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  • FIRST POST
    • BillG100
    • By BillG100 10th Dec 17, 5:32 PM
    • 29Posts
    • 8Thanks
    BillG100
    Vaillant Ecotec boiler losing pressure intermittently
    • #1
    • 10th Dec 17, 5:32 PM
    Vaillant Ecotec boiler losing pressure intermittently 10th Dec 17 at 5:32 PM
    Hi,

    My Vaillant Ecotec boiler is losing pressure intermittently but quickly and only when it is switched off! What happens is...

    1) The boiler runs fine for a period of time which could be a few days or weeks and the pressure is reasonably constant (varies about 10% to 15% with the temperature)

    2) Boiler loses pressure quickly during the overnight period when heating / water is off

    3) Boiler won't restart and an f.75 error code is displayed

    4) I add some water to re-pressurise and it starts again without a problem

    5) The cycle (steps 1 to 4) then repeat

    The expansion vessel has been re-pressurised. There's no sign of a leak and it would have to be an odd one to behave in this way. The pressure gauge reading appears to be correct.

    I'm at a loss. Any ideas?
Page 2
    • BillG100
    • By BillG100 10th Jan 18, 7:11 PM
    • 29 Posts
    • 8 Thanks
    BillG100
    British Gas supposedly escalated the problem to leak detection on 3rd January but they've still not contacted me to make an appointment. I've already chased twice and been told they are on the case. Not impressed at all by the level of service!
    • BillG100
    • By BillG100 17th Jan 18, 4:43 PM
    • 29 Posts
    • 8 Thanks
    BillG100
    Would anyone like to hazard a guess about this behaviour:

    1) Isolate one of the five underfloor heating circuits (uhc)
    2) Pressure on boiler continues to fall over a 24 hour period from about 1.4 to 0.9
    3) Switch uhc on because I assume that's not the cause of the problem
    4) Repressurise boiler BUT this time it takes a LOT more water than it usually does to get from 0.9 to 1.4. The tap needed to be switched on for about 12 secs rather than 2 or 3.

    PS: Leak detection are in on Monday.
    • Alex1983
    • By Alex1983 17th Jan 18, 5:17 PM
    • 824 Posts
    • 489 Thanks
    Alex1983
    I!!!8217;d guess it!!!8217;s more volume of water.
    • Ruski
    • By Ruski 23rd Jan 18, 11:18 PM
    • 1,546 Posts
    • 909 Thanks
    Ruski
    Any update BillG - Did Mondays 'Ghostbusters' find the ectoplasm leaking anywhere?!?

    Cheers

    Russ
    Perfection takes time: don't expect miracles in a day
    • BillG100
    • By BillG100 24th Jan 18, 11:00 AM
    • 29 Posts
    • 8 Thanks
    BillG100
    Any update BillG - Did Mondays 'Ghostbusters' find the ectoplasm leaking anywhere?!?

    Cheers

    Russ
    Originally posted by Ruski
    My wife and I were away for a couple of days last week. I've got a webcam on the boiler so was able to watch the pressure gauge steadily going down before the boiler generated an F.22 and cut out. It was left in that state for about 24 hours until we got home. Purely by chance (when the system was completely cold because of the length of time it had been off) we noticed a drip of water below the lockshield valve on the bathroom radiator. I re-pressurised the boiler and then "twiddled" the lockshield valve. That made the drip either better or worse depending on the position of the lockshield valve.

    When "Leakbusters" turned up on Monday I showed them the drip on the lockshield valve. They drained the system and fixed the leaking valve. After doing that they:

    1) Refilled the system and added an inert gas
    2) Isolated the underfloor circuits and left for 2 hours
    3) No pressure drop was detected so they opened the underfloor circuits
    4) After another hour and no pressure drop was detected

    "Leakbusters" concluded the problem was fixed and left.

    Two days later the jury is still out but initial signs are the boiler seems to be holding pressure. Can't be sure because the weather is very mild and the pressure loss seemed to be worse when it was cold.

    PS: we had checked all rads and valves several times previously but noticed nothing. It's possible the water was evaporating and it only became visible when the pipes / rads were completely cold.

    If this turns out to be the cause BG will have unnecessarily fitted a new heat exchanger, schrader valve and pressure sensor on the Vaillant.
    • BillG100
    • By BillG100 2nd Feb 18, 11:57 AM
    • 29 Posts
    • 8 Thanks
    BillG100
    After 10 days the boiler has started losing pressure again. Really was convinced the problem had been fixed! Back to square one.
    • J B
    • By J B 2nd Feb 18, 3:02 PM
    • 2,813 Posts
    • 998 Thanks
    J B
    We have a gradual 'pressure drop' problem.
    Plumber has been today and scratched his head considerably and without stripping the boiler down to investigate all valves and seals, he has suggested that we try some 'leak-stop' type of compound (a bit like Radweld in a car!)
    So, will let him do that and cross several fingers.
    • macman
    • By macman 2nd Feb 18, 4:21 PM
    • 41,920 Posts
    • 17,396 Thanks
    macman
    This is fairly typical of BG: just swap out random components in the hope that you'll eventually cure the problem, rather than do proper methodical fault finding.
    If you've ruled out the EV and a leak on the CH circuit, then it can only be the PRV. In post 11 you say that the PRV is 'OK', but don' explain how you'e come to that conclusion, unless it has been changed, or you used a bag to check for discharge from the overflow pipe (this is separate to the condensate pipe)?
    This may be hepful:
    http://www.vaillantservice.co.uk/ECOTEC_F.75_Fault_Code.html
    Is the boiler still in warranty? If so, dump BG and get Vaillant involved instead. If not, get a Vaillant -competent RGI.
    Last edited by macman; 02-02-2018 at 4:32 PM.
    No free lunch, and no free laptop
    • BillG100
    • By BillG100 2nd Feb 18, 7:04 PM
    • 29 Posts
    • 8 Thanks
    BillG100
    One question I have is what volume of water needs to be lost from the system to make the pressure drop from 1.5 bar to 0.5 bar? I've been given various answers by plumbers/heating engineers, ranging from a "medium sized wine glass" to a "bucket".
    • Alex1983
    • By Alex1983 2nd Feb 18, 7:28 PM
    • 824 Posts
    • 489 Thanks
    Alex1983
    How would you logically fault find this issue?

    I!!!8217;ve been in this situation many times working for big companies in the past and the sensible think to do is repressurise the expansion vessel, put a balloon on the PRV and isolate the flow and returns for a few days but Big companies customers tend not to allow that and want a fix, they pay yearly premium which usually includes parts so don!!!8217;t care what is fitted, which means the big companies only have the option of replacing bits and hoping it cures it.

    1.5bar to 0 is approximately 5litres.
    • BillG100
    • By BillG100 3rd Feb 18, 10:58 AM
    • 29 Posts
    • 8 Thanks
    BillG100
    This is fairly typical of BG: just swap out random components in the hope that you'll eventually cure the problem, rather than do proper methodical fault finding.
    If you've ruled out the EV and a leak on the CH circuit, then it can only be the PRV. In post 11 you say that the PRV is 'OK', but don' explain how you'e come to that conclusion, unless it has been changed, or you used a bag to check for discharge from the overflow pipe (this is separate to the condensate pipe)?
    This may be hepful:
    http://www.vaillantservice.co.uk/ECOTEC_F.75_Fault_Code.html
    Is the boiler still in warranty? If so, dump BG and get Vaillant involved instead. If not, get a Vaillant -competent RGI.
    Originally posted by macman
    WRT the PRV... BG engineer said it was ok because he'd taken it out and the washer hadn't gone. He also checked the overflow pipe and noted there was a dead spider in it which had clearly been there for a good while. Had water been dripping out the spider would have detached.
    • mossy007
    • By mossy007 6th Feb 18, 9:46 AM
    • 8 Posts
    • 1 Thanks
    mossy007
    Any update BillG100? I have exactly the same issues and have a engineer out this week. Is the pressure drop worse in cold weather?
    • BillG100
    • By BillG100 6th Feb 18, 10:38 PM
    • 29 Posts
    • 8 Thanks
    BillG100
    Any update BillG100? I have exactly the same issues and have a engineer out this week. Is the pressure drop worse in cold weather?
    Originally posted by mossy007
    The boiler held pressure for 10 days when the auto air vents were closed off and the temperature it runs at was ramped up by turning the dials about 3/4 of the way round.

    Since putting it back to how it was and fixing 2 leaks on the 18 month old bathroom towel ring (manufacturing defects rather than installation ones) the pressure holds for about 4 days.

    To answer your question the pressure drop seems to be worse when the boiler / water temperature is lower. In other words when the boiler is switched off during the nights.
    • Alex1983
    • By Alex1983 6th Feb 18, 10:57 PM
    • 824 Posts
    • 489 Thanks
    Alex1983
    Did it drop pressure with the flow and returns isolated?
    • BillG100
    • By BillG100 7th Feb 18, 7:31 AM
    • 29 Posts
    • 8 Thanks
    BillG100
    Did it drop pressure with the flow and returns isolated?
    Originally posted by Alex1983
    That has still not been done. However if the boiler held pressure for 10 days what would isolating the flow and return valves off for a few days prove?
    • Alex1983
    • By Alex1983 7th Feb 18, 9:22 AM
    • 824 Posts
    • 489 Thanks
    Alex1983
    From my understanding you have a gradual pressure lose over 10 days.

    I dont know what your setting your boiler to initially but if we say its 1.5bar. A Vaillant boiler cuts off at 0.5bar with f75 or f22.

    Your boiler is not going to think its the 10th day today Im going to lose all my pressure today, it will be gradually losing it over the 10 days. So from 1.5bar to 0.5bar over 10 days will be around 0.1bar per day.

    So logically if you isolate the flow and returns with the pressure set to 1.5bar over the course of 2days the gauge will either fall to 1.3bar proving a issue with the boiler or it will hold the 1.5bar proving a leak on your system, if that happens id guess when you open the flow and returns the boiler pressure will drop.
    • mossy007
    • By mossy007 7th Feb 18, 9:42 AM
    • 8 Posts
    • 1 Thanks
    mossy007
    Are you anywhere nearer to sorting out the issue? My boiler is now losing pressure 1 bar every 24hrs for the past 4 days. It has held for 3 weeks on 1.5 bar. It had been much colder for the past week and I seem to be under the impression that itís something to do with the temperature outside but I maybe wrong. Like yourself Baxi has been out on numerous occasions to check the boiler who have changed the expansion vessel and PRV in the last few visits it was actually better when the PRV was changed and it held on 1.5 for 4 weeks as it was losing pressure every 24hrs prior to that. It then held pressure for a further 4 weeks and then started losing pressure again. The Baxi engineer advised that they maybe a leak in the UFH so he isolated the flow and return to the boiler but it was still losing pressure. No visible leaks anywhere in CH system. The only difference other than yours is that my boiler temps are rising considerably to over 100 degrees when only the UFH is on only. When the HW and CH are on the boiler temps are fine. I am not sure if this will be related to the pressure issue but Polypipe who installed the UFH advised that they maybe a issue with the UFH zone valve sticking and may be affecting the pressure. My heating engineer is out this Fri so I will see what he can diagnose. Do you know what temps the boiler reaches when your UFH is on?
    • BillG100
    • By BillG100 7th Feb 18, 4:17 PM
    • 29 Posts
    • 8 Thanks
    BillG100
    I am not sure if this will be related to the pressure issue but Polypipe who installed the UFH advised that they maybe a issue with the UFH zone valve sticking and may be affecting the pressure. My heating engineer is out this Fri so I will see what he can diagnose. Do you know what temps the boiler reaches when your UFH is on?
    Originally posted by mossy007
    That's very interesting... we also have Polypipe but it was installed by a third party. In our case it's the overlay UH:

    http://www.polypipe.com/housing/polypipe-underfloor-heating/underfloor-heating/overlay-system

    The boiler temperatures is around 60C. The temperature on the UH can be adjusted using the mixer valve but currently it is set to between 45C and 50C.
    • mossy007
    • By mossy007 7th Feb 18, 10:40 PM
    • 8 Posts
    • 1 Thanks
    mossy007
    That's very interesting... we also have Polypipe but it was installed by a third party. In our case it's the overlay UH:



    The boiler temperatures is around 60C. The temperature on the UH can be adjusted using the mixer valve but currently it is set to between 45C and 50C.
    Originally posted by BillG100
    Believe it or not I have the exact same system as yours! I will let you know what my engineer has diagnosed on Friday. The temps you have given seem normal to me.
    • BillG100
    • By BillG100 8th Feb 18, 10:36 AM
    • 29 Posts
    • 8 Thanks
    BillG100
    Believe it or not I have the exact same system as yours! I will let you know what my engineer has diagnosed on Friday. The temps you have given seem normal to me.
    Originally posted by mossy007
    The strange thing is we've now had 3 relatively new valves developing leaks. Both valves on the bathroom towel ring and one on a circuit pipe in the loft. It's almost like there is too much pressure despite what the Vaillant shows (both gauge and digital). I wonder whether there is an issue with the UH zone valve which could be the cause of this. However I don't understand how that could be the case.
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