Water Heater Z-BIS

Podgrzewacz Z-BIS
Podgrzewacz Z-BIS

Domestic hot water heater with anti-bacterial function Z-BIS



Designed for heating domestic hot water in gas and oil boiler rooms. Prefect alternative for storage domestic hot water heaters. Features high efficiency, temperature stability, ease of use and efficient protection of domestic hot water system against bacterial growth, in particular Legionella genus.



  • effective protection against bacterial growth, in particular Legionella
  • constant domestic hot water temperature (outlet 60°C, domestic 55°C) without increasing to 90°C in peak hours
  • return heating water cooling to <57°C for compatibility with condensing boilers
  • compact size
  • significantly lower investment costs compared to storage heaters


Domestic hot water is usually heated in gas or oil boiler rooms using storage, vertical domestic hot water heaters with a heating coil. The heating coil supply requires increased temperature (up to +90°C) to guarantee a required domestic hot water temperature at peak hours. The main disadvantage of the storage heater is its low efficiency and output. Increasing the efficiency by increasing the number of heaters is not cost-effective due to high new device costs. Additional tanks may also promote bacterial growth.

Z-BIS is a perfect solution.

New solution consists in use of domestic hot water system with high-efficiency plate heat exchanger and ZCWS temperature stabilizer and pumps: supply – internal circuit in the hot water tank and circulation pump in the domestic hot water system.

Use of high-efficiency plate heat exchangers improves heater efficiency. The heat output can be 70 – 780 kW to guarantee domestic hot water at +60°C from 1200 l/h to 13800 l/h. Required heating medium temperature is +70°C, and does not require increase to +90°C as in storage heaters.

Compact design and dimensions allow installation in confined areas.

Z-BIS heaters supply domestic hot water at constant outlet temperature of +60°C. It prevents Legionella growth and Legionnaires’ disease, often resulting in death.

Based on the European studies by the National Institute of Hygiene in Warsaw, constant outlet temperature of +60°C eliminates the possibility of domestic hot water system with Legionella, without required periodical disinfection at over +70°C, which is required when using storage heaters. To protect the Z-BIS heaters against corrosion at tcw=+60°C, the system is made of 316L austenitic steel.

It provides protection against bacterial growth on inner walls and pipes.

Z-BIS domestic hot water heaters are available in eight versions (Table 1)


Design and operation

The heater is mounted on a supporting frame with sheet metal covers. All components can be removed or opened for easy access. All components are powder coated. ZCWS temperature stabilizers and domestic hot water and circulation pipes are made of 316L grade austenitic steel. Easy access component layout Easy maintenance, e.g. replacing or removing heat exchangers for cleaning.

The heater (Fig. 1) is mounted on the common ZCWS temperature stabilizer (1), heat exchanger or heat exchanger set (2) base. Pumps (3) and (4) provide internal and external circulation on the secondary circuit side.

Pump (12) provides heating medium flow. Heat exchanger (2) and pumps (3) and (4) are protected with a strainer (16). Safety valve (9) and expansion vessel (17) (optional) prevent excessive pressure.

Design and operation

Z-BIS description
1. ZCWS domestic hot water stabilizer (286) l
2. Plate heat exchanger set
3. Internal circulation pump
4. Circulation pump
5. Thermomanometer
6. Temperature sensor
7. Hot water circulation
8. Circulation line
9. Safety valve
10. Domestic hot water system supply
11. Automatic air vent
MP connection module description
11. Automatic air vent
12. Charge-supply pump
13. Heating water supply
14. Heating water return
15. Cold water supply
16. Strainer
17. Domestic hot water expansion vessel - 
    25l for standard domestic hot water systems. 
    The expansion vessel for non-standard 
    systems is selected individually.
18. Filter.

Manometer (M) and thermometers (T) with thermomanometer (5) provide current parameters readout independent from the electronic display on the control panel.Cold supply water is filtered by the strainer (16). It is mixed with the water supplied by the circulation pump (3) and flows to the plate heat exchanger (2). The heated water is mixed in the ZCWS stabilizer (1) with the medium returned from the domestic hot water circuit.

The heating medium flow via the heat exchanger (2) is controlled by the boiler control system with the temperature sensor on the ZCWS stabilizer. Circulation pumps (3) and (4) provide constant temperature in the tank (1). It eliminates water layers at different temperature promoting bacterial growth, and as a result maintains required domestic hot water parameters even at peak periods.

Z-BIS domestic hot water heaters are also compatible with high-efficiency condensing boilers. High-efficiency plate heat exchangers provide efficient heating water cooling to +43°C < +57°C and thus as opposed to storage heaters, provide a complete, continuous condensation conditions for the boilers.

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