WGJ-B PSTW 500 buffer storage tank for heating water: high-performance heat storage for heating systems

Product overview

The WGJ-B PSTW 500 buffer storage tank is a robust, steel-walled tank for receiving, storing, and controlled release of heating water or other liquids compatible with steel. It acts as a buffer between heat generators (e.g., central boilers, solar collectors, heat pumps) and the heating circuit, compensating for fluctuations in output and protecting the heating system.

The storage tank has a nominal volume of 498 dm³ and is designed for a maximum operating pressure of 0.3 MPa. The interior of the tank is unfinished, while the exterior is painted to prevent corrosion.

Construction and materials

The tank is made of black sheet steel; insulation is provided either by polystyrene foam or a rubber mat permanently attached to the tank walls. The insulation is protected by a skay-coated outer jacket.

Please note: Removing the insulation permanently attached to the pressure vessel will void the product warranty. The shell surface is made of a rock-like material.

Technical specifications (brief overview)

Volume: 498 dm³. Pipe connections: Heating element/connection MG/KP 1 1/2”, temperature sensor CT ⅜”, drain ZS ¾”. Standby losses (polystyrene foam): approx. 52–72 W, with rubber mat: approx. 47–65 W (depending on model).

Weight: 120 kg. Maximum operating parameters: pressure pr = 0.3 MPa; temperature ranges depending on insulation: with polystyrene foam tr min = 15 °C to tr max = 80 °C, with rubber mat tr min = 5 °C to tr max = 70 °C.

Areas of application

The storage tank is designed for central heating systems, combinations with solar thermal systems, heat pump systems, and as an intermediate storage tank for boiler systems. It is suitable wherever excess heat needs to be temporarily stored and released as required.

Safety regulations

Operation in closed heating systems is only permitted with a functioning safety valve (opening pressure 0.3 MPa). Ideally, this valve should be installed in the heating water return line and must not be separated from the tank by shut-off valves. A functioning safety valve may exhibit intermittent water release – a blocked outlet must be strictly avoided.

Use without a safety valve or with a defective valve is prohibited, as this can lead to damage or hazards. When using safety valves that return water to the supply network, the downstream system must be able to withstand temperatures up to +90 °C at a distance of at least 5 m.

Installation and connection

Connecting the safety valve to the cold water supply is mandatory; the arrow marking on the valve body must indicate the flow direction. No shut-off valves may be installed between the safety valve and the tank. Repairs to the water system may only be carried out by qualified personnel.

Electric heating: Installation and instructions

During the warranty period, only electric heating elements with insulated heating components may be used (e.g., type EJK from ZUG ELEKTROMET). Installation and connection must be carried out in accordance with the respective installation and operating instructions for the electric heater. Single-phase heating elements (230 V) are available in power ratings of 1.5/2.0/3.0 kW; three-phase versions (400 V) are available in 3.0/4.5/6.0 kW.

Single-phase heaters must be connected to a grounded 230 V/16 A socket. The power plug must not be inserted until the storage tank is completely filled with water. Three-phase heating elements must be connected by a qualified electrician according to the wiring diagram.

Maintenance and operation

Check the correct function of the safety valve at least once a month and before each restart. Maintenance and repair work must only be carried out by qualified personnel to avoid compromising operational safety and warranty claims.

In case of visible leaks, unusual noises, or abnormal pressure fluctuations, immediately shut down the system and have it inspected by a qualified technician. Observe the manufacturer's instructions for electric heaters and the guidelines for filling and draining procedures.

Warranty and safety information

The manufacturer reserves the right to make structural changes as part of product modernization, and these may not necessarily be reflected in the manual. Any tampering with safety-relevant components, such as removing insulation or making improper electrical modifications, will void the warranty.

Operation outside the specified pressure and temperature limits is not permitted. Ensure compliance with the prescribed operating parameters and consult qualified personnel if you have any questions.