Boiler Fault or Leak?

Was wondering if anyone had an idea as to what might be the cause to the problem I'm having with my boiler?

Turned the heating on this morning and I noticed that the radiator in the room I was in started making a racket. Checked the boiler and the pressure had dropped to 0. So I depressurised it and check all the rads and valves for leaks and didn't find any.

Ran the heating for a couple of hours and was all fine.

I later checked and the pressure had started to fall again to just under 1. I rechecked the rad and valves again and all seem to be fine so I depressurised once again.

This time when I've turned the heating on I noticed that the pressure steadily built up to 3.5, at this point I turned the heating off.

I've left it for several hours and the pressure has slowly dropped to just below 1 again. Turning the heating on once again and the pressure has hit 3 within 5 minutes.

This morning I assumed that there was a leak somewhere in the system, but with the pressure going up when the heating is one I'm thinking its possibly a boiler fault. Does anyone have any ideas on this??

It's normal for the boiler pressure to increase a bit when the heating comes on......is there any water discharging outside?
Your boiler has something called an expansion vessel in its system, which incorporates pressure increases if it's suitably charged with air. This could have a problem!
John

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reply#15

Exp vessel flat or pipe to it blocked

great thanks, seems like its a boiler issue then... will get an engineer book, didn't want to waste a £100 call out if it wasn't a boiler problem

Turns out it was the pipe to the expansion vessel that was totally blocked.

Engineer came out Tuesday and fixed it, had the heating on all the rest of Tuesday without any problems.

I noticed on Wednesday that the pressure had dropped down to about 0.3 bar, so repressurised back up to 1 bar (I did notice that the engineer hadn't turned off one of the isolation valves on the filling loop - don't know if this would have effected it in any way) and its been between 1 and 2 bar, depending on whether the heating has been on or not... until today when its dropped below 0.5 bar again (it sits at about 2 bar when the heating is running)

Is this normal to be dropping below 0.5 bar??
Before I had the original problem the pressure normally sat at 1 bar going up to 1.5 when the heating was running.

Trying to decide whether to have another call out or not

You may find the pressure relief valve seating is dirty or Spring stretched due to the previous fault.
Check the wee copper pipe coming out the wall for drips.
If not possibly a leak on the system somewhere.

Have you not spoken to the repair guy?

I'll hopefully be able to get up a ladder this weekend and check out the copper pipe.

Nope have not spoken to the repair guy, I have a boiler cover plan with HomeServe but they charge £100 call out. If it was the same issue they wouldn't charge, but if I'm still having problems but its a different fault I pretty sure they would???

You're still having pressure problems, same fault.

Did the guy who replaced the blocked pipe pump up the expansion vessel?
If he didn't he's a knob.

I really can't remember if he did pump up the vessel again... I know he did twice proir to removing it, but after he cleared the pipe I cant remember

not been able to check the copper pipe coming out of the wall for drips as its been constant raining here for the last couple of days.
have been watching the pressure constantly tho... during the day, its always between 1 and 2 bar (but the heating is running on and off all day), in the mornings tho (as the heating has been running for 6-7 hours) its between 0.5 and 0.75
I haven't filled the boiler at all again since Friday and its never dropped any lower so I'm assuming there isn't a leak... is it worth calling back and getting it looked at, other than having lower than normal pressure there doesn't seem to be any other problems at the minute
if the heatings been running everything seems total normal, would they be able to find a fault or would they be just shooting in the dark??

Well I called them back in the end and got them to have another look (was a different guy).

He let a tiny bit of water out of the expansion vessel, but other than that he reckoned that was fine. He checked over the rest of the boiler and couldn't see any problem (checked the prv for about 5 mins to make sure it wasn't dripping) the pressure according to him was dropping in a normal fashion. He didn't rule out a leak, but seeing as locating it (if there were one) would involve ripping up the real wood floors we've got over most of the house he was pretty reluctant to do it just yet. He advised me to monitor it for the time being.

So I've been keeping an eye on it for the last week.

Seeing as the temp has dropped this last week the heating has been running most of the time, and it all seems to be fine and I haven't filled up in over 10 days. I haven't noticed the pressure dropping but in the middle of the night I've heard the heating starting up, as the temp has obviously dropped low, but as its firing up you can hear a sound, which sounds akin to that of SodaStream coming from the rad in the bedroom. I'm assuming this is the boiler filling itself up a bit?? (The boiler is a Worcester Bosch Greenstar 30Si BTW)

I've just noticed today that there is a constant stream of water outside coming from the condensate pipe. I've know thats how boilers work and thats what the pipe is for, but I've never seen it running that fast and constant before, I thought that it was water coming from the gutter at first but when I turned the boiler off it went to a small drip and stopped after a minute. Is this normal?? Like I say I've never seen it running like this before (not that I have my head stuck by the drain often!)