Maintenance-free drain heat exchanger – how does it work?

How does the recycling system work and what is the risk of subsequent maintenance? Evertherm's sewage heat exchanger differs from other solutions.

Have you considered that you can see the energy in the sewer as a resource? With new heat exchanger technology, valuable energy that is otherwise flushed into the drain can be recycled and reused in a circular system. But how does recycling itself work and how good is it really? What is the risk of subsequent maintenance when the system is in place?

Risk of heat exchanger being destroyed over time

Wastewater may not be the first thing you think about when it comes to energy. But the fact is that there is a ton of thermal energy that only disappears when kitchen and bathroom water is flushed out. To take advantage of the energy, a heat exchanger is needed that can be placed in the wastewater without being destroyed over time. Many early waste water recovery solutions had a short lifespan and did not keep their promises when it came to recycling.

What if the system could be operated automatically?

Some of the risks of sewage heat exchangers are partly that the products do not hold up to a chemically challenging environment or that washed things stick and destroy the system, which requires costly calls from operating technicians. Something that is supposed to save the property owner money instead becomes an expensive burden. Imagine if the plant was self-cleaning and took care of itself instead.

Unique sewage heat exchanger that can withstand harsh and aggressive environments

The Evertherm wastewater heat exchanger is different from other solutions. The heat exchanger is built to withstand chemically challenging environments, with heat exchanger panels made of a tough, special polymeric material that repels contaminants such as fecal matter and grease normally found in wastewater. The energy recovery plant itself is also self-cleaning with an automatic stirring function. This technology has been used by Evertherm in wastewater treatment plants since 2014 - without any disruptions. Together with a fully automated control system, it enables unprecedented energy recovery.

Waste water heat exchanger automatically checked

All energy systems for real estate now have some kind of digital control function. These solutions can be more or less smart in their design. The Evertherm system includes a fully proprietary control and monitoring module that ensures functionality, optimizes energy recovery for best delivery and alarms in case of operational deviations.

How does the technology work?

Conventional sewage heat exchanger systems (pipe-in-pipes) are connected to or on the sewer pipes and have a recycling potential of up to 25% of the energy in the waste water. The Evertherm system works completely differently.

1. A pump pit for a disturbance-free everyday life

When the hot waste water is on its way out of the property, it is caught in a pump pit placed on the drain trunk. The cutting pump of the pump atomizes larger components in the water and passes it on to the buffer tank. The drain function is constantly maintained, even in case of power failure, since the pump pit is equipped with board drains and self-falls.

2. The buffer tank handles the uneven flows of the property

The waste water is collected in the buffer tank, which is intended to regulate slightly uneven flows from the apartments.

3. the collector tank with waste heat exchanger recovers at least 90 % of the thermal energy

From the buffer tank, the waste water goes to the collector tank where the thermal energy is recovered. A number of ETX panels form a collector, which recovers up to 95% of the available energy. Once the energy has been recovered, the waste water is flushed out to the sewer trunk and has the same temperature as the incoming cold water, in accordance with current regulations. The tank is emptied with heavy-duty pumps to ensure that everything comes out, preventing bottom sediment and fouling.

4. The energy can once again heat the property

The heat energy recovered is returned to the property's energy system with a heat pump and can then reheat the hot water and homes.

5. Maximum heat recovery with the control system

The control and optimization module binds the entire process together. Measurement data is collected while automatic controls ensure temperature and flow from the waste water to constantly optimize energy recovery.  

The risks of waste heat recovery are erased

This technology is proven and secured through several installations in both apartment buildings and industrial processes. The system mainly uses standard components of well-known brands and Evertherm's collector has an expected technical life of 40-50 years. Waste water heat is now recycled in apartment buildings in Umeå and Växjö,as well as several ongoing installations in other cities.

Want to know how much your property could recycle? Try counting on our calculator yourself.