🔥 How to Heat Correctly and Stop Mould (Germany Edition)

Know Your System

First, figure out what kind of heating system is in your apartment. There are two common types: central heating and gas heating.

System 1: Central Heating

If you have central heating, it’s easy to manage. Central heating warms water in one central place, often in the basement, and then sends the hot water through pipes to your apartment. The warmth in your rooms depends on how you set the thermostat on your radiator.

How a Thermostat Works

Most likely, your radiator has a thermostat. It’s important to know how it works to heat your apartment properly.

The numbers from 0 to 5 on the thermostat don’t show the heating power directly. Instead, they represent the desired temperature. Set it to your preferred level (1 to 5) and wait until the room reaches that temperature. The thermostat has a thermometer that stops heating when the room is warm enough and starts again if the temperature drops.

How to Use a Thermostat

Unlike air conditioning, you can’t set the exact temperature; you choose a level from 0 to 5. You might need to adjust it by trial and error.

Heating Up

Setting the thermostat to a higher level doesn’t make the room heat up faster. For example, if you return home to a cold room, setting the thermostat to 5 won’t warm it up quickly. Set it to your preferred level (e.g., level 3) and let it work.

When Leaving

When you’re away for a few hours or a day, don’t turn the thermostat off completely. Set it to level 1 or 2 instead. Keep the room temperature above 17 degrees to avoid cooling down surfaces, which makes it more expensive and time-consuming to heat up again. Cooler air can also cause mould.

Antifreeze Setting

Some thermostats have a star (*) setting called Frostschutz (frost protection). This keeps the radiator off unless the temperature is so low that the water in the pipes could freeze. Avoid opening windows wide for hours on cold days, as the radiator will start heating again after a while.

System 2: Gas Heating

If your apartment uses gas heating, it’s a bit more complex. With gas heating, a gas heater in your apartment warms the water for your radiators and heats your hot water for showering.

Gas heating systems have a central controller, usually in one room of the apartment. You can set temperatures for day and night. The central controller turns on the gas heater if the room temperature is lower than your desired temperature.

Because of this, the thermostat in the room with the central controller should usually be set to maximum. If it’s set to 0 or a low number, the gas heater will keep running without warming up the radiator.

Problem in Shared Apartments

In shared apartments, conflicts can occur. If your flatmate with the central controller prefers 19°C, but you need 22°C, their setting will make the gas heater stop at 19°C. One solution is for your flatmate to set a slightly higher temperature on the central controller and their thermostat to a lower level (like 4 or 3) so your room can heat up more.

Ventilation

Proper ventilation is important for effective heating. Incorrect ventilation can undo all your heating efforts.

• Correct: Several quick, intense ventilations with a fully opened window.
• Wrong: Constant ventilation with a tilted window.

For intense ventilation, open the window fully for a short time, depending on the outside temperature:

• 0 degrees and lower: 2-3 minutes
• 5 degrees: 5 minutes
• 10 degrees and higher: 8 minutes

Ventilate at least twice a day, ideally in the morning and evening. Set the thermostat to minimum while ventilating to avoid losing heat.

Mould / Mold

Proper heating and ventilation help prevent mould. If mould has already appeared, keep reading.

How Mould is Created

Mould grows from spores in the air landing on moist surfaces like wallpapers. To prevent mould, keep walls and wallpapers dry.

Moisture can come from:

• Outside: Broken pipes or holes in the wall.
• Inside: Excessive humidity in the room.

If you have a mouldy wall, especially an exterior wall, it’s likely due to humidity from inside.

Prevent Mould

Humidity inside is often caused by people, by breathing and sweating. So if nobody is in the room, for instance because you are on holiday for a longer time, you should not need to worry about moisture from inside.

While staying in your room, prevent humidity from reaching your walls:

• Heat to keep a higher temperature, as warm air holds more water.
• Ventilate to remove humid air from the room.

This is especially important if your house is not well-insulated. Mould usually appears on exterior walls and corners, so:

• Avoid placing large furniture against exterior walls.
• Keep furniture at least 10 cm away from walls.

Remove Mould

If mould appears, clean it with a cleaner containing chlorine:

• A special mould cleaner, like the one from Mellerud^[1], available at hardware stores (Baumarkt). This is the most convenient, as it comes in a spray bottle.
• Or use a cleaner like Danklorix^[1:1], available at drugstores (dm, Rossmann) and larger supermarkets. It has no sprayer, so you need to carefully put it on a sponge and then apply it on the wall. Wearing rubber gloves is recommended.

If this did not help and mould came back, you can try the next level and repaint the area with wall paint mixed with fungicide^[1:2] (Fungizid).

Legal Issues

If mould is an issue with your landlord, the general legal situation is:

• The landlord must provide an apartment without defects that could easily cause mould.
• As a tenant, you must ventilate properly.
• The landlord must prove that the apartment has no defects and that you did not ventilate correctly before charging you for any damage.

Consider seeking advice from a free renter’s counseling service.

General Tips

• Keep the area in front of the radiator clear.
• Let the sun heat your room by opening curtains during the day.
• Close curtains at night for insulation.
• Be cautious with electric radiators^[1:3]; they use more energy than the usual built-in water radiators.
• Close doors between rooms to reduce energy use.
• Insulate windows and doors with sealing strips.

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