Just headin to bed and notice water coming through, head into attic (god knows why you'd put a boiler in the attic) and sure enough its pisiing water. advice? rented accom so "constant water leak whose sourcre cannot be found" is classed as an emeregency. Im off to try and find somewhere to switch all the water off…

Is there a header tanks – either turn the vlave off that supplies it or tie the ballcock up so it doenst refill – turn the boiler off as well

not sure where the header tank is-boiler is already up high

inventory says water stop valve under sink but when i turn the blue valve thing i can still get water to run-that shouldnt happen should it?

A blue valve thing sounds like it's for the washing machine. The stop cock will typically be a brass tap somewhere. Probably under the sink.

yeah thats what i thought, cant see the bugger though

boiler pressure is maxed out i wonder if cranking on the heating will release the pressure and thats maybe why its leaking from right under the boiler

sounds like the pressure release valve is releasing pressure. now need to work out why there is so much pressure in it….

And there's no tap by the boiler itself? If the pressure is high you need to turn the bugger off, sharpish.

ok heating on and all radiators to full! cant find a bloody radiator key

as to why-heating hasnt come on because hasnt reached threshold set centrally could that cause pressure build up?

Is it a combi-boiler?

The pressure could be building up because the water intake valve has failed? There should be a filling loop – most likely under or next to it. Make sure the valves there are turned off. Can you see where the water is coming from?

In fact, take a photo and post it up. There are a couple of plumbers on here.

water seems to have slowed/stopped and pressure is falling-can see 2 blue valve handles, close both?

Are the blue valve handles near the boiler?

Sounds like these could be the filling loop. Mine has 2, I leave them both closed.

its an alpha HE CB33

one i think is the pressure relief valve and the other im not sure, ill put up some pics

from left to right

ok dumped a few cans of water from a radiator, ill wait and see if that drops the pressure at all then switch off the boiler and go to bed-why does this stuff never happen during the day?