Frequently Asked Questions

Is the Duo-Therm system electric?

Yes, the Duo-Therm system is electric: - an electric resistance is installed within the stone, which provides the necessary energy required to heat the stone radiator. The latter, in turn, is connected to the thermostat, which regulates the room's desired temperature.

Can the Duo-Therm heating system work using solar energy?

Yes, the Duo-Therm heating system can work using solar energy since the latter is converted into electricity that will supply the stone radiator. The DT system is equipped to work at any of the following electric voltages: 110V, 220V and 230V.

Is the level of energy consumption very high?

The Duo-Therm system takes advantage of the natural stone's capacity to accumulate heat to such a degree that once the desired temperature of the room is reached the system ceases to consume more energy, merely radiating accumulated heat for several hours. The system only turns on again for a few minutes at a time when the ambient temperature falls below the temperature selected on the thermostat. In this way, if the heating system is left on for a full 24 hours it will only consume energy during 6-7 hours of that time, all the while maintaining the room at a constant temperature at all times.In addition, the stone radiates heat not only to the room directly but also to the surrounding wall that will likewise accumulate heat, thereby serving as a second heat accumulator. Because the principle behind the Duo-Therm heating system is based on the radiation rather than the convection of heat energy, the same thermal effect is achieved with a lower temperature (in fact, 2ºC lower than required by other systems in which the heat is transmitted by convection.

Is it possible to test the level of energy consumption using only a single radiator?

Duo-Therm is a system and not an independent heater whose effects can only be measured truly by installing the entire system. This is because the stone radiator installed in a particular wall will also heat the opposite side of the wall in which it is placed, thereby automatically heating the neighbouring rooms. The energy consumption costs of the Duo-Therm system decrease over time because as the heating time increases the walls accumulate more and more energy radiated by the different stones, even if these are installed in neighbouring rooms, thus decreasing both the frequency and duration of the energy consumption required to maintain a room at a constant temperature. Given this information, then, one may conclude that the results obtained from consumption tests performed on a single stone are misleading (fictitious).

How long does it take to heat a room?

The time required to heat a particular room depends on a number of factors, namely: 1st- The room's initial ambient temperature 2nd- The size of the area to be heated 3rd- The degree of heating desired 4th- The quality of the room's insulation5th- The number of doors and/or windows Assuming that the room is well aired - with an area of 15 m2, - two double glass windows and a door - properly insulated walls - in December with an average outdoor temperature of approximately 7ºC - an initial room temperature of 14ºC - a desired room temperature of 20ºC Under these conditions, the time required to heat the room to the desired temperature of 20ºC using a single 650W stone-radiator is estimated at approximately 2 hours.

Does this system require any maintenance?

Once the Duo-Therm heating system has been installed it is immediately functional and does not require any kind of inspection or maintenance after a given period of time. In other words, the DT system is always in working order.

How many stone radiators does my house need?

Specific technical counselling concerning the correct distribution and location of the equipment is always provided to the customer. However, calculation of the estimated costs should be based on the principle that a single 650W stone radiator is sufficient to heat a room with a maximum area of 16 m2; for rooms whose total does not exceed 11 m2 a single 375W stone radiator is sufficient.

Where should I install my Duo-Therm system to heat the rooms at maximum efficiency?

The Duo-Therm system should only be installed in interior walls given the fact that the stone radiates heat to the wall in which it is placed. The wall accumulates his heat and, much like the stone itself, functions as a heat accumulator. Thus, neighbouring rooms that share the same inner wall in which the radiator is installed also benefit from the heat transmitted by the radiator to the opposite side of the wall. For those rooms in which it is impossible to place the system in an inner wall, we suggest the use of a Moving Heater.

Is the installation process a very complicated one? How long does it take to install the system?

The installation process is very fast and simple - a mere half hour is all that is required to install each stone radiator. Thus, in a home with 3 bedrooms, a living room, kitchen and bathroom (T4) the entire installation time for a complete system is roughly three and a half hours. - The system consists of a single stone radiator and a thermostat that regulates the ambient temperature. The stone radiator is hung by four supports affixed to the wall in the following manner: - drill four holes - place plugs in each of the four holes - screw in the support hooks - finally, hang the stone-radiator. The thermostat is installed at a minimum distance of 30 to 40 cm from the stone radiator and is never placed over top of the stone radiator. The Duo-Therm heater comes equipped with a 75 cm high temperature resistance cable without an electric plug. The connection to the system should be carried out by an electrician, respecting the safety norms in existence, particularly those of the VDE 100. This system does not need to be grounded.

Can a stone wall-heater be installed in a bathroom?

A stone wall heater is ideal for installing in bathrooms because of the triple benefits it offers: it dries the moisture on the walls, keeps towels warm and dry and radiates some heat onto the floor, maintaining a pleasant temperature. It also creates an extremely comfortable environment when you step out of a hot bath or shower. In terms of safety, both the thermostat as well as the stone heater itself are fully compliant with norms and standards that allow it to be installed in humid environments such as bathrooms, swimming pools, locker-rooms, etc.

Is it possible to install the Duo-Therm system in an older house?

The Duo-Therm system is an ideal heating system for older homes given that to install such a system the only requirement is a wall socket from which to obtain energy (for more information please refer to the section entitled "installation"), and it is not necessary to break any walls.

When should I apply a radiating floor and when should I opt for the stone radiator?

When opting for the radiating floor, keep in mind that the radiated heat is distributed; the power is only 120/150W per square metre and the temperature attained by the floor shall never exceed 25oC. On the other hand, when choosing the stone radiator it is important to know that the heat is collected in a 800W stone from which the heat radiates over time. As a result it is not possible to obtain an effective heating system with the radiating floor system in rooms whose area to be heated is much larger than the free floor surface on which to apply the radiant floor. This is often the case in bathrooms where, due to the sanitary installations and presence of various cabinets etc. the total free ground area available for the application of the radiating floor is only between 2 m2 and 3 m2 even when the room's total area is 6 to 9 m2.In such cases customers are recommended to either install the radiating floor in conjunction with a 500W stone radiator or simply to install a stone radiator without radiating the floor.The radiating floor the ideal solution for larger-sized rooms in which the objective is to achieve an even distribution of heat or when the mural-frame effect is not desired (as would inevitably occur with the installation of a stone radiator), or yet in rooms whose interior walls are not free and thus do not permit the installation of stone radiators.

Can the radiating floor be detrimental to my health, possibly causing thrombosis or aggravating varicose veins?

On the contrary, the radiating floor is beneficial to your health as it allows you to keep your feet warm, producing a mild surface temperature that can never exceed 25oC. This is achieved thanks to the presence of thermal sensors placed on the floor, integrated with the thermostat which regulate the ambient temperature (OTD Type).

In case there is a malfunction in the underfloor heating, will the entire flooring have to be opened up to fix it?

The Etherma heating cable has never had any malfunctions in the 30 years that the technology has been in use and therefore the probability of this cable malfunctioning is absolutely minimal, when it is correctly installed following due norms. However, should the cable ever malfunction it is easy to detect the point where the current has been interrupted, which would be the point of the malfunction. The floor would be prised up in that spot (about 30 cm) and the cable would be repaired at that point without it being necessary to open up all the flooring.

Can I use a rug or carpet on top of flooring that is equipped with underfloor heating?

A rug or carpet can be used on flooring that is equipped with underfloor heating as long as it is not a compact material, i.e. it must not block the passage of heat, which should not be trapped under the carpet.

Ecological Heating

Duo-Therm ® is a german heating system which exists on the northern countries markets for more tahn 30 years.

Maximum comfort with minimum consumption.
High capacity of heat accumulation.
100% environmentally friendly.