Boiler help. Baxi advanta exclusiv 35c

[Dingdangdo]

Hoping that some WACCOE plumbing engineers can help. I noticed that the pressure in the boiler had dropped slightly so went to top it up. I could hear the water going into the boiler bit the needle on the pressure gauge didn't move. Put a bit more in.....nowt the needle still didn't move. I tapped it and went in the shower. Looked and the needle had gone up to 3 bar so thought that it most have stuck so bled a radiator until I got it to 1 bar. Looked yesterday night and the pressure had dropped a little bit the needle didn't go up when I turned the hot water on. So I fired up the rads as I know that the needle would move. Rads on for half hour but the needle didn't shift. Since the rads have been on the needle has overnight gone to 0. I presume that it's still safe to use at 0 as I dont know how much water is in there due to the needle not shifting when I try to top it up. Could it be a faulty gauge or faulty expansion vessel or both

 

[Groovejet]

Needle at 0.1bar?? Unsure how this happened .
Your gauge is broke.
But if your expansion isn’t charged or it has a defect, when you typically run the heating through the night, you will wake up to a gauge showing 0bar. This is due to the Pressure relief valve blowing out the. C/h water due to boiler getting too hot & pressure rising above 3 bar.
Simple check- remove vessels dust cap & press the valve a little . If you hear air , the vessel is ok. If no air is heard, it needs recharging . If water is present....vessel is broke & needs replacing

 

[CBW]

Sounds like there’s some dirt on the gauge, or your vessel is flat and wants charging. Check for water from the prv/ safety discharge pipe (often called a blowoff). I wouldn’t continue using it until you’ve had it fixed.

 

[Groovejet]

Sounds like there’s some dirt on the gauge, or your vessel is flat and wants charging. Check for water from the prv/ safety discharge pipe (often called a blowoff). I wouldn’t continue using it until you’ve had it fixed.

Good point . For a diy’r,going outside , normally below the boilers flue outlet will be a 15mm copper pipe. This is a PRV. Pressure relief valve or slang term...’Blow Off’.
Check for dripping water on the end of the copper pipe or it maybe a copper fitting.
Also look at the wall around the pipe, signs of previous water blowing outside. Basicly the wall will have a damp/wet area.
If it is wet, your pressure has risen above 3bar & safely discharged outside, like it should do.
That’s when more detective work is needed to see why this has happened.
Like we said...Check the Expansion Vessel 1st .

 

[Dingdangdo]

An update. The expansion vessel has been replaced as well as the pressure gauge. The pressure gauge is still slowly losing pressure about 1 small mark every week. Before the EV was replaced there was no water coming from the copper pipe outside. British Gas came out and the first "engineer" said it was the valve leaking so replaced the Schrader valve but at the same time fractured the EV which was replaced the day after by another BG engineer. The same engineer also replaced the pressure gauge. I have now noticed when the BG engineer left a small amount of water was coming from the copper pipe albeit one drip every hour or so. I put a bag over the pipe for 24 hrs and saw a small amount of water collected in the bag. It was only a small amount. I think that it may be the PRV which has not seated correctly and letting a small amount of water into the copper pipe outside. I'm sure to get the boiler serviced soon so I'll get my plumber to have a look.

 

[Groovejet]

Bad habit of guys using PRV to reduce system pressure & empty the systems water when doing any work, instead of draining from a purpose made drain valve .
I dont touch PRV as it’ll always bite me on the bum , guaranteed