Common Waste Pipe for PRV Discharge

[dieselracer13]

Guys,

Can I check whether it is acceptable for the PRV from the boiler and the PRV and the combined Temp/PRV from an Indirect Unvented cylinder to discharge into a common waste pipe via their own tundish.

If so what size waste would you recommend?

As it's a timber framed house I don't want too many holes punched through the weatherproof membrane.

Cheers

Mark

 

[Madrab]

Depends - Your installer should be able to advise you as they need to be qualified to G3/UVHW for unvented.

As far as the G3 regs are concerned tho -

It needs it's own stack so there shouldn't be anything else attached to it, e.g. sinks, toilets etc
It needs to be the right material to be able to withstand the temp of water it may encounter under high temp safety release conditions
It needs to include a waterless trap, e.g. a HepvO dry trap
Depending on the size of the D2 pipes (after the tundish), you would want the waste to be larger than the biggest one.

So a few things to consider to stay within the regs.

 

[dieselracer13]

Cheers Rob,

Thanks for the quick response.

I'm assuming though that if venting straight to atmosphere to a safe location the dry trap wouldn't be required?

Mark

 

[Madrab]

It's to avoid waste/sewer gases coming back up the soil pipe and venting out of the tundish inside the property, so it would be advised and it's needed to be compliant.

 

[dieselracer13]

Sorry Rob, what I meant was that the waste pipe will not be connected into a soil stack but just passing through the wall and discharging into a flower bed. Unfortunately there is not a soil stack on the side of the house where the boiler and cylinder will be installed.

Mark

 

[Dan Robinson]

Where is the condensate going? And why is the installer not having a say in the matter?

 

[Madrab]

yep diesel, as Dan says and as in my original post, your installer should be advising, as he should be doing the job end to end and that is all part of the un-vented/CH installations?

 

[Agile]

Some of these requirements can be a little vague and seem somewhat silly too..

As far as I recall the regulations for the discharge from an unvented cylinder has to be in metal pipe [ unless its first passed through a HEPVO waterless trap after which it can be in plastic ! ]

 

[Richardthe3rd]

HEPVO Durex trap & push fit, not MUPVC or ABS waste pipe is acceptable here in Scotland. Done all the time on new builds.

 

[SandyLyon]

Some of these requirements can be a little vague and seem somewhat silly too..

As far as I recall the regulations for the discharge from an unvented cylinder has to be in metal pipe [ unless its first passed through a HEPVO waterless trap after which it can be in plastic ! ]

When used on an Unvented Cylinder there are strict guidelines that must be adhered to.
As Agile says, the plastic pipe from the HepVo valve must be Polypropylene (Pushfit) not ABS or MUPVC (solvent weld)
The HepVo valve must be installed in a vertical position and no appliances should be connected into the run.

 

[Richardthe3rd]

Some of these requirements can be a little vague and seem somewhat silly too..

As far as I recall the regulations for the discharge from an unvented cylinder has to be in metal pipe [ unless its first passed through a HEPVO waterless trap after which it can be in plastic ! ]

When used on an Unvented Cylinder there are strict guidelines that must be adhered to.
As Agile says, the plastic pipe from the HepVo valve must be Polypropylene (Pushfit) not ABS or MUPVC (solvent weld)
The HepVo valve must be installed in a vertical position and no appliances should be connected into the run.

Snap!!!

 

[SandyLyon]

Some of these requirements can be a little vague and seem somewhat silly too..

As far as I recall the regulations for the discharge from an unvented cylinder has to be in metal pipe [ unless its first passed through a HEPVO waterless trap after which it can be in plastic ! ]

When used on an Unvented Cylinder there are strict guidelines that must be adhered to.
As Agile says, the plastic pipe from the HepVo valve must be Polypropylene (Pushfit) not ABS or MUPVC (solvent weld)
The HepVo valve must be installed in a vertical position and no appliances should be connected into the run.

Snap!!!

Yep, you beat me to it by 1 minute

 

[Madrab]

According to the current G3's the D2 pipe can be in metal or a material that can demonstrate that it can safely withstand the high temperatures that may be found during an overheat discharge condition.

PolyP, CPVC and others could be used then, so it seems, though only ever used metal up to now.

 

[dieselracer13]

Where is the condensate going? And why is the installer not having a say in the matter?

Condensate will be pumped to soil stack on the other side of the house.

There is a pump that will do both the condensate and a PRV but don't believe it will do all three PRV's.

 

[SandyLyon]

Where is the condensate going? And why is the installer not having a say in the matter?

Condensate will be pumped to soil stack on the other side of the house.

There is a pump that will do both the condensate and a PRV but don't believe it will do all three PRV's.

Call me old school but for me

PRV should be unrestricted, what happens if the pump fails ?