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8 heating systems in comparison: who heats best?

Dino Eisele
8 heating systems in comparison
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R and 20 minutes, according to the statistics, the commute takes of the average commuter in Germany. How comfortably you can cover this distance by car in winter largely depends on the vehicle heating system - above all how quickly it warms up. If the heating effect only sets in when you reach your destination, it is definitely too late. But how big are the differences between the individual models, what can economical, low-displacement machines, partially electrically powered hybrids or fully electrically powered and heated cars do compared to tried and tested models in the compact, medium and luxury class?

From the small to the upper class

To find out, we ask the Hyundai i10 and for the cheap small cars the new Smart Forfour, for the compacts the Audi A3 TDI and the Ford B-Max, for the middle class the new VW Passat and for the upper class the fine Mercedes S-Class in its luxury version as a twelve-cylinder S 600 L for comparison. The BMW i3 with range extender and the new, hybrid-powered Golf GTE are intended to show what electrical or hybrid systems can offer in terms of heating comfort.

Under comparable conditions, how much heating power a vehicle develops can best be achieved by a Determine the test in the air conditioning duct. The NEDC chassis dynamometer test, which is used in a standardized manner to determine emissions and standard consumption values, provides the toughest conditions for this. The focus is on the first two test sequences, each lasting ten minutes: the cold start at minus seven degrees and the defined urban and rural areas correspond to the standardized driving profile of a commuter parking lamp. The third sequence, the motorway part of the NEDC test, is deliberately omitted.

Cold start according to NEDC rules

What makes the comparison according to standard consumption rules so interesting? It is the conflict of objectives that vehicles with internal combustion engines have to resolve. Because their engines are optimized in such a way that they should achieve the best possible consumption values ​​under the known conditions of the test. The heating effect is therefore only a minor matter for you. In the 20-minute test at TÜV Süd, we evaluated the heating curves at three different points: in the footwell, on the steering wheel in the hands area and at head height. Therespective air temperature at the measuring points after ten and 20 minutes driving time, plus the time until the measuring points together have reached the comfort temperature of 15 degrees Celsius.

That large engines with high consumption perform better than small, economical ones no surprise. In the absence of electronic fan control in the test car, the Hyundai in particular has difficulties in the manual ventilation level two specified in the test after the cars had been cooled down to minus seven degrees overnight. It is astonishing how little fuel can be comfortably heated. However, the Smart also heats a little weakly, the Ford B-Max a little unbalanced. The Audi A3, on the other hand, leaves nothing to be desired and is already positioned at a very high level. The new VW Passat also reaches the level of the far more expensive Mercedes S-Class with its very rapid and even heating of the interior, which clearly sets standards in terms of heating and air conditioning comfort.

Heating in the BMW i3 leads to a loss of range

In view of this, the comfort offered by the two alternative-powered concepts is surprising: The purely electrically driven BMW i3 leaves its passengers anything but cold and heats just as quickly as the S-Class with the electric benefit. The heating output of the Golf GTE is also respectable, with its spontaneous heat emission and good distribution achieving remarkable values. However, any heat dissipation, especially with the BMW i3, is significantly at the expense of the electric range.

However, the pure heat-up time is only part of the feeling of comfort. The heat distribution in the vehicle is no less important. Automatically regulating air conditioning and heating systems have an advantage over those that can be set manually. But even in the base, here the Hyundai i10, you don't necessarily have to freeze. In contrast to the tough NEDC test, where it constantly runs on ventilation level two, the Korean can provide pleasant warmth in practice if the driver repeatedly adjusts the ventilation and temperature settings.

Proven control principle

Warm feet, cool head - that is the motto according to which automatic systems initially regulate the interior heating. This means that the footwells are supplied with warm air first. Only in the course of the heating process is the warm air distribution shifted upwards and more diffuse; With standard models, the head area and rear area get warm last. This is different in the luxury class and in some MPVs or vans: here, additional heat exchangers in the rear often provide more climate comfort at the rear.

Additional heating systems provide a further convenience. In addition to the well-known fuel-operated auxiliary heaters, which can often also be upgraded to auxiliary heating, electrical auxiliary heaters have been standard for some years. With the exception of the i10, the Smart and theIn the S-Class (only with diesel), all vehicles in the test are equipped with PTC heating elements on the heat exchanger through which air flows. These heating elements immediately provide warm air with a heating output of up to 900 watts. In addition to quicker heating of the interior, the front window can also be freed from misting more quickly. So it works: Even commuters who drive an economical model no longer have to do without quick heat.

Subjective perception of comfort with measured values occupied

What is heating comfort? Sure, the car should get warm as quickly and evenly as possible. But that's not all: A good impression of comfort also includes a quiet fan noise and draft-free ventilation. In extensive test drives, we also took a closer look at particularly critical points: What is the temperature difference on body parts that are particularly sensitive to cold, such as hands and knees? Naturally, on the driver's side, the left side of the body facing the vehicle door is more likely to be affected by radiant cold and drafts than the right side, which is in the direct area of ​​action of the center vent. Subjectively, there are clear differences here. The same applies to the operating noise of the heating and air conditioning systems. The noise measurements were also carried out with the engine switched off in order to create a better basis for comparison and to suppress engine noises.

This is how it is in the interior quickly comfortable

Using the example of the Golf GTE, the heating of the interior is shown here at the individual measuring points over the 20-minute NEDC driving cycle. The driving test represents a common commuter driving profile with urban and rural areas. The same prerequisites applied to all vehicles: In the case of manually adjustable systems, the heating controller was set to maximum, the fan to level two. In vehicles with automatic air conditioning, the preset temperature was set to 21 ° C. All air vents were open in the test and aligned in the central position. Because comfort is particularly important, in this example the footwells are first brought to temperature, followed by the knee area together with the measuring points near the steering wheel. Comfortable temperature regions are reached here after just a few minutes. It takes significantly longer for the heat to reach the rear, the head area in front is deliberately kept a little cooler.

Upper-class heating technology

The comfort expectations for luxury vehicles such as the tested Mercedes S-Class are very high and can only be met with massive use of technology and a large number of individual measures. Instead of the usual one, luxury sedans use two heating /air conditioning units with heat exchangers, the front and rear seats independently of one anothercan heat or air-condition. For a fine response of the systems, the warming cooling water is already thermally regulated in a complex manner by the engine. In addition, the no less elaborate control of the air flows through individually controllable flaps and nozzles - combined with stepless control of the flow and noise-optimized fan - contributes to particularly draft-free and quiet air conditioning of the interior.

Since noises are perceived as particularly relevant to comfort, the developers of the S-Class also focused on the acoustic optimization of the heating system. In addition to the fans, the air intake, the air conditioning unit and the air ducts through to the air conditioning nozzles have been optimized aeroacoustically. An intelligent air mass flow control in automatic mode always ensures the highest possible thermal comfort with minimal noise.

The sensitive adjustment of the warm air distribution to the individual seats is supported by two sun position sensors in the front and rear areas, even GPS data is included in the control. In addition to conventional air heating, optional surface heating in the armrests of the doors, the center armrest and the steering wheel also contribute to comfort. The electrically heated windshield also improves comfort: If warm air is not needed to keep the windows clear and defrost, the comfort-relevant footwells can be heated earlier.

Warm up faster with auxiliary heating systems

The graphic shows the heating curves of the individual test vehicles over the 20-minute NEDC Driving cycle in direct comparison. Electrically or hybrid vehicles can offer full heating power right from the start, with the appropriate equipment and time preselection via preconditioning in practice sometimes even before that. Conventionally powered cars, on the other hand, are largely dependent on the waste heat from the engine. This is also the case with the compact Hyundai, which is also only equipped with manual ventilation control. In the laboratory test, it only gets going slowly in fan level two, which can be compensated manually in practice. It warms up faster if an automatic fan control increases the air flow rate during heating. Like the BMW i3, Audi, Ford and VW have electric heating elements which, when automatically activated, quickly ensure clear windows and comfortably warm feet.

Even savers can heat well

The days of really bad heating systems are basically over: The heating output of most current models is fully up to Central European requirements. There are still clear differences in comfort aspects such as warm air distribution, control quality and operating noise. This reflects the importance manufacturers attach to heating and air conditioning. That yourselfThe new Passat shows that it is possible to combine economical consumption and fast heating with a high level of comfort: With a conventional drive and only 5.3 liters of diesel in the standard consumption, it comes with convincing warm air distribution, the short heat-up times of the Mercedes S-Class and the just as quickly responding electric heating of the BMW i3 very close. The commuter is happy.

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