Balancing a Heating System with a Circulation Pump

Balancing, or regulating, a heating system is carried out with the aim of achieving the desired thermal performance of the system. Balancing ensures the ideal distribution of water to the radiators, thus providing thermal comfort at the lowest possible heating costs.

Why It Is Necessary to Balance Heating Systems

Water in radiators flows according to the hydraulic resistance present. The lower the hydraulic resistance, the more hot water flows to those areas. Water simply flows along the path of least resistance according to the laws of physics. This means that without balancing the heating system, water does not flow evenly; some areas do not heat sufficiently while others overheat. Radiators require a precise amount of heating medium to function correctly. Otherwise, with reduced thermal comfort, heating costs are significantly higher. This issue occurs more frequently in larger heating systems, typically in apartment buildings.

These undesirable situations are addressed by so-called hydronic or hydraulic balancing of the heating system. Balancing ensures even flow of the heating medium, i.e., the heating water. Only then can the heating be properly regulated using the valves on the radiators and at optimal consumption.

When and How to Balance a Heating System

Every heating system that transfers thermal energy through the flow of a heating medium requires proper balancing. The method of connecting and balancing the heating system must be part of the construction project documentation. Here, the designer should precisely determine the hydraulic calculation of the system.  

Balancing is therefore carried out during the installation of a new or replacement of an old heating system. The heating system must first be connected, filled, and vented. Then it is necessary to commission the circulation pump with a set constant pressure difference. The actual balancing is performed before the heating system is put into operation.

Methods of Balancing a Heating System

A static heating system has approximately constant flow. A dynamic heating system, on the other hand, has a changing flow, which is regulated using valves.

Today, the vast majority of heating systems are dynamic. This means that the individual circuits of the heating system influence each other, and as each circuit is gradually balanced, the values of those balanced first change. Therefore, the heating system must be approached as a whole and can be balanced manually or using a circulation pump. For manual balancing of the heating system, precise hydraulic calculations are needed. In the case of smaller heating systems, such as in a family house, automatic balancing using a circulation pump is much simpler.

In the case of a family house, you can easily balance the heating system using a circulation pump. 

Manual Balancing of a Heating System

Various balancing fittings are used for manual balancing of a heating system. Balancing valves are used to set and measure differential pressure and flow. They are typically used on risers. Differential pressure regulators, i.e., valves that control differential pressures in the system and allow for more precise settings, are also used.  

There are three methods of manual balancing:

1. Iterative Method: Although this is the most commonly used method, it is not entirely ideal. It is a method of gradually approaching the desired flow value, where the degree of approximation to the given value is determined by the number of repetitions. With an insufficient number of repetitions, it is a very inaccurate method. 
2. Proportional Method: First, flows are measured at all terminal units with fully open balancing valves, which are compared with the desired flow. Then the flow is gradually adjusted on all valves, starting with the last on the distribution and ending with the first.
3. Compensatory Method: The principle is to set constant conditions at all points of the system using so-called partner valves. Each setting is thus final, and there is no need to return to them after balancing other parts of the system. There is no need to measure flows before balancing. Changes during balancing are simply compensated using partner valves. This is the most suitable method, which improves and simplifies the proportional method. 

Balancing a Heating System Using a Circulation Pump

A heating system in family houses and smaller buildings can be balanced without complex interventions and detailed project documentation, thanks to the unique technology of the Grundfos ALPHA3 circulation pump, which received the prestigious Plus X Award in the categories of innovation, high quality, functionality, and ecology just three months after its introduction to the German market.

Grundfos ALPHA3 is the only circulation pump on the market with a heating system balancing function. Balancing is easily performed using the additional ALPHA Reader sensor module and the Grundfos GO Balance mobile app, which is available for free on the App Store and Google Play.

The app has modes for underfloor heating, radiators, and a combination of both. The heating system must be a two-pipe system equipped with thermostatic valves with presetting. Underfloor heating must not have any permanent bypass. In the app, you simply fill in details about the heating system and the rooms in the house. Then you connect the sensor module to the Grundfos ALPHA3 circulation pump and link it with the app. The app then easily reads all current data from the pump with closed valves (zero flow) and when they are fully open. The system then automatically balances the heating system.

After balancing, you can set the pump to the AUTOADAPT unattended mode, which always selects the most suitable operating point of the pump depending on the current need for heat supply to the building.

Electronic circulation pump Grundfos ALPHA3 with heating system balancing function. 

Risks of an Improperly Balanced Heating System

An improperly balanced heating system is particularly noticeable when some radiators heat more and others less or not at all, even though all valves are set to the same value. If the radiators are vented, the problem is improper balancing.

Other signs of an unbalanced heating system are humming and whistling, indicating unnecessarily high flows. Uneven pressures can, in the long term, lead to malfunctions and even permanent damage to the heating system.

Legal Regulations and Required Documentation

Balancing a heating system must be carried out by a qualified professional. The requirements for proper balancing of a heating system are part of decree no. 193/2007 Coll. It also stipulates the obligation to issue a measurement and balancing protocol, which is important for warranty claims.