Two separate shower traps?

[Ajax123]

The traps ability to get rid if waste is not just down to pipe size. It also depends on the trap entry not becoming air locked. I found this when I installed my own shower. I put a standard floor waste in with a 50mm pipe outlet yo a shallow p trap. It kept bunging up because the shower out water ok top faster than the it could get into the trap entry thus air locking and overflowing. I ended up changing the trap to one called a fast glow trap which as the water enters the trap it creates like a vortex stopping any air lock. Now works a treat.my shower is rated at 40litres a minute when on the pump...

 

[Qwerty]

As Alan says above, a fast flowing trap is all that is required. Are you running a combination boiler or conventional tank & cylinder?

 

[Waluigi]

..........or Unvented......or Thermal Store.

 

[Cranbrook]

Its an unvented system (two boilers in a low loss header system. I don't think a fast flowing trap will be sufficient given the flow rate, so I think I'm gonna screed in two separate drains and run separate 40mm waste