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General Plumbing and Gasfitting Talk => Plumbing => Ask Plumbers (Trade) => Topic started by: Thunderhead on October 15, 2011, 09:47:41 PM

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Title: Safe trays
Post by: Thunderhead on October 15, 2011, 09:47:41 PM
I'm an inspector and I agree with Integrated comments.


as an inspector could you answer me this...i was recently told that all inspectors in auckland will fail inspection if the HWC is installed on a safe tray and the TPR valve discharges directly into the safe tray...he said that a seperate line had to be run from the safe waste and a tun dish set up to recieve the discharge...have you heard anything of this as im just browsing the codes and cant find where it states that a safe tray cant recieve discharge from a TPR valve?...he mentioned that the council had its arse wipped in court because of this such set up...so now they will fail all such configerations.
Title: Safe trays
Post by: TS on October 15, 2011, 09:56:47 PM
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.
Title: Safe trays
Post by: Thunderhead on October 15, 2011, 10:00:54 PM
ha ha asked the damb question too early...here it is 3500.4      5.12.3 (c)     
ok now i can assimilate that bit of info...its just that if the inspector says something i want to know that what he is saying is correct before taking it as gospel as some inspectors arnt actually plumbers....cheers for the speedy reply anyways
Title: Safe trays
Post by: Thunderhead on October 15, 2011, 10:03:31 PM
5.12.3 (c) Drain Lines from expanision control or TPR valves SHALL not discharge into safe trays.
Title: Safe trays
Post by: robbo on October 15, 2011, 11:20:58 PM
hi guys,where does it say that you have to have a safetray anyway unless there is a danger of flooding another property? cheers
Title: Safe trays
Post by: Thunderhead on October 16, 2011, 12:50:57 AM
it dosent...but in the event that it does...
Title: Safe trays
Post by: robbo on October 16, 2011, 09:37:44 AM
thats right thunder, if a drain discharges into a safe tray it will eventually rot the bottom of the cylinder or the wooden supports it sits on if any, i have recently had to repair such a system that was in a roof space all because of drain into a tray,cheers
Title: Safe trays
Post by: integrated on October 16, 2011, 10:32:03 AM
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
Title: Safe trays
Post by: robbo on October 16, 2011, 01:36:34 PM
hi guys/intergrated, interesting, what form is the 40/50mm p.v.c. in, is it block or pipe? i presume that when using the s/s tray you then have to have a 40mm copper pipe from the outlet to outside?
As a matter of interest i think that we should all be able to claim these discussions as a training modual because we all learn something new from them, what do others think?cheers
Title: Safe trays
Post by: newguy on October 16, 2011, 02:17:34 PM
According to NZS 3500 Safe trays are only a requirement in AU and not NZ even if several tenancies. Good practice though.
Title: Safe trays
Post by: Thunderhead on October 16, 2011, 04:19:13 PM
you have to put in where damage would occur where there is multipucle oppuancies within the same building...example you own the flat above someone else requires a safe tray, if your cylinder is situated aghinst the boundry wall requires a safe tray where any leaking water might damage someone eles property.
i havent had to put one in myself yet though.
Title: Re: Safe trays
Post by: AlCan on August 17, 2014, 09:28:20 PM
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
Title: Re: Safe trays
Post by: Jaxcat on August 18, 2014, 10:46:47 AM
Install a continuous flow hot water system that is external to the house and you will never have to worry about HWC leaks again!
Title: Re: Safe trays
Post by: bowtieboy on August 18, 2014, 08:23:27 PM
 ;) 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 :P
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. :o
Title: Re: Safe trays
Post by: AlCan on August 18, 2014, 10:38:21 PM
Thanks Guys!   ;D

That puts a spanner right in the works...  It is a good idea, I think.  Though we are already on Mains Pressure, and I'd never want to go back. Not practical either, I suspect.

We're not on Mains Gas so I suppose Auto-Refilled Bottled Gas is the way to go?

Can anyone suggest cost comparisons versus Electric and Mains Gas, and what does it cost to set it all up? Are any Electric models available?  I know there used to be, but not sure how good they were.

Are there any Safety issues to worry about? I presume the bottles need to be Earthquake Restrained - though it looks like the examples on the elgas website are not! http://www.elgas.co.nz/for-home/refill-gas-bottles-lpg-supply-bottled-gas (http://www.elgas.co.nz/for-home/refill-gas-bottles-lpg-supply-bottled-gas). That could be fun, following an earthquake...

Also, do the bottles need to be located out of the sun so as not to heat up in summer?

Actually, I suppose the best option for all these annoying leaky valves is simply to put them under the floor! Is that permitted? That would pretty much solve the whole problem for not much expense, in my case.

What are your thoughts, please?

Title: Re: Safe trays
Post by: integrated on August 19, 2014, 09:14:53 AM
will cost you maybe $500 more to change to lpg than it would for a hwc replacement - operating costs maybe 10-15% less than electric - NG has significantly better operating costs - maybe 40% cheaper.
Title: Re: Safe trays
Post by: AlCan on August 19, 2014, 07:47:16 PM
Thanks integrated!

I've decided to stay put for now - stick with the Electric Mains Pressure and hope that I get 5 years before the next leak. Will probably have moved by then...

I do have a couple more questions though, if anyone feels like answering.

Is it permissible for a CWE valve to discharge uphill AT ALL? I can't see why not, but that doesn't mean a lot! At the moment, the outlet feeds downwards into a series of 15mm copper bends that end up in the TPR Valve overflow pipe, which drops through the floor then (slightly) downhill to the gully trap.

If I moved all the cold water in-feed valves under the floor, the CWE valve might have to exhaust slightly uphill (50-100mm?) into the overflow. Would that be an issue?

Also, is it required that there be a HWC cold water shut off valve located in the HW cupboard (before the Filter, PRV & CWE valve), or can it be under the floor?
Title: Re: Safe trays
Post by: bowtieboy on August 19, 2014, 08:24:53 PM
no, yes and all valves must be accessible.
is your answer ;D
Title: Re: Safe trays
Post by: AlCan on August 19, 2014, 09:45:46 PM
Hi bowtieboy,

Thanks for the answers.

Am I allowed to ask why? Please!

Why no uphill flow from the CWE valve outlet? The cylinder is Mains Pressure, typically runs at about 5 bar, so 100mm of "head" is inconsequential, no? I can understand why no uphill flow from the TPR valve, as boiling water doesn't want to hit a slug of cold water on its way out, but this is not the same thing, as far as I can see? Is there an official reason / explanation?

Also:

all valves must be accessible.

What does 'accessible' mean in this context?  :D

My floor is wooden, over a crawl space. The access door is about 1.5m away. Is that not sufficiently accessible? Or, does it have to be accessible from within the habitable space?