The demand for an industry trained & certified air flow test and balance professional is on the rise. New national energy codes and system design requirements are forcing the hand of the HVAC industry to prove their system installations are performing the way they were specified and designed to …
Over the years, air balancing (otherwise known as air flow test and balance) has become more and more popular … especially with the increase and progression of nationally observed energy conservation codes. While the intention of energy conservation is a noble cause, the HVAC salespeople, installers, technicians, and balancers that are at the top of their game all know that, in some cases, the codes have done more harm than good … especially when it comes down to the interpretation of the codes or how they apply to a given situation (let’s just leave that one alone).
The resulting discussions, conflicts, or interpretations of the codes has led to several heated debates in recent years. Quantifying the end result to confirm the system is operating properly is in fact the job of the test and balance company or technician.
Yet somehow, the liability or fault of the system not performing properly or to specification, and the resulting responsibility thereof, has had the illusion of falling on the balancing technician or company. The job has gone from taking readings and adjusting the system to get the numbers where they need to be (provided the system is capable), to …
- somehow having to pass a job that is obviously short on air flow.
- systems lacking in proper installation technique & being vacant in the art of observing industry “good practice”.
- installations that are missing several steps in proper design technique due to misinterpretation of the codes or lack of proper training or installation.
- GC’s & HVAC Installers realizing they need to perform air flow test and balance to obtain occupancy due to the new codes … ALL OF A SUDDEN.
All this … and yet somehow it is all on the Test & Balance Company to provide “PASSING REPORTS” … yesterday … at no additional cost (and more than likely negotiated to our discontent via a tactic I’ve coined a “reverse auction”) and it’s our fault it doesn’t meet design specifications.
Do not misunderstand these statements … This is not a complaint, but a statement of fact.
This is, however, where the proverbial “rubber meets the road”.
This is the part of the job when:
- The GC finds out how much the architect misunderstands, misinterprets, or incorrectly designs systems.
- Where the GC realizes he hired the wrong HVAC company.
- The GC realizes he should have listened to the HVAC company.
- Where the HVAC company realizes how much they didn’t know.
- The prospective owner realizes the google reviews were wrong … and that maybe the higher priced guy actually knew what he was talking about.
- Where EVERYBODY learns the GOLDEN RULE: GOOD – FAST – CHEAP … PICK TWO!
While there are several more bullet points one can make, I’m sure everyone gets the point … but this is where the fight starts.
With the advent of all the new energy codes … If all involved are unaware of where the competency lies … they’re all about to find out.
While techniques have changed and improved over the years, the goal of performing test and balance work has not. The goal has always been to verify and quantify the unit(s) performance based on a set of readings taken by highly accurate, recently calibrated (within 1 year and sometimes 6 months), industry specific (expensive) test equipment. Then, using the readings obtained, compare them to what is on the plan / specifications, and determine whether or not it is performing within a range of acceptance (usually +/- 10%, but sometimes as strict as +/- 5%).
Due to field limitations and restrictions, obtaining “good” and / or accurate readings can sometimes be a challenge.
One example would be:
If you are supposed to obtain a reading in 10 feet of straight duct in order to get a good & reliable sample in a non-turbulent, laminar flow air stream, and there isn’t 10 feet of straight duct … what does a balancing technician do? It is up to the balancing technician to find a spot within that duct to obtain a reliable reading from.
There could also be system design limitations that are not the fault of anyone … such as space to install. Sometimes, the space available will not allow the installing contractor to follow certain aspects of good practice and design.
As an example: Let’s say that you are not supposed to have a take-off within 2 feet of a fitting / reduction, within 2 feet of another take-off, and you are not supposed to have a take-off within 2 feet of the end of the duct. You have 5 take-offs to put on your system, 1 reduction, and only 15 feet in which to install the duct / run … You are mathematically out of the game! What to do?
Violating some of these “rules of thumb”, intentionally or not, makes balancing more difficult. HOW? These rules are in place to minimize duct system turbulence. Duct system turbulence can have an effect on how stable and accurate the readings can be. This effect is compounded / multiplied by having multiple violations of these rules within the same duct run or duct system.
Room / space comfort, as well as duct system resistance is especially compounded when one “violation” is right next to another. This idea (and scientific FACT) is best known and understood as the Coanda Effect (AKA Surface Effect) … but that is for a later post …
Violations like these not only have a huge impact on occupant comfort, but will have a significant impact on your systems performance … and whether or not you get a passing air flow test and balance report. There will be several posts surrounding the knowledge of this particular area in the future.
There are several things in life that have a procedure … certified are flow test and balance is no different.
It is absolutely critical that every trade related to a test and balance project do their job correctly to produce a desired result.
Only when it’s too late will someone realize who or what went wrong … and by that time, there is no way to change it.
UNDERSTANDING: One of the first things to recognize & acknowledge is, what is the building’s or structure’s purpose? Knowing this is critical in knowing what codes need to be followed, especially for fresh air requirements and air changes per hour (ACH). Once know, the load calculation is performed to determine the load on the structure for both heating and cooling. From this, one can select equipment and produce a ventilation schedule. In addition to the ventilation schedule, the terms and conditions in which the test & balance is to be performed can be generated (AKA the 15000 or 15900). Residing in these statements are anything the Test & Balance (TAB) Professional needs to know to perform his job. REST ASSURED – if there is a fresh air requirement … you will need a Test & Balance (TAB) report.
DESIGN: Once the ventilation schedule is produced, the size of the ductwork & kind / style of duct system can be determined and laid out.
It is the official corporate & professional design opinion of LaminAir Test & Balance, Inc. that all duct systems be laid out & designed to provide between 0.07 – 0.08 static pressure to help ensure proper system performance (in most commercial system cases). Special purposed / designed equipment will have independent system design parameters depending on the application or use.
READINESS: It is the responsibility of the HVAC Contractor to perform his job properly and install the system per design specifications. If the HVAC Contractor follows the plans to the letter, he cannot be held responsible for poor design … only poor installation. Once all mechanical equipment and controls are verified operationally read for testing, then and only then does the Test & Balance portion of the job begin.
CONCLUSION: Once all the above has been performed – the result should be a passing Test & Balance Report which will be used to submit to the inspecting authority to obtain an occupancy permit. There are many things that can happen on a job, but all things being equal … if everyone has done their job correctly, the reports are done, people get paid, occupancy is obtained, and the client moves in … happy and comfortable with properly installed and properly operating equipment.