Heating Water Treatment is no longer just an add-on service that SHK specialist companies "somehow manage to do". Modern heating systems, heat pumps, condensing boilers, buffer tanks, high-efficiency pumps, underfloor heating, and mixed material systems are sensitive to unsuitable filling and top-up water.
The direct answer is: ORBEN supports SHK specialist trades in standard-compliant heating water treatment according to VDI 2035 – from water analysis and action plans to filling, treatment during operation, top-up, measurement, and documentation. The service is provided on behalf of and by order of the specialist trade within the three-tier distribution channel.
This is particularly relevant for SHK companies when time, personnel, equipment, or experience are lacking. For example, during peak order periods, larger building services projects, existing systems with unusual water values, renovations, boiler replacements, heat pump projects, or recurring top-up tasks.
The benefit is clear: The specialist trade remains the point of contact for the customer, while ORBEN handles the technical execution as a specialized partner in the background. This ensures projects are handled smoothly, water values are documented transparently, and warranty risks are reduced.
Heating water treatment means treating filling water, top-up water, or existing system water in such a way that it meets the technical requirements of the heating system and the specifications of VDI 2035. The goal is heating water that, as far as possible, prevents scale formation, corrosion, magnetite formation, sludge, conductivity problems, and pH deviations.
In the day-to-day work of SHK professionals, heating water treatment primarily involves four tasks:
It's not just about adding "soft water." In modern systems, multiple parameters are crucial simultaneously: Conductivity, total hardness, pH value, temperature, particles, magnetite, oxygen ingress, and material compatibility.
VDI 2035 describes measures to prevent damage in hot water heating systems due to scale formation and water-side corrosion. Official regulatory sources attribute the guideline specifically to this purpose.
For HVAC professionals, this means: Proper heating water treatment is a technical process involving measurement and verification. It doesn't end at the filling hose.
Heating water is an operating medium. It transports heat, comes into contact with all water-bearing components, and affects the lifespan of the system. If the water quality is inadequate, damage can arise that only becomes apparent later – but was initiated early.
Modern heating systems, in particular, are designed for high efficiency. Small cross-sections, high-efficiency pumps, complex control systems, buffer tanks, and sensitive heat generators make water quality a critical operating criterion.
For HVAC professionals, heating water treatment is also economically relevant. If water values are missing, documentation is incomplete, or a system later shows issues, discussions arise regarding responsibility, warranty, and rework.
A well-documented process protects the skilled trades. It shows what water quality was introduced, what values were measured, and what measures were carried out.
VDI 2035 is the central reference point for heating water quality in the German HVAC market. DIN EN 14336 is relevant for the installation, testing, commissioning, and handover of water-based heating systems; DIN EN 1717 concerns the protection of drinking water from backflow and thus the safeguarding of filling and replenishment devices.
What matters most to practitioners is: Filling, replenishment, and documentation must be considered together. A one-time initial filling is not sufficient if unverified drinking water is later replenished.
Proper heating water treatment begins by asking: What type of water is present at which point in the system – and what purpose does it serve?
In the HVAC context, these terms should be clearly distinguished:
TermMeaning in HVAC ContextTypical FunctionFilling WaterWater introduced into the system during initial filling or refilling.Fill the system after new construction, renovation, or boiler replacement.Heating WaterWater circulating in the closed heating circuit.Transport heat and continuously flow through components.Supplementary WaterWater added during operation.Compensate for losses, maintain pressure, ensure system operation.Raw WaterSource water before treatment.Basis for the design of resin, filtration, and treatment.
This distinction is not merely academic. It determines where measurements are taken, how documentation is done, and which treatment technology is suitable.
Depending on the system, other values may be relevant, such as chloride, iron, oxygen, or temperature. However, for many HVAC projects, conductivity, pH value, hardness, and documentation are already sufficient as a central starting point.
ORBEN offers measurement and testing technology for this, such as the ORBEN Measuring Box and Measuring Box Pro. The Measuring Box records, among other things, conductivity, pH value, total hardness, and temperature; the Pro version additionally supports menu-guided measurement and automatic documentation.
An important approach in heating water treatment is demineralization. This reduces dissolved ions, which lowers conductivity and removes hardness-forming substances.
ORBEN relies on solutions for heating water applications, including THERMION 2035 pH conform. The high-performance mixed-bed resin is designed for heating system filling and heating water treatment using the bypass method and is intended for ORBEN heating water devices. In ORBEN documentation, it is described as a resin for full demineralization according to VDI 2035 with automatic pH value regulation.
Full demineralization removes dissolved ions. However, it does not automatically remove all solids from the system water. Therefore, for existing systems, additional filtration required.
In such cases, a bypass method is useful. The system water is routed through a mobile or stationary system, filtered, treated, measured, and returned to the system.
ORBEN THERMOSTIL ULTRAFLEX is an example of this: It is described as a mobile heating water filter unit for the removal of magnetite, solid, and suspended matter. After cleaning, a THERMION demineralization cartridge can be used for bypass demineralization in a second step.
For existing systems, a complete draining is not always advisable. Here, a In-operation treatment help. The system is treated via defined connection points in bypass mode.
The advantage: HVAC companies can improve existing water without immediately shutting down the entire system. This is particularly beneficial for larger heating circuits, multi-family homes, commercial buildings, or building services systems where interruptions are costly.
THERMOSTIL mobil and THERMOSTIL fix are examples from the ORBEN range. THERMOSTIL mobil is a ready-to-connect mobile complete system for heating water treatment in new and existing systems using the bypass method, in accordance with VDI 2035 and DIN EN 14336. THERMOSTIL fix is designed as a stationary system for larger existing installations and continuously monitors heating water quality.
Many problems don't arise because HVAC companies ignore the issue. They occur because heating water treatment on construction sites is often done under time pressure, with unclear responsibilities, or without complete documentation.
The classic scenario: The system is filled with readily available tap water without checking raw water values, hardness, conductivity, or target values.
This might work, but it's not guaranteed. Hardness and conductivity vary significantly depending on the region. For modern heat generators, heat pumps, or larger building services systems, this poses an unnecessary risk.
Better approach: Test raw water, define target values, design appropriate treatment, and document measurement results.
Many systems are correctly filled during commissioning. However, unsuitable water is often replenished repeatedly over the years.
The problem: Even small replenishment volumes add up. Each replenishment can introduce hardness, salt load, and oxygen. Without a water meter and proper documentation, it's difficult to track how much make-up water has entered the system.
Better approach: Install a replenishment unit, record make-up water volume, and monitor resin capacity.
Hardness is important, but it's not the only factor. A system can be filled with soft water and still have unfavorable conductivity, a critical pH value, or particle issues.
Better: Consider conductivity, pH value, total hardness, and temperature together. For problematic systems, additionally check for iron, chloride, particles, or oxygen ingress.
Especially with existing systems, simple demineralization is often insufficient. If magnetite, rust sludge, or particles circulate in the system, pumps, valves, heat exchangers, and filters can be affected.
Better: Check filtration before or in parallel with demineralization. For sludged-up systems, a mobile bypass filter with magnetite separation can be beneficial.
A single reading is not very informative if it's not clear where it was taken. Raw water, treatment outlet, return flow, system water, and make-up water point can all show different values.
Better: Define measurement points and record them in the log. At a minimum, the measurement point, date, time, system, operating status, and responsible person should be documented.
Ion exchange resin has a limited capacity. If the raw water quality is worse than expected or if larger quantities of water are needed, the capacity can be exhausted more quickly.
Better: Calculate resin capacity before project start, monitor conductivity, and don't wait until limit values are exceeded to plan resin replacement.
Technically sound work loses value if it cannot be verified. Without a log, it will later be unclear which values were measured, which quantity of water was treated, and which process was used.
Better: Properly document the system log, measurement protocol, photo documentation, water values before and after treatment, make-up water quantities, and materials used.
Some heating water projects are only escalated when the system is about to be filled, but values, equipment, or personnel are missing.
Better: For larger or uncertain projects, it's wise to check early whether an external filling and treatment service makes sense. This is exactly where ORBEN can relieve the burden on skilled trades.
For the SHK/TGA context, the most important are VDI 2035, DIN EN 14336 and DIN EN 1717 relevant.
VDI 2035 is the central standard for preventing damage in hot water heating systems due to scale formation and water-side corrosion. It is particularly relevant for the planning, filling, operation, replenishment, and documentation of heating systems.
For SHK companies, this means: heating water treatment should not be done merely by feel. It requires target values, measurement, and verifiable documentation.
DIN EN 14336 addresses requirements for the installation, acceptance, and handover of water-based heating, cooling, and domestic hot water systems in buildings. This makes it important in the SHK/TGA context when systems are flushed, tested, filled, commissioned, and handed over.
ORBEN explicitly describes the filling and treatment service in connection with DIN EN 14336 and VDI 2035.
DIN EN 1717 concerns the protection of drinking water installations against contamination by backflow. This is relevant for heating system filling and replenishment, because drinking water installations and heating systems must not be connected to each other without adequate protection.
In the ORBEN SERASTIL program, the "ready" variants with system disconnector type BA are described. They combine an automatic filling valve, system disconnector, and demineralization cartridge as a treatment concept for replenishment water.
Documentation is not a bureaucratic appendix. It is proof that the heating water treatment was carried out professionally.
Key documentation points include:
The ORBEN service documents list the documentation of measurement results, including a photo series, in the system logbook according to DIN EN 14336 and VDI 2035 as part of the service package.
There isn't one single solution for every heating system. The appropriate heating water treatment depends on the system's condition, water quantity, target values, timeframe, materials, and operator requirements.
Depending on the system's condition and objectives, various methods are available for heating water treatment. The Full demineralization is primarily used for initial filling, refilling, replenishment, and treatment via the bypass method. It removes hardness-forming substances and significantly reduces the water's conductivity, thereby reliably meeting the requirements of VDI 2035. However, existing sludge or magnetite deposits are not removed by this process.
The Softening is particularly suitable when primarily hardness-forming substances are to be reduced. The process is relatively simple and proven, but some of the salt load remains in the water. Therefore, for systems that should operate with as little salt as possible, softening is not always the optimal solution.
For existing systems or those with larger water volumes, bypass treatment is often used. In this process, the heating water is treated during ongoing operation without the system having to be shut down. However, suitable connection points and an appropriate measurement and monitoring concept are prerequisites. For example, ORBEN offers mobile and stationary Thermostil systems for heating water treatment and filtration using the bypass method.
If sludge, magnetite, or other solids are already present in the system, filtration or magnetite separationis recommended. This protects pumps, heat exchangers, and valves, and maintains the system's efficiency in the long term. However, dissolved salts, pH deviations, or conductivity problems cannot be remedied by filtration alone.
For ongoing system operation, makeup water units play an important role. They ensure that makeup water is also treated according to the requirements of VDI 2035 and that water quality is permanently maintained. The resin capacity and the actual amount of refilled water must be regularly monitored. For this purpose, ORBEN offers various SERASTIL makeup water units with integrated documentation of the refill volume.
In addition, a measurement and documentation service provides the necessary proof. Regular monitoring of conductivity, pH value, water hardness, and other parameters provides assurance for specialist tradespeople, operators, and manufacturers. However, the results are only meaningful if measurement points, measurement procedures, and documentation are consistently and professionally carried out. VDI 2035 explicitly requires complete documentation of initial filling, refilling, and maintenance.
1. Clarify system context: New construction, renovation, boiler replacement, heat pump, existing system, or makeup water?
2. Determine water volume: Consider system volume, buffer tank, pipe network, heating surfaces, and potential make-up water volumes.
3. Test raw water: Measure hardness, conductivity, pH value, and other relevant values as needed.
4. Define target values: Consider VDI 2035, manufacturer specifications, and system materials.
5. Select method: Demineralization, bypass treatment, filtration, make-up unit, or a combination.
6. Plan implementation: Clarify connections, flushing lines, filling speed, power supply, accessibility, and timeframe.
7. Measure and document: Record values before, during, and after the procedure.
8. Secure make-up water supply: Permanently ensure make-up water quality, use a water meter, and monitor resin capacity.
An HVAC specialist company manages an apartment building with multiple heating circuits, a buffer tank, and modern heat generation. After a renovation, the system is to be recommissioned. The system volume is larger than in typical single-family homes, the existing water values are unusual, and the company has several construction sites running concurrently.
The challenge: The specialist company wants to professionally treat the system according to VDI 2035 and document it thoroughly. Simultaneously, within the specific timeframe, they lack personnel, measuring equipment, and experience with larger bypass treatment.
First, the system water is tested. Conductivity, pH value, hardness, and temperature are recorded. Additionally, it is assessed whether magnetite or dirt is present in the system.
For filtration, a mobile filter and treatment system is an option. For permanent needs, a stationary solution or a suitable make-up water unit can be added.
The HVAC company remains the customer's contractual partner and point of contact. ORBEN handles the practical implementation on behalf of the skilled trades. The system is professionally treated, water values are documented, and the make-up water supply can be controlled in the future.
The result is not just "treated water". It is a transparent process that unburdens the specialized company and protects the system long-term.
ORBEN supports HVAC companies with products, services, and solutions for heating water treatment according to VDI 2035. Crucial here is its market role: ORBEN operates in the heating water sector through a three-tier distribution channel and offers services in the name and on behalf of the skilled trades.
ORBEN's documents describe the comprehensive service for heating water treatment, refilling, or replenishment explicitly as a relief for skilled trades during peak workloads, staff shortages, or for less common larger systems. This may include water analysis, an action plan, the provision and commissioning of a suitable system, consumables, measurement, evaluation, and documentation.
This analysis forms the basis for any professional measure. Without it, the system design remains uncertain.
Based on the analysis, the appropriate approach is determined. The action plan may include, for example:
The advantage for the HVAC/plumbing business: The process becomes predictable. Before starting, it is clear which system, materials, and measurement points are required.
ORBEN can handle on-site implementation. This is particularly helpful when the specialist company itself lacks the appropriate equipment or available capacity.
Common reasons include:
The service is not provided as a direct-to-end-customer model, but rather as support for specialist trades.
THERMOSTIL mobil is a mobile complete system for heating water treatment in new and existing systems using the bypass method. It combines, among other things, fine filters with magnetic filtration, a pump, a sampling tap, a water meter, a stainless steel treatment cartridge with THERMION 2035 pH conform, a conductivity meter, and connection hoses.
This is relevant for HVAC companies when a mobile solution is needed on the construction site. The systems are designed for practical use in the boiler room and are clearly part of the HVAC product range and branding.
If existing systems are sludged up or magnetite is suspected in the heating water, mere demineralization is often not sufficient. THERMOSTIL ULTRAFLEX is described as a mobile heating water filter unit for the removal of magnetite, solids, and suspended solids. Subsequently, a THERMION demineralization cartridge can be used for further treatment in bypass.
This is particularly useful for systems where pumps, heat exchangers, or valves might already be affected by particles.
For larger existing systems, a stationary solution can make sense. THERMOSTIL fix is a stationary complete system for heating water treatment using the bypass method. The control unit continuously monitors the heating water quality, starts the treatment as needed, and reports an upcoming resin change.
This is suitable for HVAC systems, larger apartment buildings, or other buildings where heating water quality needs to be continuously monitored and maintained.
Make-up water addition is one of the most common weak points in operation. ORBEN SERASTIL systems are refill cartridge systems for make-up water according to VDI 2035. The "ready" versions combine an automatic filling valve, a type BA system disconnector, and a demineralization cartridge. Additionally, water meters, capacity control, or conductivity sensors are part of the product logic, depending on the series.
For specialist trades, this means: Make-up water addition can be documented more technically soundly, more transparently, and more easily.
THERMION 2035 pH compliant is the ORBEN mixed-bed resin specifically designed for heating water treatment. It is used in ORBEN heating water devices and is intended for full demineralization and pH stabilization in heating water systems.
What's important here is not just water quality, but also process reliability: Resin capacity, conductivity, and replacement timing must be monitored.
With ORBEN measuring boxes, key values such as conductivity, pH value, total hardness, and temperature can be checked and documented. The Messbox Pro additionally supports menu-guided measurement and automatic report generation.
This is an important component for HVAC companies, because documentation is becoming increasingly important for customers, manufacturers, and operators.
ORBEN also follows the principle of reusable resin in the heating water sector. Current HVAC documents state that THERMION resins from mobile bypass treatment units can be regenerated, and that from 2024 onwards, exhausted mixed-bed resin in the HVAC sector will be regenerated, recycled, and reused where possible.
For specialist trades and wholesale, this is an additional sustainability and process advantage – without departing from HVAC principles.
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In daily HVAC operations, different requirements for heating water treatment arise depending on the system's condition. For new constructions, boiler replacements, or renovations, standard-compliant filling, filtration, and water treatment according to VDI 2035 are central, while in larger existing systems, ongoing quality assurance and documentation are crucial. For regular make-up water addition, make-up units with capacity monitoring are used to continuously ensure water quality. Unusual water values require professional analysis, evaluation, and the derivation of suitable measures. Additionally, ORBEN supports HVAC specialist companies with measurement and documentation technology as well as complete services to relieve them during peak workloads.
Heating water treatment is the targeted treatment of filling water, make-up water, or system water, so that a hot water heating system operates with suitable water quality. In the HVAC context, it primarily concerns conductivity, hardness, pH value, particles, magnetite, and documentation. Treatment can occur during initial filling, refilling, make-up water addition, or during ongoing operation. Typical processes include full demineralization, filtration, magnetite separation, and bypass treatment. The goal is to prevent scale formation, corrosion, sludge, malfunctions, and subsequent warranty discussions. For specialist companies, it's important: Not only must the water be suitable, but also the proof in the system logbook.
A plumbing, heating, and air conditioning company needs a service when project scope, timeframe, personnel, equipment, or documentation requirements go beyond normal day-to-day site operations. Typical examples include larger existing systems, heat pump retrofits, boiler replacements, renovations, systems with unknown water quality, or short-term order surges. Even if water analysis, bypass treatment, filtration, measurement protocols, or system logbook documentation are required, an external specialist can be beneficial. ORBEN provides such services on behalf of and by order of the skilled trades. The specialist company thus remains the customer's point of contact but receives technical support for execution, measurement, and documentation.
In day-to-day plumbing, heating, and air conditioning operations, at least conductivity, pH value, total hardness, and temperature be checked. Depending on the system, iron, chloride, oxygen, particles, or magnetite may also be relevant. Conductivity indicates the dissolved salt content. Total hardness indicates hardness-forming substances that can cause scale formation. The pH value is important for corrosion behavior and material compatibility. Particles and magnetite can impair pumps, valves, and heat exchangers. The measuring point is also crucial: raw water, treated fill water, system water, and make-up water can have different values. Therefore, measuring points and measurement times should always be documented.
Fill water is the water introduced into the heating system during initial filling or refilling. Heating water is the water that subsequently circulates in the closed heating circuit and transports heat. Make-up water is water that is replenished during operation to compensate for losses or pressure drops. This distinction is important because each type of water has different functions and monitoring requirements. A system may have been correctly filled but later receive poorer water quality due to unsuitable replenishment. Therefore, not only the initial filling but also ongoing replenishment must be ensured.
VDI 2035 is the central technical reference point for heating water in hot water heating systems. It describes measures to prevent damage from scale formation and water-side corrosion. For plumbing, heating, and air conditioning companies, this means: filling, replenishment, measurement, and documentation should be planned so that the system operates with suitable water quality. The guideline does not replace on-site technical assessment but provides the professional framework. In practice, water values, system volume, materials, manufacturer specifications, and operating mode are considered together. ORBEN aligns its heating water services, products, and documentation with this plumbing, heating, and air conditioning context.
Demineralization and softening serve different purposes. Softening primarily reduces hardness-forming substances such as calcium and magnesium. Full demineralization additionally reduces the dissolved salt load and thus lowers conductivity. For low-salt operation and modern heating systems, full demineralization is often the more comprehensive approach. It can reduce hardness-forming substances and conductive ions. Nevertheless, full demineralization is not automatically the only measure. For existing systems, additional filtration, magnetite separation, flushing, or bypass treatment may be necessary. The right decision depends on raw water, system water, materials, manufacturer specifications, system volume, and target values.
During treatment in ongoing operation, the heating water is usually via bypass routed through a mobile or stationary treatment system. The water is drawn from the heating circuit, filtered, demineralized or treated, measured, and returned to the system. This allows water quality to be improved without completely draining the system. This is particularly beneficial for larger existing systems, multi-family homes, and building services (TGA) systems. Important factors include suitable connection points, controlled flow rate, regular measurements, and clear documentation. If particles or magnetite are present, filtration should be integrated into the process.
ORBEN supports replenishment with suitable top-up units, cartridge systems, and measurement and service concepts. SERASTIL systems treat make-up water according to VDI 2035 and are equipped, depending on the version, with a system disconnector, filling valve, water meter, capacity control, or conductivity sensor. For specialist trades, it's important to note: replenishment is no longer considered uncontrolled refilling, but a documentable process. Make-up water quantities can be recorded, resin capacities monitored, and water values checked. This helps maintain the water quality achieved during initial filling, even during ongoing operation.
Specialist trades should document which system was filled or treated, what quantity of water was processed, what raw water values were present, what target values were set, and which procedure was used. Additionally, conductivity, pH value, hardness, temperature, measurement points, measurement times, resin used, cartridge changes, replenishment quantities, and the responsible person should be recorded. Photo documentation is also important if it is intended for the system logbook or operator file. Good documentation protects the specialist company because it demonstrates that the heating water treatment was carried out professionally. In case of later inquiries, it's not memory that counts, but proof.
ORBEN's heating water service is geared towards specialist trades and wholesale in the three-tier distribution channel . ORBEN supports SHK specialist trades on behalf of and by order of the specialist company. For private operators, this practically means: The SHK specialist company remains the central point of contact. ORBEN acts as a specialized service partner when analysis, treatment, filling, replenishment, or documentation require technical and organizational support. This structure is important because it aligns with SHK sales practices and relieves specialist companies of demanding projects without replacing their customer relationships.
Heating water treatment is a central component of professional system planning, commissioning, and maintenance in the SHK and TGA sectors. It's not just about filling a heating system with water. It's about water quality, material protection, efficiency, operational safety, replenishment, measurement, and documentation.
For SHK specialist companies, the greatest benefit lies in a clear process:
ORBEN supports exactly this process with products, services, and solutions through a three-tier distribution channel. These include THERMION 2035 pH conform, THERMOSTIL mobil, THERMOSTIL ULTRAFLEX, THERMOSTIL fix, SERASTIL replenishment units, ORBEN measuring boxes, and the complete service for heating water treatment, initial filling, and replenishment.
The key recommendation for trade professionals is: Plan heating water treatment early; don't wait until water values are abnormal. Anyone who properly organizes analysis, treatment, replenishment, and documentation from the outset reduces technical risks and gains security with customers, operators, and manufacturers.
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