SEISMIC RESTRAINTS FOR GAS WATER HEATERS & APPLIANCES
Gas hot water heaters and other gas appliances that require seismic restraint have been affected by changes to NZBC C/AS1 to AS7, Protection from Fire. In particular changes to clause 7.2.2, which modifies the newly adopted gas Standard AS/NZS 5601.1 to say that gas appliance seismic restraints "shall be designed in accordance with B1/VM1 Paragraphs 2.0 and 3.0". This basically means that restraint loadings shall be to AS/NZS 1170 (set + NZS 1170.5) and the design to NZS 4219.
Up until now for the restraint of a gas HWC most designers and plumbers have relied on manufacturer's details or the simple solution in NZBC G12/AS1, figure 14 (a few straps and blocks). In point of fact the solutions in G12/AS1 did not even comply with the old NZBC C/AS1-AS7, let alone the new changes. The changes will make it important for manufacturers to prove their solutions comply with NZBC C/AS1-AS7 and custom solutions will have to be designed by an Engineer. There is no simple generic answer anymore and you cannot leave it to the plumber to make one up.
Masterspec sections have been updated to reflect these changes, but we recommend that, in the short term at least, you check with the manufacturer that their details do comply with these new requirements. Remember, we are in the transition period for these changes, but they become mandatory on 18th June 2014.NOTE; The changes to NZBC C/AS1-AS7 do not affect non-gas HWCs (electric, wet-back, solar, etc), these can still use the simple generic restraint requirements of NZBC G12/AS1, including figure 14 where applicable.