Ceiling Heating with Capillary Tube Mats vs. Conventional Underfloor Heating

A System Comparison

The future of heating and cooling rooms belongs to radiant heating. This can be seen in the growth rates in the underfloor heating industry. 50% of new single-family houses in Germany are equipped with underfloor heating. Underfloor heating is also being used more and more frequently in the modernization sector. The reasons for this development can be explained by the advantages of radiant heating. Compared to classical radiator heating technology, surface heating requires low flow temperatures. It is also economically feasible to use environmental heat as a heating source. Radiant heating ensures a high level of living comfort and pleasant warmth without the technology visibly influencing the room design.

Which system uses the advantages of surface temperature control most efficiently? Underfloor heating or ceiling heating? In the following, the advantages and disadvantages of traditional underfloor heating and ceiling heating with BEKA capillary tube mats are compared.

Conventional Underfloor Heating

The market-defining technology of conventional hot water underfloor heating is now more than 60 years old and has accordingly been tried and tested. The systems available on the market do not differ significantly in terms of their technical solution. With all water-bearing underfloor heating systems, pipes are laid in a meander or spiral shape. The pipes are mostly made of plastic. The outside diameter of the tubes is 14 to 17 mm. The pipes are usually laid at a minimum of 150 mm.

The classic structure of this underfloor heating, unlike the low profile variant, usually has an installation height of at least 90 mm. A large part of this is made up of the heated screed close to the surface, which protects the insulation below against traffic loads. The heating pipes are located in the insulation layer. A typical underfloor heating structure looks like this:

 

Ceiling Heating with Capillary Tube Mats

Ceiling heating has its largest market share in new office buildings. But ceiling heating is also increasingly being used in hospitals, industrial buildings and private homes. This is also due to the additional function of the ceiling cooling, which creates pleasant working and living conditions even in summer.

The ceiling heating with capillary tube mats is characterized by a tight network of 3.35 mm thin capillary tubes. The wall thickness of the capillary tubes is 0.5 mm or 0.8 mm. The capillary tube mats can either be attached to the ceiling structure and thinly plastered, or they can be hung in drywall constructions. Furthermore, capillary tube mats can also be integrated in metal cassettes.

Comparison Criteria

Indoor air flow

The underfloor heating transfers the heat into the room through around 60% radiation and 40% convection (warm air rises upwards). The people in the room also absorb heat directly through the contact between their feet and the floor. The convection (air movement) in the room leads to the vertical transport of suspended matter and germs from the floor to the living area. The germ-contaminated air flow in the room can irritate the respiratory tract and the mucous membranes, similar to classic radiator heating. In addition, not all people perceive the warmth on their feet as being pleasant over the long term. Depending on the flow temperature and duration, the heat from below can become a strain on the blood vessels of the feet and legs.

The thermodynamic connection “warm air rises upwards - cold air falls downwards” is not the driving force behind the warming of ceiling heating. The heat is mainly brought into the room via radiant heat from the ceiling. The heat transfer through convection is much lower with ceiling heating than with underfloor heating. This leads to less dust turbulence and fewer allergens in the room air. This is another reason why more and more hospitals are opting for heating and cooling ceilings.

Despite the high proportion of radiant heat, the heating output of the ceiling is sufficient to completely heat the room. New buildings and modernized houses have a low heat requirement of a maximum of 60 W / m² or less. Objects in the room and all areas surrounding the room are heated evenly by the heat rays from the ceiling heating. This creates a feeling of cosiness and constant warmth comfort.

Reaction speed

The heating screed above the heating pipes builds up a thermal resistance that counteracts efficient heat dissipation into the room. If the temperature changes briefly, the underfloor heating usually only reacts after 5 hours and later. If not so much heat is needed in the room, then the screed heats up as a "heat store". Even complex control systems can only partially compensate for the sluggishness of the underfloor heating. Depending on the floor covering, this problem is exacerbated.

The thin capillary tube mats lie just below the surface to be tempered. This means that the ceiling heating can react quickly and be precisely regulated. After less than 15 minutes, the new temperature is set on the ceiling surface and the heating process begins.

The room surfaces absorb the heat and act as a heat store. So it doesn't matter if some heat is lost when the windows are opened briefly to ventilate the room. The room is then quickly back to the desired temperature.

Modernization

Conventional underfloor heating with heated screed is rarely suitable for modernization. The installation height leads to inconsistent floor heights and tripping hazards, especially when retrofitting individual rooms. In addition, the room height is reduced by the construction height. The considerable additional load of approx. 110 kg / m2 which is applied to the existing ceiling must also be taken into account with this construction.

Ceiling heating can be retrofitted comparatively easily. The ceiling is usually freely accessible and, especially in old buildings, sufficient room heights remain despite the suspended ceiling. Dry construction systems are particularly suitable for retrofitting. The capillary tube mats are either suspended or, in the variant, can be screwed onto the CD support profiles as a pre-assembled element. The supply lines are in the area between the original ceiling and the drywall construction.

Energy efficiency

The energy efficiency of a heating system is directly dependent on the flow temperature of the system. The lower the system-specific flow temperature, the less additional energy has to be used to achieve the desired room temperature. A low flow temperature saves energy. In addition, a low flow temperature enables more efficient use of ambient heat and other regenerative energy sources.

Due to the thermal resistance of heated screed and floor covering, the flow temperature of conventional underfloor heating, depending on the installation distance and the floor covering, is 40 ° C and more.

Due to the location of the capillary tubes directly on the surface, the BEKA ceiling heating, on the other hand, manages with a flow temperature of 30 ° C in order to heat a room sufficiently. The savings potential is directly dependent on the energy source. When using a brine-water heat pump, for example, a flow temperature of 10 ° C lower can mean a 40% reduction in electricity costs.

In addition, due to the large number of capillary tubes that are only 10-15mm apart, the heat is distributed very evenly over the entire ceiling surface. This is not only verifiable with thermographic recordings, but can also be felt very well.

Ceiling heating - additional benefit through cooling function

The ceiling heating can also be used as a cooling ceiling in summer. For cooling operation, cold water at approx. 16 ° C is sufficient that a reversible heat pump can provide it. With the appropriate control technology, dew formation on the ceiling surface is reliably excluded. The cooling through the ceiling is very pleasant. The function of the cooling ceiling is many times more effective than cooling via the floor. It is noiseless and also significantly more energy-efficient than ventilation cooling.

Overview

 Conventional underfloor heatingCeiling heating with capillary tube mats
Heating energy consumption / flow temperature
Suitability for heat pump technology
Suitability for solar energy use
Responsive heating
Construction height
Suitable for modernization
Healthy and pleasant room climate
Dual use of heating and cooling
Investment costs

Detailed system comparison with additional information on economy and corrosion behavior [PDF]

System comparison as PDF: conventional underfloor heating vs ceiling heating

Ceiling Heating vs Underfloor Heating

System comparison