For a new private house, for a cottage or a summer residence, the equipment of the “warm floor” heating system will become a successful and effective way of heating. The information that exists today suggests that in terms of its efficiency, such a heating system for residential premises is quite effective. Water heated floors today are becoming more and more popular in private households, given the large selection of technical means, materials and fixtures needed to install such a system. The quality of heating in any case depends on the heat source. If there are no special questions with gas and electric boilers when installing a warm floor, then the combination of a solid fuel boiler and underfloor heating will make you tinker.
The main reason lies in the absence of a clear and effective mechanism for adjusting the heating temperature of the coolant. The temperature of the boiler water, which diverges along the circuit for underfloor heating, must not exceed the permissible parameters. The slightest malfunction of the heating device and on your floor, right in the room, you can cook food. Let’s consider the problem from different angles.
Underfloor heating — its efficiency and compatibility with solid fuel boilers
The main advantage that a heated floor has in comparison with other heating methods is a uniform heating area of the internal space. In a room that is equipped with underfloor heating, there are practically no warm or cold zones. The heated floor covering radiates heat. Warm air currents rise evenly, displacing cooler air. Due to natural convection, regular air exchange takes place in the heated room.
Important! In terms of its efficiency, underfloor heating, powered by a solid fuel heater, is only slightly inferior to similar systems powered by gas boilers.
Due to the fact that the temperature of the coolant in the heating circuit for a water-heated floor is lower than with convection heating, a significant saving in fuel resource is achieved. In the case of solid fuel boilers, this fact is important. The heated screed is a kind of heat accumulator, which is capable of giving off the accumulated thermal energy to the internal space for a long time. Even when the boiler stops, warm floors remain warm for quite a long time.
The proposed video describes in detail and shows the main technical subtleties and nuances that arise during the installation of this heating scheme.
For those who choose a home heating system for underfloor heating from a solid fuel boiler, a whole range of nuances and technical aspects must be taken into account. Proper selection of a heating device for a heating system, proper piping and connection will allow you to get the maximum expected result from the operation of heating equipment. Solid fuel boilers, due to their high inertia, represent a warm floor for the heating system, a “double-edged sword”. On the one hand, it is good when the boiler cools down for a long time and hot coolant continues to flow into the pipeline for some time. This will allow for some time to avoid a rapid drop in temperature inside the living quarters.
Also read: water heated floor from a gas boiler.
On the other hand, it is not possible to quickly reduce the heating temperature during the operation of solid fuel boilers. The system is difficult to adjust. Installation of additional protective devices is required to compensate for the lack of technological flexibility of heating equipment operating on wood or coal.
The list of disadvantages associated with wood-fired or coal-fired boiler equipment can be continued:
- the need to regularly load the next batch of fuel (at least not less than 1 time per day);
- cleaning and cleaning the boiler is carried out manually, which will also take a lot of time;
- the need to store a certain supply of coal or firewood in the immediate vicinity of the fuel unit;
- regular check of the chimney operability and the state of ventilation in the house;
- a sharp drop in the efficiency of the heating system due to a decrease in boiler power.
On a note: The last point for underfloor heating is not so relevant, remembering the ability of a concrete screed to play the role of a heat accumulator.
Despite the obvious difficulties, the water floor in a country house, powered by a solid fuel unit, has its positive aspects. In the first place here is autonomy. For a country house, such a plus in the heating system is, if not the most important, then the key. The cost-effectiveness and efficiency of heating units operating on wood, woodworking waste, coal or fuel briquettes are also important aspects that should be paid attention to.
Ways to connect a solid fuel boiler to a floor heating system
Solving the main problem
The main problem is that most solid fuel heaters used in private homes lack the automation that we are used to when operating gas or electric units. In most models, the boiler stops in semi-automatic mode, the blower closes, the boiler goes out. Is such a principle of operation of the heating boiler suitable for efficient underfloor heating in the house?
Underfloor heating from a technological point of view is the equipment for which there is a fundamental limitation on the heating temperature. Overheating of the floor will lead to the fact that you will have to forget about the comfort in the house for a while. A working boiler produces an order of magnitude more thermal energy than is necessary to supply the heating circuit. The problem can be partially solved by installing a mixing valve or an electric pump in the system, which will ensure the circulation of the hot coolant through the pipes. However, in this case, the main advantage of solid propellant devices, their autonomy, is lost.
For reference: The recommended floor surface temperature in residential premises should not exceed 29-300C. The maximum threshold of 33 degrees is allowed in bathrooms, in bathrooms, where the flooring is usually made of tiles or ceramic tiles.
It is not uncommon in winter when, in case of bad weather, the power supply to residential buildings is disrupted. In such a situation, stopping the circulation pump threatens to overheat not only the heating device, but also the destruction of the main components and elements of the heating system. Restoring the power supply will cause the superheated coolant to again begin to flow into the heating circuit, which is not able to withstand such temperatures. As a result, a breakthrough and failure of the entire heating system. What it is fraught with, you can imagine!
In order to protect yourself from such troubles, it is better to equip an autonomous heating system with additional devices for removing excess heat energy. It will not be possible to immediately extinguish the boiler and it will not be possible to immediately reduce the heating temperature, especially at night. Additional devices can do this work for you.
Method one. Connection of heating radiators
Important! Without the installation of a three-way valve (usually 3-8 pieces in the number of circuits), the operation of your heating system will be constantly at risk. The mixing unit, equipped with three-way valves, will be able to solve the problem of cooling the heated coolant at the right time.
Having at your disposal a wood-fired floor heating boiler, it is enough to install additional heating radiators in the house. The main task that is assigned to them is to compensate for the excess heat coming from a working heater. The hot coolant will circulate freely through the batteries, giving off excess thermal energy. Usually, 1-2 radiators are installed for this purpose, in rooms that are periodically visited by the inhabitants of the house (corridor, basement, dressing rooms).
A cast iron battery is quite capable of coping with this role. Cast iron radiators withstand high pressure (superheated steam). The main task during the installation of the radiator is to obtain a large heat transfer area.
On a note: at a coolant temperature at the outlet of the boiler at 45-600C, only the installation of an additional radiator reduces the temperature of the boiler water by 5-8 degrees.
The battery is connected in such a way that the boiler water enters it naturally. A system equipped in this way will be able to withstand significant overheating and not collapse. In this case, you can do without an expansion tank, if we are talking about solid fuel units of low power, in which the combustion chamber has a small volume.
Method two. Installing a heat accumulator
If you have a house of considerable size, you can give preference to a more reliable and efficient option. A thermal accumulator, in other words, a large capacity for collecting a coolant, successfully copes with the role of a temperature regulator for heating a coolant.
Important! Here you should also remember the need to install a three-way (thermomixing) valve. As a rule, any heating system is not complete without such a device.
The proposed scheme clearly demonstrates how simple and easy it is to install a storage tank in a common heating system.
According to the principle of operation, a thermal accumulator is the same hydraulic gun, only of a larger size. The main task that the heat accumulator solves is the selection of thermal energy. The operating boiler will heat the coolant that first enters the storage tank. Already from the storage tank, the coolant that has cooled to the required temperature will diverge through the heating circuit of the warm floor.
Typically, the volume of such a tank is calculated based on the ratio — 40 liters per 1 kW of power of the heater. With this technique, you are no longer afraid of equipment overheating. Thanks to the heat accumulator and the efficiency of the underfloor heating, you will be able to significantly reduce the number of fuel loads into the boiler. The savings are there!
Choosing a solid fuel boiler for underfloor heating
Having decided for yourself to create maximum comfort and coziness in the house with the help of a solid fuel boiler and a “warm floor” heating system, you should not build any special illusions. This circuit is so sensitive and gentle in operation, so you will need constant attention and control to the working equipment.
In order to somehow facilitate your task in the future, you must strictly consider the choice of a solid fuel unit.
You can use a traditional wood-burning unit, only then you have to spend more time on its maintenance. The situation looks better with boiler equipment equipped with an automated fuel supply mechanism. Solid fuel pellet machines are good in this regard. By installing a pellet bin next to the heating unit, you can free up a lot of time for yourself.
For example: loading a bunker, on average, 1-2 m3 of fuel in the form of pellets, will allow a 50 kW boiler to operate smoothly for almost a week. The heating system is practically protected from defrosting during your long absence.
To balance the shortcomings characteristic of traditional solid fuel units, pyrolysis-type boilers will allow.
Even with manual loading, you only need to fully load the furnace of the unit 1-2 times. The duration of fuel burning in the furnace, the presence of a heat accumulator in the system, the physical properties of the concrete screed in the complex will provide the necessary and comfortable temperature inside the living quarters.
Assessing the technical capabilities of solid fuel units with the expectation of installing underfloor heating in a house, the following conclusions can be drawn. The technical solution in this case is viable. Solid fuel boilers, together with underfloor heating, can give the expected effect if you responsibly approach the solution of the issues raised and do not save on materials.
It should be noted that the underfloor heating system functions better together with solid fuel boiler equipment, when the house has a large consumption of thermal energy, the hot water supply system works. The more points of heat use in the house, the more functional your heating will become. For small residential buildings, it is not worth chasing a large power of heating devices, counting on the installation of a warm floor. Otherwise, you will have to additionally solve the problem of excess heat consumption.