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Alpha 32C Combi - Pressure Always Going Too High

Discussion in 'Plumbing and Central Heating' started by tododo, 29 Dec 2017.

  1. tododo

    tododo

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    Hi all

    Just after some advice - Ive had nothing but grief with our now 10 year old Alpha boiler we had installed when we moved in

    Its working but every time heating is on the pressure increases and never really goes back to where it should be ie around 1bar

    The filling loop is connected but its closed by two tap valves - but will try disconnecting just in case anyway

    Every time we turn the heating on it leaks on the outside so the pressure release valve is working at least!

    I hear it could be the heat exchanger - is there any way to test that theory???

    i removed some over pressure two days ago and the pressire is already climbing back up - well obver 2 bar with the heating currently on - will see what it goes back to when cold

    Could it be the expansion vessel in any way as Im not sure that is set at the correct pressure as its soooo awkward to get at and Im not exactly sure how to repressurise it - do I empty the system entirely first as im sure when I tried that I just kept pumping air into it and nothing happening

    Any thoughts guys - and thanks too!!

    I have a feeling its timee to get a wocester
     
  2. AngelesPlumbing

    AngelesPlumbing

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    If you invest for a long run then get ur system flushed and put new boiler in but not Worcester, or try get gas engineer to have a look at it might be just need recharge EV.
     
  3. Terry lambert

    Terry lambert

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    You havnt said anything that would suggest you need a new boiler.

    I would call an engineer in to check your expansion vessel
     
  4. flameport

    flameport

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    If it was the heat exchanger, the pressure would increase all the time even when the boiler was switched off.

    More likely it is the expansion vessel either flat, busted or grossly overpressured (particularly if you have just been pumping air into it with no regard to the pressure).

    For the vessel, switch the boiler off, allow the whole system to cool.
    Remove all pressure from the system - this can be done via the relief valve, and although that can cause problems with it not resealing, yours has evidently been flapping open all the time anyway.
    Another option is via any air vent, or a bleed point on a radiator. In any case, you need to leave one point open.
    Attach air pump with pressure gauge to the expansion vessel, and add air until the correct pressure is achieved. Water may leak out of the vent or bleed point you left open earlier as the air pumped in displaces the water.
    Remove pump, close bleed point / vent / whatever. System pressure should still be zero at this point.
    Refill to 1 bar or whatever the boiler manufacturer suggests.

    If the problem continues, remove pressure from the system and check the expansion vessel pressure - if it's zero, then the vessel is bust and will need replacing. Or install another one elsewhere if it's difficult/expensive to replace.
     
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  5. tododo

    tododo

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    Thanks for the advice guys

    Im did get a gauge pump on the expansion vessel but I have a feeling i may not have done it quite right - will do as you say and take all pressure off and try again - Ive seen some schrader valve extensions that you can get and they should help immensely trying to get a pump attached as its so hard t get too

    Argh Ok so I have to leave a radiator bleed valve open ??? I havent done that before so that may help !!!

    Thanks again
     
  6. Terry lambert

    Terry lambert

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    I wouldn’t use a bleed vent

    Put a hose on a drain point and leave it open whilst charging vessel
     
  7. flameport

    flameport

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    Something has to be left open, otherwise you are trying to pump air against a sealed system full of water, which won't work.
     
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  9. dilalio

    dilalio

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    And you may have to change the PRV!
     
  10. tododo

    tododo

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    OK managed to get some time away from little one and tried again to empty system and try this out

    I just seem to be pumping and pumping and pumping some more...... the gaugue on my brand new bicycle pump stays at zero when attched to the schrader valvle at all times

    The only way I can get pressure into the system is to close the valve on radiator and pump air into the whole system I guess - doing it this way the boiler pressure then goes up

    Surely it shouldnt take a lot of pumping to pump the expansion vessel up???

    That is the only way I can see there is pressure in the system is by looking at the booiler pressure

    I havnt seen any water come out of the shrader valve at all yet but I think the expansion may have gone myself

    Anybody think of anything else I could try?

    Thanks again
     
  11. ianmcd

    ianmcd

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    They take a lot of pumping, if you press the shraeder valve after pumping for a while and air under pressure is realeased then the vessel is fine and you just need to stick with it
     
  12. tododo

    tododo

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    Hi guys quick update - followed the guide in the FAQ and the boiler is much better - its definately not going high like it was now
    However it has been dropping pressure now - and just came home from work and can still see its leaking outside from the pressure release type pipe

    Do you think the release valve is gone - not sure why its leaking there at all - I have changed this valvle in the past butt just wanted to see what you think

    Could it be anything else??
     
  13. ianmcd

    ianmcd

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    yes when the expansion vessel causes the PRV to operate over a period of time it is common for the PRV to drip, you will have to change it again .
     
  14. dilalio

    dilalio

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    A lot of PRV’s are FUBAR’d once they have been activated... which is a ball ache!
     
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