Solar system

The „drain-back” name refers to the operation principle of the solar collector system as it means “to flow back”. Thus, according to the scheme on the figure below, water can be diverted from the solar collector back into the storage tank with the help of a built-in magnet valve, using gravitation, if it is justified from heat technological point of view.

>> Detailed description of operation principle <<

Main characteristics of DL-Drainback solar collector system

As compared to solar collector solutions available in the market today, the advantages of drainback solar collector system developed by Direct-Line Ltd. lie in its operational principle, constructional layout and base materials used.

The advantages due to operation principle are the following:

  • High system efficiency, no direct heat loss
  • Protection against frost and boiling
  • Protection against power outage
  • Intelligent, user-friendly control
  • Continuous status display
  • Possible problems are reported in the form of error messages and warnings
  • The system is operating at atmospheric pressure, so no pressure keeping vessel is required (the tank is made of polymer)
  • The heat transmission fluid is water, so no antifrost medium is required
  • No dead hot water, which is more favourable from hygienical point of view
  • Low maintenance need
  • The production and operation of the system represents an environmental friendly technology
  • The operation of the system does not require specialized knowledge

Constructional layout and advantages of use of stainless steel base material:

  • Excellent resistance to aggressive agents
  • Ability to be used for direct pool heating
  • Almost unlimited life-cycle (50 years)
  • Minimal convective heat loss due to small air gap
  • Its specific investment, operation and maintenance costs are lower
  • Aesthetical layout

>> DL-solar collector systems catalogue <<

>> DL-drainback solar collector leaflet <<


Elements of DL-Drainback-Solar collector system

DL-Solar collector
The first step toward energy rationalization and savings in energy costs is to use solar collectors. In the last decade, significant R&D efforts have been made at Direct-Line Ltd. to define, develop and test the adequate materials and manufacturing technologies. As a result of these efforts, the plain sheet solar collector body that can be manufactured from stainless steel very efficiently has been created.

The advantages of DL-Solar collector
One of the main advantages of our solar collector as compared to solar collectors available in the market today lie in its material. The most important positive features raised by stainless steel material and constructional layout are the following:

  • Aesthetical layout
  • Excellent resistance to aggressive agents and environmental pollution
  • Low maintenance need
  • Favorable mechanical features
  • Insulation free of vacuum and gas filling
  • Small air gap leads to minimal convective heat loss
  • Almost unlimited life-cycle
  • Provides energy for a long time after the return of its investment
  • Its manufacturing and operation represent environmental friendly technologies
  • It can be integrated into existing solar collector systems

In case of pool heating, the panels are made of stainless steel base material of type 1.4404, resistant to acid and alkali.

The lifetime of our stainless steel solar collectors significantly exceeds 40-50 years indeed. Consequently, its specific investment, operation and maintenance costs is lower than the less time-resistant layouts. We undertake a guarantee of 15 years for our solar collectors.

Technical parameters of our DL-Solar collector

  • Dimensions (external dimensions): 1995 x 1140 x 75 mm
  • Useful collector surface: 1,95 m2 (without edges collecting water)
  • Largest performance: 2,08 kW (perpendicular solar position, clean, sunny and calm weather)
  • Filling volume: appr. 4,5 litre
  • Total weight: 65 kg
  • Connection dimensions: 4 pipe ends 18×1
  • Mounting: with stainless steel profiles
  • Collector body material: 1.4301 austenitic stainless steel
  • Cover: iron-free, water clean tempered glass of 4 mm and gasket

In order to manage different statuses of DL-Drainback-Solar collector, we have developed an intelligent microcontroller-based control, which control surface is user friendly.
For details of control, click here.

One of the main advantages of our the tank we have built in the solar collector as compared to other tanks available in the market today lie in its material. The tank built in DL-Drainback-Solar collector system is made of polymer.

The advantages of drainback tank

  • Easy to deploy
  • Good resistance to oxidation and environmental pollution
  • Aesthetical layout with soft white, shiny cover
  • Favorable mechanical features
  • Closed insulation
  • Long lifetime
  • Heat exchanger with large surface
  • There is no dead water in sanitary hot water
  • It stores energy for free long after its return of investment

Sample offer
Our general sample offers for solar systems, without deployment, with elements fixing the system onto roof for 2012:


System design
We design the solar collector system that fully complies with your unique needs! The solutions we have developed and sold contain the solar collectors, tank and related hydraulic and electric building elements. System scale is performed on the basis of energy needs.

Please, contact our experts so that you can gain profits offered by solar energy as early as possible.

Send us back the data request form filled in via e-mail or fax and we will contact you with an informing offer.
Fax: +36 24 492 112

In case of further information needs, do not hesitate to contact our colleagues.

We manufacture the main elements of the solar collector system in our plant located in Dunaharaszti, Hungary. During the fulfilment of an order, we deliver each system element from our store.

In case of fulfilment of an order, we undertake delivery and deployment of system elements. Traditionally, solar collectors are mounted onto roof, roof plane or separate stand. Furthermore, the layout we have developed can be fixed onto southern front of buildings or sunk into the wall, depending on the operation principle of the system. The insulation costs that can be saved this way permit the deployment of a larger collector surface. In winter months, a larger efficiency can be obtained due to low sun position than in case of layout mounted onto roof. Further advantage emerges in the fact that glass surfaces can be kept clean easier. It is under development to offer a secondary use of solar collectors as space filling elements of railing systems, canopies or billboards.

In case of demand, we undertake annual maintenance and check of the solar collector system that includes the following services:

  • Check of electric equipments
  • Check of tank and hydraulic engineering work (water level, water quality) cleaning
  • Cleaning of collector surface, check of collector quality

© Készítette - Direct Line - Bemind Kft.