Comparison test Air conditioning systems in the laboratory - Reisemobil International 06/2014
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Comparison test
Air conditioning systems in the laboratory
Reisemobil International 06/2014
More comfort on the move
Climate change
by Karsten Kaufmann
Rooftop air conditioning systems for motor homes are very popular nowadays.
But which system cools the best? Dometic, Telair and Truma competed in a complex comparison
test in the climate chamber.
Perspiring is a thing of the past, today the focus is on comfort,
which is why many motor home owners are opting for high-
performance air conditioning systems in their motor home.
Rooftop systems in particular are highly popular. No wonder: they
fit precisely into the 40 x 40 cm roof cut-out of small skylights,
which means they can be installed quickly and inexpensively.
The manufacturers also supply their air conditioning systems in
different performance classes for various vehicle lengths. Reisemobil
International selected three rooftop air conditioning systems for The more varied the air flow at the air distributor can be set, the
vehicles of around 7 metres for a comparison test: the Dometic more precise the cold air distribution in the motor home.
Freshjet 2200, the Telair Silent 7300H and the Truma Aventa
Comfort. All three devices work with compressors and cost around
2,000 euros with outputs of between 2,100 and 2,400 Watts.
The most important factors of a high-performance air
To ensure a fair comparison, Reisemobil International conditioning system therefore are reducing the temperature and
commissioned an independent test institute – the EDAG in humidifying the air; but the living space should be cooled to a
Fulda. In the climate chamber of this technology and vehicle sensible, not the maximum level. Experts recommend that the
development testing specialist, all three devices needed to prove inside temperature should not be reduced by more than 6 to 7
their mettle in the climate conditions of Trieste, which has a degrees below the outside temperature – this recommendation
mean summer temperature of 35 ° Celsius and 55 % relative air was used as the basis for the assessment by Reisemobil
humidity. All the devices were installed on a Bürstner Nexxo T International (see box page 4).
690 Fiftyfive over the dinette.
This recommendation also applies at tropical outdoor
In addition to this test, Reisemobil International also compared temperatures of 38 °C. Basically, the air conditioning device
the performance of the Truma Aventa Comfort with its would need to reduce the temperature by at least 12 ° to
compressor technology and the Ebercool Holiday 3 from achieve values in the comfort zone. In this case, campers would
Eberspächer that uses evaporator cooling technology in Truma‘s feel absolutely fine inside the vehicle, but the frequent change
climate chamber. Were the systems equal? For more information between indoors and outdoors would place the cardiovascular
and results of this interesting test, please go to page 8. and immune system under considerably stress. To put it briefly:
The comfort zone is an optimum, but not necessarily the ideal
But which features actually typify a good air conditioning situation for a motor home.
system? Just the cooling output? Far from it. Automobile
manufacturers invest a lot of time and money in developing In the test the devices all managed to reduce the temperature
high-performance air conditioning systems for luxurious vehicles inside the Bürstner by six degrees with varying degrees of
that, with peak outputs of six to eight kilowatts, can acclimatise success. The Truma Aventa Truma outclassed its competitors
the tiny space inside the vehicle to a pleasant level within just a by a long margin and took just 30 minutes to complete the cold
few minutes. This involves reducing the temperature as quickly test. Dometic took almost two hours; Telair was well behind
as possible, whilst at the same time humidifying the air without with three hours. As far as humidification is concerned, all three
blasting the driver directly with icy air. performed satisfactorily.
The conditions under which a person actually feels comfortable
are shown in the „Comfort zone“ diagram on the next page.
Compared to cars, air conditioning systems in motor homes In all other tests, it was a neck-and-neck race between Truma
have a much more difficult task. They have no high-performance and Dometic. Telair‘s Silent 7300H was not able to keep up with
motor to drive the compressor, and peak values of two to the two high-performance devices from Truma and Dometic.
three kilowatts are exceptionally good. Not forgetting that the
air conditioning system needs to cool down 25 or more cubic In brief: The Dometic unit is lighter, more compact and quieter
metres, not just the meagre 3 cubic metres in a car. At the same than the competitors, and puts less strain on the fuses at
time, the sun shines mercilessly through the large windows with camping sites when started due to the short current peaks. In
around 1 kilowatt per square metre. A formidable task, which contrast the Truma unit has a clever system that distributes
is just one more reason why clever motor home owners always and controls the air flow in the vehicle. The control units are
try to park their vehicles in the shade to make the most of the designed so that even the least technically minded of campers
cooling effect of the air conditioning system. can easily understand how to use them.
2 REISEMOBIL INTERNATIONAL 6/2014
In terms of features, Truma and Dometic are on a par. Both devices
allow the start times to be programmed and the menu navigation of How Reisemobil Inter
the remote controls is easy to understand. When the start times are
programmed, both devices can cool the motor homes down before national tested and
the owner returns – this is a feature missing in the Telair unit. assessed the units
And? Who is the ultimate winner?
A standardised comparison test of compressor air
conditioning systems for motor homes is only effective
under standardised test conditions.
Temperature
EDAG is a service provider for the automotive industry and
specialises in testing and developing parts and models through
to entire vehicles for automobile manufacturers. With its
Temperature (°C)
workforce of 1500 in Fulda and more than 70 international
locations, EDAG is the most reputed service provider to the
automotive industry in the world.
Bürstner provided a Nexxo T 690 Fiftyfive, a semi-integrated,
with two single beds in the rear for the test. Before the test
started, the Bürstner was equipped with seven combined
measuring sensors (air humidity/temperature): one at the end
of each bed, one at head height between the beds, one in the
centre of the living space and one each at head height on the
driver‘s and passenger‘s side.
Time in hours
Each air conditioning system was installed and configured by
a technician from the manufacturer‘s company to guarantee
Air humidity best air distribution and cooling. After the installation and
configuration work, the EDAG climate chamber was heated
overnight to 35 °C and 55 % relative air humidity. To ensure that
Absolute humidity (g/m3)
the Bürstner heated up as evenly as possible during this period,
all windows and doors in the vehicle were left open all night.
Each installed air conditioning unit underwent the night-time
heat-up phase.
Before the test was started in the morning, all windows and
doors of the Nexxo were closed, the climate chamber was kept
constant at 35 °C and 55 % relative air humidity. The test always
started with the cool-down test: The systems now needed to
prove how quickly they could reduce the inside temperature.
Time in hours
Comfort zone
Power consumption
Relative humidity (%)
Power consumption (A)
Temperature (°C)
The field marked in red indicates the range at which a person
feels comfortable; the blue area is barely comfortable. It is
considered good for health if the inner temperature is cooled
Time in hours to maximum six degrees below the outside temperature.
REISEMOBIL INTERNATIONAL 6/2014 3
How were the test criteria weighted?
A star is not just a star Power consumption – 8 per cent
Depending on the weighting of the sub-test, evaluation stars Independent operation is practically impossible in this
with various evaluation points flowed into the final result. The performance class – when plugged into the mains, lower
cooling performance makes up 24 per cent of the total result; consumption really saves money.
each evaluation star is therefore worth 4.8 points. Weight
makes up 8 per cent of the result; each star therefore raises Noise level – 12 per cent
the final result by 1.6 points. The noise created by the air conditioning device is of
particular relevance at night. Inside the vehicle, the operating
Weight – 8 per cent noises of the compressor and the air distributor overlap. From
In the weight evaluation, there was a difference of 4.8 kg a subjective point of view, the noises produced by all three
between the Dometic and the Telair; a deviation of more than devices are similar: Therefore assessing the sound level in
10 per cent and therefore a weight difference that needed to dB(A) is easy: Two dB(A) is an audible difference, three dB(A)
be taken into account in the evaluation. is almost twice as loud.
Dimensions on the roof – 8 per cent Air distribution – 20 per cent
The size of the air conditioning device on the roof decides This in combination with the cooling output is the primary
whether or not a model can be installed in a vehicle. If there is factor of all evaluations. How well can the air distribution
sufficient space, the dimensions are irrelevant. of the air conditioning device be set to the various layouts
and individual needs of the motor home owner? Can the air
Height inside air distributor – 10 per cent quantity and blow angle be changed? Can the air flow be set
A high air distributor reduces the standing height and can to a specific point or a fan distribution?
hinder the opening of doors (bathroom). Also, a bulky frame
is unattractive. Cooling performance – 24 per cent
How quickly does the system reduce the temperature inside
Start-up current – 10 per cent the vehicle by six degrees? This is by far the most important
The level and duration of the start-up current decide whether factor in all evaluations. Another important factor is its weight.
the fuse at the camping site will trip or not. If the start-up
current is flat and brief, the fuse will probably not trip. Heating performance:
However there is no guarantee for this, it depends largely on The different heating performances of the air conditioning
the installed fuse and the quality of the installation. systems does not flow into the results because the heat
pumps (Telair, Truma) and heating rod (Dometic) have
advantages that are difficult to compare.
Truma‘s Aventa and the Dometic Freshjet are on an equal
footing in this test. Both devices scored around 90 from a
possible 100 points earning the grade „Excellent“.
However Truma‘s Aventa achieved much better marks for the
mandatory tests – cooling output and air distribution – that are
so decisive for air conditioning devices, thereby just pipping the
Domestic device at the post. Congratulations.
Just one point behind: the Dometic Freshjet 2200. With its high
performance, it will remain first choice for some motor home
enthusiasts, for instance, when there is little space available
on the roof or if quieter operation at night plays a decisive role.
Based on these factors, Reisemobil International‘s purchase tip
is the Dometic Freshjet 2200.
Climate continued: Read some interesting facts about the
operation of air conditioning systems and why under bunk air
conditioning systems can be an attractive alternative to rooftop
units in the next issue of Reisemobil International. Which air
The Aventa conditioning system is suitable for self-sufficient campers and
can be operated
for whom are lower-performance devices a good option? All this
via the new CP plus
display of the Combi in the July edition.
heating system.
4 REISEMOBIL INTERNATIONAL 6/2014
Test protocol Dometic Test protocol Truma
Freshjet 2200 Aventa Comfort
Dometic has incorporated lots of modern air conditioning
technology in its Freshjet line. The technicians have been able to
make by far the most compact device in this performance class.
The smallest Freshjet only needs just 0.44 square meters of
space on the roof, in contrast the Truma Aventa commands 0.66
square meters of space. The compact dimensions are reflected
in the weight: the Dometic weighs in at 32 kilograms; the Truma
device puts a further 1.7 kilograms on the roof.
Although both products consume similar levels of power, the
Dometic is at a clear advantage in terms of start-up current.
Whilst the oscilloscope registered around 25 amperes for both
devices during start up, this only lasted for 65 milliseconds for The Truma Aventa Comfort stands out in the core disciplines of
the Dometic unit; the peak current for the Aventa lasted 100 an air conditioning system: It allows the air flow to be varied for
milliseconds. This means that the Freshjet puts less strain on the different layouts and individual needs, and also cools the
the fuse and, depending on the fuse type at the camping site, interior much faster. Nominally, its cooling output of 2,400 Watts
this may be a decisive factor in terms of whether or not the fuse only lies 200 Watts above the performance of the Dometic
trips. Freshjet. This is a comparatively small difference that in no way
Dometic also are ahead in a further aspect: it was quieter than explains the dominance of the Truma unit in terms of its cooling
the other tested models. In particular in the night mode, the output. In the test, the technicians of the companies were called
fan purred quietly. The reason that the noise evaluation marks upon to set the air distributor to meet the requirements of the
were so similar is due to the additional function of the Aventa layout in the vehicle; a task that the technicians from Truma
that shuts down the fan of the rooftop cooling device at night to
avoid annoying the neighbours.
The areas where the Dometic Freshjet lost ground were the
evaluations of the air distribution and cooling output, where
Truma clearly outdid the competition in these important
disciplines. The tested Chillout air distributor not only has
air nozzles at the front and back, it also has two that blow
downwards; however, the test did not identify any positive effect
in terms of particularly homogenous air cooling. On the contrary,
the rear measuring sensor in the sleeping area showed that the
cooling effect in the rear was delayed.
The flow geometry for all nozzles is fixed in the Dometic unit;
only the air quantity at the nozzles can be varied. The Dometic With a thickness
of just 45
lost the most points in the cooling output assessment. The millimetres, it
Freshjet took 1 hour 48 minutes to reduce the temperature is the flattest
inside the Bürstner Nexxo by six degrees; in contrast the Truma air distributor in
Aventa only took 30 minutes. the test. The air
flow can be set
variably, which
In addition to the pure laboratory data: The Dometic unit had is a decisive
clearly dehumidified the inside of the vehicle after just a few advantage of the
minutes, and circulated noticeably cooler air into the motor Aventa.
home. The pleasanter atmosphere inside the vehicle was
apparent within a few minutes.
Summary Dometic apparently solved extremely well thanks to the various setting
Anyone seeking a compact and unusually quiet rooftop air options. All seven measuring sensors in the vehicle recorded
conditioning system will be hard pushed to find something even homogenous cooling inside the vehicle. The Aventa
better than the Dometic Freshjet 2200. The cooling reduced the temperature inside the vehicle by six degrees to
performance is good, even though it does not reach peak 29°C in just 34 minutes; the relative air humidity dropped to
performance values. 42.95 per cent, the absolute value being 10.62 grams of water
Tel.: +492572/879195, per cubic metre air – this is a clear indication that the air was
www.my-caravanning.com humidified. In terms of weight, the amount of start-up current
and space requirements on the roof, the Truma took second
REISEMOBIL INTERNATIONAL 6/2014 5
and cooling output categories, the more modern units from
Dometic and Truma were clearly ahead. The Telair was only
just able to reach the target value of 29°C inside the vehicle.
Regardless of the measured values, from a subjective point of
view, the Telair also noticeably cooled and dehumidified the
inside of the vehicle. On the other hand, the competitors set
standards in terms of noise levels that were too high for the
Telair. In the lowest fan level, the rumbling and rough running
compressor and fan were more than 10 decibels louder than
the quiet Dometic. A difference that is clearly audible, especially
at night. The menu navigation and operation of the Telair are
as simple and easy to understand as always. Anyone seeking
a power heating function in an air conditioning system will find
one in the Telair unit: The integrated heat pump heats at outside
temperatures of around 4°C with 2,300 Watts.
Summary Telair
Aventa
comfort The Telair Silent 7300H cannot match the strong competitor
products from Dometic and Truma. The price is attractive and
it has enough potential to ensure noticeable cooling on the
inside of the vehicle. A tip for price-conscious buyers who
are not bothered by the loud operating noise.
place behind the Dometic unit. Also, the Aventa was much Tel.: +498921/129995,
louder in night mode with almost three decibels. However the www.supporttelecogroup.com
Aventa reduces the fan noise in this operating mode on the
roof, which is certainly a relief for neighbouring campers – a
bonus point in the sound level category. A further advantage:
the Aventa can be operated via the new CP Plus display of the
Combi heating system.
Summary Truma High-tech simulates
Thanks to the excellent cooling performance and variable air perspiration
distributor system, the Truma Aventa Comfort won the test
narrowly but deservedly. May we introduce Eddy? Not the friendly man in the picture;
Tel.: +4989/46172020, that’s Matthias Schultheiß, an engineer at EDAG. No, Eddy is
www.truma.com the monstrous technical device at the front of the picture. His
task? To perspire. Eddy was developed to test and optimise seat
air conditioning. His surface can perspire and at the same time
record where he can best get rid of moisture and heat. In the
Reisemobil International test, fat Eddy (he weighs 75 kilograms)
records any specific cold spots, i.e. areas that are specifically
cooled by the air conditioning system. This is an effect that is
to be avoided because the driver of the motor home would find
Test protocol Telair these icy air flows
Silent 7300H unpleasant.
Positive: In the test
At a price of just 1,600 euro Telair is by far the most inexpensive Eddy felt equally
and, with just 2,100 Watt, nominally the weakest device in the comfortable
test. Telair could have sent the 2,350 Watt Silent 8300H unit with all three air
into the test, but apart from the cooling output, it is technically conditioning units.
the same as the smaller unit and at 1,760 euro would have
almost cost the same as the two other competitor units. The
remote control is included as standard; in contrast to Dometic
Eddy‘s sensors
and Truma, the Silent does not allow the start time to be
show relatively
programmed. homogenous
cooling of the front
The Telair could not keep up with the other two units in the test. side of the body.
The Silent was not able to win any of the test categories. Only
its size and power consumption values are similar to the other
units. In particular in the important sound level, air distribution
6 REISEMOBIL INTERNATIONAL 6/2014
Assessment of the compressor air conditioning
systems in the comparison test
Manufacturer/device Dometic Freshjet 2200 Telair Silent 7300H Truma Aventa Comfort
Price* (device/air distrib.) 2,029 Euro complete 1,600 Euro complete 1,998 Euro complete
(1,799 / 230 Euro)
Remote control/timer function yes/yes yes/no yes/yes
max. cooling output 2,200 Watt/7,500 Btu/h 2,100 Watt/7,200 Btu/h 2,400 Watt/8,200 Btu/h
max. heat output (system) 1,200 Watt (electr. heat rod) 2,300 Watt (heat pump) 1,700 Watt (heat pump)
recommended vehicle length max. 7.0 metres max. 7.0 metres max. 7.5 metres
Weight 32,0 kg 36,8 kg 33,7 kg
8 per cent ✩✩ ✩
Points 8 4,8 6,4
Dimensions on roof 562 x 232 x 787 mm 650 x 235 x 980 mm 660 x 251 x 1.008 mm
8 per cent ✩✩ ✩✩
Points 8 4,8 4,8
Height inner air distributor 47 mm 65 mm 45 mm
10 per cent ✩✩
Points 10 6 10
Start-up current 25,1 A/65 ms 27,4 A/140 ms 25,2 A/100 ms
10 per cent ✩✩ ✩
Points 10 6 7
Power consumption per fan level 1,07/1,06/0,95/1,01 kWh 1,34/1,20/1,19 kWh 1,17/1,05/0,94/0,94 kWh
8 per cent ✩
Points 8 6,4 8
1. 56,7 dB (A) 1. 59,2 dB (A)
Noise level 2. 52,1 dB (A) 1. 64,1 dB (A) 2. 50,8 dB (A)
(60 measured values per minute 3. 46,2 dB (A) 2. 58,0 dB (A) 3. 48,6 dB (A)
- assessed mean value on every fan level) 4. 43,8 dB (A) 3. 57,7 dB (A) 4. 46,7 dB (A)
12 per cent ✩✩ ✩
Points 12 6 9,6
Fixed geometry of the four Air quantity and blowing Distribution, quantity and
nozzles: Front and rear, two angle can only be varied at blow angle can be set
downward, air quantity can
Air distribution the same time, two nozzles: individually at the front
be regulated Front and rear and rear
20 per cent ✩ ✩
Points 16 16 20
Cooling output (fast and even
Distribution in the vehicle)
24 per cent ✩ ✩✩
Points 16,8 14,4 24
Total points 88,8 65,6 89,8
REISEMOBIL INTERNATIONAL 6/2014 7
Concept comparison:
A compressor air conditioning system versus an evaporator cooling system
What system can do what?
Dometic, Truma and Telair all use compressors in their air The Ebercool stands out in one important aspect for some motor
conditioning systems; in contrast Eberspächer uses the home users: If there are adequate battery reserves, it can be
evaporator cooling technology in the Ebercool Holiday 3. The operated via the 12-Volt on-board supply both at a standstill or
cooling devices for the rooftop assembly look similar at first when the vehicle is moving. If the fan output is lower, it draws
glance, but the technology inside is completely different. Both between two and four amperes from the batteries. Attractive
systems were mounted in a 40 x 40 centimetre rooftop cut-out values for self-sufficient campers.
that is standard for a Mini-Heki. The systems are mounted
quickly; a practiced technician needs just half an hour. Whilst
the technician additionally needs to fit a thin power cable for + runs with 12 Volt
the compressor air conditioning system, the installation of + also functions when vehicle is moving
the finger-thick hose to the fresh water tank for the Ebercool + moderate cooling performance at very low air humidity
Holiday requires much more time and effort. This is reflected in + low weight on the roof
the higher installation costs and significantly qualifies the price +/– roof hood (important) and windows/doors may and must
advantage of 300 euros for this device that costs 1,670 euros. remain open
+/– always sucks in outside air, no circulation of interior air
– noticeable cooling of the entire interior, only possible in
Ebercool Holiday 3 in the test extremely dry climates
– requires up to two litres of water from the fresh water
Evaporator systems evaporate water, removing heat from the tank per hour
air thereby cooling it. The drier the suctioned-in ambient air, – only the fan function is useful when the air humidity is
the more effective this process is. However, due to the air that high, the cooling function almost ineffective
is blown in, the air humidity inside the vehicle increases. This is – raises the air humidity in the vehicle, therefore ...
an counterproductive because values in the comfort zone are – ...no dehumidification of the air at any time
only reached in exceptional cases (see page 3), for instance – cannot rule out possible recontamination of the
in extremely dry climates with relative air humidity levels of evaporator surface in the fresh water
between 10 and 25 per cent. Values that we experience very
rarely in Germany, Italy, France or Spain.
In the Reisemobil International test, the climate chamber is set
to an outdoor temperature of 35 °C and a relative air humidity Truma Aventa in the test
of 50 per cent. These are moderate summer values for Europe,
in the evening the air humidity can quickly rise to well over 75 As soon as it is switched on, the Truma Aventa blows cold
per cent. During the course of the test, the Ebercool cooled the air into the vehicle within a few seconds. Anyone standing
inside of the vehicle by around four degrees (more accurately, or sitting close to the air distributor will feel immediate
by four Kelvin). The air humidity in the vehicle at this time was relief. Cooling and dehumidification operate in parallel in the
oppressively high, despite the slightly opened window. When compressor device. The goal of the technology is to bring the
the testers opened the roof hood and window even further, the temperature and air humidity inside the vehicle as close to the
air humidity in the vehicle sank, however the temperature at the comfort zone as quickly as possible. In this combination of a
seven measuring sensors in the vehicle soared quickly almost pleasant temperature and air humidity level, occupants will feel
reaching the starting values. comfortable and sweat less. After around 30 minutes the Aventa
It is more pleasant in those areas where there is a slightly cool reduces the inside of the vehicle to a pleasant temperature that
air flow. Anyone who sets the nozzles so that the body is directly is six degrees below the outside temperature.
or indirectly exposed to the air flow, feels a cool breeze and After 1 hour and 30 minutes, the temperature and air humidity
experiences noticeable but slight relief. reach values within the comfort zone.
Summary concept comparison
An evaporator cooling system is only to be recommended for acclimatising the entire inside of the vehicle in
extremely dry climates. Anyone who is satisfied with a slight breeze and likes to keep their windows and doors open
should think about installing an Ebercool Holiday 3.
Truma Gerätetechnik GmbH & Co. KG Telefon +49 (0)89 4617-2020
Wernher-von-Braun-Straße 12 Telefax +49 (0)89 4617-2159
85640 Putzbrunn service@truma.com
Germany www.truma.com More comfort on the moveYou can also read
