Boiler problems...

stevetuk

I've got an Alpha CB24X boiler. The pressure was showing as 0.25 on cold, below the green zone, so I topped it up til the needle reached the green.

I then turned the heating on, and the needle went crazy and shot around past 4 bars all the way to beneath 0 again so it's now obviously got too much pressure.

How can I release the pressure in the system? I tried turning off the mains water at the stop !!!! and then tried turning taps on and the needle did drop back down but the moment I turned the taps off it went back up past 4.

Help!

Ectophile

The easiest way to reduce the pressure is to let some out through the bleed valve of a radiator, but if it's that high, you'd need to let quite a lot out. There also may be a little tap below the lowest radiator in the system. They normally need a square key to open.

Double check that the filler valves at both ends of the filling loop are properly turned off.

Really, the pressure should not be able to go above maximum (about 3 to 4 bar). There is supposed to be a pressure relief valve in the boiler to stop that happening. If it isn't working, you need to get it seen to, as it's a safety feature to stop things going bang.

stevetuk

Thanks for the quick reply. I tried bleeding a radiator downstairs but you're right that it wasn't dropping the pressure enough with what I got out so I think I'd have needed to bleed it for hours before it had any impact.

For now I turned the boiler off at the mains electric supply and as I've got Homecare with British Gas I've booked an engineer to come tomorrow.

Checking now, the pressure has dropped a bit from underneath the 0 to where I'd guess '5' would be if it was on the dial...
I'm hoping desperately that it will keep going.

There is an outlet pipe at the side of the house and this is dripping water outside so I wonder if that's the overflow kicking in?

Also, the boiler itself is dripping from one of the pipes underneath. So I've put a bowl under that for overnight.

For now, no heating or hot water

stevetuk

The pressure is down to 3.5 this morning and the pipe outside is still dripping, slowly.

I booked a BG engineer as I have Homecare 200 - will I be charged the £50 excess as a call out fee even if no work is required? Should I just cancel the appointment?

Steve

macman

It's still way over pressure, around 1 bar at cold normally. You have a leak from the PRV-now it's lifted due to over-pressure, it'll almost certainly need replacing.
The filling loop may have a valve on each end, one end is either leaking or you failed to close it properly. All you had to do was close the other end and then bleed a rad to get the pressure back to normal.
The other causes of the original issue are a faulty EV or a leak on the CH circuit.

Lgas

Don't cancel the appointment, pressure still way too high, engineer needs to drain the boiler, check the air charge in the expansion vessel, and clean or replace the pressure relief valve. Possibly a leak somewhere but usually it's a flat EV - or if the engineer's unlucky, the EV needs replacing.

I also think your filling loop is still open - check both ends of the flexible hose.

Lgas

Oops didn't see Macman's response, pretty much the same thing!

StuC75

there should be a drain valve at the lowest point, that you could connect a hose pipe onto - this could be on one of the radiator feed pipes - or if you have a magna valve 'thing' that will have a valve that can be opened to drain it quick - this is best done when the heating is cold so as not to scold - plus you need the cold water pressure to be right...

stevetuk

Lgas wrote: »

Don't cancel the appointment, pressure still way too high, engineer needs to drain the boiler, check the air charge in the expansion vessel, and clean or replace the pressure relief valve. Possibly a leak somewhere but usually it's a flat EV - or if the engineer's unlucky, the EV needs replacing.

I also think your filling loop is still open - check both ends of the flexible hose.

Thanks for all the replies, really appreciate it. Kept the appointment and sure enough it was a flat EV and needed the prv and filler loop replacing. The engineer drained the system, sorted the pressure out, replaced the parts, and away we go.

For now he's capped the filler loop ends and left the pipe on the top if I ever need to use it. Apparently it shouldn't have been left connected, although the system had been losing pressure periodically which I thought was normal, hence topping it up now and then. The flat EV was apparently why the pressure skyrocketed because I didn't fill it any more than I have done previously in one go.
All sorted now. And my house is still standing

Ectophile

In theory, you're always supposed to remove the filling loop once you've finished filling the system.

Nobody ever does, though.

Lgas

Excellent, glad it's sorted