Advanced Valve Temp & Relief MI 20mm 600kpa

The Advanced Valve Temperature & Pressure Relief (T&P) Valve (20mm / 600kPa) is a critical safety component designed to protect pressurized water heaters (geysers) from catastrophic failure. This valve acts as a "double-guard" by monitoring both the internal pressure and the water temperature, automatically discharging water if either limit is exceeded.

Technical Specifications

• Inlet/Outlet Size: 20mm (3/4") — Male Iron (MI) threaded inlet.
• Pressure Rating: 600 kPa (6 Bar).
• Temperature Trip Point: 93C to 99C.
• Body Material: High-grade DZR (Dezincification Resistant) Brass.
• Internal Components: Stainless steel spring and heat-sensitive wax probe.
• Certification: SABS Approved (Compliant with SANS 198).

Key Safety Features

• Dual Protection Mechanism: * Pressure Relief: If the pressure inside the 150L or 200L geyser exceeds 600 kPa (often due to a failing Pressure Reducing Valve), the spring-loaded disc opens to bleed off excess pressure.
  • Temperature Relief: A specialized thermal probe extends into the tank. If the VK11 Thermostat fails and the water approaches boiling point, the probe expands and forces the valve open to prevent a steam explosion.
• DZR Brass Construction: Specifically engineered for South African water conditions to prevent "pitting" and mineral buildup, ensuring the valve doesn't "seize" over time.
• Manual Test Lever: Features a top-mounted lever that allows the homeowner or plumber to manually "crack" the valve open to ensure the waterway is clear and the spring is functional.
• High-Flow Discharge: Designed to evacuate water at a high L/min rate, rapidly cooling the tank by allowing cold replacement water to enter via the inlet.

Installation & Professional Tips

• Placement: The T&P valve must be installed directly into the designated "Safety" port on the geyser, or as close to the top of the tank as possible. The thermal probe must be submerged in the hottest water (the top 150mm of the tank).
• Discharge Piping: You must connect a 20mm copper discharge pipe to the outlet. This pipe must run to the outside of the building and point downward. Never "plug" this pipe or connect it to a closed drain—it must be open to the atmosphere.
• Thread Sealing: Use a generous amount of PTFE (Thread Tape) or plumbing hemp on the 20mm MI threads. Tighten using a Kaufmann shifting spanner, ensuring the discharge port faces the correct direction for the overflow pipe.
• The "Drip" Test: It is normal for a T&P valve to "weep" slightly during the heating cycle as water expands. However, a constant flow indicates either a failed valve seat or that your system pressure is exceeding 600 kPa.
• Winter Maintenance: During your Winter Bulk 2026 checks, pull the manual test lever for 5 seconds. If no water comes out, or if it won't stop leaking afterward, the valve is likely "scaled up" and must be replaced before the Easter 2026 holiday peak.

Common Use Cases

• Standard Residential Geysers: Essential for all 600 kPa rated high-pressure systems.
• Solar Water Heating: A mandatory safety requirement for solar collectors which can reach extreme temperatures.
• Industrial Boilers: Protecting small-scale pressurized tanks in warehouse or farm environments.

Pro Tip: Never replace a 600 kPa T&P valve with a 400 kPa model (or vice versa) unless the entire system—including the Pressure Reducing Valve and the geyser tank itself—is rated for that specific pressure. Using a 600 kPa valve on a 400 kPa tank is extremely dangerous and can lead to a tank rupture.