Pumps for central heating - what types are there and when which one to choose?

The central heating pump is a component without which a modern heating system simply would not work as it should. It's what sets the water in motion, delivering heat from the boiler, heat pump or heat exchanger to radiators and underfloor heating. It allows you to enjoy a constant temperature in each room, and the heat is distributed evenly.

In this guide we will explain what types of CO pumps are currently used, how to choose the right model for your installation, and what mistakes in installation and operation can shorten the life of the device.

How does the circulation pump work in a CO system??

The principle of the circulating pump is simple: the device creates enough pressure to allow the water in the system to overcome the resistance posed by pipes, elbows, valves and other system components. As a result, hot water goes where it is needed - to radiators, floor loops or heat exchangers.

When choosing a pump, attention is paid to several basic parameters:

• Capacity (m³/h) - Indicates how much water the pump can pump per hour.
• Lifting height (m) - determines how much pressure the device can generate to overcome the resistance of the installation.
• Power consumption (W) - has an impact on operating costs.
• EEI (energy efficiency index) - The lower it is, the more energy efficient the pump is.

Types of pumps for heating

Variable speed electronic pumps

Currently, central heating systems mainly use electronic pumps. Thanks to built-in automation, they can adjust their speed to the current demand of the installation. They can operate in constant-pressure mode, proportional-pressure mode, or in automatic mode, in which they adjust operating parameters independently.
This solution is quiet, energy-efficient and helps extend the life of the entire heating system.

➡️ View our offer electronic pumps.

Constant-speed pumps - only in older installations

Constant-speed pumps were widely used in the past, but due to current energy efficiency (EEI) requirements, they have been virtually completely replaced by electronic pumps. Nowadays, they are mainly encountered as elements of existing, older installations.

Hot water circulation pumps

A separate type is pumps for DHW circulation. Their task is to maintain a constant circulation of hot water in the system, so that when you turn on the tap, water is available immediately, without waiting for it to flow from the storage tank or boiler.
They require the use of materials approved for contact with drinking water, such as bronze or stainless steel.

➡️ Check pumps for DHW circulation.

Pumps for solar installations

Solar thermal systems that use solar collectors to heat water use special solar pumps. Their task is to force the circulation of the working medium between the collectors and the water storage tank. This type of pump has to work under special conditions - often at high temperatures and under varying loads.

What is the difference between a solar pump and a regular CO pump??

• Resistance to high temperatures - Solar pumps can operate at medium temperatures as high as approx. 110°C continuously, and withstand temperatures as high as 140°C in the short term.
• Construction materials - bodies and seals resistant to prolonged contact with propylene or ethylene glycol, which is the most common medium used in solar systems, are used.
• Range of adjustment - in solar pumps it is common to find the possibility of infinitely variable speed control to adapt the flow to the current output of the collectors.
• Cooperation with solar automation - These pumps are usually controlled by dedicated controllers, which decide whether to switch them on based on the temperature difference between the collectors and the storage tank.

➡️ See pumps for solar installations.

Wet rotor or dry rotor?

In wet rotor pumps, the moving parts are cooled by water from the system, ensuring quiet operation and no lubrication. This is the solution most often used in domestic heating systems.
Dry impeller pumps have higher efficiency and are better suited for industrial or high-power installations, but are noisier and require more maintenance.

How to choose a pump for your installation - a practical guide

1. Determine the required capacity
In a typical single-family home of approx. 120 m² water flow requirement is typically 0.8-1.2 m³/h.

2. Check the lift height needed
For simple domestic installations, 3-6 m is sufficient. In larger buildings, with long circuits or a large number of fittings, a higher value pump may be needed.

3. Match the operating characteristics to the installation

• Proportional mode often works well in radiator installations.
• With underfloor heating, stable proportional pressure is better for preventing noise and improving thermal comfort.
• In mixed installations, it is worth using the automatic mode, which independently adjusts the parameters of the pump's operation.

4. Consider energy efficiency
Choose models with an EEI ≤ 0.23 - they will use less electricity.

5. Note the dimensions and connections
Standard mounting spacing for residential pumps are 130 mm and 180 mm.
Also very important is type and diameter of the connection:

• In single-family homes threaded connections with diameters of G1, G1 ½ or G2(DN25, DN32 and DN40, respectively).
• In larger installations - For example, in multi-family buildings, public facilities or industrial plants - larger diameters are often used (DN50, DN65, DN80 and more) and flanged connections, which make it easier to install and remove heavier pumps and provide a tighter connection.

The choice of diameter and type of connection should be consistent with the cross-section of the pipes in the installation - a connection that is too small may restrict the flow, and one that is too large will unnecessarily increase the cost of purchase.

Selection for different types of installations - examples

• Small single-family house with radiators: electronic pump 25-40 with a flow of approx. 1 m³/h and a head of 4 m.
• Flooring with manifolds: electronic pump with proportional mode and low EEI.
• Mixed installation: pump with automatic capacity adjustment mode, working with a mixing valve.
• DHW Circulation: a pump with a bronze or stainless steel body, preferably with a built-in timer or thermostat.

The most common mistakes when selecting and installing pumps

1. One of the most common mistakes is oversizing the pump - Too much power causes noise in the installation, unnecessary power consumption and faster wear of components.
2. The second problem is incorrect installation - the pump should be mounted with the shaft in a horizontal position, and the body must be aligned with the direction of flow.
3. A third common omission is lack of protection against pollution. Sludge or scale deposits can quickly damage the device. The solution is pollution separators or filtroodmulators.

Pump maintenance and replacement

A pump that begins to make noise, has a noticeably lower flow rate, or overheats usually requires inspection or replacement. In modern installations, with the use of filters and separators, electronic pumps can operate without failure for up to 10-15 years.

Automation and pump control

Increasingly, pumps are connected to control systems that automatically regulate their operation depending on the outside temperature, schedule or current demand.
As a result, the installation runs stably and operating costs are lower.

➡️ Check out our offer district heating automation.

FAQ - the most common questions

What is the difference between a central heating pump and a DHW circulation pump?
The CO pump works in a closed heating circuit and is resistant to higher temperatures. The DHW pump maintains a constant circulation of domestic water and is made of materials approved for contact with drinking water.

How to calculate the required lift height?
You need to add up the hydraulic resistance in the longest circuit of the system. In single-family homes, this is usually in the range of 3-6 m.

Does replacing an old pump with an electronic one pay off?
Yes - electronic pumps use much less energy, run quieter and extend the life of the system.