Installation to comply with NZBC Clause G12 (2001) or NZS 4607:1989
- Valves must NOT be installed in ground.
- Valves must be installed in a position where reasonable access is provided for maintenance and/or replacement.
- Caution: do not apply heat near valves during installation.
- IMPORTANT: TAPS, VALVES OR OTHER SHUT-OFF DEVICES MUST NOT BE INSTALLED IN THE RELIEF OR EXPANSION DRAIN LINES.
- Drain line should be copper, they should fall continuously from the valve outlet and be of the shortest possible length.
- The discharge end of the drain line must be positioned so as any discharge will be visible, but not cause damage or a nuisance.
- Drain lines must not be smaller than the outlet of the valve to which they are connected.
- If relief valve drains are combined, a 25mm air gap must be maintained.RECOMMENDED
- In frost areas fitting an EVT7.6 can protect cylinders in the event of exhaust pipe freezing
High (Mains) Pressure Installations
*R.V and E.V drains may be combined provided discharge is via a minimum airbreak of 25mm. Drain must have a minimum size of 20mm diameter and be one size larger than the largest relief valve outlet. (Refer diagrams)
** 1.0m minimum copper pipe length from cylinder to Tempering Valve and 250mm minimum vertical heat trap to Tempering valve (as per G12).
Note: If the drain exceeds a factor of 12 as a combination of length in metres and number of bends (e.g. 7 metres & 5 bends – 12) a SVB vacuum break must be fitted as per G12.
Low Pressure Installations
Open Loop Solar Installation
Mains Pressure, Wetback Installation
Marine Hot Water Cylinder Installations
- Apex marine relief valves are available at settings up to 415 kPa (60psi).
- It is important that the relief valve is set about 70 kPa (10psi) above the pump outlet pressure.
- The TPR valve and maximum cylinder working pressures must be greater then the relief valve setting.
- The TPR drain is plumbed overboard. If the valve discharges the complete contents of the hot water cylinder, due to an over heating fault, the cold water tank could be damaged
- Drain lines must have fall and be piped in half hard copper pipe. On alloy hulls, take precautions to prevent electrolysis. If the water tank is not vented, run the drain line to waste.