Combi boiler high pressure

ariba10

It matters not which way as long as it is across the pipe.

The only way you can lower the pressure is to let some water out of the system.

If you have the time and inclination you can bleed one of the rads.

(Any one)

fantastapotamus

I did try bleeding one of the rads before but it didn't seem to make much difference. I took about a small panful of water out, maybe it wasn't enough. I'll give it another go later. I'm guessing I can't take too much out, as long I keep the pressure at a decent level? I turned off a few radiators yesterday in the hopes it might help the pressure, and I'm not sure if I was draining one which was off (not sure if that makes a difference). Will any radiator do, or should it be one near or far away from the boiler?

Thanks for the replies, really appreciated.

pogg000

roddydogs wrote: »

Are you sure that a filling "loop" is not bypassing? Should be 1 bar when cold.

drain from any rad until pressure drops to 1 bar, if the pressure does not drop then water is possibly passing by filling loop

macman

fantastapotamus wrote: »

That makes sense - does it matter which way across the pipe it goes? Does the boiler have some sort of cut off so you can't put too much water in the system? I'm just wondering why that isn't working now - obviously I don't want to increase the pressure further, but that's how I did it previously.

Yes, once it hits about 3 bar the the PRV will (or should) lift and vent water. If it's not doing that then it needs urgent attention, as that is the safety device-and it's no longer safe.
You need to drain off some water via a rad bleed valve and get the pressure back to about 1 bar when cold, and isolate and detach the filling loop if it's not closing properly. That's why they have a valve at each end.
Turning off the rad makes no pressure difference, as you are only isolating one end of it, where the flow comes in.

fantastapotamus

macman wrote: »

Yes, once it hits about 3 bar the the PRV will (or should) lift and vent water. If it's not doing that then it needs urgent attention, as that is the safety device-and it's no longer safe.
You need to drain off some water via a rad bleed valve and get the pressure back to about 1 bar when cold, and isolate and detach the filling loop if it's not closing properly. That's why they have a valve at each end.
Turning off the rad makes no pressure difference, as you are only isolating one end of it, where the flow comes in.

I'm guessing the PRV is doing something, because it's not going past 3 when it's resting. I drained a fair amount from one of the radiators again, it dropped to around 2 and then stopped decreasing even with water still coming out the radiator. Then it went back up to 2.5...

Could I have somehow broken the black lever on the filling loop? I have a feeling some water is still trickling in even though I set it to off, but I can't hear water coming through the loop. If I try to turn the lever on (so it runs with the pipe), it's not putting more water in the boiler like it did before. I have a feeling that if I unscrew the filling loop I'll get a faceful of water!

macman

Not if you isolate it at the other end (the upstream end) first...
Or you can always turn off the mains supply temporarily while you disconnect it.