Heating water treated in accordance with VDI 2035 is also an important issue for biogas plants. At the Doimerhof in Pfaffenhofen/Ilm, Bavaria, the 500m3 buffer tank was prepared and filled directly on site using a truck trailer from Orben. The whole campaign was successfully carried out after three days: The energy generated by the biogas plant has since been fed into the district heating network and can supply up to 1200 households.‍

At the Doimerhof in Bavaria, the Weichselbaumer family produces food in an ecologically thought-out cycle with great commitment and love for nature. The pigs live animal-friendly with plenty of light and air in an open barn and feed is grown in-house without genetic engineering.

‍Power from the Doimerhof for up to 1,200 households fed into the district heating network

Biogas plant operators Barbara and Michael Weichselbaumer are also facing the challenges of the energy revolution. Biogas is an ideal addition to the renewable energy sources wind and sun. In contrast to wind and solar energy, biogas can be produced and stored regardless of the weather. Plant or animal material, in the case of the Doimer farm clover grass, corn and manure, is decomposed with the aid of bacteria in the absence of oxygen, producing biogas.

From this, electricity and heat can be generated directly on site in a combined heat and power plant and fed into the district heating network, for example at the Doimerhof. By storing excess heat energy, it is possible to respond to changing energy requirements and ensure a reliable and efficient heat supply. In this case, the heat carrier is water. However, it must not simply be of tap water quality, but must be converted into heating water through special treatment.

That is why fresh water must be treated

Modern heating systems are now highly efficient high-tech systems. In contrast to the past, systems with high-efficiency pumps (i.e. wet-running circulating pumps built after 2013) or systems with modern heat exchangers in boilers can no longer simply be filled with tap water. What old heating systems could do with is slowly but surely ruining modern systems.

Heating water treated in accordance with standards is therefore state of the art. Untreated heating water leads to stone formation, corrosion, damage and, in extreme cases, complete and permanent failure of the system. Heating water treatment in accordance with VDI 2035 and its documentation is a prerequisite for a warranty for many leading manufacturers of boilers and highly efficient circulation pumps. If the heating water does not meet the VDI-compliant values, the warranty for parts in contact with heating water may expire.

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Water hardness, oxygen, pH value and conductivity — key factors for heating water quality

Untreated water, e.g. drinking water from the tap, contains too much lime, especially in southern Germany. This is deposited and can not only impair the efficiency and efficiency of the heat exchangers, but also negate the efficiency advantage of the entire system. At an advanced stage, the deposits in the pipes produce an insulating effect or can even lead to a total failure of the heat exchanger or the system due to stress cracks.

35 tankers or 500 containers with a capacity of 1,000 liters

It should also start immediately after approval to operate the biogas plant in Pfaffenhofen. But filling the buffer tank from the manufacturer van Bebber from Straelen, Lower Rhine, was not so easy. How do you get 500,000 liters of treated water? This quantity corresponds to 500 containers of 1,000 liters or 35 tankers of 14 m³ Water, a logistical challenge.

Delivery times of six to eight weeks were the result of some initial research and the cost suggestions also exceeded the planned price range. The biogas plant operator finally found what he was looking for at the Wiesbaden-based company Orben. After initial contact, Orben not only developed a concept for mobile on-site processing within three days, but also provided the TR-10 mobile trailer. The reverse osmosis system installed on the trailer allowed tap water to be converted into standard-compliant heating water.

Reverse osmosis: 500,000 liters of water from the hydrant become heating water

Pfaffenhofen drinking water has a hardness of 2.85 mmol/l,
This corresponds to a value of 16 °dH (degree of German hardness), i.e. “hard” water with an increased percentage of lime.

These and other values were determined through a preliminary water analysis by an Orben employee. Drinking water from a hydrant was used as feed water for the TR-10 and the plant water produced by reverse osmosis was pumped directly into the buffer tank.

Heating water treatment by reverse osmosis is based on the principle of the selective permeability of a membrane, which only allows certain substances to pass through while retaining others. First, tap water is pretreated to remove larger particles, suspended matter and contaminants.

In the next step, the water is pressed onto the reverse osmosis membrane under high pressure, causing it to pass through the membrane and retain pollutants and salts.

A specially trained Orben employee connected the trailer, supervised the complete processing and prepared the trailer for transport after the end of the measure. The operator established the on-site conditions. The entire project, including assembly and dismantling, took just three days.

Non-standard-compliant heating water as a warranty claim

Investors and operators should specifically demand or comply with the quality of the correct plant filling water. Manufacturers of boilers and heating devices set requirements for the quality of filling and supplementary water in their installation and operating instructions.

In Germany, these are based on VDI Guideline 2035, which is also used in the event of damage. In terms of the financial risk of plant damage, the costs of treating the filling water in accordance with standards are negligible.

Orben, a specialist in heating water from Wiesbaden, provides professional heating water treatment in accordance with VDI 2035 for systems of all sizes nationwide.