Carbon Monoxide Detector

Carbon monoxide detectors (CO detectors) are safety devices that measure the concentration of carbon monoxide (CO) in the air and trigger an audible and/or visual alarm if a threshold level is exceeded. Carbon monoxide is an odorless, colorless, highly toxic gas produced by incomplete combustion in heating systems, fireplaces, gas stoves, and other combustion appliances, and can quickly reach life-threatening concentrations in enclosed spaces. Along with smoke detectors, CO detectors are one of the most important safety systems in buildings with combustion appliances.

How They Work and Technical Requirements

CO detectors operate on an electrochemical principle: A sensor continuously measures the CO content in the air. If the concentration exceeds the threshold value (50 ppm for continuous operation, 400 ppm for immediate alarm), the device triggers an alarm. High-quality devices compliant with the European standard EN 50291 are certified and have a service life of 5-10 years. CO alarms should be installed in locations where CO typically accumulates: near heating systems, gas water heaters, fireplaces, and in bedrooms.

Legal Requirements and Recommendations

In Germany, carbon monoxide detectors are not yet required by law nationwide-unlike smoke detectors, which are mandatory in living spaces in all federal states. However, some federal states have specific requirements or recommendations. Nevertheless, the installation of a CO detector is strongly recommended for every heating appliance: Chimney sweeps and the fire department expressly recommend CO detectors, particularly for room-air-dependent gas boilers, pellet and wood-burning fireplaces, and in underground garages. For rental properties, installation is also relevant under the duty of care.

CO Poisoning as an Underestimated Risk

Every year in Germany, several dozen people die from CO poisoning, and hundreds are seriously injured. The insidious thing is that CO manifests itself through headaches, dizziness, and drowsiness, which can easily be mistaken for other conditions. People who are asleep often don’t notice anything until it’s too late. A functioning CO detector saves lives. Once the device has reached the end of its service life (follow the manufacturer’s instructions), the detector must be replaced.

Typical causes of CO production in residential buildings: clogged exhaust pipes or defective chimneys, room-air-dependent gas boilers operating simultaneously with a range hood (negative pressure), poorly maintained oil heating systems with incomplete combustion, and improperly operated or leaky wood and pellet stoves. The risk increases significantly in winter when buildings are poorly ventilated and heating systems are operating at full capacity.

Operating Costs and Allocability

CO detectors are classified as safety devices. Their purchase and replacement costs are to be treated as operating costs of the property. For landlords, the question of allocability arises: The ongoing costs for maintenance and replacement of safety devices are not apportionable as part of general operating costs under the Operating Costs Ordinance (BetrKV)-they fall under the landlord’s maintenance obligation. The purchase costs are immediately deductible as maintenance expenses (for rented properties, as income-related expenses from renting and leasing).

Combined Safety Systems

In modern residential construction, CO detectors are increasingly being combined with smoke detectors in a single device (combination detectors). These detect both smoke and CO and offer a space-saving and cost-effective solution. For new construction and extensively renovated buildings, we recommend networked systems in which all detectors in the building react together in the event of an alarm-this significantly increases the response time, especially in larger buildings or apartment complexes.

Practical Tip for Property Owners in Nuremberg and Franconia

In Nuremberg and Franconia, gas boilers, oil-fired heating systems, and fireplaces are standard in many older buildings. Especially in poorly ventilated older apartments from the Wilhelminian era-with deep floor plans and few windows-CO can accumulate quickly if a fireplace is defective or the chimney draft fails. We recommend that all owners and landlords install at least one CO detector compliant with EN 50291 in every room with a fireplace and in adjacent bedrooms.

The cost is low (€20-50 per unit), and the benefit is invaluable. When handing over a rental apartment, a CO detector should be just as standard as a smoke detector. During regular heating system maintenance, performed by a chimney sweep or heating engineer, we also recommend having the CO detector checked for proper functioning. At my-home.de, we always remind buyers and tenants of this safety measure.

Frequently Asked Questions

Where should I install the CO detector in the house?

In every room where there is a heating appliance (heating room, living room with a fireplace), as well as in bedrooms in the immediate vicinity. CO is lighter than air and spreads evenly throughout the room; the detector should be mounted at breathing height (approx. 1.5 m) or according to the manufacturer’s recommendations.

Does the legal requirement for smoke detectors also apply to CO detectors?

No. The legal requirement for smoke detectors in Bavaria applies to all bedrooms, children’s rooms, and hallways in residential spaces, but not explicitly to CO detectors. Nevertheless, installing CO detectors is strongly recommended for landlords from liability and safety perspectives.

As a landlord, am I required to install and maintain CO alarms?

This is not yet explicitly required by law in Bavaria, but the landlord’s duty to ensure safety includes protection against foreseeable hazards. In the case of fireplaces in the apartment, failure to install a CO alarm may result in liability consequences in the event of damage. We strongly recommend providing CO detectors and having them inspected regularly.

How often does a CO detector need to be replaced?

CO detectors have a limited lifespan because the electrochemical sensor uses up its sensing material over time. Most devices need to be replaced after 5-7 years; high-quality models after 10 years. The expiration date is printed on the device and must be strictly observed-an expired CO detector is no longer reliable and may fail to trigger an alarm in an emergency. Regular visual inspections and tests using the test button (recommended monthly) are also important.

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