Water balancing is a procedure that is done to maintain and optimize a hydronic system so that it can function as designed. In order to understand this, we must first discuss what a hydronic system is.
Although most people are familiar with the use of heated and cooled air to condition a building or area for human comfort, the use of liquids to serve the same purpose is less frequently discussed. Water is a good choice for a temperature conditioning system because of its high heat capacity, although its tendency to expand volumetrically when transitioning to a solid state means that water is only a good choice for systems that are going to be operating exclusively above freezing temperature. A hydronic heating system heats water and then circulates it through the interior of the building envelope in order to spread the heat, using radiative heating principles. Hydronic heating systems gain their efficiency from the fact that water can be heated in bulk at one location, and then maintain that heat quite effectively even after traveling significant distances through piping to reach all corners of the building. Most hydronic heating systems use a gas boiler to supply the heat energy. Hydronic cooling systems work on a similar principle, but usually use an electric cooling system at the central location.
This system seems almost too easy. But what can shatter that impression is when the system loses efficiency because it is out of balance. This is why water balancing is so important. As stated in “What Is a Hydronic System and What Is Needed to Balance It?”: “[h]ydronic balancing is the process of optimizing the distribution of water in a building’s heating or cooling system by equalizing the system pressure. This provides the intended indoor climate at optimum energy efficiency and minimal operating cost.”1 Much like a conditioning system that uses air as the thermal medium, a hydronic system also requires the correct pressure balance to induce flows without wasting energy. As some might remember from high school Physics, fluids will tend naturally towards areas of lower pressure and, conversely, will resist being moved to areas of higher pressure. Therefore, it’s clear why pressure imbalances can put undue stress on motors and pumps and decrease their efficiency, wasting energy. While water balancing is a recurring maintenance cost, it will save on energy bills while the system stays in balance and is operating optimally. Testing this pressure differential requires a specialized set of tools, distinct from those a technician would use when performing a similar test on an air-based temperature conditioning system. As stated by Jennifer Williams, “[t]he instrument used to balance a hydronic system is called a hydronic manometer. A Hydronic Differential Pressure Manometer… measures the differential pressure across valves. The typical hydronic manometer connects to the system via hoses and piercing gauge adapters.” This is one method of testing the balance of a hydronic system, which then allows the technician to correct any disparities in a process called water balancing. Altering the pressure in problem areas can involve sectioning off the area by closing valves, manipulating its pressure with volumetric additions or subtractions, and identifying any leaks to ensure that the area stays balanced longer. This key maintenance procedure can keep the system operating as designed.