If you’re planning to cultivate plants year-round, you’ll need a greenhouse heater to keep the temperature warm during colder months. Choosing the best greenhouse heater can be overwhelming, but with some research, you can find a heater that meets your needs. In this article, we’ll help you choose the best greenhouse heater. You will also find out what to consider when selecting a greenhouse heater, types of heaters available, and how to maintain them.
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Why Do You Need a Greenhouse Heater?
A greenhouse heater is essential for maintaining the right temperature for plants. In colder months, temperatures can drop below the optimal range for plants, which can stunt growth or even kill them. A greenhouse heater can help keep temperatures at a consistent level, ensuring plants can thrive year-round. However, it’s important to take appropriate steps to insulate your greenhouse in order to prevent excessive loss of heat. We suggest reading our guide on how to insulate your greenhouse and save money.
Factors to Consider When Choosing a Greenhouse Heater
Before purchasing a greenhouse heater, there are several factors to consider to ensure you find the perfect fit for your needs.
Size of Greenhouse
The size of your greenhouse is a critical factor in selecting the right heater. You’ll need to choose a heater that can provide enough heat to warm the entire space. A general rule of thumb is to have a heater that can provide at least five watts of heat per square foot of greenhouse space.
Type of Plants Grown
The type of plants you grow in your greenhouse can also influence the type of heater you choose. Different plants require different temperatures to thrive. Some plants, such as citrus trees or tropical plants, require warmer temperatures, while others, like succulents, can handle cooler temperatures.
Local Climate
The local climate can impact the type of heater you choose. If you live in an area with mild winters, you may only need a small heater to keep your greenhouse warm. However, if you live in an area with harsh winters, you’ll need a more robust heater that can handle colder temperatures.
Cost and Efficiency
The cost and efficiency of the heater are also critical factors to consider. Some heaters may be more expensive upfront but can save you money in the long run with lower energy bills. Additionally, some types of heaters may require more maintenance or have a shorter lifespan, which can increase their overall cost. Remember to reduce the heat loss and therefore decrease the cost of heating by insulating your greenhouse.
Types of Greenhouse Heaters
There are several types of greenhouse heaters available, each with its own benefits and drawbacks.
The most popular greenhouse heaters include:
- Electric Heaters (Fan Assisted Electric Heater & Electric Tube Heater).
- Propane Gas Heaters
- Paraffin Heaters
- Solar Heaters
Electric Heaters
Electric heaters are simple to use and don’t require much upkeep. They can be plugged into a regular electrical outlet and generate heat using either convection or infrared radiation. However, they can be expensive to operate, especially in areas with high energy costs.
There are two main types of electric greenhouse heaters: Fan Assisted Heaters and Electric Tube Heaters.
Fan Assisted Heaters
Fan assisted heaters are great because they circulate heat around the space, preventing cold spots and reducing the likelihood of mould and fungus growth. They also typically have thermostats, which can help control energy costs by only delivering heat when necessary. A 2.8kw heater is usually sufficient to heat an 8’x14’ (approx. 2,5m x 4m) greenhouse or a 12’x20’ (approx. 3.5m x 6m) frost-free area.
It’s a good idea to have a separate thermostat in the greenhouse, as most built-in thermostats on heaters aren’t very accurate.
- Fan heater with 2000 W heat output.
- 2 heat modes – fan and fan plus heater.
- Splash-resistant and suitable for damp rooms – IPX4 – rating, (IP rating explained)
- High air output with an air circulation of 210m³/h.
- Temperature range: 0 °C – 85 °C.
2# Light House 2kW Greenhouse Space Heater with Temp. Control Quiet Fan and Heater:
This is a robust and easy-to-use heater with a built-in controllable thermostat to sustain your desired temperature.
3 modes with a option to regulate temperature:
- Fan only (no heat)
- Half power (single element) 1kW
- Full power (both elements) 2kW
Suitable for approx. 20m² of heating area,
Air Output: 186 m³/hr
Product dimensions: 9.84 x 9.45 x 13.78 cm & 3.99 Kg
To our knowledge this heater isn’t IP-rated, which could be an issue if you expect your heater to encounter splashes of water. If you want your greenhouse heater to be waterproof, you’ll need to find one that has a good IP rating, (IP rating explained).
Light House 2kW Greenhouse Heater is not totally thermostatically controlled but the heat output can be adjusted using a second rotational switch. When the set temperature is reached the heater switches off, but the fan remains on. On one hand it is beneficial for the air to be circulated, but it also increases the cost of electricity used.
Electric Tube Heaters
Electric tube heaters are ideal for low-level background heat. They are less expensive than fan heaters but usually aren’t controlled by a thermostat and operate at a lower wattage. They are best suited for simple frost protection.
- Uses less than 50w per foot which is similar to an ordinary light bulb and 25% less than most similar tube heaters,
- Available in 45w (size 305mm), 80w (size 605mm) and 135w (size 915 mm) versions (depending on your need). Remember you can always install more than one in your greenhouse,
- can be mounted on the walls,
- Splash-proof: All models are IP55 rated, meaning that they will not be damaged by splashes and spillages caused by accidents or active watering systems, (IP rating explained)
- no thermostat,
Propane Gas Heaters
Propane gas heaters are a popular choice for larger greenhouses as they can provide significant amounts of heat quickly. They’re also more efficient than electric heaters, making them an ideal choice if you’re looking to save on energy costs. There is no need for a power supply in your greenhouse as is the case with electric heaters. Gas heaters may be thermostatically controlled, and also have slightly lower running costs. However, you will need to ensure that your greenhouse is ventilated, as gas heaters produce water vapour.
The main disadvantages are the possibility of the gas running out, and the initial cost of the gas bottle deposit. A typical 1.5kw gas heater would be sufficient for heating an 6’x8’ (1.8m x 2.5m) greenhouse, or for maintaining a 8’x10’ (2.5m x 3m) frost free area.
Lifestyle Eden Greenhouse Gas Heater 2kW
Heat output: 2 kW
Power: 2000W
Gas Type: Propane (LPG) only (red bottle) – any size bottle will fit, but on average 19kg bottle should last a winter.
Dimensions: Width: 33 cm, Depth : 13 cm, Height: 48.5 cm,
Weight: 4.5kg
Fit for average-sized greenhouses (<60ft²),
Thermostat controlled – The Eden Gas Greenhouse Heater 2kW’s thermostat activates the heater when the temperature drops below your pre-set level and deactivates it once the pre-set temperature is reached. The pilot light remains lit at all times, so it will use a little bit of gas every day unless you turn it completely off.
Paraffin Heaters
Paraffin heaters are an economical option for smaller greenhouses. They use paraffin wax as fuel, which is inexpensive and readily available. However, they are less efficient than other types of heaters and require frequent refilling, which can be time-consuming. They also produce moisture, leading to a humid greenhouse environment, and lack thermostatic control, requiring manual temperature monitoring.
Depending on the greenhouse’s size, multiple heaters may be necessary, but the units themselves are much cheaper than electric or gas models.
Paraffin heaters can be positioned anywhere in the greenhouse without the need for cables or gas pipes. A single burner paraffin heater is estimated to be sufficient for keeping a 6’x8’ (1.8m x 2.5m) greenhouse frost-free, while a double burner could handle an 8’x10’ (2.5m x 3m) space.
Solar Heaters
Solar heaters provide an environmentally-friendly way to heat greenhouses by utilizing solar energy through solar panels. They are a cost-effective option as they do not require electricity or fuel. However, the main limitation of solar heaters is the inconsistency of solar energy availability. Without sunlight, you will need to either store energy in batteries or use a backup generator to have electricity at night or on cloudy days.
This limitation is significant when using solar heating as the primary heating source for a greenhouse since the greenhouse needs heat most when the sun isn’t out. Thus, it is best to consider solar heating as a supplement to other heating systems.
Commercial solar heating systems offer at least three options:
PV panels which convert solar energy to electricity to power a space heater,
Solar furnaces that are placed in the greenhouse walls to absorb sunlight and heat the air inside the greenhouse,
Hot water panels which heat water that is pumped through pipes in the greenhouse floor or walls.
How to Maintain Your Greenhouse Heater
Proper maintenance is essential for keeping your greenhouse heater running efficiently and safely.
Clean Regularly
Cleaning your greenhouse heater regularly can help prevent dust and debris from accumulating, which can decrease the heater’s efficiency. Be sure to follow the manufacturer’s instructions for cleaning and maintenance.
Check for Damage
Regularly inspect your greenhouse heater for any signs of damage, such as cracks or corrosion. If you notice any damage, stop using the heater immediately and contact a professional for repairs.
Schedule Maintenance
Schedule regular maintenance for your greenhouse heater to ensure it’s running correctly. A professional can perform a thorough inspection, clean any necessary components, and make any needed repairs. Make sure your heaters are in a good working order before you actually need them on a cold winter night.
Conclusion
Choosing the perfect greenhouse heater can be overwhelming. However, by considering factors such as the size of your greenhouse, type of plants grown, local climate, cost and efficiency, you can find a heater that meets your needs. Proper maintenance and greenhouse insulation is crucial for keeping your heater running efficiently and safely.
FAQs
- Can I use a space heater in my greenhouse?
- While it is possible to use a space heater in your greenhouse, it’s not recommended. Space heaters can be inefficient and expensive to run, and they may not provide enough heat to warm the entire greenhouse.
- How much does it cost to run a greenhouse heater?
- The cost of running a greenhouse heater will depend on the type of heater, the size of your greenhouse, and your local energy costs. Electric heaters are generally more expensive to run than propane gas heaters or paraffin heaters. Solar heaters are the most cost-effective option, but they do have significant limitations. A good greenhouse insulation can help to reduce cost of heating your greenhouse.
- Can I use a greenhouse heater to cool my greenhouse?
- No, greenhouse heaters are designed to provide heat, not cool the environment. To cool your greenhouse, you’ll need to use fans or other cooling devices. Please note that some heaters like electric fan heater comes with a fan only settings.
- How do I know what size heater I need for my greenhouse?
- To determine the size of the heater you need, you’ll need to calculate the total square footage of your greenhouse and choose a heater that can provide at least five watts of heat per square foot.
- Can I leave my greenhouse heater on overnight?
- It’s generally safe to leave your greenhouse heater on overnight, but be sure to follow the manufacturer’s instructions for safe use and positioning.
Electric Heater IP rating explained:
IP rating – Ingress Protection rating is the international standard used to define levels of sealing effectiveness of electrical enclosures against intrusion from foreign bodies including dirt and moisture. Each number as a specific meaning.
The first number indicates the degree of protection for dirt, dust and intrusion protection, with the second number defines the level of protection against moisture.
| IP Rating for first digit | IP Rating for second digit |
|---|---|
| X – Protection rating has no significance to the product | X – Protection rating has no significance to the product |
| 1 – Protection from a large part of the body such as hand (but no protection from deliberate access) from solid objects greater than 50mm in diameter | 1 -Protection against condensation |
| 2 – Protection against fingers or other object not greater than 80mm in length and 12mm in diameter | 2 -Protection against water droplets deflected up to 15° from vertical |
| 3 – Protection from entry tools, wires etc. with a diameter of 2.5mm or more | 3 – Protection against spray up to 60° from vertical |
| 4 – Protection against solid bodies larger than 1mm (e.g. fine tools) | 4 – Protection against water spray from all directions |
| 5 – Protected against dust that may harm equipment | 5 – Protection against low pressure water jets from all directions |
| 6 – Totally dust tight | 6 – Protection against string water jets and waves |
| 7 – Protection against temporary immersion | |
| 8 – Protection against prolonged effects of immersion under pressure |
The larger the value of each digit, the greater the protection. As an example, a product rated IP65 would be better protected against environmental factors than another similar product rated as IP42. E.g IPX4 the dust and intrusion protection is not relevant although the moisture rating is rated at 4 which is applicable to the product.