countries. This standard has two types of test available: Single Direction Multi Point Test and Dual Direction Multi Point Test. A lot of the groundwork for ATTMA was completed in the September release (1.1.7) however due to time constraints and the size of the feature some functionality was pushed into the October release. The biggest piece of this feature to be added is to allow user input of the fan flow equation parameters received when a test fan is re-calibrated, and have these parameters be used in
Read more »