underground tank


Water tanks take over crucial tasks in heating and / or cooling systems, whether as the heart of energy management or as an intermediate storage for heat or cold. For systems that can not use an efficient tank for reasons of space, unitec Energietechnik GmbH offers an alternative with the underground tank system. Due to the thermal insulation, a simple installation in the ground is possible, waterproof and pressure-stable. A special surface coating of the insulation additionally protects the tank. The manhole allows a walk-in cover as a control opening.

  • selection of the operating pressure possible
  • insulation up to 200 mm
  • alternatively available as a recumbent version 
  • version as buffer or combination tank

Factory standard versions

   typecontentheat exchangerHelix-exchanger
800827 liter2,4 m²7 m² / 65 liter
10001152 liter3,0 m²8 m² / 75 liter


  • combined System of buffer tank and drinking water tank possible
  • ideal for integrating solar systems, heat pumps, solid fuels, oil, gas
  • accessible cross-over cover as control opening (also passable)
  • no waste of space due to Underground construction
  • highly effective thermal insulation
    with Special Surface coating
  • ideal for integrating solar systems

Helix - the innovative stainless steel corrugated tube

The drinking water is heated by the flow process and thus not stored temporarily. The hot water comes straight from the pipe and stays alive and fresh! Already from the first shower
you will notice the difference clearly!


Why a corrugated pipe?

  • 50% larger surface than smooth tubes
  • better heat transfer through turbulence formation at low flow rates 
  • laying in great lengths
  • heat and fluidically optimized pipe profiling


Also in an underground tank?

Sure, of course! It does not matter where the tank is - it can be buried, too. Underground
tanks have the advantage of being perfectly positioned - the solar system in the vicinity,
the fresh water line leads directly to the tank, ...

Improved overall performance and hygiene of spiral corrugated pipes compared to parallel corrugated pipes. No dead water zones, constant turbulence.

Individual designs

Not always a factory model is sufficient or is ideal for the requi-rements of the plant. We also offer individual advice and planning for underground tank systems! The tank is manu-factured by us and isolated by a long-term partner with your desired strength and provided with a protective layer. Thus, nothing stands in the way of use for almost any purpose.

Up to 10,000 liters underground tanks are usually made standing - lying containers with 200,000 liters of content
are also no problem!

The insulation decides over the lifetime of the tank and when
it comes to this, we do not compromise!
For our high demands we use foamed PU-material up to 200 mm thickness and a hard PU-coating for the final protection.