Faulty pressure guage?

sb29

My Vokera Vision 30c was showing various error codes. Since it is under warranty (lapses next month), we got an engineer in today and he found that the pressure guage was faulty. He replaced it with a new one. When he left, the pressure was just above 1 bar.

However, right now, the pressure guage shows 0 bar. The boiler is working perfectly (both CH and hot water). Switching on the hot water or the CH doesn't move the pressure guage at all. I read the information on the forums and have done the following two things:

1. Tried to re-pressurize using the filling loop. Although on opening the filling loop, I could hear no water sound.

2. I went to the highest radiator in the house and bled it. The water gushed out with full force.

Can it be that the replaced pressure guage is faulty as well?

I can call the engineer again, but just wanted to make sure it is not a problem outside of the boiler. Although the boiler is under warranty, there is a high call-out charge if the problem is not with the boiler itself.

Le_Kirk

If the boiler is working it would seem that it thinks the pressure is OK.  I did read last week on here that some boilers (can't remember if it is a Vokera - but you could try searching the forum) did have an infernal pressure gauge (digital) plus an analogue one for display.
Just found your manual: -
https://library.plumbase.co.uk/flipbooks/RE/vokvis30c_24691_t/mobile/index.html#p=11
Check out page 7 as it shows fault codes A04 - low water pressure.  Do you have a fault code displayed?  If not and the boiler is firing, seems like it is a faulty gauge.  Time to call back the engineer.  The manual seems to confirm it is only an analogue gauge.

TELLIT01

If the guage was showing 1 when the engineer left and is now showing 0 there is a problem of some kind.  Get the engineer back, there can be no justification for a call out charge.

Jeepers_Creepers

Hi SB.

As said above.

This is the model with a round digital display to the left of the controls AND a small analogue pressure gauge on the right? As Le Kirk  says. this boiler will have an internal (and often infernal) pressure sensor in order to control the boiler, and that's what flashes up warning codes and tells the boiler to stop working when the pressure has dropped.

The wee analogue dial is just for the user - yourself. If that is showing 'zero', then it's faulty. Yes, surprising it's happened again, but there you have it.

You can feel confident that if your boiler is continuing to operate as normal, then your pressure is adequate; after all, it flashed up a warning the last time. So trying to refill the system was a baaaaaad move... 

Why bad? Because if you had let it reach around 3bar, you'd have introduced other issues, tho' none of it fatal - so don't worry. However, it could have opened the safety valve, and these are a pain for not releasing afterwards; they can continue to drop, so you'll have slow pressure loss afterwards. Fingers crossed your level of competence meant that you didn't manage to top it up... :-)

Call them up and report the issue; "New pressure gauge has gone to zero BUT the boiler is working perfectly with no error codes, so I'm guessing it's just the wee gauge itself. Could you come out and fix at your earliest - ta muchly."

Don't mention that you tried to top it up.

 

sb29

Jeepers_Creepers said:

Hi SB.

As said above.

This is the model with a round digital display to the left of the controls AND a small analogue pressure gauge on the right? As Le Kirk  says. this boiler will have an internal (and often infernal) pressure sensor in order to control the boiler, and that's what flashes up warning codes and tells the boiler to stop working when the pressure has dropped.

The wee analogue dial is just for the user - yourself. If that is showing 'zero', then it's faulty. Yes, surprising it's happened again, but there you have it.

You can feel confident that if your boiler is continuing to operate as normal, then your pressure is adequate; after all, it flashed up a warning the last time. So trying to refill the system was a baaaaaad move... 

Why bad? Because if you had let it reach around 3bar, you'd have introduced other issues, tho' none of it fatal - so don't worry. However, it could have opened the safety valve, and these are a pain for not releasing afterwards; they can continue to drop, so you'll have slow pressure loss afterwards. Fingers crossed your level of competence meant that you didn't manage to top it up... :-)

Call them up and report the issue; "New pressure gauge has gone to zero BUT the boiler is working perfectly with no error codes, so I'm guessing it's just the wee gauge itself. Could you come out and fix at your earliest - ta muchly."

Don't mention that you tried to top it up.

 

An update: the engineer called and asked me to open the filling loop again. This time, the pressure guage went up to 1 bar. He then said that I must have a leaking radiator somewhere. I spent the morning trying to find a leak but failed.

In all this, the boiler has been working OK. The pressure on the dial has been dropping since I topped it off and now it is just below 1 bar.

Jeepers_Creepers: You said that topping off the boiler may be a bad move. Did I screw this up listening to the engineer?

Le_Kirk

If the boiler has been working with a pressure gauge showing zero, it suggest the pressure switch has failed in the closed (electrically) position.  That should not happen - time to get your man back!

Myser

sb29 said:

He then said that I must have a leaking radiator somewhere. I spent the morning trying to find a leak but failed.

If there is a slow leak, it might be difficult to spot as the water will evaporate when the radiators come on.

If you have copper pipes to the radiators, look for green oxidisation on them.

Is there any sign of water escaping from the pressure relief pipework from the boiler outside?

Jeepers_Creepers

sb29 said:

 

An update: the engineer called and asked me to open the filling loop again. This time, the pressure guage went up to 1 bar. He then said that I must have a leaking radiator somewhere. I spent the morning trying to find a leak but failed.

In all this, the boiler has been working OK. The pressure on the dial has been dropping since I topped it off and now it is just below 1 bar.

Jeepers_Creepers: You said that topping off the boiler may be a bad move. Did I screw this up listening to the engineer?

My apologies, SB; no, you did not do wrong. I had assumed that the analogue gauge was faulty, and that the pressure was actually ok (since the boiler kept running). In which case topping up more would have been a bad move - it can open the safety release valve. From what your plumber says, tho', your pressure was, in fact, low.

This is a weird set of circumstances. The boiler will have an internal electronic pressure sensor which is what 'controls' how the boiler responds; if the pressure drops to typically below, say, 0.5 bar, then it'll flash a warning code and also shut down the boiler. That is what it did in your first post.

The analogue pressure gauge is there simply to tell you, the user, what the pressure is like so you can keep it at the correct ~1bar. It doesn't 'control' anything (other than you :-)  )

If you compare what happened before with what happened now - in both cases the pressure seemingly dropped low - the first time the boiler reacted correctly and shut down, flashing a warning code, but this time - on 'zero' - it kept on running!

So, this begs two questions; (1) why did the boiler keep running at 'zero' pressure - is the internal, electronic, sensor faulty? And (2) why did the pressure drop to zero from the 1 bar set by the plumber the first time? Where did that pressure 'go'?!

Has your plumber explained any of this?

Jeepers_Creepers

sb29 said:

We had a clear day after long and yes, there is water escaping from the pipe outside. What does that mean?

The boiler is still running smoothly at about 0 bar pressure. I did not top it off any more.

This is the 15mm COPPER pipe? In which case that's your safety discharge pipe.*

Inside your boiler is a pressure release valve which is forced open at around 3 bar for obvious safety reasons. I think it's pretty clear that your system must have hit this high pressure at some point, either through a fault (usually in the expansion vessel) or by the user accidentally opening the top-up valve for too long. The problem is that, once forced open, this safety valve often doesn't close fully again so continues to allow water to escape even after the pressure has been normalised. Ergo, your pressure continues to fall...

It remains a mystery to me what your system's ACTUAL pressure is! Each scenario comes with its own issues... As far as I can see, it's either:

a) The actual pressure is 'ok' (1 bar-ish) and that is why your boiler is still working. Ie, the electronic pressure sensor inside your boiler - which controls the boiler's 'brain' - is reading the correct pressure and has deemed it to be above whatever the boiler needs to work properly - usually around 0.5 to 0.7bar. This would mean, of course, that the analogue gauge - which reads 'zero' - must be faulty. And this in turn must mean you've replaced a faulty analogue gauge with another faulty one! Very unlikely. Or,

b) The actual pressure is near-zero, so the new analogue gauge is working fine. This would not be a surprise since it appears you are losing water... However, what this would then mean is that the internal - electronic - pressure sensor is faulty (or the PCB is) because your boiler has not stopped working - which it really should. AfaIk, all modern boilers will have this level of safety control, so will shut off and flash a warning code if the pressure falls below the min safety level. Vokera - a good make - MUST surely have this! So, in this scenario, your boiler is continuing to heat water with near-zero pressure... That's a 'gulp' for me.

Since your boiler is seemingly still releasing water outside, then my best guess is that it's 'b'. Gulp.

You need Vok out again - pdq - under the boiler's warranty.

* If it's a white, 22mm plastic pipe, then water out here is normal. However, in rare instances it can also be abi-normal.

sb29

I am sorry, it is the plastic pipe that's discharging water. That's why I deleted the post as I realized my mistake. In any case, will get the vokera guy in again on Monday to check everything thoroughly.

Jeepers_Creepers

If that plastic pipe issues 'slugs' of water at regular intervals whilst the boiler is running, that's normal. If it does so when cold and off, that's usually a bust main exchanger - unusual.

Anyhoo, please report back when the cause is found - it's an interesting one :-)