Heizung Wird Nur Zur Hälfte Warm

Willkommen in Deutschland! You've arrived, settled in, and are ready to explore. But wait, something isn't quite right. The German winter can be surprisingly chilly, and you might find yourself noticing that your Heizung (radiator) isn't quite performing as it should. Specifically, it's only getting half warm. Don't worry; this is a common issue, and often, it's easy to resolve yourself. This guide will walk you through the most common causes and how to fix them, ensuring you stay cozy during your visit.

Understanding the German Heizung System

Before diving into troubleshooting, let's briefly understand the basics of the German heating system. Most apartments and houses use central heating, meaning a central boiler heats water which is then circulated through pipes to the radiators in each room. The intensity of the heat is usually regulated by a thermostatic valve on each radiator.

These valves are typically marked with numbers (often 1-5) or symbols (snowflake, sun, etc.). These aren't temperature settings in degrees, but rather indicators of the *relative* amount of hot water allowed to flow into the radiator. Setting the valve to '5' allows the most hot water, while '1' restricts it significantly. A snowflake symbol usually indicates frost protection, preventing the radiator from freezing in very cold weather, but providing minimal heat.

Why is My Radiator Only Half Warm? Possible Causes

There are several reasons why your radiator might only be partially heating up. Let's explore the most common culprits:

1. Air in the System (Luft im System)

This is by far the most frequent reason for a radiator not heating properly. Air bubbles can get trapped inside the radiator, preventing the hot water from circulating fully. The warm water will only reach the lower part of the radiator, leaving the upper part cold. You might also hear gurgling or hissing noises coming from the radiator.

How to fix it: You need to bleed the radiator (Heizkörper entlüften). This involves releasing the trapped air. You'll need a special radiator key (Heizkörperschlüssel), which you can usually find at any hardware store (Baumarkt) or sometimes borrow from your landlord (Vermieter). Here's how to do it:

Turn off the heating system: This is crucial! Find the main thermostat or boiler control and switch it off. Let the radiators cool down for at least an hour.
Locate the bleed valve: This is a small valve, usually on the upper side of the radiator, on one of the ends. It typically has a square-shaped indentation.
Prepare for water: Place a small container (like a bowl or a cup) and a cloth under the bleed valve to catch any water that might escape.
Insert the radiator key: Carefully insert the radiator key into the valve.
Slowly open the valve: Turn the key slowly counterclockwise. You should hear a hissing sound as the air escapes.
Wait for water: Keep the valve open until water starts to drip out *without* any air bubbles.
Close the valve: Once only water is coming out, carefully close the valve by turning the key clockwise. Do not overtighten!
Repeat for all radiators: Start with the radiator closest to the boiler and work your way outwards. Remember to check the pressure gauge on your boiler and top up the water if necessary (see section below on water pressure).
Turn the heating system back on: After bleeding all the radiators, turn the heating system back on and check if the radiators are heating up properly.

Important Note: After bleeding your radiators, you might need to top up the water pressure in your heating system. Look for the pressure gauge on your boiler (usually a small dial with a needle and numbers). The optimal pressure is usually indicated by a green zone on the gauge, typically between 1.5 and 2 bar. If the pressure is too low, you'll need to add water to the system. The process for adding water varies depending on the boiler model, so consult your boiler's manual or ask your landlord for assistance.

2. Thermostatic Valve Issues (Thermostatventil Probleme)

The thermostatic valve controls the flow of hot water into the radiator. If it's stuck or malfunctioning, it can restrict the flow, leading to only partial heating. There are a few possibilities here:

Valve is stuck: Sometimes, the valve pin inside the thermostatic head can become stuck in the closed position, especially if the heating hasn't been used for a long time.
Thermostatic head is faulty: The thermostatic head itself might be broken and not responding correctly to temperature changes.

How to fix it:

Unsticking the valve pin: Remove the thermostatic head by unscrewing it (usually a screw or a clip holds it in place). Once removed, you'll see a small metal pin. Gently try to push the pin in and out several times. You can use pliers to gently pull the pin outwards if it's stuck in the retracted position. Lubricating the pin with a drop of WD-40 or similar lubricant can also help. After freeing the pin, reattach the thermostatic head and see if the radiator heats up properly.
Replacing the thermostatic head: If unsticking the pin doesn't work, the thermostatic head itself might be faulty. You can purchase a new one at a hardware store and easily replace it. Make sure to buy a compatible model for your radiator.

3. Sludge and Sediment Buildup (Schlamm und Ablagerungen)

Over time, sludge and sediment can accumulate in the radiator and pipes, restricting the flow of hot water. This is more common in older heating systems. This usually manifests as the lower part of the radiator being cold while the upper part is warm, which is almost the opposite of having air in the system.

How to fix it: Unfortunately, this is a more complex issue that usually requires professional help. A plumber (Klempner) can flush the system to remove the sludge. While not a DIY fix, it's worth mentioning as a possible cause.

4. Blocked Pipes (Verstopfte Rohre)

Similar to sludge buildup, blocked pipes can also restrict water flow. This is less common, but still possible, especially in older buildings.

How to fix it: Again, this usually requires a professional plumber to diagnose and clear the blockage.

5. Incorrect Thermostat Setting

This might sound obvious, but it's worth double-checking that your thermostat is set to a temperature that is actually calling for heat. Ensure the thermostat is turned up high enough and that it is functioning correctly. A faulty thermostat might not be accurately sensing the room temperature.

How to fix it: Try increasing the thermostat setting significantly and see if the radiator starts to heat up. If the thermostat seems unresponsive, it might need to be replaced.

6. Furniture Blocking the Radiator

Make sure that furniture isn't blocking the radiator, preventing the heat from circulating properly into the room. Curtains, sofas, or large pieces of furniture placed directly in front of the radiator can absorb the heat and reduce its effectiveness.

How to fix it: Simply move the furniture away from the radiator to allow for better airflow.

7. Imbalanced Heating System (Unausgeglichenes Heizsystem)

In some cases, the heating system might be imbalanced, meaning that some radiators are receiving more hot water than others. This can happen if the system hasn't been properly adjusted. This is less common in smaller apartments but can occur in larger houses or multi-story buildings.

How to fix it: Balancing a heating system is a complex process that involves adjusting the valves on each radiator to ensure an even distribution of heat. This usually requires specialized tools and knowledge and is best left to a professional plumber.

When to Call a Professional (Wann einen Fachmann rufen?)

While many radiator issues can be resolved yourself, there are times when it's best to call a professional plumber (Klempner) or your landlord (Vermieter). These include:

If you're not comfortable working with the heating system yourself.
If bleeding the radiator doesn't solve the problem.
If you suspect a blocked pipe or sludge buildup.
If the pressure gauge on your boiler is consistently low, even after topping up the water.
If you notice leaks or other problems with the boiler itself.
If you are living in rented accommodation it is important to inform your landlord of any faults, as they are legally obligated to fix them.

Finding a reliable plumber in Germany can be done through online directories, recommendations from friends or neighbors, or by contacting your landlord. Be sure to ask for a quote before any work is carried out to avoid unexpected costs.

Staying Warm in Germany: Additional Tips

In addition to ensuring your radiator is functioning properly, here are a few extra tips to stay warm during your stay in Germany:

Dress in layers: The German climate can be unpredictable, so dressing in layers allows you to adjust to changing temperatures.
Use a Wärmflasche (hot water bottle): A classic way to stay warm in bed!
Drink hot beverages: Tee (tea) and Glühwein (mulled wine) are popular choices for warming up from the inside out.
Seal drafts: Use draft excluders to seal gaps under doors and windows.
Enjoy indoor activities: Germany has plenty of museums, cafes, and other indoor attractions to escape the cold.