HTS Viessmann Vitodens 333 WS3A Pressure Relief Valve 26 kW PRV 7815766 Instruction Manual

1. Product Overview

This manual provides essential information for the installation, operation, and maintenance of the HTS Viessmann Vitodens 333 WS3A Pressure Relief Valve, model 7815766. This component is designed to ensure the safe operation of compatible boiler systems by releasing excess pressure.

Figure 1: Front view of the HTS Viessmann Vitodens 333 WS3A Pressure Relief Valve. This image shows the brass body with a red cap, indicating the pressure release mechanism.

The pressure relief valve (PRV) is a critical safety device for heating systems, preventing damage from overpressure conditions. It is specifically designed for use with Viessmann Vitodens 333 WS3A boilers, 26 kW models, and other compatible systems as listed by the manufacturer.

2. Safety Information

• Professional Installation Required: Installation and maintenance of this component must be performed by a qualified and certified heating engineer or plumber. Improper installation can lead to serious injury, property damage, or system malfunction.
• System Depressurization: Always ensure the heating system is fully depressurized and drained before attempting any installation or service work on the valve.
• Hot Water Hazard: The valve may discharge hot water or steam if the system is overpressurized. Ensure the discharge pipe is correctly installed and routed to a safe location, away from personnel and property.
• Component Compatibility: Verify that this valve (Model 7815766) is compatible with your specific boiler model and system requirements. Refer to your boiler's documentation.
• Do Not Tamper: Never attempt to modify, disable, or bypass the pressure relief valve. This is a safety device and tampering can lead to dangerous operating conditions.

3. Installation

The HTS Viessmann Vitodens 333 WS3A Pressure Relief Valve is designed for integration into the boiler's heating circuit. Follow these general guidelines, but always prioritize the specific instructions provided by the boiler manufacturer.

1. Preparation:
   • Ensure the boiler is switched off and isolated from the power supply.
   • Close all relevant isolation valves to the heating system.
   • Drain the heating system to relieve pressure and remove water from the installation area.
2. Location: Install the PRV in the designated location within the boiler's hydraulic circuit, typically on the flow side or as specified by the boiler manufacturer.
3. Connection:
   • Ensure clean, properly threaded connections.
   • Apply appropriate thread sealant (e.g., PTFE tape or pipe dope) to the male threads of the valve.
   • Tighten the valve securely using a suitable wrench, taking care not to overtighten and damage the valve or pipework.
4. Discharge Pipe:
   • Connect a discharge pipe to the outlet of the PRV. This pipe must be of adequate diameter, made of suitable material, and routed to a safe discharge point (e.g., a tundish leading to a drain).
   • The discharge pipe must have a continuous fall and be free from obstructions.
5. System Refill and Test:
   • Once installed, refill the heating system slowly, bleeding air as necessary.
   • Check all connections for leaks.
   • Restore power to the boiler and test the system according to the boiler manufacturer's instructions.

Figure 2: Side view of the valve, showing the DN15 and 1/2 inch markings, indicating connection size. An arrow on the brass body indicates the direction of flow.

4. Operation

The HTS Viessmann Vitodens 333 WS3A Pressure Relief Valve operates automatically. It is a passive safety device designed to open and discharge water if the system pressure exceeds its set limit (typically 3 bar, as indicated on the valve). There is no user interaction required for its normal operation.

• Automatic Function: The valve is factory-set to a specific pressure. When system pressure rises above this set point, the internal mechanism opens, allowing water to escape through the discharge pipe, thereby reducing pressure.
• Pressure Indication: The red cap often includes markings (e.g., "3 bar") indicating the pressure at which the valve is set to open.

Figure 3: Top view of the valve's red cap, clearly showing the "3 bar" pressure setting, along with CE certification marks.

5. Maintenance

Regular maintenance is crucial to ensure the continued safe and effective operation of your heating system and its components, including the pressure relief valve.

• Annual Inspection: It is recommended that a qualified heating engineer inspect the pressure relief valve annually as part of the boiler's routine service.
• Visual Check: Periodically check the valve and its discharge pipe for any signs of leaks, corrosion, or blockages. Any signs of discharge when the system is operating normally may indicate a fault with the valve or excessive system pressure.
• Testing (Professional Only): Some PRVs can be manually tested by briefly opening them. However, this should only be performed by a qualified professional, as improper testing can lead to system depressurization or damage.
• Replacement: If the valve shows signs of wear, leakage, or malfunction, it must be replaced immediately by a qualified professional. Do not attempt to repair a faulty pressure relief valve.

6. Troubleshooting

If you experience issues related to the pressure relief valve, consult a qualified heating engineer. Do not attempt to diagnose or repair the valve yourself.

• Valve Leaking:
  • Possible Cause 1: System pressure is too high. Check the boiler pressure gauge.
  • Possible Cause 2: The valve is faulty or has reached the end of its service life.
  • Action: Contact a qualified engineer to inspect the system pressure and the valve.
• No Discharge During Overpressure:
  • Possible Cause: The valve is seized, blocked, or faulty, preventing it from opening. This is a critical safety issue.
  • Action: Immediately shut down the boiler and contact a qualified engineer. Do not operate the boiler until the issue is resolved.

Figure 4: Angled view of the valve, highlighting both threaded connections and the DN15 1/2 markings, providing a comprehensive view of the component.

7. Specifications

8. Warranty and Support

This HTS product comes with a 1-year replacement part warranty from the date of purchase. This warranty covers manufacturing defects under normal use and service.

For warranty claims, technical support, or further assistance, please contact your original point of purchase or the manufacturer, HTS. Please have your proof of purchase and the product model number (7815766) available when contacting support.

Information regarding spare parts availability is currently unavailable. Please consult with a qualified professional for replacement part inquiries.