Carbon Monoxide: Maintaining Your Greenhouse Heater
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Why You Should Maintain Your Greenhouse Heater

hotbox shilton 3kw greenhouse heater

A poorly maintained gas greenhouse heater can pose significant risks, including the potential for elevated carbon monoxide (CO) levels. Carbon monoxide is a colourless, odourless gas that you get from burning fuels like propane or natural gas. When combustion is incomplete due to poor maintenance, the greenhouse heater can release higher levels of CO into the air, creating a hazardous situation.

Risks of Carbon Monoxide in Your Greenhouse

Here are some of the risks associated with elevated CO levels in a greenhouse due to a poorly maintained heater:

1. Health Risks of Carbon Monoxide

High levels of CO can be toxic to humans and animals. Exposure to carbon monoxide can cause symptoms like a headache, dizziness, weakness, nausea, confusion, and in severe cases can cause you to lose consciousness or even kill you. CO exposure can also damage your plants, as it can interfere with their ability to photosynthesize.

2. Ventilation

Poorly maintained heaters may not be burning fuel efficiently, leading to a higher amount of CO being released. Adequate ventilation is essential to dissipate CO and ensure a safe environment within the greenhouse. Inadequate ventilation could trap CO inside the space.

3. Fire Hazard

Poor maintenance can lead to malfunctions or even fires in the heating system, potentially causing significant damage to the greenhouse and its contents.

Preventing Carbon Monoxide Increase in Your Greenhouse

To minimize the carbon monoxide risk associated with a poorly maintained greenhouse heater, consider the following precautions:

1. Regular Maintenance

Ensure that your greenhouse heater is serviced regularly by a qualified technician. This should include cleaning, inspecting, and repairing any parts that may be damaged or malfunctioning. Insufficient ventilation of your heater will produce soot in the burner that will eventually cause it to shut down. If you’re using a Hotbox heater, we offer Greenhouse Heater Servicing on all our own heaters.

2. Proper Greenhouse Ventilation

Install and maintain proper ventilation systems in the greenhouse to allow fresh air to enter and CO to exit. We recommend installing a 4-inch-diameter drainpipe on the floor of your greenhouse, starting 2 or 3 inches behind the heater and running through the side of the greenhouse. This will provide sufficient oxygen to the heater. You’ll also need a permanent vent at a higher level to allow the carbon monoxide to escape.

3. Use CO Detectors

Install carbon monoxide detectors in your greenhouse to provide an early warning if CO levels become elevated. This is especially important if you use a fuel-burning heater.

4. Safe Fuel Storage

If you store the fuel for your heater in the greenhouse, do so in a well ventilated area and follow proper storage and safety guidelines.

5. Safe Heater Storage

When your heater is not in use for long periods and allowed to get cold, it must be suitably stored and/or protected in a plastic bag. Sometimes, spiders and other small insects will spin webs or cocoons in the venturi tube and gas burner. This can cause problems when you try to use your heater again, resulting in a characteristic yellow flame or possibly a flash back fire. If this happens, you must not use your heater until all obstructions have been cleared by a gas engineer or competent person.

6. Education and Training

Ensure that anyone working in or around the greenhouse is aware of the risks associated with CO exposure and knows how to respond in case of an emergency.

7. Emergency Plan

Have an emergency plan in place in case of a CO leak, including evacuation procedures and access to medical assistance if necessary.


If you have a poorly maintained greenhouse heater, this can pose a serious carbon monoxide risk that can have severe consequences for your health and safety. Regular maintenance, proper ventilation, and the use of CO detectors are essential steps to mitigate this risk and maintain a safe greenhouse environment.