Unvented Hot Water G3 discharge

[Steelmasons]

Even the rod type is not going to be reading the highest water temp leaving the element.

 

[Dan Robinson]

What you sayin'?

Just sayin'

 

[Steelmasons]

It would appear the top 100 gas man has missed the point completely..

 

[bernardgreen]

The issue here is the temperature of water going to a standard plastic stack.

At least in a plastic stack that might might be deformed the dangerously hot water is contained. It is when the hot discharge empties on to an area where it could harm people that things need to be improved

As said already the safety cutouts that are fitted in immersion heaters to prevent the water at the immersion heater from reaching boiling point cannot ensure safety unless the immersion heaters are fitted at the top of the cylinder. And yet cylinders are installed with low level immersion heaters with their own safety cutouts but with no means of detecting over heated water at the top of the cylinder and switching off the supply to the immersion.

 

[philtheplumber]

This is my point that the water isnt contained if left for a long period as i have seen plastic stack go like an S and break.
Can you imagine the mess when in a block of flats where it is also serving toilet waste.
The stipulation of the pipe coming off the stack feeding just the unvented cylinder is for that one outlet only. The stack is then used for whatever is piped into it.
Plastic Stacks do not take continued running hot water as they soften.

The issues reguarding Immersions and the overstats is a valid point but irrelevent to the discharge not doing the purpose it is there for.

This issue would not of happened if the discharge was Metallic as it was originally in G3.

This is a safety issue

 

[Roger928]

NHBC says..

Plastic piping systems for soil and waste discharge (low and high temperature) within the building structure.
The pipe should be marked with the following at max 1M intervals:

a) Manufacturer’s identication.
b) The number of the British Standards ‘BS 5254’ or ‘BS EN 1451’.
c) The material code (PP)
d) The nominal size.

http://bit.do/NHBC-Technical-guidance-2016

Seems like they are stipulating pp for the soil also.
Some sources say a maximum of 80c continuous flow for PP and 60c for upvc continuous flow.

In any serious iinjury claim won't the installer be to blame?

 

[philtheplumber]

Saw this today, this is on the fifth floor of a block of flats and that's picking up all kinds of waste.

I'm seeing a lot of Thermalstore units being replaced with Unvented. The stack is therefore approx 10 year old plastic pipe.
The installer looks at how he installs it via NHBC and G3.
He then connects and self certificates as G3 approved.

I think if approved as it is then the Governing body should be to blame.

 

[Roger928]

What floplast say....

Working Temperature
Soil and Waste systems may be used to carry liquids when subjected to a continuous flow, with a maximum temperature of 76°C. Intermittent discharges of up to 100°C may occur, provided that a duration of less than two minutes is observed.

 

[Roger928]

I think if approved as it is then the Governing body should be to blame

But nhbc say the soil must be PP to BS 5254’ or ‘BS EN 1451’.
Its on their paper work.

Anyway I've never seen a soil stack made from PP.
Marley say 100c for their akatherm HDPE to BS EN 1519:

Geberit say this about their hdpe drainage discharge piping..
Hot water does not affect the material at temperatures of up to 80 °C – or even up to 100 °C for short periods and without mechanical load.

 

[Agile]

Phil, where a stack has folded, who has ended up paying for the replacement?

 

[philtheplumber]

Not sure who paid in then end as being sorted by housing association / insurances.

I had a call back from NHBC technical today and the guy said yes it is ok for the stack to be plastic. When I asked that the building was put up before 2008 when the Reg came in he said it was still fine as approved today.
He also said he had heard of no cases being reported and could I keep them of any such issues I attend.
I'm a little perplexed with his answer but yet not surprised.
There really is a safety issue with discharging to old plastic stacks in flats in my opinion but they will not look into until more people have suffered with issues.

Oh well I will proceed as normal.

Please notify NHBC if anyone has such issues. I know I will.