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How to balance a heating system by a circulator pump

Balancing or regulation of a heating system is performed to achieve an equal water flow through the house. Balancing ensures ideal distribution of water to the radiators, and thus thermal comfort at the lowest possible heating costs.

Why we need to balance a heating system

Water simply flows according to the laws of physics through the path of least resistance. Meaning the lower the hydraulic resistance, the more hot water flows into these pipes. Without balancing the heating system, water does not flow equally, in some rooms radiators recieve overheated water while on the contrary in other rooms only lukewarm water. Radiators need an optimal amount of heating medium in order to heat properly. Otherwise, heating costs are much higher and thermal comfort is greatly reduced. This problem occurs more often with larger heating systems, typically in apartment buildings.

All these problems can be solved by the so-called hydronic or hydraulic balancing of a heating system. Balancing ensures an even flow of the heating medium, ie hot water. Only with properly balanced system you can set the heating correctly using the valves on the radiators and at optimum consumption.

When and how to balance a heating system

In case of a new building, the method of connection and balancing of the heating system must be part of the project documentation for the new construction. It is the planner's job to do an accurate hydraulic calculation of the system.

Balancing is performed while installing a new or replacing an old heating system. The heating system must first be connected, primed and then bled. Then  start the circulator pump with a set constant pressure difference. The balancing itself must be done before the heating system is put into operation.

Heating system balancing methods

Static heating systems have an approximate constant flow. Dynamic heating systems, on the other hand, have a dynamic flow that is regulated by valves.

Current majority of heating systems are already dynamic. This means that the individual circuits of the system interact with each other and the values ​​of those that were balanced first change as the individual circuits are gradually balanced. The heating system must therefore be treated as one unit and can be balanced manually or by a circulator pump. Manual balancing of a heating system requires you to have accurate hydraulic calculations. In the case of smaller heating systems, for example in a family house, automatic balancing by a pump is therefore much simpler.

In the case of a family house, you can simply balance your heating system by a circulator pump.

Manual balancing of the heating system

To manually balance your heating system various balancing valves can be used. Balancing valves set and measure pressure difference and flow. Typical usage is for example for risers. Differential pressure regulators can also be used, which are valves that control the differential pressures in the system and allow more precise setting.

There are a total of three methods of manual balancing:

  1. Iterative method: although it is the most commonly used method, it is not entirely ideal. It is a method of gradual adjusting to the required flow rate, while success is given by the number of repetitions. In case of insufficient number of repetitions, this is a very inaccurate method.
  2. Proportional method: first the flow rates at all end units are measured with the balancing valves fully open and then compared with the required flow rate. Then the flow is gradually adjusted on all valves, starting with the last on the distribution and ending with the first.
  3. Compensation method: the principle is to prepare constant conditions at all points in the system using so-called partner valves. Each adjusting is therefore final and it is not necessary to return to them after balancing other parts of the system. There is no need to measure flow rates before balancing. Changes during balancing are easily compensated by partner valves. It is thus the most suitable method, which improves and facilitates the proportional method.

Balancing a heating system using a circulation pump

Heating system in family houses and smaller buildings can be balanced without complex interventions and detailed project documentation, thanks to the unique Grundfos ALPHA3 circulator pump which won the prestigious Plus X Award in the categories of innovation, high quality, functionality and ecology.

Grundfos ALPHA3 is the only circulator pump on the market with a heating system balancing function. You can easily balance using the optional ALPHA Reader and the Grundfos GO Balance mobile app, which is available for free in the App Store and Google Play.

The application has underfloor heating and radiator modes and their combination. The heating system must be two-pipe and equipped with pre-set thermostatic valves. Underfloor heating must not have any permanent bypass. You simply fill in the data about the heating system and the rooms in the house in the app. Then connect the sensor module to the Grundfos ALPHA3 circulation pump and connect it to the application. The GO Balance app simply reads all current data from the pump when the valves are closed (zero flow) and when they are fully open. Then the system automatically balances the heating system.

After the process is done, you can set the pump to the AUTOADAPT, which automatically selects the most suitable adjustement depending on the current heat supply needed in the building.

Grundfos ALPHA3 electronic circulator pump with AUTOADAPT.

Risks of incorrectly balanced heating system

You can recognize an incorrectly balanced heating system mainly by touching the radiators. Some radiators produce more heat and others less or not at all, even though they are set to the same value on all valves. If the radiators are bled, the problem is incorrect balancing.

Other signs of an unbalanced heating system are humming and hissing, which signals unnecessarily high flow rate. Uneven pressure can lead to failures in the long run, or to permanent damage of the heating system.