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bang bang from boiler!

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  • 27-02-2014 12:05am
    #1
    shooter69
    Registered Users Posts: 179 ✭✭


    Hi. I have a veismann boiler in new house - approx 18mths. 2 stats, one upstairs one down. Last few days ive noticed thatwhen boiler fires to bring temp up to set stat temps there are two bang bang noises coming from boiler. Doesnt happen everytime just now and then.. any ideas? All rads and water heating as normal and pressure on boiler normal too..
    thx


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    #2
    Dtp1979
    Registered Users Posts: 12,734 ✭✭✭✭Dtp1979


    shooter69 wrote: »
    Hi. I have a veismann boiler in new house - approx 18mths. 2 stats, one upstairs one down. Last few days ive noticed thatwhen boiler fires to bring temp up to set stat temps there are two bang bang noises coming from boiler. Doesnt happen everytime just now and then.. any ideas? All rads and water heating as normal and pressure on boiler normal too..
    thx

    Is there any hissing noise from the boiler ?
    Is the banging like somebody playing drums on the boiler o


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    #3
    shooter69
    Registered Users Posts: 179 ✭✭shooter69


    Dtp1979 wrote: »
    Is there any hissing noise from the boiler ?
    Is the banging like somebody playing drums on the boiler o

    Hi
    No there is no hissing, yes like two bangs like drums! Almost like someone banging inside the boiler! Doesnt happen everytime though and everything else eeems ok...


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    #4
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    Is the system fully zoned with motorised valves?
    Possibly no automatic bypass fitted & the motorised valves are not wired using the orange auxiliaries to fire the boiler. This will mean that the boiler is firing against a closed circuit until the motorised valve opens, thus causing occasional banging on start up.


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    #5
    shooter69
    Registered Users Posts: 179 ✭✭shooter69


    shane0007 wrote: »
    Is the system fully zoned with motorised valves?
    Possibly no automatic bypass fitted & the motorised valves are not wired using the orange auxiliaries to fire the boiler. This will mean that the boiler is firing against a closed circuit until the motorised valve opens, thus causing occasional banging on start up.

    Yep it is a zoned system with motorised valves. Cant understand how its only happening in last few days and never before though..?? Weird!


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    #6
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    Not saying that is the issue, but it's a starting point. Motorised valve could be starting to open slower than normal.

    When you switch on the time clock, does the boiler start to fire immediately or is there a time delay of approx 30 or so seconds before the boiler begins it's ignition process?


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    #7
    shooter69
    Registered Users Posts: 179 ✭✭shooter69


    shane0007 wrote: »
    Not saying that is the issue, but it's a starting point. Motorised valve could be starting to open slower than normal.

    When you switch on the time clock, does the boiler start to fire immediately or is there a time delay of approx 30 or so seconds before the boiler begins it's ignition process?

    Yep there is a delay -not thirty seconds though, id say more like less than 10 seconds.


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    #8
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    shooter69 wrote: »
    Yep there is a delay -not thirty seconds though, id say more like less than 10 seconds.

    Hmmm... 10 secs might be too short for a MV to open & close the micro-switch circuit.
    Inconclusive, as some boilers can take a few secs to begin their process.

    Do you know if you have an auto bypass valve fitted? If so, open it fully & see if this revolves the issue,
    Also, do you have a MV on your hot water circuit or just the heating circuits?

    The reason I am not thinking sludge issue is the Viessmann has fairly large heat exchanger passageways & unless you have a major system problem, sludge will be unlikely with such a young system, but I'm not ruling it out. Just checking the obvious first.


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    #9
    shooter69
    Registered Users Posts: 179 ✭✭shooter69


    No theres no motor valve for water. We have hot water priority if we click water on time clock. Doubt its sludge as weve used inhibitor. Where would i find that valve you speak of??
    Thx


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    #10
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    shooter69 wrote: »
    No theres no motor valve for water. We have hot water priority if we click water on time clock. Doubt its sludge as weve used inhibitor. Where would i find that valve you speak of??
    Thx

    Ah, back to my original so. I would be checking to see if the orange aux wire from the MV is actually wired.


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    #11
    shooter69
    Registered Users Posts: 179 ✭✭shooter69


    shane0007 wrote: »
    Ah, back to my original so. I would be checking to see if the orange aux wire from the MV is actually wired.

    Thx Shane, will have a look and give plumber a shout
    Thx for help


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    #12
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    Sorry, forgot to ask does it happen when hot water is on?


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    #13
    shooter69
    Registered Users Posts: 179 ✭✭shooter69


    shane0007 wrote: »
    Sorry, forgot to ask does it happen when hot water is on?

    No only when boiler fires for rads
    Thx


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    #14
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    shooter69 wrote: »
    No only when boiler fires for rads
    Thx

    I would be fairly confident it's what I originally said.


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    #15
    shooter69
    Registered Users Posts: 179 ✭✭shooter69


    shane0007 wrote: »
    I would be fairly confident it's what I originally said.

    Think youre right. I checked a few times today by firing the boiler by increasing temp on both stats and it seems now that it bangs only when upstairs stat fires the boiler..faulty mv maybe?


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    #16
    shane0007
    Closed Accounts Posts: 4,677 ✭✭✭shane0007


    Could be or the valve is not firing the boiler through the aux wire. Either way it's a valve issue.
    It's a much better problem to have than a heat exchanger issue though! Much easier & cheaper to fix.


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    #17
    shooter69
    Registered Users Posts: 179 ✭✭shooter69


    shane0007 wrote: »
    Could be or the valve is not firing the boiler through the aux wire. Either way it's a valve issue.
    It's a much better problem to have than a heat exchanger issue though! Much easier & cheaper to fix.

    Good stuff. Thx for your help mate


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