Ventilated Discharge Brunch System

• Main Ventilating Stack joins the main ventilating stack above the spill over level for the appliances
• Each appliance has its waste vented
• Brunch Ventilating Pipe:
  • MIN 25mm if < than 15m
  • 32mm if > 15m or > 5 bends or serves > 1 appliance
  • 750mm MAX from the trap to the vent pipe 
  • ifindplumbers

Stub Stack System

• preferred where the numbers of sanitary appliances and their distance to a discharge stack are large
• NO WC connected above 1.3m from the invert of the drain
  • On the stub stuck system the MAX height above the invert to the centre of WC bunch is 1.5m
• MAX 2m from the invert to the highest brunch connection
• Stub Waste connection – direct waste pipe connection to the drainage system
• The top of the Stub Stack SHOULD be finished with End Cup (Screwed Access Plug) or Air Admittance Valve (CAN terminate inside a building)
• Stub stacks may also be used on upper floors where the discharge from the stack is to a ventilated soil stack.

Primary Vented Stack System

• previously known as the single stack system
• Installed in most new buildings and domestic premises
• NO separate ventilation pipe required
  • The discharge stack and branch pipes are sized to avoid the need for separate ventilating pipes
• There are limits on length, diameters, gradients and branch waste pipes
  • ​ this system saves space and costs 
  • The distances of sanitary fittings can be exceeded if using resealing (or antisiphon) traps and branch pipe air admittance valves
• Appliances SHOULD be grouped closely together
• BS EN 12056-2 allows external pipework on buildings up to three storeys
• To minimise noise transmission it's recommended 25 mm of insulation around soil pipes passing through a bedroom or living room.

Secondary Ventilated Stack System

• The venting stack is usually half diameter of the discharge stuck
• Appliances SHOULD be grouped closely together
• Separate ventilating overcomes pressure fluctuations that could cause trap seals to be lost