What You Need to Know About the New Drainback Technology from Vaillant

Dubai - 23.12.2013

Solar radiation across the GCC region exceeds the 2,000 kWh/m2, makes it two times higher than many other countries in Europe and other parts of the world. The benefits and harms to any Solar Water Heating system due to this fact can be significant.

To begin with, the benefits can be briefed by the reduced system size and the high efficiency due to the high solar radiation. On the other hand, the harm can be great to any solar water heating system due to overheating of the flat plate solar collectors for example, and more specifically pressure/temperature build up and stagnation problems inside the system that can cause undesired outcomes to the existing system.


As a practical and efficient Water Heating solution to this inevitable dilemma, Vaillant has unveiled its brand new stagnation-free Drainback Solar Water heating system which improves the performance and lifetime of solar thermal systems, as well as reduce maintenance costs.

Designed with commercial applications in mind which tend to require hot water throughout the day when the building is in use, such as hotels, schools, healthcare, the simple-to-install Vaillant Solar Thermal Drainback system consists of a solar collector array, pump, drainback vessel, heat exchanger and control.

The drainback Solar Water Heating system works by allowing the solar fluid to fully drain from the Solar collector and back into the discharge vessel within the Solar Drainback module as soon as the heat demand in the cylinder is met.

When the cylinder then calls for heat again, the module senses this demand and automatically pumps the fluid back up to the solar collector to capture the sun’s heat energy and transfer it back into the cylinder.


With Vaillant’s Solar Drainback system, the solar thermal system does not stagnate, meaning the solar fluid does not degrade as quickly. This increases lifetime, lowers on-going cost and reduces the need for maintenance. It also means that there is no requirement for an expansion vessel, thus saving space.

The shorter length of solar circuit due to the loading unit design means that there is less need for solar fluid and the addition of high efficiency pumps mean there is less need for electrical consumption, increasing the relative solar coverage.