As we enter the heating season in many parts of the world, it is a good idea to review some basics of hydronic balancing.
Most of today’s new HVAC systems are designed with individually controlled temperature zones to improve occupant comfort. Additionally, variable speed fans and pumps are becoming more commonplace to provide the exact amount of heating and cooling system capacity in a manner that minimizes overall energy usage. As such, the demand for testing, adjusting, and balancing is critical to balance today’s complex HVAC systems.
In addition, after several years of use, even the best designed buildings and HVAC systems can experience operating problems. The following are just a few “refresher’ tips on hydronic balancing.
With unbalanced systems, some circuits receive more water than they require while other circuits don’t receive adequate water to provide the required heating or cooling. Many HVAC pros like to use control valves to reduce the flow in the circuits getting more water than they need, which allows the under-used circuits to regain the correct flow. However, during high-load periods (heating in winter and cooling in the summer) all the control valves often operate in the open position. This means some valves are not receiving enough flow.
The beauty of hydronic balancing is that it limits the flow in those circuits getting to much water and provides more water through those circuits that aren’t efficient. This results in the required design flows being available to all circuits so the system can provide the required indoor climate. This also saves significant energy because the pump is not doing unnecessary work. It also reduces operating cost and can reduce the size of the pump required, thereby reducing your acquisition costs.
Proper balancing also saves energy and operating costs by reducing the amount of time between starting the system and achieving the desired indoor environment. The process of balancing will also identify some basic system problems, such as clogged filters, impaired pipes, incorrectly mounted terminal units, back-to-front check valves, etc. There can be a variety of causes for improper operation but balancing valves provide measurement of differential pressure, flow and temperature so you can pinpoint the problem.
Tips for Hydronic Balancing Success
The HVAC Hydronic Balancing process can be greatly enhanced by following these recommendations.
- Proper start-up of Hydronic Equipment.
- HVAC controls are complete and fully operational to allow TAB to commence.
- Construction strainers are removed from pumps after systems flush/cleaning.
- Proper pipe diameters should be reviewed to ensure accurate measurements on flow measure devices.
- Hydronic systems should be verified to be free of air and properly vented at the highest points in the systems.
Here are some other sources I have found very valuable on the topic of hyrdonic balancing.
- American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) — ASHRAE seeks to advance the arts and sciences of heating, ventilation, air-conditioning, refrigeration, and related human factors to serve the evolving needs of the public and its ASHRAE members.
- National Energy Management Institute (NEMI) — NEMI is a not-for-profit organization that has created a training and certification program to provide the HVAC industry with qualified technicians.
- National Environmental Balancing Bureau (NEBB) — An international certification association for firms that deliver high performance building systems. Their members perform testing, adjusting and balancing (TAB) of heating, ventilating and air-conditioning systems, commission and retro-commission building systems, execute sound and vibration testing, and test and certify laboratory fume hoods and electronic and biological cleanrooms.
- Sheet Metal and Air Conditioning Contractors’ National Association (SMACNA) — The voluntary technical standards and manuals developed by SMACNA Contractors have found worldwide acceptance by the construction community, as well as foreign government agencies. ANSI, the American National Standards Institute, has accredited SMACNA as a standards-setting organization. SMACNA does not seek to enforce its standards or provide accreditation for compliance.
- International Certification Board/Testing, Adjusting, and Balancing Bureau (ICB/TABB) — Find qualified Testing, Adjusting, & Balancing professionals that synchronize all components of the complex HVAC industry. ICB/TABB ensures that HVAC systems operate at the highest standards of energy efficiency and ventilation effectiveness.
If you’re going to spend money, spend it wisely and feel comfortable at the same time. Hydronic balancing is the cost saving feature that everyone benefits from.