Underfloor Heating

Underfloor Heating

The latest in heating technology has come with underfloor heating or hydronic heating, based on the basic principle of solar radiation that consists of radiating heat in all directions in a uniform and natural way.

Air conditioning is to give comfort to the users of a space. To do this, different technologies and procedures are used throughout the world where most heat the environment in various countries through radiators or conditioning of circulating air. However, these systems, often operated by fuel, have become obsolete and this is why many users around the world opt for replacement with radiant heating.

This new technology, called underfloor heating, has been making its way into the market, starting in Europe, where most of the traditional heaters were cast iron radiators powered by firewood or gas, and today they are the main users of hydronic heating.

Underfloor heating is presented as an excellent option to achieve the ideal environment with a silent, safe and economical system, whose main feature is that it heats the spaces from the bottom up, influencing first the objects and not the air like other methods, thus avoiding cold or hot drafts.

What is underfloor heating?

Underfloor heating systems have high effectiveness in heating spaces where boilers participate to heat water at levels similar to those used in water for showering. This water passes through ducts and pipes (which are installed prior to the application of finishes on the floor) radiating the temperature reached inside the rooms.

For their control, these systems have thermostats that help mediate the calorific requirements according to the ambient temperature, in addition to the more thermostats there are in a construction (in its different rooms, rooms, bathrooms) there will be greater possibilities of optimizing the use of energy by heating only the spaces that are going to be used.

In order for the heat to reach its final disposal, water is first heated inside the boiler, and then passes through a network of feed pipe that reaches the floor support, that is, solid slab, losacero, joist or vault, where in turn the cross-linked polyethylene (PEX) pipe is tended in the form of a zigzag through the entire room in question. Based on the characteristics of the pipe, the engineers design the coil, that is, the bending of cable so that the pipe is attached which is then accompanied by a thermal insulator (high-density polystyrene) that prevents heat loss downwards by heating areas that are not required or the same firm. Finally the system is covered by the casting and the final finish (marble, tile, wood, carpet ...).

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A bit of history...

The water-based (hydronic) underfloor heating system has its origins in Ancient Rome when emperors heated their bathrooms and main rooms by carrying the hot gases of wood combustion through intricate trenches and underground tunnels that were part of an ingenious natural ventilation system known as "hypocasus".  Similar systems were used in Spain, where they were called "glorias", in Korea similar constructions were also used.

In 1939, a group of English chemists were studying the reaction between ethylene and benzaldehyde. Using an extremely high-pressure autoclave, it exploded, and destroyed most of the laboratory.  Then they noticed that inside the remains of the autoclave was a substance like white wax. Although initially they did not know what it was, later studies revealed that it was a gas that when put under such pressure solidified creating polyethylene.

Years later, after this material became popular, Thomas Engel, a Swedish scientist, created in the 1960s, what is known as cross-linked polyethylene (PEX). This material thanks to its unique molecular structure can withstand water at 93°C, even under pressure, and due to its ability to recover it always returns to its original shape. In practical terms, the PEX can be heated and cooled as many times as necessary, it can be deformed, crushed, or twisted and when heat is applied the material returns to its original shape as soon as it cools.

Professor Engel took his discovery to various chemical companies, until a neighboring poultry farmer asked him if he could make tubes of this new material thinking about this corrosion-proof plastic being installed in the ground under his hens, which would feel warmer and lay more eggs.  After this application, Engel took his material to the Swedish pipe manufacturer Wirsbo, who began the manufacture of pipe with such material that they used under the lawn of the Olympic Stadium in Munich in 1972, getting great attention.

When the OPEC oil embargo arrived in 1973, Europeans began to learn more about radiant hydronic heating by operating at much lower cost than any other type of central heating system.

Before the energy crisis, many Europeans heated their homes with sturdy cast iron radiators, used high-temperature water and when the oil embargo happened, engineers in the region noticed that they could save money by lowering the water temperature.  Of course, they had to manufacture larger radiators to compensate for the low water temperature.

With the entry of PEX, things became easier. The pipe of this material is able to withstand more stress (expansions, pressures and variable temperatures) than that of copper or steel, is corrosion-proof, and is easy to work, qualities that allowed Europeans to use the entire floor as a radiator.

To compete with radiant floor manufacturers, several European radiator manufacturers began to make their radiators more extensive so that they too could heat a place with water at low temperature.

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Along this network, inlet (hot water) and outlet (warm water), manifolds and valves are installed, where in turn different thermostats are placed to control the temperature of each area of radiant floors.

For the installation of these systems, suppliers perform meticulous calculations where the customer's heat needs are evaluated considering the physical characteristics of the construction, possible complex areas to be heated and even with the knowledge of the materials to be integrated as finishes. This helps radiant flooring systems to be perfectly well adapted to each space offering the end user total comfort.

Why an underfloor heating system?

Since its appearance on the market, air conditioning by this method has reported all kinds of benefits both in terms of installation and in energy expenditure and comfort, among others.

A. Savings: Since the entire installation can be operated by a single boiler per level (in two-level constructions one boiler per level can be occupied), the unnecessary expenditure of heat energy is avoided.

In addition to this, it is remarkable the modularity condition that these systems have, that is, they can be installed as units in different rooms with the use of thermostats, to heat exclusively the spaces that require conditioning. For example, during the night, it is possible to heat only the rooms, a situation where a fraction of the total capacity would be used, representing adequate heating with only a fraction of the energy consumption.

On the other hand, the boilers used in hydronic heating systems are not flame or full capacity, but variable capacity. Thus, when a room is turned on, the boiler detects what is the demand that is being had and as more rooms are turned on, it begins to give more power to meet the need. Also when the heating is turned off in different rooms the boiler again reduces its capacity.

These variations can result in cases where boilers will have lower efficiency, however there are brands that allow you to follow the consumption closely to achieve greater energy savings.

In hydraulic consumption, these systems also have interesting savings. Since these facilities use 1/2", 3/4" or 1" pipes (which also transport hot water silently) they consume only a small proportion of the fluid, with optimal results in terms of heating, since water is capable of transporting up to 3400 times more energy than air.

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B. Flexibility: The successful acceptance of hydronic or underfloor heating also lies in the adaptability it has to meet the needs of users in shape, size, modularity, growth options and of course total control.

The underfloor heating can be installed in practically any space, and combined with other heating elements such as radiant towel rails in bathrooms, forced convection radiators in kitchens, zoclos, radiators and many other options that exist in the market for calorific contribution of spaces; no risk of interference. Likewise, thanks to the fact that at no time is it on the surface, it does not represent a hindrance to place furniture or any other object in the air-conditioned spaces.

To offer users maximum comfort, these systems can be easily controlled through thermostats for each area of the installation or even by means of timers, so that when entering a particular room it has the ideal temperature without the need for idle energy expenditure.

On the other hand, in case it is required to extend the coverage of the system to other rooms, it is not necessary to modify the entire network, the same condition that occurs in case of repair.

In addition, although the boilers or boilers normally used to heat the circulating water are gas (ignited by electrical energy, like thermostats and hydraulic card), there is the possibility that they also work with electrical energy, oil, firewood, diesel, or even with alternative energy such as solar, geothermal and biomass, among others.

Previously the boiler and the hydraulic board were put separately, now they are integrated into a single piece allowing to use less space in addition to functioning as a unit.

C. Effectiveness: Thanks to the fact that underfloor heating heats the environment from the bottom up, they are ideal for spaces with high ceilings, where air conditioning systems are less effective since the heat migrates to the upper part of the room.

Likewise, its efficiency is maximized in installations where the finishes are temperature conductors such as marble and tile, having fewer effects in spaces finished in wood or carpet that limit heat exchange, so the temperature effects take longer to be perceived (see box What are the optimal conditions for radiant flooring systems?).

On the other hand, the effectiveness of hydronic heating systems allows the optimization of energy resources as highlighted in the saving section, achieving the reduction of energy consumption by up to 40% compared to other types of air conditioning.

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Advantages of hydronic heating:

IT IS SILENT since the boilers are normally installed in exterior sections of the buildings, they do not generate noise inside the buildings, in addition to being silent equipment by nature.

THE ENVIRONMENT DOES NOT DRY out unlike systems that generate drafts that frequently remove moisture. Radiant flooring systems do not have these effects because their heat projection is not through the air.

SAVE ENERGY since heat is transferred by radiation not by natural or forced convection, which is the characteristic of other heating systems.

IT IS TOTALLY SAFE, since no person or animal is in danger when approaching. It even promotes better blood circulation when heat enters the feet and there is no risk of disease from temperature changes. In addition, in installations that have to be carried out indoors, the equipment is added with controls such as carbon monoxide detectors, to ensure that there are no risks of toxicity in the environment.

IT DOES NOT GENERATE DRAFTS, where cold and heat are often mixed. Also for this reason, it is not feasible to propagate dust, pollen and other elements.

IT DOES NOT AFFECT THE DECORATION, nor does it occupy idle space because it is installed inside the apartment. It does not store heat in the roof unlike other methods of air conditioning where the air is denser because it is hot, accumulating on the roof.

In fact, in radiant flooring systems such as the hottest surface is that of the floor, heat accumulates in this area and rises progressively, which is why it is recommended in spaces with high ceilings.

They can be combined with other heating solutions. There are properties where it is no longer possible to install radiant floors, but in the extension it is. In this way, in the previously built part, radiators, convectors or other systems are installed and the same boiler is used to heat the circulating water in the hydronic systems.

It requires little maintenance, being advisable to maintain it twice a year. Although it is not common for major repairs to be made, but it is usually done due to the need to change batteries in the thermostat, or lack of gas or water.

It is very durable. The installation, including mesh and pipe has guaranteed service life for 100 years with the manufacturer.

The system is modular, that is, it can be divided into as many zones as necessary. Each of them can be controlled by its own thermostat

The insulation prevents heat from migrating to unwanted areas, so there is no risk of it affecting roofs in the case of constructions of more than one floor.

The use of thermostats allows the best temperature control, in addition to working as a system switch, and in segmented installations serves to more efficiently manage sections in a simple way. Currently thermostats have screens that facilitate the rapid reading of temperature and allow to store the user's preferences in their internal memory.

It works automatically through the thermostats placed in each area of the construction, so it does not need constant maintenance. It is advisable to install thermostats for each heating module so that the savings are more visible, since it is controlled in which rooms the heating is on.

Growth of underfloor heating

Europe is the main user of these air conditioning systems due to the low temperatures reached in these regions, as well as others with similar conditions. In Mexico, the application of this technology has so far not reached its maximum potential, being a good opportunity for the market.

Likewise, the changing climatic conditions, which report low temperature levels in different areas of the country and surrounding regions, are indications of the coming growth of this and other methods of air conditioning. Currently, the installation of heating or other types of space conditioning in Mexico represents an investment that not many people want to make, however, the imminent need to include these solutions as integral parts of any construction and the indisputable efficiency they present, will make hydronic heating systems, among others, increasingly be considered as benefits, rather than as unnecessary expenses.

When using wood or other bad heat conductors, the system for screwed wood should be used, where the wooden dogs are placed at the base, then the insulation between the wooden dogs, as well as the pipe network, the casting or sand goes up and finally the finishes.

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