Baxi Combi Instant 105e - Pressure Dropping 3 Times A Day

Discussion in 'Plumbing and Central Heating' started by robtherevelator1969, 7 Mar 2016.

  1. robtherevelator1969

    robtherevelator1969

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    I have the above boiler. This has been an ongoing problem for a long time. It had been fixed by an engineer a few years ago whilst i had boiler cover, but the repair never lasted. Now i have to top up the pressure a few times a day.

    The water is being passed out the discharge pipe, i checked this using an empty container. Water comes out the small valve at the top of the expansion vessel. The expansion vessel has never been replaced, does it sound like this is the problem?
     
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  3. BigSnoopy01

    BigSnoopy01

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    it sounds like you need a new / external expansion vessel fitting and maybe a new prv if the old one cant hold water back now its operated.
     
  4. When u say water comes out of the expansion vessel. Is it leaking? Or only when pressed?

    If it's leaking it'll need replacing. Depending on the install (add a photo if possible) boiler may have to come off the wall to do it.

    If it's not leaking and u have space an external vessel can be fitted
     
  5. robtherevelator1969

    robtherevelator1969

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    thanks guys, i think the prv was replaced a few years back and never fixed the problem.

    I should have said, water comes out the valve when pressed. There is room to fit an external one but it would look bad as my boiler is housed in a kitchen wall unit. Ill try and post a pic.

    If i set the pressure to 1 bar when cool, switch the heating on, it goes up to 3 bar so i think the prv is ok.

    [​IMG]

    [​IMG]

    [​IMG]
     
    Last edited: 7 Mar 2016
  6. Agile

    Agile

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    Carefully fitted without enough room to replace the EXV !

    An external EXV will do the job.

    I am surprised none of the engineers have not done this!

    Tony
     
  7. robtherevelator1969

    robtherevelator1969

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    Going way back when i bought the house, it was new 7 years ago, it always lost pressure but it was only needing topped up every few days. So it was tolerated. The builders were a small group and sent an engineer, he replaced the prv, this did not fix the problem, the builders did not send anyone else round and went bust.

    I put up with this for a long time, at one point i had boiler cover with British gas, their engineer replaced something (not the exv) and this seemed to fix the problem, again after a while the problem came back. The cover was cancelled due to unemployment, when the problem returned i was not covered.

    I am still unemployed, that's why i cant afford to get this fixed at the moment, so any temporary fixes would be great.
     
  8. Agile

    Agile

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    You can turn a radiator into a temporary EXV.

    It may be in the FAQ here.

    I am sure that I and probably others have explained it several times before.

    You need to do a little searching.

    Tony
     
  9. Aquaheat

    Aquaheat

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    External EV could be fitted in the cupboard below the boiler if you could afford to lose a little space. New PRV and you should be laughing.

    Shouldn't be too hard a job and would be done in about an hour or so. PRV might take a little longer than usual though as its so much easier working from the side with the panel off but still simple enough.

    Jon
     
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  11. DP

    DP

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    You have a leak at the pump area also going by the stains

    Any loss of water from the system is a bad idea. Loss amounting to three fills a day is akin to a disaster waiting to happen.

    When the pressure is low or zero, attach a foot pump to the valve on the expansion vessel and pump till boiler pressure guage reads 1.5 bar. If the pressure drops again, do this a few times. What you are doing is purging the expansion vessel

    Boiler will by now have other issues related to lack of service

    Location of boiler is poor, situation made worst putting a cupboard round it. Would not be surprised if the expansion vessel has never been topped up as there is a bar that needs removing to access the aforementioned valve
     
  12. robtherevelator1969

    robtherevelator1969

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    Thanks for the replies guys. Ill see if i can get to the bottom of this before i go getting an external EV fitted. Its always an idea if it can be fitted out of sight in the cupboard below.

    For now i thought i would recharge the EV, i pumped air in, let water out radiator bleed valve to lower pressure, did this a few times. When i removed the pump nozzle, air was escaping from the EV valve, i put the plastic cap on and used pliers to make it mice and tight, no more air was escaping. I will run the CH system on full blast for a couple of days and see how it performs. So far the pressure is not going past 2.5bar which is good. If this performs well for a couple of months then i can put up with topping up the EV every 2 months. If it does not last ill need to consider a repair or external EV.

    Dp the stains were there since i bought the house, there was a leak and it was fixed, to be sure i have cleaned all that area up so ill keep an eye on things to ensure there is no leaks.
     
  13. easyflow

    easyflow

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    Think your find with that model, its boiler off the wall to replace EV, so external EV might be your best bet.
     
  14. MANDATE

    MANDATE

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    Don't expect your problem to be cured.
    The air valve on the expansion vessel has leaked. The air that escapes gets replaced with water.
    The volume of air for compression gets reduced.
    When this reduced volume of air gets compressed, it's pressure rises far higher than 3bar and opens the PDF
    It's important when recharging a expansion vessel, that the vessel diaphragm has pushed all water out of the vessel,giving the maximum volume of air for compression.
    The air valve on the vessel will continue to leak unless replaced and tightening the dustcover will not achieve a repair.
    A blockage in the pipe connecting the vessel to the system pipework would prevent the vessel operating properly.
    Vessel should be charged to 1bar, with system cold and zero pressure on the water side
    Following this the water pressure should be set to 1bar. With heating on, the increase in volume will push the diaphragm and compress the air.
    The 1bar water pressure will rise to approx 2bar.
     
  15. robtherevelator1969

    robtherevelator1969

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    Thanks for the good information, gives me some insight on how the EV works.

    Ok i wont think its cured but if this is something i can do occasionally i wont mind, if this means saving money on fitting an external EV. Im skint and without a job you see. I let the boiler cool down last night and it was switched off, i set the pressure to 1 bar, i left it running all night, switched it off today and let it cool, the pressure was still 1 bar, this is a massive improvement.

    As the valve is leaking, is it the exact same as a tyre valve ie, Could i use a valve tool to try and tighten the valve or perhaps replace the core of the valve?
     
  16. Yea core can be replaced. Standard schrader available from Halfords etc
     
  17. robtherevelator1969

    robtherevelator1969

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    thanks, i order a few off ebay, hopefully this will stop the leaking valve.
     
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