The temperature comfort that a person feels while in rooms heated by various thermal devices is different.
Let’s see with you why, and what is the most favorable and more comfortable method of heating a room for a person at the present time. Thermal comfort indoors can depend on many factors.
The main of these factors is the method of heat exchange of the heater, how exactly heat is transferred from the heater to the air and objects in the room.
There are three main ways to transfer heat:
– thermal conductivity,
— convection,
– thermal radiation.
Let’s take a closer look at each of these transmission methods.
Thermal conductivity. Thermal conductivity is the property of a substance to transfer (conduct) heat. Metals have excellent thermal conductivity, other solids, such as brick, natural stone, transfer heat a little worse. Various thermal insulation materials, such as polystyrene foam or mineral wool, have low thermal conductivity. In its pure form, thermal conductivity as a method of heat transfer during space heating from various heating objects does not make sense, since thermal radiation and convection are always used in this case in various proportions, the numerical proportion of which depends on the specific type of heating device.
Convection. Convection is the process of heat transfer due to the movement of various heat carriers, liquid or gaseous. It should be noted here that the process of convection and heat conduction work together. The coolant, heated by the process of heat conduction, transfers heat from the heating element (boiler) to the radiators using the process of forced or natural convection. Further, the room air contacts the surface of the heat exchanger radiator (usually finned, to increase the contact area), heats up, the heated air rises and contacts the furniture, walls, ceiling, heating them, thereby raising the temperature in the entire room.
Thermal radiation. The process of thermal radiation consists in the fact that the heated surface of the heater emits infrared electromagnetic waves, and the colder surface (furniture, walls, ceiling, etc.) absorbs it, while increasing its own temperature, as well as the overall temperature inside the room . It should be noted that heat transfer from heated objects occurs both due to convection and thermal radiation. The larger the mass and the higher the temperature of the heater, the more heat it radiates. In various heaters that are used to heat a room, the ratio of thermal conductivity through convection and thermal radiation is different. In convectors, most of the heat is transferred through convection, and the proportion of heat transferred through thermal radiation is negligible. In sectional and panel radiators, depending on their design, the proportion of thermal radiation to convection can be: for conventional radiators approximately 50:50, and for radiators with convection fins – 30:70. Heating systems such as “warm walls” and “warm floors” mainly use the method of transferring heat through thermal radiation. To create comfortable conditions and well-being of people inside a heated room, important components are the uniform distribution of air temperature in the horizontal direction, as well as a slight decrease in its temperature when moving away from the floor.
Sectional and panel radiators.
This type of heating devices, as a rule, is installed on the outer walls under the window openings. Cold air entering the room through cracks or openings in the windows mixes with warm convection air heated from the radiator and then spreads throughout the room. If radiators are placed on the inner walls, then it will be much cooler near the windows and the outer wall, which will generally affect the distribution of heat throughout the room – temperature discomfort will be felt. Air circulation when using sectional or panel radiators occurs as follows: the air heated by the heater rises, heats the walls, and then the ceiling, gradually gives off its heat and, cooling, gradually descends. As a result of this circulation, warm air is always at the top of the room, and cooler air is at the bottom. In this room, the head will be warm and the feet cold.
Convectors. These heaters give off most of the heat by convection. They do not heat the walls near them, but heat the air directly. Convectors are recommended for use in rooms with a large glass area. If only convectors are used in the room, the distribution of air temperature may not be very comfortable. Usually, warm air collects at the top under the ceiling and does not naturally move, and therefore does not transfer heat down the room (there is no air circulation). Typically, in such rooms, the temperature near the floor is much cooler than in rooms heated with panel radiators. When installing convectors, the above facts must be taken into account. They should not be placed too high, which will contribute to the heating of the air exclusively under the ceiling, while the temperature difference between the top and the floor will be strongly felt. The use of convectors will allow the air near the heaters not to overheat or dry out, as is usually the case when using panel radiators. Do not forget that, together with heated air, convectors are able to lift dust particles up, which is extremely undesirable for people suffering from allergic reactions.
Heating system “warm floor”.
When using a floor heating system, it is always warmer at the bottom (near the floor) and cooler at the top (under the ceiling). In such a room, streams of warm air do not circle around the room, but are evenly distributed over its entire area, moving from floor to ceiling. The use of this room heating system is considered the most optimal, since in this case the legs will constantly be warm, and the head will be cold.
Heating system “warm walls”.
In rooms where this heating system is used, the distribution of warm air occurs evenly, over the entire height of the room. In these systems, the temperature of the heating elements does not exceed 550C, and the temperature directly on the surface of the heater has an even lower temperature. Inside the room, the air will not be “dry”, there will be no “dust caking”, which usually causes unpleasant dryness in the throat and irritation of the mucous membrane of the respiratory tract. A person in the room will feel thermal comfort, reminiscent of the warmth of a bright sun on a winter day on a snowy slope – the body receives heat from the radiation of the wall, while breathing freely and easily. I would like to pay special attention to the “warm walls” and “warm floor” systems.
In a room using these heating systems, the feeling of comfort will remain even if the temperature of the indoor air drops by several degrees, compared to heating with radiators. It should be remembered that reducing the temperature of heating devices by 10C allows you to save about 6% of thermal energy, and therefore reduce the operating costs for heating the entire house.
We hope that this overview of the currently most common heating systems will help you choose the right heating system for your home, which will not only provide the necessary heat, but also create a comfortable and cozy atmosphere.