Every updated NEBB Procedural Standard will have these statements or something very similar. What makes an efficient NEBB firm is knowing when to use these tools and when to use common sense.
The Required Instrumentation Lists have been produced by a large group of volunteer committee members encompassing all the NEBB disciplines. A lot of time and effort has been put into researching the instruments available and the standard of care and accuracy that NEBB believes we owe our clients and our industry.
These instruments are a minimum that need be in the firm’s possession and calibrated, but they are not the only tools in the shed. They are for gathering and recording measurements that will be placed on a NEBB Certified Report. But often, field activities, trouble shooting, and quick verifications do not need the accuracy or resolution called for in our requirements. In many instances, a reference is needed more than a true measurement.
For instance, analog instruments do not meet NEBB standards for accuracy or resolution. However, an analog hood is excellent when needing to “watch” flows fluctuating in a system to troubleshoot or demonstrate non-steady flows (building pressure issues, systems that affect each other, doors opening and closing, etc.). Small analog pressure gauges for water systems are inexpensive and helpful.
Calibration of these gauges can be verified with the required water meter each day before use. The gauges are light and quick to install on readily available ports in water systems. Multiple gauges can be temporarily installed at several points in a system to monitor pressures concurrently during operation. Monitor pump head, chiller bundle, and main coil drop all at once which can be important when troubleshooting or looking for a quick “blip” type issue. Otherwise, you are moving your heavy expensive meter all over the place for one reading at a time.
Electrical meters need to be accurate, true RMS meters to take measurements around a VFD, however, the procedural standards allow for using the VFD unless the need for manual measurement is present, such as multiple motors connected to the same VFD. Although not a required instrument, an electrical meter with remote/wireless head capabilities to take readings inside a pressurized fan chamber is useful. Otherwise, opening the door to take the reading changes airflow for example when electronically commutate motors (ECM) are involved.
Temperature is a measurement most often used for troubleshooting and evaluating systems. NEBB requires a very accurate and calibrated temperature meter with multiple probes to meet minimum requirements. However, having a few quick and easy reference gauges for grabbing snap shots in real time makes the process more efficient. The coveted “Blue Box” is an excellent meter. Reasonably priced, very accurate, easy to use and calibrate. But it has a downfall of being relatively slow compared to alternative methods. The certified firm is required to own an approved instrument but save it for field calibration verifications and situations that require certification. The more affordable and fast acting instruments can be purchased in multiples and used quickly.
For example, when looking for a quick verification that a system is in HEATING or in COOLING. Having an instrument that can differentiate between a discharge temp of 110.2°F and 110.9°F does not make a difference when you are trying to read a rising temperature to know if the hot water control valve is opening. Likewise, in cooling, the need is for a wet and cool coil. Exact temperatures are not required, only that it is below dew point and providing a wet coil for proper total TAB airflows.
Not unlike temperature measurement instruments, in Retro Cx, a highly accurate and calibrated set of data loggers is required to meet NEBB minimum standards. But when troubleshooting, the need to see changes in half a degree is not required. Status such as ON/OFF or HEAT/COOL do not require accuracy or resolution. Having multiple less accurate and less expensive data loggers on hand will provide the data that is needed. The required data loggers are needed for verification, in house calibrations, and to meet the instrument requirements, but are not always the best tool for the job.
Improvise, adapt, overcome. Learn the tricks and be creative when doing your job. A piece of surveyor tape, a paper towel or piece of toilet paper is a valuable tool for TAB and Commissioning. Sometimes all that is needed is a visual representation of flow or pressure. When in front of a group of 5 or 6 people showing a neutral airflow at the filter intake of a fan powered VAV Box, the flag method has always been the best way to show it.
When you decrease the box fan speed enough for the toilet paper to fall off, or even blow off, everyone watching knows what just happened without the need for an instrument. Building or Room Pressure can be demonstrated by a ping pong ball in a tube between spaces. Balancing Hoods are required and one of the more expensive packages that a firm must purchase.
However, when the project is missing an inexpensive ceiling tile installed around a grill that is not the standard 24×24 lay-in, the expensive hood becomes useless by itself. Although not standard or desired, cutting a piece of cardboard to form a blank off in the field is solid theory. Keeping the flow contained within and through the hood instead of escaping around the grille is the goal, even if it is a piece of cardboard instead of a ceiling tile.
Velgrids are often larger than required for smaller openings. Even though engineers frown upon this and question its validity, all 16 holes are not always needed. Seal off the holes not in the airstream so only the affective area of airflow is measured. Some manufacturers have now started selling half and quarter grids based on this same principle.
Finally, an unwritten requirement for a NEBB Certified Firm is common sense. Unfortunately, so the saying goes, common sense is not all that common some days. But it is the most valuable tool and instrument to have. Do what makes the most sense to get the job and the project completed accurately and efficiently and know that these suggestions do not necessarily work for all projects. Approaches to small vs large projects or complex vs simple will differ. Do not perform tasks just because it is required and not do others because it is not specified.
Some specifications state TAB work should not begin until systems are 100% ready and complete. TAB can do lots of testing before final building enclosure is ready. In construction, completion is a relative term. If TAB waits until the project is truly complete, it may be well into occupancy before it can be finished, or possibly even started. Worse yet, when work during occupancy is not allowed or it is by escort only, your efforts can be drawn out well past your budgets. Not only will this disrupt TAB fees, but also potentially scheduled manpower for other projects.
Pre-Balance work and setup includes items that can be done before completion. Everything that is done before “complete” are tasks that do not have to be done after. Drilling holes for traverse locations or pressure readings in air handlers can be done at any time. In a system that is operating, with proper investigation, risers can be proportionally balanced to each floor before the project is complete.
Investigation before the ceilings are closed in allows the firm to find missing or damaged dampers, grilles that are missing ductwork, outlets/inlets that have been covered up by sheetrock and a multitude of additional items that will be put on a deficiency list. Finding those items while the mechanical and finish contractors have manpower on-site gives the project team time to plan and finish, rather than just react to your list while you wait, or waste work already completed. There is always a way to be productive and proactive that help the process in the long run.
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