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unvented hot water blow off

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B

buckley plumb

just re done my unvenvented and 5 years ago was told if discharging into a soil stack then pushfit must be used just been told today it should be solvent weld what is correct . got part g and it does not realy state
 
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Re: unvented ho****er blow off

does it not state a suitable material that can cope with the temps? cant remember actual figures off the top of my head but i know pushfit normally has a higher max working temp compared to solvent weld. This does not mean solvent weld may not cope but from previous jobs its always been pushfit used.
 
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Re: unvented ho****er blow off

title should have said unvented hot water blow off dont know what went wrong.

d 2 can terminate into a soil stack with a hepvo trap its in bulding regs and on course copper is better i know .
 
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Re: unvented ho****er blow off

AWheating said:
does it not state a suitable material that can cope with the temps? cant remember actual figures off the top of my head but i know pushfit normally has a higher max working temp compared to solvent weld. This does not mean solvent weld may not cope but from previous jobs its always been pushfit used.
Click to expand...


part g states polybutalene or PEX is this solvent weld or pushfit
 
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Re: unvented ho****er blow off

ne1ls0n said:
any blow off should be copper, never plastic !!!!!
Click to expand...

thats why the course is now a 5yr ticket rather than evergreen, so that you can pick up the changes, get yourself some updated info, its not mandatory for you to upskill in between the 5 yr cycle but it will keep you up to date on changes which may make you more capable of assessing a job correctly, the new rules allow plastic discharge if done properly using the correct design and materials
 
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Re: unvented ho****er blow off

buckley plumb said:
now i am totaly confused as the link says these materials are for hot and cold supply but thats what part g says. how can the colleges that train the unvented not know
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ask for a full explanation from the college, you have paid them to re-assess you and you should come away with the updated info and facts, its not hard but if something isnt explained well it becomes confusing
 
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Re: unvented ho****er blow off

kirkgas said:
ask for a full explanation from the college, you have paid them to re-assess you and you should come away with the updated info and facts, its not hard but if something isnt explained well it becomes confusing
Click to expand...

hi mate i did and they said its always been that i was taught wrong last time - but my argument is i got home and posted on here and realised what page 24 says in part g .cant be glued as its same material as hep pipe why dont they make the regs clear . phoned local authority but they have no idea .someone should know any lecturers on here

ant
 
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the bpec notes we use state solvent pipe isnt allowed, and if using plastic it needs to be push fit, as others have said more manufacturers are making more materials available, and if connecting to a stack use a hep2o valve
 
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Re: unvented ho****er blow off

thanks everyone i thought i was taught correct the first time i did my unvented . it just goes to show that if the gas and plumbing standards etc were made more user friendly and in plain english there would be no confusion . even colleges and trainingcentres get it wrong
 
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Re: unvented ho****er blow off

kirkgas said:
why? i know you are saying its your view but im interested to know why not
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In days of old I worked for a certain manufacturer whereby there was a discharge and the amount/temp of the water brought a stack down causing a considerable amount of damage. My public liability does not want testing out thanks.
 
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Re: unvented ho****er blow off

Technical Circular
Discharge pipes from unvented hot water storage systems
Note: The following guidance does not apply to discharge pipes from combi boilers or sealed central
Amend
heating systems. These systems could discharge at higher temperatures and so the discharge should be
terminated externally in accordance with Technical Circular 8.1/08.
If a safety device of an unvented hot water storage system (UVHWSS) operates, a substantial quantity of
scalding water and steam is discharged. It is important that this discharge does not cause harm to people.
The following locations for the discharge pipe are acceptable.
Low level
■
Into a gully below the grating but above the water level (see diagram 1).
Diagram 1
Diagram 2
Diagram 3
■
Onto the ground (drive, path or garden area). The pipe should discharge downwards and be no
more than 100mm above ground level. The discharge should be protected (normally by a wire cage
(see diagram 2) or alternatively by a proprietary plastic fitting (see diagram 3)) to prevent people
coming into contact with scalding water.
Issued:
21 February 2007
Supersedes:
12 December 2005
Authorised by:
P R Crane
Page
1/3
Page 2

8.1/03
High level
High level discharge is only acceptable:
- onto a flat or pitched roof capable of withstanding water at high temperature and at least 3m
away from plastic guttering, or
- into a metal hopper and downpipe which terminates at low level (see diagram 2).
Where discharge pipes extend down the outside of buildings, it is not necessary to provide protection
to the exposed pipe (the discharge should still be protected as shown in diagrams 1, 2 or 3).
Connection into SVP
Connection into an SVP is acceptable for all locations as an alternative to low and high level
discharge arrangements described on page 1.
Connection into an SVP is only permitted with the use of a Hepworth HepVo waterless trap installed
as shown (see diagram 4).
The trap should be installed vertically.
The minimum discharge pipe sizes and lengths must be met.
The discharge pipework should not connect with any other waste pipework/traps.
Amend
Pipework material
The discharge pipe and fittings should normally be metal. Alternatively polypropylene pipes and fittings,
as described, are an acceptable alternative material:
Polypropylene pipes and fittings should be marked to either BS 5254 ‘Specification for Polypropylene
waste pipe and fittings’ or BS EN 1451-1 ‘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 identification.
c) The material code (PP).
b) The number of the British Standard ‘BS 5254’ or ‘BS EN 1451’.
d) The nominal size.
As polypropylene cannot be solvent welded, pushfit joints should be used.
Polypropylene pipework should be adequately supported in accordance with the manufacturer’s
recommendations (normally clipped at 300mm centres).
Polypropylene pipework can be affected by sunlight so is unsuitable for use externally.
Amend
Issued:
21 February 2007
Supersedes:
12 December 2005
Authorised by:
P R Crane

























 
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Re: unvented ho****er blow off

lbp plg & htg said:
In days of old I worked for a certain manufacturer whereby there was a discharge and the amount/temp of the water brought a stack down causing a considerable amount of damage. My public liability does not want testing out thanks.
Click to expand...

i appreciate you are speaking from experience, either good or bad we learn (but usually we learn more from the bad but thats life)
 
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The important factor is the type of plastic used - it needs to be able to withstand a 'large' quantity of boiling water, in the event of a big discharge.
As mentioned earlier, Polypropylene is the material required. This is used for push-fit pipes, traps, HepVo traps, etc.
Polypropylene can withstand around 120C, where as ABS is rated for around 70C, but can take 95C for several minutes.
Be aware that plastic soil stacks are generally ABS, but the expectation is that the water will have cooled down sufficiently before reaching the SVP!
I always find this a grey area and my preference where possible is always to use copper to discharge externally.

I'm renewing my G3 soon and I will quiz the tutor on this area, but I suspect no one will have a clear definitive answer!
 
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