Balancing of heating and cooling systems is performed to ensure that the correct amount of water is present at all consumption points. Balancing is carried out by building balancing valves into the system, thereby adding adjustable resistance.
The valves in the system closest to pump system are adjusted to provide a higher resistance than valves placed further away from the pump system. This compensates for the increased pressure loss in the longer pipe sections. When there is the desired relationship between the different flow rates in the system, it is said to be balanced.
The pressure losses across the balancing valves should be kept as low as possible, so the pressure loss at the most distant valve is close to zero. Doing this will help minimise unnecessary power consumption for pump operation during the system’s lifetime.
There are two types of balancing valves available: static and dynamic.
Static balancing valves serve as a permanent resistance, built into the system. The settings for these valves must therefore be calculated and adjusted accurately, as changing just one of them in the system could change the flow through all other valves.
Dynamic balancing valves work as flow limiters. They are set to a desired flow rate and ensure that a larger flow rate does not take place. If the pressure in front of the valve increases, it will close some more, so the pressure loss across the valve becomes correspondingly higher. This maintains the desired flow rate in the specific path.
The inlet pressure for a dynamic balancing valve needs to be higher than a certain limit for it to operate properly. This means that the resistance at the most distant valve cannot be close to zero, as is the case with static valves.
Balancing valves are available from numerous manufacturers. Some of these provide electronic measurement equipment that allows measuring the flow through their valves. This is done by measuring the pressure loss across the valve and calculating the flow according to the kv-value of the present position of the valve.
Grundfos supplies circulator pumps for heating and cooling systems and supports the system contractor, who usually carries out balancing during commissioning. The task is often documented in a report, which indicates the measured flow rates.