Solar heating from Viessmann: innovative collectors for DHW generation and auxiliary heating
What’s new at a glance:
-ThermProtect, the innovative automatic shut-off, now protects not only Viessmann flat-plate collectors from overheating, but Vitosol vacuum tube collectors, as well.
-The two new vacuum tube collectorsViessmann is now presenting,Vitosol 300-TM and Vitosol 200-TM, are the first of their kind in the world: both heat pipe collectors have ThermProtect temperature shut-off and can be installed in any position – evenhorizontally.
ThermProtect: automatic overheating protection for flat-plate and tube collectors
By equipping the Vitosol 200-FM and 100-FM flat-plate collectors with the ThermProtect temperature shut-off – the first and only one of its kind in the world – Viessmann already set a milestone in the efficiency and operational reliability of solar thermal systems. Now the new Vitosol 300-TM and 200-TM vacuum tube collectors also feature this automatic shut-off to reliably prevent the collectors from overheating.
Solar thermal systems with ThermProtect: durable and reliable
With ThermProtect, even large collector surfaces can be planned without having to worry about stagnation. This Viessmann technology shuts off the collectors as soon as they reach a preset temperature limit. The temperature shut-off on Vitosol flat-plate and tube collectors works completely independently of the system configuration, control setting, and installation position of the collectors. The thermal loads on the system components and on the heat transfer medium always stay within normal range. This makes them last longer and work more reliably compared to conventional solar thermal systems.
Reduced installation outlay
The installation outlay is reduced because auxiliary vessels and stagnation coolers are no longer required. What is more, since there are no longer any worries about the heat transfer medium giving off vapor with the Vitosol 300-TM, 200-FM, and 100-FM collectors, the hydraulic lines can be laid in many more different ways.
Vitosol 200-FM and 100-FM: crystals prevent overheating
In the Vitosol 200-FM and 100-FM flat-plate collectors, a crystalline absorber coating regulates the energy input. The ThermProtect coating functions physically by means of temperature-dependent changes in the crystal structures. Above a collector temperature of about 75°C, these crystal structures reflect more of the solar radiation striking them. A further rise in temperature is limited, thus reliably preventing vapor formation.
If the temperature in the collector falls again, the crystal structure returns to its original state. The energy absorbed by the collector is no longer radiated back into the surroundings and can be used in the solar thermal system. The change in the crystal structure is indefinitely reversible and the function is therefore permanently available.
Vitosol 300-TM and 200-TM: heatpipes with temperature shut-off
In the new Vitosol 300-TM and 200-TM vacuum tube collectors, the ThermProtect temperature shut-off takes over a self-regulating heat pipe, which is integrated into the heat exchanger of the collectorby means of a dry connection. The solar heat vaporizes the medium trapped inside the heat pipe. During the following liquefaction in the condenser, the heat is released back to the solar thermal system and the medium flows back into the sunlit area of the vacuum tube.
When a temperature limit of approx. 120°Cis reached, the medium can no longer condense. This phase-change temperature shut-off interrupts the heat transfer and thus protects the system from excessive stagnation temperatures. The cycle in the heat pipe does not restart until the collector temperature is low enough and solar heat is again transferred into the heating system.
Reliably avoid overheating
A solar collector generates heat whenever sunlight strikes the absorber – even if this heat is not needed. So conventional collectors without temperature shut-off can be expected to overheat and form vapor especially in summer, when they remain unused for long periods of time. For example, when the homeowner is on vacation and the solar heat is not being used in the house: the circulation pump switches off and the solar thermal system goes into stagnation. If the sun keeps shining, the rise in collector temperatures can cause the heat transfer medium to vaporize and put a high thermal load on such system components as seals, pumps, valves, and the heat transfer medium. Vapor can be reliably avoided in systems with a higher system pressure (for example,3 bar) and collectors that switch on and off.
Advantages for trade partners
-High operational reliability and long lifespan of all components thanks to lowering the stagnation temperature
-Independent of collector installation position, control settings, electricity supply, and mechanical devices
-Considerable reduction in thermal load on system components.
Advantages for users
-Longer lifespan of all system components thanks to low thermal load
-Higher system availability and greater energy utilization thanks to quicker collector restart
-ThermProtect temperature shut-off on all standard collectors is purely physical and self-regulating without any additional external components and auxiliary energies
Technical data
-Collector surface: 2.3 m2 (flat-plate collectors)
-Collector surface: 1.26 to 3.26 m2 (vacuum tube collectors)
Delivery date
The Vitosol 200-FM and 100-FM flat-plate collectors have already been launched on the market. The new Vitosol 300-TM and 200-TM vacuum tube collectors will be available starting in April 2017.
Vitosol 300-TM:new heat pipe collector that can be installed regardless of position
The new Vitosol 300-TM is the world’s first vacuum tube collector to have the ThermProtect automatic overheating protection that reliably prevents vapor formation in the solar thermal system, and which can be installed horizontally. It thus unites three outstanding characteristics in a single product: high output, reliably protection from overheating, and great flexibility. The collector, which can be installed regardless of position, is designed for use in single-family homes and large residential buildings.
Horizontal heat pipe
Vitosol 300-TM works on the heat pipe principle, in which the solar medium does not flow directly through the tubes. Instead, a separate medium vaporizes in the heat pipe and releases the heatto the solar medium through condensation by way of the Duotec twin-pipe heat exchanger. The design of the heat pipe allows the collector to be installed in practically any position – vertically or horizontally on slanting roofs, horizontally on balcony balustrades, lying or standing on flat roofs.
High solar yields
Almost all the solar radiation striking the surface of the glass tubes is retained by the absorbers inside them with their selective coating. The vacuum ensures that hardly any heat is lost to the surroundings. This substantially increases the Vitosol 300-TM’ssolar yield compared to an equivalent surface area of conventional collectors. This collector needs no mirrors behind the absorber, which unavoidably diminish in effectiveness as they get dirty over time. The permanently evacuated tubes and the collector enclosure insulated with melamine foam, an excellent thermal insulation material, guarantee that almost all the heat is transferred to the solar thermal system with little loss.
The absorbers can be adjusted toward the sun in order to increase the solar heat yield, depending on the installation position. For this purpose, the individual tubes can be turned axially by plus-minus 25 degrees.
Advantages for trade partners
-A world first – horizontal heat pipe with ThermProtect temperature shut-off
-Unlimited uses because installation is possible in any position
-Considerably lower loads on system components thanks to ThermProtect
-Temperature shut-off functions regardless of control settings, electricity supply, and mechanical components (for example,valves)
-Easier system planning
-Flexible product selection thanks to various collector sizes
Advantages for users
-Long lifespan of the system thanks to low stagnation temperatures and avoidance of vapor formation
-Protected from overheating during long periods of sunshine when no heat is being used
-Self-sufficient function – ThermProtect is always operational
-Fast restart after system standstill
-Enhanced auxiliary solar energy to cover heating and DHW generation thanks to larger collector surface
-Low operating costs thanks to long durability of solar components
Technical data
-Collector surface: 1.26, 1.51 and 3.03 m2
-Operating pressure: 3 bar
Delivery date
The new Vitosol 300-TM vacuum tube collector will be launched on the market in April 2017.
Vitosol 200-TM: vacuum tube collector with ThermProtect for larger solar thermal systems
Large solar thermal systems are often affected by stagnation in the warm months of summer. Hence the new Vitosol 200-TM has been designed especially for large residential buildings, schools, and commercial buildings. It also has ThermProtect to prevent overheating and can also be horizontally mounted on flat roofs because its absorbers can turn 45 degrees.
Absorber can turn up to 45 degrees
The heat pipe in the new collector is designed to be installed in nearly any desired position– even horizontally, with simultaneous temperature shut-off by ThermProtect. The solar heat is released to the solar medium from the heat pipe by having the medium inside it vaporize and then condense in the copper heat exchanger. Thanks to their dry connection with the vacuum tubes, the absorbers can be turned by up to 45 degrees even during operation. This enables them to be adjusted exactly to the sun with a minimum of shading.
Maximum utilization of solar energy
Inside the Vitosol 200-TM vacuum tubes are absorber plates with a highly selective coating. High solar heat yields are achieved in combination with the permanently evacuated tubes and the heat insulation on the collector enclosure. The collector can therefore convert even low levels of solar radiation into useable heat. Mirrors that direct additional sunlight onto the absorbers are not needed in the Vitosol 200-TM.
Advantages for trade partners
-A world first – horizontal heat pipe with ThermProtect temperature shut-off
-Considerably lower loads on system components thanks to ThermProtect
-Self-sufficient temperature shut-off– regardless of control settings, electricity supply, and mechanical components (for example,valves)
-Easier system planning
-Especially well-suited for large systems and horizontal installation on flat roofs
-Reduced ballast when installed horizontally
-Flexible product selection thanks to various collector sizes
Advantages for users
-Long lifespan of the solar thermal system thanks to low stagnation temperatures
-Protection from overheating during long periods of solar radiation
-Self-sufficient function – ThermProtect is always operational
-Fast restart after system standstill
-Enhanced use of solar energy thanks to larger collector surface
-Low operating costs thanks to long durability of solar components
Technical data
-Collector surface: 1.63 and 3.26 m2
-Operating pressure: 1 bar
Delivery date
The new Vitosol 200-TM vacuum tube collector will be available starting April 2017.
Images / captions
Fig. 1: Viessmann offers a comprehensive program of various Vitosol flat-plate and vacuum tube collectors, all of which have a ThermProtect temperature shut-off to protect against overheating.
Fig. 2: During regular collector operation, the ThermProtect coating on Viessmann’s Vitosol 200-FM and 100-FM flat-plate collectors acts like any conventional absorber coating. Above a collector temperature of 75°C, however, much more radiation is released, thereby reliably preventing overheating and vapor formation.
Fig. 3: The self-regulating heat pipe in Viessmann’s Vitosol 300-TM and 200-TM vacuum tube collectors: when the temperature limit of approx. 120°C is reached, the medium can no longer condense, thus interrupting the heat transfer and protecting the system against excessively high stagnation temperatures.
Fig. 4: The new Vitosol 300-TM from Viessmann is the world’s first vacuum tube collector to have ThermProtect automatic overheating protection to reliably prevent vapor formation, and can also be installed horizontally.
Fig. 5: Viessmann’snewVitosol 200-TM vacuum tube collector is designed primarily for larger systems and for horizontal installation on flat roofs.
March 2017