how to choose a DAB dry-running pump for heating

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Selecting the right dry-running pump for heating is not only a matter of performance, but primarily about how the device behaves in emergency situations and during maintenance. DAB Technologies brings solutions to this segment that combine reliability with simple service maintenance, which is critical for the operation of the entire heating system.

Difference between monoblock and double flanged design

When selecting a pump for heating, the first decision regarding the motor and impeller construction leads us to two main types: monoblocks and double flanged models. Monoblocks are compact and cheaper, but their motor is often exposed to higher temperatures and vibrations, while double flanged versions have the motor separated from the pumping part, which reduces the risk of overheating and simplifies disassembly.

Double flanged pumps allow motor replacement without the need to disassemble the suction pipe.
They are ideal for industrial applications and long-term operation in demanding conditions.
Monoblocks are sufficient for standard domestic or smaller commercial buildings with lower load.

Key parameters for calculating the required performance

To select the correct pump, you must know the exact pressure drop and volumetric flow required by the system, as dry-running pumps must be able to overcome the resistance of the piping even under full load. In heating, it is important to consider not only static pressure, but also dynamic resistance caused by the length of the pipe, the number of bends and the height difference between the boiler and the furthest radiator.

A practical example is the selection for a building with a floor area of 150 m², where you need a flow of approximately 2 m³/h and a pressure of 0.8 bar; in such a case, you could choose a model such as FEKA FXV 20.07 M-NA, if it is a specific application, or a standard dry-running pump with a frequency inverter for stabilization.

Always add a 10% reserve for possible deposits in the system.
Check the maximum temperature of the liquid that the pump can transport (usually up to 110 °C).
Check the compatibility of the connection with your existing piping (e.g. DN40 or DN50).

Safety in emergency situations and dry operation

Dry-running pumps are designed to withstand short-term operation "dry", which is essential when the system is drained for repairs or in the case of accidental tank drying, thus preventing damage to the mechanical seal. Unlike standard submersible pumps, which would be immediately damaged, these machines use advanced bearing and sealing materials that can withstand friction without a cooling medium.

It is, however, important not to abuse this feature and not to operate the pump dry for longer than a few minutes, as the heat generated by friction can permanently damage the shaft sleeve. For most heating applications, it is therefore advisable to install dry-run protection or to use pumps with built-in electronic control.

Long-term dry operation leads to deformation of seals and bearing failure.
Use of dry operation is only for emergency situations and short time periods.
It is recommended to monitor motor current to detect loss of liquid.

Mounting components and related accessories

Correct installation of a dry-running pump includes not only physical connection to the piping, but also installation of accessories that ensure smooth operation and easy maintenance, such as air venting kits and check valves. Without a quality 6/4" air venting kit, air pockets can form in the system, which block the flow and cause noise, significantly shortening the life of the pump.

An example is the use of model DKLP 40-1800 M, which is supplied with double flanges and requires precise alignment of the pipes to prevent stress in the connections. It is always recommended to use flexible couplings and sound-insulating pads under the motor to minimize vibrations transmitted to the building structure.

DKLP 40-1800 M Dry-running pump - double flanged is an ideal solution for such applications.

Maintenance and diagnosis of common problems

Reduced maintenance is one of the main advantages of DAB dry-running pumps, but regular inspection of the condition of seals and bearings is still necessary to preserve their lifespan. A common problem is water leakage through the mechanical seal, which is indicated by dripping under the pump, and this requires immediate replacement of the sealing elements to prevent damage to the electric motor.

Another common fault is the blocking of the impeller by foreign objects that enter the system, so it is advisable to install a mesh or filter before the pump. During longer periods of inactivity of the system, it is recommended to run the pump at least once a month to prevent parts from sticking together.

Replacement of seals requires disassembly of the pump and thorough cleaning of the seating surfaces.
Regular vibration checks help detect shaft misalignment early.
Preventive bearing replacement before reaching their lifespan prevents failures.

Advantages of frequency inverters and intelligent control

Installation of a frequency inverter on a dry-running pump allows automatic speed regulation according to the current heat demand, significantly saving energy and reducing machine wear. Modern inverters such as those on SP4M pumps can monitor system pressure and adjust performance to maintain a constant level, which is key to living comfort.

This system also eliminates the problem of frequent starting currents, which can damage the electrical network, and at the same time provides detailed diagnostics of potential faults, such as the stopping of a multi-stage NKV pump due to overload. Intelligent control also enables remote monitoring of operation and parameter settings via mobile applications.

The frequency converter reduces energy consumption by up to 30 % compared to the standard mode.
The software automatically detects changes in the system and reacts to them in real time.
Operating noise is reduced, as the pump runs at minimum speed under low load.

Frequently asked questions

How long can a dry-running pump operate dry?

DAB dry-running pumps are designed for short-term dry operation, usually up to 2 to 3 minutes, to prevent permanent damage to mechanical seals and bearings.

Can I use the same pump for heating and for sewage water?

No, use clean dry-running pumps for heating, while sewage water requires special submersible pumps such as FEKA, which have more robust impellers and more durable seals.

Why does the multi-stage NKV pump stop and how to fix it?

A common cause is the impeller being blocked by foreign objects or motor overload, which requires disassembly and cleaning of the pumping part or replacement of damaged components.

Conclusion

The choice of the correct DAB dry-running pump for heating depends on the accurate calculation of hydraulic parameters and consideration of possible emergency situations that may occur during operation. The correct choice between a monoblock and a double flanged version, together with high-quality accessories, ensures a long system lifespan and minimizes maintenance costs.

Do you have a question about this topic?

Having trouble deciding or dealing with a specific situation in your home? Write to us – we are happy to help.