Our customised sewer heat exchanger system Therm-Liner consists of the heat exchanger modules and their optimum connection to the heat pump. Read interesting facts about the functionality and installation here and ask us how you too can use the innovative UHRIG technology.

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Team Energy from Wastewater
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Stephan von Bothmer
Management Board
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How the Therm-Liner works

The Therm-Liner from UHRIG is a patented, modular sewer heat exchanger system for installation in sewers. It can be used in new sewers and existing sewers can also be retrofitted with it. The modules are custom-made double-shell pressure vessels made of stainless steel, which is resistant to pitting and corrosion and is ideally suited for use in wastewater. The modules are manufactured precisely to suit the sewer situation and are inserted into the sewer via the existing shaft infrastructure and securely installed.

The warm wastewater flows over the entire surface of the heat exchanger, which in turn has a cool working medium (usually water) flowing through it. The warm wastewater releases energy to the cooler liquid – and warms it up. Using the principle of compression, the connected heat pump increases the temperature level of the wastewater heat obtained in this way and increases the usable energy output. Buildings can now be heated with this thermal energy. If the building is also to be air-conditioned, a reversible heat pump is used: The cycle is then simply reversed in summer and the building is cooled via the wastewater flow. The extraction capacities in the projects we have realised range from 50 kW to 8 MW.

A Therm-Liner system can also be extended or dismantled at any time without any problems. The heat exchangers are designed for a service life of up to 50 years. The actual operating time ultimately depends on the downstream system technology.


Possible heating systems and heat distribution

The Therm-Liner system is suitable for heating individual buildings, entire neighbourhoods or for feeding (district) heating networks. Depending on the type of use as well as local, economic and ecological aspects, the Therm-Liner system can be integrated into various heating systems. A monovalent, bivalent or multivalent design of the heating system is possible, i.e. wastewater can serve as the sole heat source, but a combination with other forms of heating is also feasible.

There are two options for heat distribution:

  • Cold heat networks: Here, each energy user has their own heat pump. The flow and return to the heat exchanger is cold and without insulation.
  • Warm heat networks: This variant has a central heat pump. The primary circuit between the heat pump and the respective energy user is a warm, insulated network; the secondary circuit between the heat pump and the duct heat exchanger is a cold network.


Our products

UHRIG offers two different patented Therm-Liner systems for wastewater heat utilisation, tailored to the respective sewer. We deliver the heat exchanger elements ready for installation and install them. Key characteristics include:

  • The modules have been developed for retrofitting in sewers.
  • The modules do not interfere with the actual sewer operation and fulfil all sewer construction requirements according to DWA-M 114.
  • The modules are custom-made and adapted to the respective sewer situation.
  • The modules can be easily mounted over the existing shaft infrastructure.
  • The modules can be extended or dismantled at any time.
  • The technology is patented and certified.

UHRIG Therm-Liner Form A and Form B are available for sewer cross-sections larger than DN 400, ideally DN 800 and larger. The UHRIG team will be happy to provide you with more detailed information: Give us a call or write to us.


Wastewater pressure pipes and special solutions

Wastewater pressure pipes can also be used to generate heat from wastewater. However, heat exchangers can only be installed in these pressure lines if they can be taken out of service for this purpose. This is rarely the case, so a bypass, a second pipe with an integrated heat exchanger system, is built parallel to the existing pipe and the wastewater is diverted after completion. Even at sewage treatment plants, increasing thought is being given to generating heat from wastewater. Here, too, we have already realised customised solutions with the Therm-Liner system. The framework conditions for such projects are different, but we can assess them quickly. Give us a call or write to us.


The variants of the Therm-Liner at a glance

Therm-Liner Form A

  • Sewer cross-sections greater than DN 800
  • Sewer cross-sections larger than DN 400 as a slide-in solution in conjunction with our Quick-Lock system



Therm-Liner Form B

  • Sewer cross-sections greater than DN 800
  • Sewer cross-sections larger than DN 400 as a slide-in solution in conjunction with our Quick-Lock system


Good reasons to choose Uhrig
Sustainability & Environmental protection

Sustainable and careful action is not just a cliche for us. We make bodies of water clean again and ensure that our groundwater always remains clean.

Experience & Know how

With over 55 years of experience in civil engineering and sewer construction, we know what is important in our complete solutions which are well thought out from start to finish, so that we can hand over a project that is ready for operation.

Innovation & Engagement

There is always an adjustment, that would enable us to do even better with our products. We therefore constantly work on innovations and improvements.

Are you interested in making an idea a reality with us?