Water heating for a greenhouse: which one to choose, how to calculate and do it with your own hands

Water heating is one of the most important components of designing the ideal growing environment for plants in a greenhouse, which requires careful consideration of many other factors. The growth and health of any plant, be it exotic, vegetable, or flower, depends on the temperature you maintain. This guide will cover the various types of water heating systems available for greenhouses, how to estimate your requirements, and how to set up your own system.

There are a number of options available when selecting a water heating system for your greenhouse, each with pros and cons of their own. A popular option is a radiant floor heating system, which distributes heat evenly by circulating water through pipes beneath the greenhouse floor. Using a water boiler or heater linked to pipes that go through the greenhouse beds or around the perimeter is an additional choice.

Calculating your greenhouse’s heating needs is crucial before choosing a water heating system. How much heat your greenhouse will require depends on a number of factors, including its size, the desired temperature range, the amount of insulation it has, and the climate where it is located. Through precise evaluation of these variables, you can select the most economical and effective heating option for your particular requirements.

It takes multiple steps to determine how much heating your greenhouse needs. To find the square footage of your greenhouse, first measure its dimensions. Next, think about your greenhouse’s insulation level, as this will determine how much heat it retains. Next, find out what temperature the plants you’re growing need to thrive in the selected setting.

It’s time to set up the system after you’ve assessed the heating needs of your greenhouse and selected an appropriate water heating system. Depending on how complicated the system is that you’ve selected, you might need to hire an expert or do the installation yourself. In order to stop heat loss and water leaks, make sure all parts are sealed and connected correctly.

Installing a water heating system in your greenhouse can be a fulfilling project that gives you control over your growing environment and gives your plants the warmth they require. You can create the perfect environment for healthy and thriving plants year-round by knowing your greenhouse’s heating requirements, selecting the appropriate system, and adhering to installation guidelines.

Types of Water Heating Calculation and DIY Tips
1. Electric heaters – Calculate the greenhouse volume in cubic meters (length × width × height) and multiply by the desired temperature rise (usually around 15-20°C).
2. Gas heaters – Determine the BTU (British Thermal Unit) needed based on greenhouse size and desired temperature increase. Divide by the heater"s BTU rating to find out how many units are needed.
3. Solar water heaters – Assess the sunlight exposure of your greenhouse location. Install solar panels or collectors on the roof to harness solar energy. Use a pump to circulate water through the collectors, heating it before distributing it in the greenhouse.
4. Biomass heaters – Estimate the heating demand based on the greenhouse area and desired temperature. Build or purchase a biomass heater, such as a wood stove or pellet burner. Ensure proper ventilation to prevent carbon monoxide buildup.
5. Geothermal heaters – Evaluate the soil and groundwater temperature beneath your greenhouse. Install a geothermal heat pump system to extract heat from the ground and transfer it to the greenhouse via a water-based heating system.

The advantages and disadvantages of the water heating of the greenhouse

The circulating water flow heating system used in greenhouse construction is not all that dissimilar from residential building systems.

The following summarizes the primary distinctions:

  1. The water heating system should not overdry air indoors. Greenhouse plants, for which it would be a preferred dry, cool atmosphere, practically does not exist. Therefore, the humidity level should be at least 85% at a temperature of 18-20 o.
  2. Increased energy consumption. Even in greenhouses lined with cellular polycarbonate, the power of the heating system per square meter should be twice as much as for residential premises.
  3. The water heating system is installed, as a rule, inside the greenhouse, smoke gases must be out. In this case, the chimney and the boiler firebox simultaneously perform the function of an additional ventilation system.
  4. The rooms of the greenhouse cannot be completely isolated from the environment. If you cimple all the cracks, then even with a normally functioning water heating, plants may suffocate.

The greenhouse’s remaining water heating system operates similarly to that of a residential structure. Since the system needs heating constantly in the winter and early spring, it is typically designed to be as autonomous as possible. in order to limit daily visits to the greenhouse to one.


Most tiny greenhouses are constructed without an electrical connection. It is commonly acknowledged that during the day, plants receive adequate sunlight and warm up. However, heat alone is insufficient in practice, particularly for thermophilic and photophilous cultures like those of peppers, eggplants, and tomatoes. While plants won’t freeze or sustain burns, the ultraviolet radiation provided by heated water is insufficient.

When contrasting gas-air and water heating, the following are some of the most significant drawbacks:

  • increased requirements for the quality of installation of pipes, warming registers, batteries;
  • Additional costs for the acquisition and installation of the water circuit of the water circuit inside the greenhouse will be required;
  • The filled heating system cannot be left unattended in winter;
  • A thorough preliminary calculation of the pipe laying scheme is required.

Low-temperature schemes are referred to as the water heating system. The radius over which the air is heated is small because the pipes’ surface only reaches temperatures of 60 to 70 °C, necessitating an increase in the number of heating devices.

Another drawback is that the greenhouse’s heating system operates largely without human intervention, particularly at night. even though the house is close to the greenhouse building. As a result, you are forced to either install automation or continue using the antiquated gravity-based self-sided water circulation system.


The following are some advantages of water heating:

  1. A simple design, the scheme is fully developed in practice, its shortcomings and features of functioning are well known.
  2. The system has great inertia, slowly heats up, accumulates heat and also gradually gives it.
  3. An additional heater in the form of a thermo -geliobatary can be connected to the water heating system with a water circuit.
  4. The scheme is very good to regulate, sets up for the necessary operating mode.

Additionally, you do not need to buy pricey imported equipment, special boilers, or boilers in order to build water heating in a greenhouse. All of the same components, pipes, and machinery used in residential building heating systems can be used.

Vital! A water circuit can be used to install an additional heat accumulator. Either the water flow itself or the heating of the furnace walls can produce heat. These two procedures have the capacity to store energy.

Water heating is widely utilized in nearly all stationary greenhouses made of polycarbonate, with an area ranging from 40 to 50 m 2. Options with a circulating water flow will be more profitable than coal stoves or electricity heating if we compare the costs and heating efficiency.

When it comes to heating a greenhouse, choosing the right water heating system is crucial. With various options available, from traditional boilers to modern solar-powered setups, it"s essential to consider factors like efficiency, cost-effectiveness, and environmental impact. Calculating the heating requirements based on the greenhouse size, climate conditions, and crop type is a key step in selecting the most suitable system. DIY enthusiasts can embark on building their water heating setup, but it requires careful planning and adherence to safety guidelines. By understanding the different heating options, calculating the needs, and following proper installation procedures, anyone can efficiently heat their greenhouse to create an optimal growing environment for plants.

How this heating system works?

In actuality, they employ a few of the most straightforward and well-tested methods to heat the greenhouse by circulating water through the pipes. First of all, the types of energy sources used in heating systems vary. It could be a steel stove with an extra radiator, a brick stove with a heat exchanger, or a boiler. As a result, the fuel and mode of operation employed differ.

Boiler or stove

Boilers are best suited for greenhouses larger than 80–90 m³; if gas is available, that is the option to take. The popularity stems from the fact that contemporary gas devices are reliable, affordable, and enable more economical fuel combustion when used for greenhouse water heating. There is no specific distinction between periodic devices and constant heating boilers.

The ideal choice for small buildings would be a brick furnace equipped with solid fuel burning grates and a gas burner. For instance, coal or firewood. The water heat exchanger stove is more cost-effective than the boiler and can be filled with lumber or briquettes. It is also more practical.

Small country greenhouses up to 40 m 2 in size are typically equipped with a homemade stove made of sheet metal and an extra steel or copper water exchanger. A brick furnace with a mounted heat exchanger and a cumulative-tank-accumulator would be the ideal option if the stove is placed close to a private residence.

You can use the stove to heat the water circuit at night, and even in the winter, the heat produced by it will keep the room’s temperature from falling below fifteen or twenty degrees Celsius until the next morning.

Many owners choose to directly connect the greenhouse’s heating system to the home building’s water circuit rather than installing a boiler or stove. There are benefits to the project because it will save you money on purchasing a second boiler. However, in extremely cold weather, there’s a chance that the system could defrost if the light is abruptly cut off.

As a result, the majority of greenhouse owners install a separate stove that has a water circuit. This decision’s rationale is clear. If the house is heated by coal, propane, or a fairly expensive natural gas, you can use any attractive material for the greenhouse’s water heating system and brick stove, such as brushwood or dry tree residue from building materials.

This is fascinating! All year long, fresh veggies that you manually heat in the greenhouse. One way to keep plants safe from the cold is to manually heat the greenhouse.

Radiators or pipes

You must select a heating circuit and the kind of heating equipment in addition to the boiler. It could be a cast-iron or steel radiator, or a homemade register that’s boiled water pipes. No one is going to use bimetallic or contemporary aluminum batteries in a greenhouse.

Furthermore, radiators are not the best option for heating greenhouse water. They were mostly intended to be installed in homes, next to the leisure areas of the occupants, beneath window sills. First and foremost, even heating must be distributed throughout an ordinary greenhouse without cold air pockets because it lacks windows.

Registers can be used to assemble a water circuit. These pipes are arranged around the greenhouse’s perimeter in multiple rows, horizontally. The most popular plan is this one since it allows for more even heating inside the greenhouse. Simultaneously, a barrier is formed to stop chilly streams from entering the building through multiple gaps in the walls.

The setup of a heated floor represents the third choice. In other words, installing the identical heating pipes at the greenhouse’s floor’s base. This option, which is thought to be more contemporary, is typically utilized when building new greenhouses out of steel profiles and polycarbonate.

Samotent or circuit diagram

In terms of manufacturing costs, gravitational (self-propelled) water heating systems are less expensive. Very manually, if a standard brick stove had been there prior to the greenhouse repair. In this instance, installing an expansion tank and gaskets for pipes will be all that is needed to switch to water heating. The water-based system’s main drawback is its high inertia, which makes it challenging to swiftly heat the greenhouse’s interior. If the greenhouse building is situated near open winds, this needs to be considered.

You must keep the stalk inside the greenhouse in addition to using the self-heating system to prevent problems with frosty air. The steel stove’s thin walls allow it to heat the air within 10 to 15 minutes, which is sufficient heat until the water circuit warms up. Alternatively, you could install a more sophisticated and costly water heating system with automation and a circulation pump.

Calculation of the heating system

Selecting a plan with a heated floor is the best option if installing heating equipment in the greenhouse yourself is only something you want to do in the future. As a result, the room closes less frequently, and this is also thought to be a more efficient technique to promote growth. Such heating improves soil temperature beneath plants and maintains consistently high air humidity levels in all weather situations.

However, if the plan in the greenhouse is to grow vegetables on tables or racks, it is preferable to go with the option that has laying registers around the room’s edge.

We calculate the required amount of energy

The boiler or furnace power is chosen according to a standard that stipulates that there should be at least 200 watts per square meter of floor area. For instance, an 8 kW system will be needed for a 40 m 2 building. Furthermore, the greenhouse has a minimum amount of insulation, in contrast to a residential building. Consequently, the temperature of the air outside the room has a significant impact on the thermal energy losses.

Use of the table’s correction coefficient will be required in this situation. For instance, a stove or boiler with a minimum 10 kW capacity will be needed for a greenhouse building that has a total area of 40 m 2.

Hearing contour

The number of pipes installed to the greenhouse floor or around the room’s perimeter will require another tiny computation. It is acknowledged that the register is constructed from four pipes arranged horizontally above one another for simplicity’s sake. Two-inch pipes are most frequently used. Installed in the same step, four 50 mm pipes create a package that is 40 cm high.

A register of this kind transfers 140 watts of heat per meter of length. Multiplying the amount of heat transfer by the room’s perimeter in meters is required to determine the heating circuit’s heat production. For instance, a greenhouse measuring 10 by 4 meters would have a perimeter length of 28 meters. Multiplying that length by 140 watts would result in 3920 watts.

This indicates that one bag of four pipes will obviously not be sufficient to heat the greenhouse with water. It will be required to either use the three-inch-diameter workpieces or increase the number of pipes in the bag. As a result, one linear meter of a water circuit will have 300 watts of heat transfer. Installing this kind of water heating system for a small greenhouse would be an absurd solution because it is already a fairly large design.

Installing the necessary amount of pipes at the floor’s base is far simpler. The distance between the threads should be at least 20 cm, but not more than 50 cm, if you’re using inch pipes.

Maintaining ideal growing conditions in your greenhouse requires selecting the appropriate water heating system. There are various choices available, each with advantages and things to think about of their own. Before choosing between a solar-powered setup, a radiant heating system, or a traditional boiler system, it’s critical to assess your needs and financial situation.

To ensure effective operation, determining the size of your water heating system is essential. The right capacity depends on a number of factors, including the size of your greenhouse, the desired temperature range, the amount of insulation, and the local climate. You can avoid going over budget for an overly large system or sacrificing performance for a system that is too small by carefully evaluating these factors.

A satisfying project for those who prefer a hands-on approach is installing your own water heating system. To help you through the process, a plethora of resources are available, ranging from DIY kits to online tutorials. But it’s crucial to put safety first and follow local building laws and ordinances. It is quite possible to build a specialized heating system that meets the specific needs of your greenhouse if you have the necessary supplies and expertise.

Whichever heating system you select, longevity and effectiveness depend on regular maintenance. Performance can be maximized and operating costs can be reduced by routinely checking and cleaning parts, keeping an eye on energy usage, and quickly resolving any problems that crop up. Investing in thermal curtains and double-glazed windows, for example, can also lower heat loss and increase energy efficiency.

In conclusion, careful consideration of a number of factors, such as the heating method, capacity requirements, and maintenance requirements, is necessary when choosing and installing a water heating system for your greenhouse. You can minimize energy use and costs while fostering a healthy plant growth environment by carefully evaluating your options and making plans in accordance with them. Whether you choose to DIY or purchase a prefabricated system, success in the end comes from putting efficiency, sustainability, and safety first.

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