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How Much Electricity Does A Greenhouse Heater Use?

One burning question echoes through the minds of greenhouse enthusiasts: "How much will it cost to run my greenhouse heater?" The answer, however, isn't as straightforward as one might hope. The intricacies of greenhouse heater use are influenced by a multitude of variables.

Two West & Elliott, gardening and greenhouse experts provide us with a breakdown of the key factors behind greenhouse heaters, revealing how much electricity your heater uses.

Choose the correct heater for your greenhouse

When choosing an electric greenhouse heater, consider various options to find the most suitable one based on your needs. The power, measured in watts or kilowatts, indicates energy consumption per hour. Generally, lower wattage means more cost-effective operation.

For example, electric tubular heaters are economical, starting at 28 watts per foot length. After selecting the right heater for your greenhouse, calculate its hourly or daily operating cost by comparing wattage and electricity cost per kilowatt-hour. Other popular greenhouse heaters include:

Slimline Eco Heaters: 1ft tubular heaters for greenhouses, weatherproof IP44 rating, built-in thermostat for automatic temperature control. Cost-effective and Ideal for background heating.

Electric Fan Heaters: Versatile fan heaters in various sizes and wattages for greenhouses. Choose based on space, consider power and dimensions. Can be placed on surfaces or hung from the roof.

Bio Green Phoenix: Efficiently warms 10ft x 12ft greenhouses with 2.8KW power. Foot brackets for standing or chains for hanging. Adjustable settings (1KW, 1.8KW, 2.8KW) double as a fan in summer.

Example: below is a list of popular types of greenhouse heaters and their running costs:

Keep in mind that the mentioned costs are maximum estimates for continuous 24-hour operation. If your heater has a thermostat, it will regulate itself, turning off and on as needed to maintain the set temperature. Continuous operation is only necessary in extreme cold conditions or when aiming to sustain a high internal temperature.

Other factors that affect your greenhouse heater costs:

The price of your electricity as a whole

Determining the expense of running electrical devices, including your greenhouse heater, starts with checking your electricity bill for the cost per kilowatt hour (kWh). Using a simple formula based on the item's power and your kWh cost, you can estimate daily, monthly, and yearly costs.

The formula needs you to know the kW of your electrical item and the kWh that you pay. For example, you can work out how much you spend to run your fridge.

If the wattage of your fridge is 350 watts and you pay 34p per kWh, what you would pay:

0.35 x 0.34 = 0.119 per hour to run 0.119 x 24 = £2.86 per day 1.19 x 7 = £20.02 per week 20.02 x 52 = £1041.04 per year

Therefore If your greenhouse heater is 2kW, your calculation would be:

2 x 0.34 = 0.68 per hour to run 0.68 x 24 = £16.32 per day 16.32 x 7 = £114.24 per week

Electric greenhouse heaters offer simplicity, safety, and efficiency. They often feature thermostats for temperature control and fans for even heat distribution. Unlike gas or paraffin heaters, electric heaters don't affect humidity or air quality. With no need for fuel replenishment, they remain hassle-free as long as there's no power outage. While the running cost may be higher than some alternatives, the ease of use makes electric heaters a compelling choice for greenhouse heating.

Maintaining the Ideal Temperature in Your Greenhouse

For year-round use of your greenhouse, heating becomes essential, especially in the UK's fluctuating weather. The table above outlines potential costs for using an electric heater, but let's now focus on determining the temperature you want to maintain during colder months – a key factor affecting heater usage and associated costs.

Greenhouses serve diverse purposes, from cultivating tomatoes (about 90% of greenhouse usage) to nurturing alpines, cacti, orchids, and more. Specialized growers know their plant-specific temperature needs, while newcomers may seek guidance.

When growing from seed, consult the packet for germination temperature guidance. For overwintering tender plants, maintaining a frost-free environment is often sufficient, resulting in lower costs compared to cultivating tropical plants. Strategically moving sensitive plants to the greenhouse in colder months can be a cost-effective alternative to replacing frost-damaged plants.

Outside temperatures

Before investing in a heater, assess if frost prevention is your goal. Use a max-min thermometer to compare greenhouse and outside temperatures. Ideally, use two thermometers for accurate readings. Even in an uninsulated greenhouse, expect a 2-3°C higher temperature inside.

Ensure your outdoor thermometer is weatherproof. We recommend insulating your greenhouse before adding a heater to cut heating costs. Insulation alone can raise the temperature 5-6°C above outside levels—often enough for frost prevention. Plan, install insulation, and monitor temperatures for a week to gauge the effectiveness before deciding on a heater.

The state of your greenhouse

Before firing up your greenhouse heater, ensure your space is cost-effective and efficient. Give your greenhouse a quick checkup to prevent warm air from escaping and money going to waste. Clean and secure the glazing, checking for any damage. When adding insulation, remember it can reduce light, so clean both inside and outside panes thoroughly. Stick to soapy water and avoid harsh chemicals to protect your glazing and plants. Seal any cracks with all-weather tape or sealant, and replace severely damaged panes.

Don't forget to inspect moving parts like doors and vents, ensuring they operate smoothly with a touch of WD-40 or silicone-based lubricant. Tighten security by replacing damaged draught excluders. Keep your greenhouse in top shape for the colder months ahead.

About Two Wests & Elliott

Two Wests & Elliott is a UK-based gardening supply company that specialises in greenhouse equipment, garden accessories, and various horticultural products.

Two Wests offers a wide range of items related to greenhouse gardening, including greenhouse staging, shelving, heaters, irrigation systems, pest control solutions, and more. A reputable supplier for both amateur and professional gardeners and has been serving the gardening community for 48 years.

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This story was published on: 17/11/2023

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