Hydronic HeatingWater carries 3,400 times more energy than air, so a relatively small volume of water is needed circulating through the radiant floor pipe.
Healthy and efficient, this is how this system that is revolutionizing the heating market in Mexico could be defined. Due to its multiple advantages, about 50 percent of newly built homes in developed countries have chosen to temper the environment with hot water radiation.
In palaces of Ancient Rome, emperors heated their bathroom and master rooms with hot air that circulated below the floors through tunnels receiving heat produced by burning firewood. This ingenious underfloor heating system was known to the Romans as "hipocasus"; "glories", they called it in Spain. The evolution of this method was giving rise to a current technique of heating rooms by means of hot water, one of the several modalities of Hydronic Heating (CH).
The principle of CH is to take advantage of the thermal gain of the heat emitted by hot water, making it flow through cross-linked high density polyethylene (PEX) tubes; it is also possible to install copper tubes. To generate heat, high-efficiency boilers or heaters are used. The temperatures of the rooms are controlled individually with thermostats strategically installed in the areas to be heated, which allows heating only the areas that are required. Since the fifties in Germany, Holland and Switzerland, radiant heating has been used in pipes under the floor and sometimes installed in walls or ceilings. The latter is an interesting option for properties in which you do not want to raise the floor; it offers exactly the same advantages, requires much less civil works and the installation can be done at any time. However, people with little hair should consider not placing radiant ceilings because the skin on the scalp may feel the effects of heat.
Although the system is not exactly new, its name, as a concept, is. Ch modalities include radiant floors, thermal sockets, radiators and forced convectors. In particular, zoclos are an excellent alternative when in a building the installation of a radiant floor system during the construction process could not be considered.
The origins of PEX
As is often the case with great inventions, polyethylene was created as a result of an accident. There is a well-known anecdote that is worth remembering. An explosion nearly destroyed the laboratory of a group of English chemists, who in 1939 were studying the reaction between ethylene and benzaldehyde inside a metal vessel at extremely high pressure. Inside the container were remains resembling white wax; when subjected to studies, these residues turned out to be a gas that at high temperature solidified and created polyethylene.
In the sixties, Thomas Engel created what is now known as cross-linked polyethylene (PEX). Due to its molecular structure, it is able to withstand water at 93 °C; it always recovers its original shape regardless of the number of times it expands, bends, deforms, crushes or twists.
Upon learning that Engel had visited several companies to publicize his discovery, a farmer neighbor asked him if he could make several tubes of the new anticorrosive material to place underground in his chicken coop. Thus, the hens "would feel warmer and lay more eggs." The Swedish scientist did. Soon after, Engel took his material to a Swedish firm, in charge of manufacturing the entire pipe of the Olympic Stadium in Munich 1972.
The hot water is generated by a wall boiler designed especially for these systems
Characteristics of CH
Since the invention of the tube manufactured with PEX and its variation, the PEX-Aluminum-PEX tube, these have been the most favorable materials for the conduction of hot water in CH systems, especially for the installation of radiant floor; however, it is important to note that there are tubes designed for plumbing systems (without oxygen barrier) and others designed specifically for CH systems (with oxygen barrier), which allow the metal elements of the system not to suffer corrosion.
"Hydronic Heating is that heating that uses water as a means to transmit energy between the generator and the energy sink. Any heating that works in this way is known as Hydronic Heating, "said in an interview with Mundo HVAC&R the engineer Ricardo Tavera, director of the company Ecovent Suministros.
According to his explanations, "the hot water power generator can be a gas boiler (most often), a solar or electric heater, or a heat pump. The most common energy sinks are four: underfloor heating (a radiant pipe under the floor), radiators, convectors (with or without a fan) and thermal sockets."
According to the expert, hydronic systems, due to their hot water nature, are centralized: "A unit generates energy that it distributes to several areas and to several emitters that can even work at different temperatures. The same system can power zoclos (operating above 80 °C), radiators (these do so at 60 ° C, or more) and radiant floors (which work with water at 50 ° C, or less). They are not exclusionary systems; on the contrary, they can work with each other to solve the heating of areas with different needs within the same construction. One part generates the heat and pumps the water into all the peripheral elements."
When it uses gas for its operation, CH produces heat at one-third the cost of electricity. Compared to other traditional heating systems, it saves up to 40 percent of energy. Another reason for economic efficiency results from the lower gas consumption in the heaters used than traditional heaters, as they are also of modulating capacity; they transmit to the water a greater percentage of the heat generated by the flame and the amount of polluting waste released into the atmosphere by the chimney is minimal. Also contributing to savings is the possibility of having the heating on only in the desired areas, without spending energy in unoccupied areas.
"Hydronic Heating systems have been installed in Europe and the United States for more than 100 years. It has proven to be the most comfortable, healthy and efficient means of heating available to date," José Medina Arias, general administrator of Hergom Mexico, shared in an interview for this publication. "By taking advantage of the large thermal coefficient of water, much higher than that of air, they bring heat easily and economically to the point where it is needed, radiated through the floor, from an aluminum radiator or bath towel rails."
Medina Arias explains that "radiant heat is evenly distributed: this avoids cold or too hot areas, in addition to annoying air currents that transport dust, mites and other allergenic agents. Its operation is based on the heating of water through a central boiler; the hot water is recirculated by the house, so that it gives the heat through radiant elements that can basically be radiators or radiant floor coils".
The CH heats the rooms in their entirety by generating a soft and extended heat
The CH is easy to install, says the interviewee: "That is why they are ideal for already inhabited houses (especially the zoclo systems or radiators), although in buildings in the process of construction it would be preferable. Its best known modality is through the radiant floor; another is with aluminum radiators. The installation of underfloor heating is done by embedding the pipe before the firm floor. In the case of aluminum radiators, these are mounted on walls with a defined finish. The underfloor heating CH system or aluminum radiators is installed in office areas, domestic rooms and anywhere it is required to maintain a comfortable temperature."
Ch heats the rooms in their entirety (not just half or some areas) by generating a soft, continuous and extended heat. It does not work in cycles, as happens with heating by turbines that constantly turn on and off, and only create temperature steps that make people uncomfortable with their subsequent cold-heat lapses.
In the case of floor heating, the heat distribution is achieved at the bottom of the rooms, making it ideal for high-rise buildings, such as industrial buildings, churches, sports centers, barns, warehouses, auditoriums and large conference rooms. It is especially recommended for hospitals, nurseries, nursing homes and where people with respiratory problems live, since it does not alter the humidity of the environment and prevents the concentration of dust. It also does not carry bad smells from one room to another.
Ch talks about savings, flexibility, effectiveness, durability, adaptability and safety. The risks of burns, flames, electrocution, fires or blows due to contact with the emitters disappear. The material of the tubes is very resistant to corrosion and is compatible with lime, plaster and concrete; In addition, its expansion due to temperatures does not harm the pavement.
These systems use very little energy to move heat. Water can carry more energy than air, so a relatively small volume of water is needed circulating through the entire pipe in floor heating. Due to its diversity of adaptation and the low temperature it requires, the thermal generator can be combined with solar panel systems.
"As part of the heat generator, the most innovative are solar systems; especially because of the current ecological awareness that, with the passage of time, has been increasing due to an important economic aspect: the increasingly high cost of energy," said engineer Tavera, who said: "I am not talking about photovoltaic energy, which converts light into electrical energy, but solar thermal energy, which captures direct radiation from the sun and takes it to thermal energy within a fluid; in this case, water."
He also mentioned that in hydronic systems the heat source (often a gas boiler) is supported by a solar system that in a certain percentage also contributes to the heating of the building. "Lately, the average number of customers requesting cleaner boilers and energy systems has risen interestingly. A year ago, out of a hundred customers, two or three requested it; at this time, out of 10 customers, at least two request that their system have an alternative energy contribution; basically solar."
Bifunctional heater, recirculating pump and radiators
In Mexico, most heaters are usually placed outside the house; sometimes in the bathroom (in most cases it is in the engine room or service yard). In the United States they are installed inside a closet with direct ventilation to the outside; in Europe it is customary to place it in the kitchen. As a suggestion of experts, it is worth installing the CH heater inside the house, as long as it is easy to take out the shot (chimney); in this way, the heat that emanates, both heater and shot, is used in its journey through the interior of the property. It is best to look for a suitable place so that this caloric energy does not bother in hot times.
One of the most recurrent questions is whether the conventional heater already installed can be used to power the CH.
In reality, conventional heaters do not work for CH, mainly because they are not designed to operate in a closed circuit and do not provide security for either the user or the system; other reasons are that its efficiency is low, its capacity is fixed, it loses warranty by the manufacturer and does not have the necessary elements to control the system.
You can choose a bifunctional heater, such as those used in Europe (it is possible to leave the one that is already installed, if the user wishes, and continue using it for its usual functions). In addition to their high efficiency, bifunctional heaters offer the advantage of heating the water from the shower and the water that will go to the CH system. In England they call them COMBI because they combine both functions.
One of the strictest specifications pointed out by the engineer Tavera is that "you can not install a conventional boiler or heater because it does not have certain elements that the hydronic system needs: water recirculator, expansion tank, air separator, air eliminator valve, mixing valves, thermometer, manometer, flow switch, pressure switch and automatic filling.
"The boilers that come from Europe, made exclusively for heating, incorporate all that inside a gabinetito. If the floor boiler measures 1m x 1m x 1m, the European model measures 80 x 60 x 40 centimeters (without occupying floor space), with the inconvenience that the boiler to the floor would take the entire installation outside. Using a special European boiler for high-efficiency heating is more economical, by far more than half, than making a whole Frankenstein in the floor boiler."
Unlike radiant floors – which radiate heat from hot water – radiators emit radiation and hot air by convection. In case the customer decides to use radiators for CH, there are different models, decorative styles and colors. Those placed in the bathroom are usually used as towel rails. Some models are almost imperceptible because they run very discreetly on the zoclo. Fanless radiators have the advantage of being very quiet.
If you've ever wondered why radiators are installed under windows, the answer is simple: because they lighten the flow of icy drafts entering in the form of a waterfall. When the air comes into contact with the radiator, the efficiency of the radiator increases slightly.
Some radiators include a continuous working fan that generates more heat and, at the same time, distributes it faster; they are called forced convectors. This choice decreases the installation space because a single radiator with a fan equals four without a fan of the same dimensions. They are an excellent alternative to heat the house faster. Generally, the air current produced by the fan, barely noticeable, does not disturb, does not transport dust or allow the formation of bacterial habitats. Unlike turbine heaters – based on convection systems – the heat inertia of the hot water of the radiators maintains the uniform temperature. The uncomfortable thing about turbines is that the temperature goes very fast from hot to cold and vice versa.
Recent studies conducted in the United States showed that more than half of indoor air quality problems come from hot air ducts integrated into heating systems. In CH there are no ducts to clean, and these do not transport dust or trap bacteria.
Radiant heating is emitted in the form of infrared radiation. Human skin is known to be an excellent recipient of radiation
Radiant floors
Every design responds to a principle of functionality and comfort. It is known that the human body needs, by nature, more heat in the feet than in the head; hence, a temperature of between 23° and 25° C in low areas of the rooms, and 19° to 21° C in the upper part would be ideal to achieve an optimal state of well-being.
The application of radiant flooring includes practically any place: houses, apartments, dressing rooms, terraces, pool platforms, offices, warehouses, greenhouses, parking lots, infirmaries, prisons, stadiums, churches, gyms, nurseries, nursing homes, schools, shopping centers, universities, self-service stores, car agencies, hangars and airports; zoos, kennels, cold storage hospitals, military centers.
With this system it is possible to generate a warm, healthy and silent climate, which does not dry out the environment, does not generate drafts (which significantly reduces the movement of dust and prevents the accumulation of burnt dust), does not interfere with the decoration, does not give off any smell; It is very durable (up to 100 years in its pipe), safe, it can be left running throughout the winter season, without having to be aware of turning switches off or on.
Radiant floors can also be adapted in swimming pools. Its function is to prevent the flow of hot water that enters through the glass and minimize the evaporation of water, the largest source of heat losses in a pool. When installing radiant floor around, the heat emanated provides a pleasant sensation when stepping with bare feet.
Radiant floors are said to be the CH's luxury option, because the pipes are hidden under the floor. One advantage, even over radiators, is that radiant floors require water to be at a temperature of around 45°C, while conventional radiators need at least 70°C. However, the installation cost is often lower than the other CH options.
Radiant floors represent an interesting energy saving due to the possibility of adapting your thermal generators to alternative energy sources: solar energy, chimney recuperators, coal and wood boilers, waste heat from industrial processes, hot springs and heat pumps, among others.
Its installation is safe because the underfloor heating does not have joints: all its circuits begin and end in collectors; this, together with the quality of the tube, ensures the absence of breakdowns. Other systems where metal tubes are used joined by numerous joints are prone to a greater number of breakdowns and to generate maintenance costs that, otherwise, would not exist. When malfunctions occur, customers experience less sense of insecurity in the facility.
Experts in radiant flooring suggest that customers consider two "drawbacks": carrying out the installation when the house or building is still under construction or taking advantage of remodeling processes. Another important aspect is that the height of the floor where the system will be installed will increase on average by eight centimeters.
Radiant floors do not burn, break, moisten, wet or mistreat any type of finish, whether tile, marble, ceramic, quarry, concrete or wood. He treats wood for life, keeps it free of any moisture that damages or lifts it.
A fact that lovers of wooden floors should not miss is that, precisely, wood acts as an insulator from heat, so that the rise in temperature takes a little longer. Although possibly no one would, it is recommended not to cover radiant floors with cork, unicel or sawdust finishes; nor use rugs, carpets, wool or cotton. By enclosing the air, these materials isolate the heat.
So far there has been talk of CH to generate heat; however, there is also radiant cooling, with the same principle, except that for this a cold fluid is used by means of circuits or capillary pipe mats normally placed on walls and ceilings. These elements uniformly decrease the radiant energy of people and raise the quality of their surroundings.
The question then would be whether or not to place wooden floors. Engineer Tavera responds bluntly: "Yes you can. Almost all customers lay wooden floor. What happens is that ceramic or stone floors (marble, granite, quarries or slabs) transmit heat better. Woods take longer to do so. In case of having a room with a ceramic floor and a wooden one, what could be done is to compensate for the speed with more pipe under the wood. I would suggest avoiding carpets because, in addition to being the largest mite receptacles, they are perhaps the best heat insulators."
In idronic heating systems, solar panels can be installed for water heating
Installation process
Referring to the installation process, the director of Ecovent Suministros comments that it must begin by having the area clean of tecatas (remains of turmoil that remain in the slabs). "At the conclusion of the first firm, an insulation is placed that adheres with waterproofing; once the insulating plates are glued, there are different construction methods."
Before continuing, the engineer Tavera believes that in projects of this type the ideal is to support it with engineering; that is: "Consider from the beginning the location of boilers, thermostats, manifolds (devices that regulate the distribution of pressure and water flows); from here a list of materials must be detached: the exact amount of nails, plastic belts, etc. Everything, no more, no less.
"At this stage," he says, "it is assumed that the client has already defined whether he will place a wooden, tile or marble floor. A marble with a thickness of one inch is not the same as a tile of half a centimeter; nor is a glued staves the same as a natural wood. The next step will depend on this: if electrowelded mesh is placed under the pipe or if the pipe is placed first and then the mesh above, how many centimeters will be the firm that covers the pipe until the final floor is placed. "
Basically, Tavera points out, "the complete process is to place the insulation, lay the pipe according to the design of the project, reach the manifolds, make the feed between manifolds and boiler, leave the electrical preparations for thermostats and strain the firm. Once the white work is finished, the customer calls us to install the final equipment in the engine room. We close it with the feeds that we have left and, then, there is still some time to finish installing thermostats and controls to, immediately, start the tests of the entire system.
Its facilities, perfectly ordered, prevent accidents due to blows or electrocution
"In itself, the installation does not take long. We have installed systems that in a week could be ready to start operating; but since the construction is not that fast, it turns out that we are among the first to enter the work and practically those who close the door. That is, the installation takes time not because of the construction process of the heating, but because the process of integral construction of the work goes in stages".
Installation and maintenance costs
According to data provided by the general manager of Hergom Mexico, costs vary according to the size of the project. For an average house (one room and three bedrooms) the quote goes from 50 thousand pesos, with an annual maintenance service, at a cost of 2 thousand 500 pesos, plus spare parts. José Medina pointed out that "the Hydronic Heating market has grown in Mexico, especially in the last 10 years."
To this, the engineer Tavera adds that, "as these are centralized systems, the larger the Hydronic Heating project, the cost decreases. In systems of small proportions, the square meter costs about a thousand pesos and can go down to 600 pesos, depending on the dimensions of the area to be installed. Usually, we install surfaces of 150 to 200 square meters, for a cost ranging from 120 to 150 thousand pesos. Now, the cost of maintenance varies according to the number of boilers installed. Generally speaking, it's about two thousand pesos."
Hydronic Heating in Mexico
To the question of how popular CH has become in Mexico, both experts issue their opinions. "Followed by chimneys," says Medina, "CH has already positioned itself over other heating products, for achieving greater efficiency and for being a more comfortable, healthy and efficient means."
"This system, with modern elements, technically suitable for CH, is about 20 years old," says Tavera. Although ch has been gaining a lot of ground within the heating sector, in general terms, it still lacks. It has taken us a lot of work to introduce it fully to the market. Starting from the comparison that can exist with air conditioning, the difference is a lot. You talk about air conditioning and everyone knows what it's all about. When we installed our first CH, about 20 years ago, it was not known at all what the radiant floor was, because the technology and know-how of that system were almost unknown, as well as the control elements and pipes it requires."
To conclude, the director of Ecovent Suministros mentions that in Europe, particularly, the CH by radiant floor has had a tremendous explosion. "In recent times, all parts and spare parts are manufactured especially for the CH system. Special boilers for radiant floor accept, through a card, direct information from the solar system; radiant floor CH distribution manifolds are specific to that application, as well as thermostats, zone actuators, piping and insulation. Each of the pieces corresponds to a specific application design; that is, it is already something that is manufactured expressly for CH. All the technology generated in Europe, in a way, has splashed us a little of their knowledge in the little we do in relation to them, which I celebrate."
CH is especially recommended for hospitals, nurseries, nursing homes and where people with respiratory problems live
