Pressure Relief Valves


  • Low pressure hot water systems.
  • Pressure systems for marine applications.
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Features & Benefits

Features and Benefits

  • Forged, high quality, corrosion resistant DR brass body.
  • Silicone rubber seals able to withstand 99°C.
  • Body easily unscrews to allow cleaning of seats and seals, no body screws.
  • Unique vacuum break provided means valve retro fits all other similar relief valves at replacement.
  • Vacuum relief provided failsafe against over pressure and implosion.




  • Inlet:
20mm, 3/4" BSP (male)
  • Outlet:
15mm, 1/2" BSP (male)
  • Length:
80mm (valve)107mm (c/w vacuum break)
  • Standard pressure settings: 37, 75 and 120 kPa
  • Special settings up to 415 kPa (60psi).
  • Maximum temperature: 99˚C.
  • Kilowatt Rating: 12 kW

Sectional View


Product Codes

RV 3.7 37 kPa
RV 7.6 75 kPa
RV 12.2 120 kPa
RVHP Settings up to 415 kPa on request for marine cylinders.

Installation & Servicing


  • Refer to Technical Area for installation guide.
  • Install approximately 1 metre above Pressure Reducing and Cold Water Expansion Valves.
  • May be installed vertically or horizontally provided vacuum break is used.
  • Provide 150mm heat trap.
  • Do NOT apply heat near valve during installation.

Thermal Expansion

Under normal conditions, a 180 litre hot water cylinder when heated from cold to 65°C will expel 3.6 litres (12.6 meters of 20mm copper pipe) of water due to thermal expansion. The amount of expansion will vary depending on the volume of hot water used and cylinder capacity.   expansion


  • VBN Vacuum Break
  • 15mm Female to 20mm Male reducer.



  • Complies with NZ Building Code G12 (2001)
  • Complies with NZS 4608:1992
  • NZ Patent No. 209613

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