Dražice Indirect Water Heaters: Installation and Operation Manual

Product Overview

Dražice stationary indirect water heaters of the NTR and NTRR series are designed for preparing domestic hot water (DHW) in conjunction with a heating system, typically a gas boiler. The NTRR models can be combined with two heat sources, such as a gas boiler and a solar system or heat pump. These water heaters are suitable for large residential units, businesses, and restaurants due to their high output, ensuring a sufficient supply of DHW even during peak demand. They can also function as instantaneous water heaters when DHW is drawn continuously.

Key features include:

• Enamelled steel tank for hygienic DHW quality.
• Built-in magnesium anode for corrosion resistance.
• High-quality polyurethane foam insulation for minimal heat loss.
• Adjustable DHW temperature up to 74°C.
• Suitable for multiple draw-off points.
• Models with two heat exchangers can utilize two heat sources or be connected for double heat exchange surface.
• Indicator light for heating operation.
• DHW temperature control.
• Possibility of connecting a circulation system for DHW.

Technical Specifications

The water heaters are constructed from steel sheet, tested at 0.9 MPa overpressure. The interior is enamelled. A flange is welded to the bottom of the tank, to which the flange cover is screwed. The cover contains sockets for the thermostat sensor and thermometer. An anode rod is mounted on the M8 nut. The tank is insulated with rigid polyurethane foam. The electrical installation is located under a removable plastic cover. The water temperature can be adjusted via the thermostat. Heat exchangers are welded to the pressure vessel.

Detailed dimensions and specifications for various models are provided in the tables and figures throughout this manual.

Example Table:

Installation Information

General Requirements:

• The installation location must be frost-free and accessible for maintenance.
• Ensure compliance with national regulations and local utility requirements for electrical and water connections.
• Do not install the heater in areas with flammable liquids or gases.

Wall Mounting:

• Check wall load-bearing capacity and use appropriate anchoring material.
• NTR/Z series heaters must be mounted vertically. The bottom edge should be at least 600 mm from the floor.
• OKCV NTR series heaters must be mounted horizontally.
• For combined tanks, connect heating water inlet and outlet elbows before hanging to determine the correct mounting orientation (right or left).
• Anchoring system must be chosen individually based on wall conditions. Professional installation is recommended.
• Ensure sufficient clearance around the heater for electrical connections and maintenance. A 600 mm space is required below the heater.

Water Installation:

• Install shut-off valves on the DHW inlet and outlet for easier maintenance.
• Connect the DHW return line to the port marked 'CIRCULATION' if a circulation circuit is used.
• All pressure tanks must be equipped with a pressure relief valve, installed on the cold water inlet.
• The pressure relief valve must be easily accessible and installed as close to the tank as possible.
• The inlet pipe must have a diameter at least equal to that of the pressure relief valve.
• The discharge pipe of the pressure relief valve must be routed downwards and be open to the atmosphere.
• Regularly check the function of the pressure relief valve (at least monthly and after any extended shutdown).
• A check valve should be installed on the inlet pipe to prevent the tank from emptying automatically.
• For water with high mineral content, consider installing a water filter or setting the thermostat to a maximum of 60°C.

Electrical Installation:

• Ensure the thermostat sensor is fully inserted into its socket.
• The heater can be connected to any water heating boiler up to 50 kW.
• The heater is powered directly from the boiler with a 230 V/50 Hz control voltage.
• Use a flexible cable CYSY 4Cx0.75 for connection.
• Connection terminals are marked on the terminal block.

Operation

Thermostat Operation:

• The water temperature is set by turning the thermostat knob. Align the desired symbol with the fixed point on the control panel.
• The lower limit of the temperature range is approximately 5°C.
• The 'anti-freeze' setting is around 8°C.
• The upper limit of the temperature range is approximately 74°C (or 80°C for some models).
• The 'optimal' temperature is around 55°C.
• Setting the thermostat knob to the left stop does not permanently switch off the heating element.
• It is not recommended to set the temperature above 65°C if the daily electricity tariff is not blocked. Choose the 'ECO' symbol if available.

First Commissioning:

• Check the water and electrical installations. For combined tanks, also check the heating system installation.
• Ensure thermostat sensors are correctly positioned in their sockets.
• Open the hot water tap on the mixing tap.
• Open the cold water inlet valve to the tank.
• Once water flows from the hot water tap, the tank is full. Close the tap.
• If leaks are observed at the flange cover, tighten the screws.
• Attach the electrical installation cover.
• For heating via the hot water system, open the heating water inlet and outlet valves and vent the heat exchanger if necessary.
• Flush the heater until the water runs clear.
• Complete the warranty card.

Maintenance and Care

Regular Checks:

• Regularly check and replace the magnesium anode. Its lifespan depends on water hardness and composition, typically around two years.
• Ensure no shut-off valve is installed between the tank and the pressure relief valve.
• If the mains water pressure exceeds 0.6 MPa, install a pressure-reducing valve before the safety valve.
• All hot water outlets must be fitted with mixing taps.
• Before filling the tank for the first time, check that the flange connection nuts are tightened.
• Do not manipulate the thermostat other than adjusting the temperature with the knob.
• Electrical installation adjustments and regulation element replacement should only be performed by authorized service personnel.

Cleaning:

• If water contains a lot of minerals, an expert should be called to remove scale buildup, typically after one to two years of operation.
• Scale formation depends on water hardness, temperature, and usage.
• For cleaning, drain the tank, remove the flange cover, and clean the tank. Use new seals during reassembly.
• Do not use descaling agents or abrasive cleaners on the internal enamel surface. Clean with a wooden tool and vacuum or wipe dry.
• Clean the exterior casing with a damp cloth and mild household detergent. Avoid solvents like nitro-thinner or trichloroethylene.

Troubleshooting

Common Issues:

• Water temperature does not match set value: Check thermostat, or it may be faulty.
• Water continuously drips from the pressure relief valve: Check inlet pressure (may be too high) or the pressure relief valve may be faulty.

For any issues, contact a qualified service technician. Provide the model designation and serial number.

Disposal

Dispose of packaging material and the product itself in accordance with local regulations for waste disposal and recycling.