Air venting of the system using the 6/4" kit

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Deaeration of the heating system is a key step that often determines the quiet operation and energy efficiency of the entire device. When installing powerful pumps, such as the dry-running DAB models or multi-stage units NKV, the need for air removal is critical to prevent hydraulic faults and damage to impellers.

The Criticality of Removing Air Pockets

Air in the system forms so-called air pockets that disrupt the smooth flow of heat and cause localized overheating or cold zones in radiators. If air accumulates on the suction side of the pump, cavitation occurs, leading to rapid wear of bronze impellers and a noise resembling gravel.

This problem is especially common when using double flanged pumps, where an incorrectly set water level or faulty placement of air vents can cause an immediate drop in performance. The correct implementation of the 6/4" assembly ensures that even at maximum pressures, the system remains fully filled with liquid without air blockages.

Technical Solution of the 6/4" Assembly

The 6/4" assembly represents a specific reduction solution that allows standard air vents to be integrated into pipes with larger diameters, commonly used in industrial and professional heating systems. This set eliminates the need for expensive and complex adapter rings, as it directly connects the different pipe and valve parts.

In the diagram, you can see the principle where the large-diameter pipe (6") passes through a reduction into a smaller opening for the valve (4"), thus maintaining hydraulic continuity while allowing simple maintenance. This type of construction is ideal for pumps of the DKLP 40-1800 M type, which require a stable suction pressure without turbulence.

Installation Strategy and Placement

We recommend installing air release points at the highest points of the system, as well as directly on the discharge arms of the main tank, where air naturally accumulates. When using submersible sludge pumps FEKA FXV 20.07 M, it is essential to ensure that the suction tract is not clogged with air, which could lead to excessive motor heating.

Install the first valve immediately after the pump discharge, where the pressure is highest.
Install the second point at the top of the highest pipe branch in the building.
Add intermediate points every 10 meters of horizontal pipe runs.
Use automatic air vents for systems with variable flow.
Use manual air vents only in accessible locations for regular inspection.

Maintenance and Fault Diagnosis

Regular inspection of the functionality of air vent assemblies is essential, as mechanisms can become stuck or clogged with deposits, leading to an inability to release accumulated air. If you notice that the multi-stage pump NKV 1/14 S T starts vibrating or its flow decreases, the first diagnosis should be to check the condition of air pockets in the system.

A common mistake is ignoring small leaks around the reduction, which gradually suck in air from the outside instead of releasing it. In such cases, it is sufficient to replace the sealing gasket or tighten the joint, but if the valve itself is damaged, it is better to replace it with a new one rather than risk the failure of the entire pump.

Impact on Energy Efficiency

An insufficiently deaerated system forces the pump to work against air resistance, increasing electricity consumption by up to 15% and shortening the motor's lifespan. High-performance pumps, such as the model FEKA 600 T-NA 10H07, are designed for high-efficiency operation, which they lose in the presence of air blockages in the pipes.

Reduced efficiency is manifested not only by higher energy costs but also by uneven heating of spaces, where distant radiators remain cold. A properly set up 6/4" assembly is therefore not just a technical aid but an investment in long-term savings and stability of the heating system.

Practical Examples and Recommendations

In practice, we have recorded cases where the installation of an incorrect air vent led to the complete blockage of the impeller in a DAB-type pump, requiring the disassembly of the entire section. Choosing the correct assembly according to the pipe diameter and material (e.g., brass for corrosion resistance) is therefore critical for safe operation.

For systems with a high content of impurities, as is the case with sludge pumps, we recommend a combination of manual and automatic valves with a filter on the inlet pipe. This prevents the valve from clogging with impurities and ensures smooth air venting even in harsh conditions, similarly to when installing FEKA pumps.

Hydraulic Separation of Suction and Discharge Tract

This detail shows why it is critical to place the reduction and valve immediately after the pump discharge, where the pressure most effectively helps to push the air out, while on the suction side a vacuum could form, drawing air in through leaks.

Utilization of Density Differences in Horizontal Installation

With long horizontal pipe sections, air naturally settles in the upper parts, so the air vent must be placed precisely at the highest possible level of this segment to utilize gravitational force and the different density of gas compared to water.

Configuration for a system with multiple branches

In systems with parallel branches, it is necessary to ensure air venting at the end of each individual branch, as air can become trapped at the most remote point of a specific circuit, even if the main distribution is correctly equipped with a 6/4" set.

Frequently asked questions

How often should a new system be vented?

With a new system, venting must be performed several times during the first weeks of operation until all the air has settled and the water is heated.

Can the same sets be used for different pipe materials?

Yes, the 6/4" set is universal, but it is advisable to choose the valve material (brass or stainless steel) according to the chemical composition of the water and the type of pipe to prevent corrosion.

What to do if the valve gets stuck?

Try gently tapping the valve body and then carefully turn it; if this does not help, the valve must be disassembled and cleaned or replaced.

Proper venting is the foundation for long and trouble-free operation of your heating system and prevents unnecessary repair costs and energy loss.

Do you have a question about this topic?

Not sure or dealing with a specific situation in your home? Write to us – we are happy to help.