Piping unvented discharge in plastic

[Sharp Point]

Hello peeps,
I have got 5 new build flats to do and the hot water is provided by a direct unvented cylinder. As the flats are located in an unsavory area, the client has requested that no copper is ran on the external walls of the dwellings. I have always installed discharges in copper to either a gully or hardstanding, but i understand it can be ran in plastic to a soil and vent pipe? this would be quite handy as the internal stacks are located about 0.5m from the current cylinder location. I know you have to use a fanny trap vertically, with the usual 300mm minimum before bend, but what type of plastic do i have to use? pushfit 32/40mm pipe and fittings or abs solvent weld?

Thanks in advance.

 

[Stigster]

Push-fit Polypropylene is correct. The solvent weld type is not designed for this application.

 

[SJB]

Fanny trap! Brilliant name for a hep2o!

 

[Rckape]

As Stigster said, polypropylene in 32mm is spot on.

 

[oz-plumber]

Fanny trap! Brilliant name for a hep2o!

Fanny Trap - I hope you poms
( Welsh, Irish and Scotsman included){ regret if I have excluded any breeds due to mis information / ignorance }

refer to the fanny as we in oz refer to it - not the American version of fanny.
( American sister in-law went to a shop requesting a 'fanny pack' once - brother had to inform her that fanny meant quite the opposite over here)

Anyway - going to send the apprentice to suppliers tomorrow to ask for a Fanny Trap.
He's only been on for 3 weeks - can't wait for the phonecall - from him or the person serving him.
Hopefully the person serving him has 3 weeks experience!!!


As for your question - look up your local regs

 

[townfanjon]

Its pushfit chaps , providing it is capable of taking high temps, as far as I know not all pushfit is, check with manufacturer to be 100%

 

[townfanjon]

Fanny trap! Brilliant name for a hep2o!

I must admit when I first heard fanny trap , I couldnt stop laughing for ages lol

 

[ShaunCorbs]

Push-fit Polypropylene is correct. The solvent weld type is not designed for this application.

why is push fit suitable and solvent weld isnt, just temp ?, would trust push fit as far as you could throw it with high temp.

and why dont you do it in steel (mapress)?

 

[tolly]

why is push fit suitable and solvent weld isnt, just temp ?, would trust push fit as far as you could throw it with high temp.

and why dont you do it in steel (mapress)?

Im sure its just a temp thing with ABS solvent weld not being able to handle it, although im sure OSMA solvent waste pipe is MUPVC which I think has an even higher temp rating than pushfit.

 

[tolly]

whenever ive done it previously I do it in 22mm tube until its near the stack, then elbowed down and use a 22-42mm EF reducer into a vertical 1 1/2" Hepvo with the adapter so you can tighten the reducer onto the Hepvo, I see loads where the 22mm is just poked into the top of the hepvo loosely and never really trust them, either that of the tube is poked in so far that the "fanny" part is opened which means its no longer a trap lol, and you start getting smells out the tundish.

 

[Ermintrude]

Solvent is fine providing correct class. Push fit is ok but u must fit as per mI ( leaving 5mm slip on each collar) and clip every 300mm.

 

[lame plumber]

I did a stint of contract combining/trucking in the states in my early 20s. The bosses wife bumped into me soon after I arrived, and her comment of "jeeze I wish I had a smaller fanny" left me wondering what the hell was going on for a bit, she saw the puzzled/startled rabbit look on my face and slapped her arse, to indicate what she meant by fanny, then asked what did I think she meant 🙂 I didnt have the heart to tell the truth, being as she had 5 kids at the time 🙂🙂🙂

 

[chris watkins]

whenever ive done it previously I do it in 22mm tube until its near the stack, then elbowed down and use a 22-42mm EF reducer into a vertical 1 1/2" Hepvo with the adapter so you can tighten the reducer onto the Hepvo, I see loads where the 22mm is just poked into the top of the hepvo loosely and never really trust them, either that of the tube is poked in so far that the "fanny" part is opened which means its no longer a trap lol, and you start getting smells out the tundish.

The recommended way is to use this with the 22mm tun dish fitted to the reduced spigot.

As it is new not retro real consideration should be given to discharge to external not to soil stack, as it states in PartG (because they will not check for discharge from the tun dishes).

Why not run the discharge pipe work internally following the the soil stack before popping out to external at low level.
22 or 28mm plastic pressure pipes such as hep or speed-fit can be used. Or a single discharge waste run so long as it is one size larger than the largest calculated single.

 

[tolly]

The recommended way View attachment 22159 is to use this with the 22mm tun dish fitted to the reduced spigot.

As it is new not retro real consideration should be given to discharge to external not to soil stack, as it states in PartG (because they will not check for discharge from the tun dishes).

Why not run the discharge pipe work internally following the the soil stack before popping out to external at low level.
22 or 28mm plastic pressure pipes such as hep or speed-fit can be used. Or a single discharge waste run so long as it is one size larger than the largest calculated single.

I prefer doing it my way with the bulk of it in copper then a 42mm reducer, looks neater then one of those tundish adapters with a hepvo valve and a load of pushfit next to a neat cylinder install, but I agree if its a new build then your much better off finding a route to discharge outside at groundfloor.

 

[solutions]

Im sure its just a temp thing with ABS solvent weld not being able to handle it, although im sure OSMA solvent waste pipe is MUPVC which I think has an even higher temp rating than pushfit.

My understanding is that the Osama solvent weld is fine as a colleague of mine posed the very same question as the op to Osma who stated that there product could be used in that situation. However I suspect that they may stipulate a provision to deal with expansion on long pipe runs.
The likely hood of released water or steam remaining at high enough temperatures to damage the pipe work after the D1 and tundish is small if the volume of water being released is high, then the cylinder will be getting an equally high flow of cold water if the release is slow which in my experience is more common then the temp drops significantly through d1 and the tundish and doesn't expose the plastic pipe to anything like the temps the Reg's require the plastic to be capable of.

 

[chris watkins]

My understanding is that the Osama solvent weld is fine as a colleague of mine posed the very same question as the op to Osma who stated that there product could be used in that situation. However I suspect that they may stipulate a provision to deal with expansion on long pipe runs.
The likely hood of released water or steam remaining at high enough temperatures to damage the pipe work after the D1 and tundish is small if the volume of water being released is high, then the cylinder will be getting an equally high flow of cold water if the release is slow which in my experience is more common then the temp drops significantly through d1 and the tundish and doesn't expose the plastic pipe to anything like the temps the Reg's require the plastic to be capable of.

Sorry solutions but the use of solvent weld uPVC or ABS plastics for safety valve discharge wastes is not Osama's or your call, they simply are not allowed under the Building Regulations despite what you may be told or see installed.

It really is quite explicit in the Regs & the training / assessment of the Part G ticket reflects this.

If you have seen a T&P open up on temperature either in real life or on the test rig's used in the training centres you would be left in no doubt as amount & temperature of the water/stream emitted & therefore the importance of installing the correct material.

 

[Stigster]

Planning Portal - Part G - Frequently Asked Questions

The above link provides answers to the question of what to use for the D2 discharge pipe.

 

[solutions]

Sorry solutions but the use of solvent weld uPVC or ABS plastics for safety valve discharge wastes is not Osama's or your call, they simply are not allowed under the Building Regulations despite what you may be told or see installed.

It really is quite explicit in the Regs & the training / assessment of the Part G ticket reflects this.

If you have seen a T&P open up on temperature either in real life or on the test rig's used in the training centres you would be left in no doubt as amount & temperature of the water/stream emitted & therefore the importance of installing the correct material.

You are undoubtedly correct. I retract my previous post.
It is dissapointing that a manufacturer would supply information contrary to the regs. Then again if the material and manufacture are capable of fulfilling the given role perhaps the regs specification needs to be revised.
Have you seen the affect of the temperatures you reffered to on solvent weld d2? I am curious to know the extent to which the pipe work materials are affected.
Thanks Chris, for your insight and clarity on the matter.

 

[chris watkins]

You are undoubtedly correct. I retract my previous post.
It is dissapointing that a manufacturer would supply information contrary to the regs. Then again if the material and manufacture are capable of fulfilling the given role perhaps the regs specification needs to be revised.
Have you seen the affect of the temperatures you reffered to on solvent weld d2? I am curious to know the extent to which the pipe work materials are affected.
Thanks Chris, for your insight and clarity on the matter.

I once went in to sort out the after mouth of a safety valve that had been discharging only 82degs water through copper D1 of around 2metres (yes I know it was too long but it was not subject to Building Regs) before it discharged into a uPVC gully connected to run of 110mm suspended pipe through a ceiling void (& it was good stuff = S/W Terrian) Just not clipped close enough, under the heat the pipe sagged so that looked like a great sea serpent between them. It stretched so much that it came away at the trap & the very hot water came through the ceiling onto a poor unsuspecting lady below.

Needless to say it ended up in a claim, very fortunately it was not a direct hit & it had to bring the false ceiling down first otherwise it could have been very very much more serious.

You have to remember that if these things go off, they discharge all the stored hot water until the temperature drops back below say 85deg C, they do not turn the heat source off so it reheats quickly & discharges again, cycling like this until someone turns the dam thing off which if they don't see the discharge (cause lets say it goes via a soil stack & the tun dish is hidden) can be some time.

 

[tolly]

Sorry solutions but the use of solvent weld uPVC or ABS plastics for safety valve discharge wastes is not Osama's or your call, they simply are not allowed under the Building Regulations despite what you may be told or see installed.

It really is quite explicit in the Regs & the training / assessment of the Part G ticket reflects this.

If you have seen a T&P open up on temperature either in real life or on the test rig's used in the training centres you would be left in no doubt as amount & temperature of the water/stream emitted & therefore the importance of installing the correct material.

Whats Bin Laden got to do with D2's anyway? :smiley2:

 

[chris watkins]

Whats Bin Laden got to do with D2's anyway? :smiley2:

LOL, Oops

But Solution started it off, I was just copying him, Sir, honest.

 

[solutions]

Planning Portal - Part G - Frequently Asked Questions

The above link provides answers to the question of what to use for the D2 discharge pipe.

Thanks for that link the following section was interesting. They do like to make sure they retain a good swathe of grey area.

Paragraph 3.60 of the Approved Document says that if a discharge pipe is connected to a soil stack the discharge pipe should be either polybutalene or cross linked polyethylene. Does this mean a polypropylene discharge pipe cannot be used?

As stated in its Introduction section, the guidance in the Approved Document is intended to provide advice on how to comply with the requirements set out in the Building Regulations and that “there may well be other ways of achieving compliance with the requirements”.

The Department’s view is that it would be acceptable, subject to also complying with sub-paragraphs a, b and d of 3.60, (better go find sub paragraphs a, b and then) for these pipes to be polypropylene to BS EN 1451-1, as recommended in BRE Information Paper 8/07.



Paragraph 3.60 of the Approved Document allows safety relief discharge pipes to connect to a soil stack if it can safely resist the temperature of the water discharged. Which materials are considered to be suitable?

Metal pipework, such as cast iron, is suitable.

For smaller hot water systems, BRE Information Paper 8/07 indicates that discharges can be made to PVCu stacks, provided that:

relief discharge is from domestic unvented hot water storage systems only – not combi boilers or sealed system boilers.
storage volumes do not exceed about 210 litres.
stacks are fully ventilated (ie. no stack cap or air admittance valve).
pipework complies with BS EN 1329-1:2000 or BS 4514:2001.

 

[chris watkins]

Thanks for that link the following section was interesting. They do like to make sure they retain a good swathe of grey area.

Paragraph 3.60 of the Approved Document says that if a discharge pipe is connected to a soil stack the discharge pipe should be either polybutalene or cross linked polyethylene. Does this mean a polypropylene discharge pipe cannot be used?

As stated in its Introduction section, the guidance in the Approved Document is intended to provide advice on how to comply with the requirements set out in the Building Regulations and that “there may well be other ways of achieving compliance with the requirements”.

The Department’s view is that it would be acceptable, subject to also complying with sub-paragraphs a, b and d of 3.60, (better go find sub paragraphs a, b and then) for these pipes to be polypropylene to BS EN 1451-1, as recommended in BRE Information Paper 8/07.



Paragraph 3.60 of the Approved Document allows safety relief discharge pipes to connect to a soil stack if it can safely resist the temperature of the water discharged. Which materials are considered to be suitable?

Metal pipework, such as cast iron, is suitable.

For smaller hot water systems, BRE Information Paper 8/07 indicates that discharges can be made to PVCu stacks, provided that:

relief discharge is from domestic unvented hot water storage systems only – not combi boilers or sealed system boilers.
storage volumes do not exceed about 210 litres.
stacks are fully ventilated (ie. no stack cap or air admittance valve).
pipework complies with BS EN 1329-1:2000 or BS 4514:2001.

Yer it good in it, all you have got to do is pick the wood from the trees & it will be as clear as mud.
They don't help themselves (or us) these people do they?