I'm planning the plumbing side of a new boiler install (Gassafe man will be doing the gas side) It is a standard W-B boiler 24Ri I have an external expansion vessel fitted with a PRV I'm not sure on the requirements for the discharge pipe from the PRV. Ideally I'd like to go straight through the wall in copper and down to a rainwater gully terminating the pipe just above the gully grating. I feel that this will give an air break to stop back siphoning and a visible means of noticing a leak. Any jet of hot water will be directed downwards safely into a trap full of cold water.
PRV has a 1/2bsp outlet, so I assume 15mm copper will be adequate?
The WB installation manual shows a pipe through a wall with a simple downward facing bend as soon as it exits the wall - seems more dangerous than my method
Will my method be OK?
Searching through building regs, G3 talks about discharge from unvented hot water tanks and the need for a tundish etc but I've yet to find chapter and verse on boiler PRV discharge and I really don't want a tundish indoors.
TIA
Bob