Out of sheer curiosity ... pressure relief pipe

[CMairiD]

I stood this evening bemused and watching, what I believe to be, a neighbour's pressure relief pipe rhythmically dump out large gushes of water, then lighten up a bit and repeat over and over.

What would cause such a defined pattern of water loss? Could it be the pump? If it were the PRV, wouldn't it be a more steady stream of water?

 

[clarkerothwell]

sure it wasn't a condensate pipe? was it copper?

 

[CMairiD]

Yep, copper. Sited a few feet under the flue. Sticks out a few inches then bends downward for what looked to be a couple of feet.

 

[dd1975]

they may not have closed the filling loop properly if they recently topped up their system or a temp control failure on boiler could be another

 

[clarkerothwell]

prob the filling loop not closed or, faulty DHW heat exchanger split topping boiler up constantly. Normally a couple of dischargers of water would lower pressure enough for PRV to close.
At least its not your boiler!