common faults and solutions in apartment metering units

Apartment metering units and boiler modules are the heart of every heating system in apartments and family homes, but their proper function depends on precise installation and regular maintenance. Frequent failures often do not appear suddenly, but are the result of long-term wear, incorrect settings, or neglect of basic inspection points.

Incorrect pressure and air in the system

One of the most common causes of malfunction is a drop in system pressure, which causes the pump operation to be interrupted and the boiler to shut down. If the pressure drops below 0.8 bar, safety components block the heat supply, resulting in cold radiators even when the boiler is operating. Regular inspection of the pressure gauge and topping up the water in the system are key to maintaining the stability of the entire circuit.

• Air pockets in the upper part of radiators cause noise and reduce heating efficiency.
• Pressure that is too high, above 3 bar, can activate the safety valve and cause water leakage.
• Incorrect system filling leads to the formation of bubbles that block the flow in the pump.

Circulation pump failure

Circulation pumps are the most sensitive component of boiler modules, where they can jam or their bearings can be damaged after several years of operation. During regular use, it may happen that the pump starts making noise, vibrating, or completely stops rotating, which immediately stops the heat circulation. Replacing an old pump with a new, more efficient version, such as model DAB.EVOSTA3 or Grundfos UPM3, can significantly improve system stability.

High-quality solutions, such as Boiler module HEAT BLOC K31 with Grundfos UPM3 Auto L 32-70, include pumps with automatic power regulation that adapt to the system's needs and minimize the risk of mechanical damage. Regular inspection of the pump's condition and partial disassembly for cleaning from deposits can extend its lifespan by several years.

Problems with the bypass valve

Bypass valves are a critical component for protecting the boiler from overheating in the case of low flow, but they often suffer from being stuck in the open or closed position. If the valve is stuck in the open position, water recirculates directly back into the boiler without passing through the heating units, causing rapid temperature fluctuations and increased gas consumption. Conversely, if it is stuck in the closed position, dangerous overheating and activation of the safety valve may occur.

• The valve may be mechanically clogged with impurities from the system, preventing its movement.
• Incorrectly set differential pressure causes inefficient operation of the entire module.
• The electrical connection of the control signal may be broken, causing the valve to lose its ability to respond.

Sequential errors in mixed units

Mixed boiler units use three-way valves for precise mixing of hot and cold water, which requires very precise calibration and servo motor function. If the three-way valve does not move correctly, the system cannot achieve the desired temperature in the radiators, leading to unstable heating and unnecessary outages. A common cause is damage to rubber sealing rings or mechanical jamming of the valve in one position.

When installing such systems, it is essential to ensure the correct flow direction and proper differential pressure setting to prevent unwanted oscillations. For simpler solutions where mixing is not required, we recommend using Boiler module HEAT BLOC K31 non-mixed DN 32, which eliminates the risks associated with the movement of three-way valves.

Visual diagnostics and maintenance

Regular visual inspection and maintenance are the best ways to prevent serious failures and extend the life of the entire system. Technicians should regularly check the condition of seals, filter cleanliness, and the proper functioning of all valves, which significantly reduces the number of emergency interventions during the heating season. Neglecting this maintenance leads to the accumulation of deposits, corrosion, and eventual failure of more expensive components.

• Cleaning the filter before the pump is essential at least once a year to maintain flow.
• Checking the tightness of connections and valves extends operational safety.
• Replacing old sealing rings prevents water and pressure leaks.

Choosing the Right Components

The correct selection of components is key to the long-term reliability of the system, so it is important to choose quality materials and proven brands. The use of cheap alternatives can lead to frequent failures and the need for frequent repairs, which in the end will cost more than an investment in a quality product. For example, Apartment measuring set without a cabinet offers a robust design suitable for more demanding conditions, where resistance to corrosion and mechanical stress is important.

The choice between different types of pumps, such as DAB or Grundfos models, should be based on the specific requirements of the system and the available space. Proper pump sizing according to the DN diameter and boiler power ensures optimal flow and minimum operating noise. It is also important to follow the manufacturer's instructions for installation and wiring to avoid technical problems in the future.

Servomotor Fault Diagram

Frequently Asked Questions

Why can't the boiler module start?

The most common cause is low pressure in the system or a seized pump that blocks the heat flow. Check the pressure gauge and try manually rotating the pump shaft.

How often should filters in the boiler module be changed?

Filters should be cleaned or replaced at least once a year, ideally before the start of the heating season, to prevent clogging of the flow.

What to do if the relief valve gets stuck?

In this case, it is necessary to disassemble the valve, clean it of dirt, and check the condition of the seals, or replace it with a new one.

Regular inspection and timely resolution of minor problems will prevent major failures and ensure smooth operation of your heating system. An investment in quality maintenance and the correct selection of components always pays off in the form of lower repair costs and a longer lifespan of the equipment.

Do you have a question on this topic?

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