A circulation pump is a type of centrifugal pump used to create liquid flow in heating and cooling systems. In other words, a circulation pump forces water to circulate. This phenomenon was first used in 1929. The most important component of a circulation pump is the motor, which drives the shaft and impeller. In traditional gland-sealed pump models, the motor is separated from the liquid. Nowadays, however, glandless pumps are much more popular—wet-rotor pumps or highly efficient pumps using ECM technology with an electronically commutated motor.
How does a central heating pump work?
Pressurized heating systems use circulation pumps to force water to circulate. A central heating circulation pump significantly improves the operation of a heating system. When using one, there is no need to use large-diameter pipes or install the boiler in the basement. A circulation pump may be built directly into the boiler. Otherwise, the pump must be purchased separately, but its installation is not complicated. Central heating pumps are compact and lightweight. Their operating principle is based on creating a pressure difference between the pump inlet and outlet. The pump draws water from the boiler. The stainless-steel impeller is driven by the motor and transfers potential and kinetic energy to the liquid. This increases its pressure and velocity.
In the pump's cast-iron housing, kinetic energy is converted into potential energy, meaning that the pressure increases further. This pressure makes it possible to circulate water through the heating pipes and deliver it to the radiators. In single-family homes, glandless pumps are used, in which the motor is immersed in the liquid. Their service life is approximately 15–20 years. A central heating circulation pump should be equipped with an automatic air vent valve and a mesh filter. Remember that filters must be cleaned regularly! Modern central heating circulation pumps not only increase the comfort of using the heating system but can also reduce electricity consumption by up to 50%.
How do you choose the right circulation pump?
Glandless circulation pumps for central heating do not require maintenance, lubrication, or seal replacement. However, it is very important to select their parameters correctly, because installing a pump that is too small or too large will have negative financial and operational consequences. A circulation pump that is too large will consume a disproportionate amount of power, and its components will wear out faster than they should. On the other hand, choosing a pump that is too small may make it difficult for the system to achieve the required water flow, resulting in insufficiently heated rooms. The most important parameters to consider are capacity, pump pressure, power consumption, impeller speed, and the level of noise generated. The circulation pump's parameters should be matched to the length of the pipes, the number of radiators, and the resistance of the system. The pump's capacity—that is, its head and flow rate—should be specified in the system design. If the investor does not have this information, the most sensible solution is to seek professional assistance with the calculations.
It should also be remembered that pumps with higher capacity will be needed for underfloor heating and in multistory homes. It is worth choosing electronically controlled circulation pumps that offer automatic motor-speed regulation. These pumps are recommended for systems with thermostatic valves. Speed regulation is usually available in three or four stages. The pump should operate at its highest setting most of the time. The power-consumption parameter will determine operating costs. Efficient boiler operation will only be possible when the circulation pump's parameters are correctly matched to the requirements of the heating system.
