I do recall seeing that somewhere in the regs, will have to wait until I'm back at work next week to look it up.

5.12.3 (c) Drain Lines from expanision control or TPR valves SHALL not discharge into safe trays.

it dosent...but in the event that it does...

due consideration needs to be given to material of tray

i have used both copper & stainless hwc overflow trays as an alternative solution for a tun-dish in commercial applications

yes it is a greater cost in material but that is off-set through lower labour/material content not having to run independant drains for safety valving

the nzbc gives a hell of alot of freedom and scope for the design and installation of plumbing systems - g12/13/asnzs3500 are all but one means of compliance - as long as you meet/surpass the performance criteria and functional requirements of the nzbc you cant go wrong


how many plumbers discharge a hwc vent/exhaust onto zinc/zincalume roof?!?
plenty from what i have seen and replaced
within 18mnths the sheet of iron that vent dischrges onto will be pitted and corroded away

who lifts there hwc off the base of their overflow tray to prevent sweating and premature failure?
when doing this i use 40/50mm pvc as it wont hold moisture

According to NZS 3500 Safe trays are only a requirement in AU and not NZ even if several tenancies. Good practice though.

Hi All,

I know this is an old thread, but I'm a new member and would like to add to / reactivate this discussion. Please forgive me if there's a better place to do this.

I'm contemplating installing a safe tray in my HW cupboard. However, it's very tight, and I haven't found a standard tray that would fit properly. Also, I'm not particularly worried about the possibility of a leak from the HWC itself. Let me explain.

We bought our current house about 3 years ago. As I soon found out (after we moved in), the HW cupboard contained a small, "permanent" lake, about 5mm deep. Not good. The entire Mains Pressure HW system was only slightly over 5 years old, and just outside the warranty period on the Methven / NEFA valve gear installed. The leak was coming from the small breather hole in the side of the Pressure Limiting Valve - which looked exactly like an oversize version of one of those round, spring-loaded, barrel shaped non-return valves. Not too sure why it was leaking as I never pulled it apart, but I suspect the bore was scored by dirt or rust in the water. Replaced it with an Apex valve.

All good, for a while. Then, noticed a stain spreading into the floor by the wall separating the HWC from the hall. ANOTHER lake in the Hot Water cupboard. Nothing to do with the previous problem, though that was my first thought.

This time, the Tempering Valve was leaking from the Temperature Adjustment screw recess. Again, a NEFA... This failure was less understandable. I had never even touched the adjustment. Apparently, the O-Ring sealing the adjustment screw had perished, even though it looked normal. But the problem only went away after I replaced the O-Ring.

I put this failure down to bad plumbing. The Tempering Valve was originally installed into the wall opposite the top of the cylinder, connected by a short length of 20mm copper pipe, meaning that it is always hot, due to hot water convection, conduction etc. Also, there appears to be no non-return valves built into this model TV, and none were fitted externally, so (I imagine) after a while, the valve got hot enough to open the cold side inlet, causing massive reverse circulation (thermo-siphoning) of hot water down the cold water feed pipe to the bottom of the cylinder. I fixed this by adding a non-return valve in the cold leg when I replaced the Pressure Limiting valve (but the TV leak happened a few months later).

Anyway, my point is that in the space of less than 12 months, I had two HW System leaks that we not due to the HWC, and probably would not have been saved by a standard "Safe Tray", which is designed to catch leaks from the Cylinder itself.

I'm considering adding a Safe Tray, but it would have to be custom made. I'm thinking galv sheet would be suitable, as it should not be wet, most of the time. However, in order to be any real use, it needs to catch leaks from all the valves and connections etc. In the case of the PLV, the leak came straight out the side of the valve, ran along the body about 30mm then dripped off the edge. The TV leak, on the other hand, ran around the body of the valve and all the way down the Cold water feed pipe to the CWE valve, then dripped off that onto the floor.

As I'm planning to reconfigure the entire HW System, moving the TV down closer to the floor and running the Hot Water supply down to it in 15mm copper, I want to try to create a Safe Tray that will catch all these potential leaks. I'm thinking the best thing to do would be to make the tray wall-to-wall, then run the various feed, overflow and outlet pipes through holes in the bottom of this tray. These holes would have to be sealed up in some way, otherwise water is likely to simply run down one or more pipes, then find its way between the tray and the floor... But any pipe that it routed outside the tray is going to create the perfect path for leaks to trickle down into walls or onto the floor.

I want to make a Safe Tray that can live up to its name, but it's not as easy as it sounds.

Would it be permissible to run pipes through holes in a Safe Tray bottom, does anyone know? Or, does anyone have any other ideas or suggestions, please?

Thanks for taking the time to read all this, by the way!

Regards,
Al

  that was what I was thinking too Jaxcat!
why bother with all the cost and work when you can simplify the whole system by going instantaneous with a minimum amount of valves too! AND upgrade your system to mains pressure
imho nefa products are not what they used to be, and I wouldn't recommended them!
Over the last 15 years I have removed way  more nefa, tv, prv, and limiting valves than any other brand.