In a balanced system every radiator gets just enough hot water to allow it to heat up fully.
In an unbalanced system there will always be favoured circuits that receive more water than they require. These favoured circuits steal flow from unfavoured circuits which will not then be able to provide the heating or cooling required. Control valves may temporarily help by gradually reducing the flow in favoured circuits, thus allowing unfavoured circuits to achieve the correct flow. This will however cause long delays in reaching the set temperature in the building after night setback and will make the installation very inefficient.
Balancing an installation is a complicated and involved procedure because closing or throttling a valve will increase the flow in other parts of the installation. That is why a very structured procedure must be followed. The two most used methods are Compensated balancing and Proportional balancing. Both use an iterative methodology that will result in properly distributed flow in full load situation. The complicated nature of these balancing procedure is the reason that automatic solutions are gaining traction because it reduces or eliminates the need for complicated balancing procedures. Because of that differential pressure controllers and pressure independent valves are getting more and more popular.p
The act of balancing can reveal common glitches such as wrongly mounted terminal units, damaged pipes, back-to-front reversed check valves and blocked filters. Ideally, these flaws should be exposed while they can still be cheaply fixed. That is, before control equipment is commissioned, before ceilings are mounted, and most important, before tenants move in.
