Combi boiler auto filling to 2.5 bar

Discussion in 'Plumbers' Talk' started by Tellboy1, Jan 11, 2018.

  1. Tellboy1

    Tellboy1 New Member

    Seen a thread here from 2015 similar to mine, help needed, i got a worcester 28i junior combi, cannot get c h gauge no lower than 2bar, started after street mains got turned off, i had to drain and refill c h system, run ch after about 10 seconds banging noises along pipework dor around 30secs then calms down, bled c h again, no good, removed all rads, pressure hosed them, (loadsa black muck), refilled and same, theonly way i can lower pressure in c h is by mains stopcock then i have low tap pressure, or i turn on a tap and that lowers it to 1 bar and holds it there. there was no plumbing work done, suggested sludge had moved to heat exchanger, noise does seem to be coming from centre of boiler. Anyways just bled a radiator upstairs, nothing but air, when nothing else came out i check boiler gauge, zero, i link fed system to 2bar, re bled all radiators, wont go below 2 bar to 2 1/4 bar, isolated mixer taps and shower mixed via inline isolators, turn ch on and 10 secs later banging pipes, gauge fluctuating all over the place, bout 40secs later all calms down for now until boiler kicks in again when via thermostat? Puzzled, so am i, i will be getting in a local plumber even if its for a diagnostic, im just inquisitive as to why, like i said all ok till mains outside turned off, coincidence? I got short videos too while doing checks.
     
  2. terrymac

    terrymac Active Member

    Can't say I fully understood all of your post ,but if your boiler pressure ,when cold ,is 2.5 bar ,and you let air out by bleeding a radiator ,and it goes down to 0 bar ,and then upto 2.5 bar without you doing anything else ,then it sounds like your filling loop is not fully closing.
     
  3. Tellboy1

    Tellboy1 New Member

    Filling loop is disconnected, its an external flexi and only connected @1 end
     
  4. Tellboy1

    Tellboy1 New Member

    I tooped up system via filling loop to 2bar, then remove loop, tried dropping pressure by bleeding rads but it slowly tops bk up to just over 2 bar
     
  5. The Teach

    The Teach Active Member

    when was the boiler last serviced,not safety checked but actually serviced ?

    how old is the boiler ?

    items to check include the filling loop/link, heat exchanger,expansion vessel and a few more :)
     
  6. Mike83

    Mike83 Active Member

    Maybe a burst plate heat exchanger filling heating side.
     
    Devil's Advocate and terrymac like this.
  7. terrymac

    terrymac Active Member

    Pressure should be set to 1 bar ,when boiler / heating is cold. Have you bled all of the radiators of air ,if not do so. When all rads are free of air and fall of water , can you fill via filling loop to one bar ? If the boiler is filling itself you have a problem inside the boiler as the mains cold water going into the boiler to be heated and turned into hot water for your taps ,must be mixing with the primary water ( which gets pumped around your rads ) and the system pressure is increasing to that of your mains pressure.
     
  8. Tellboy1

    Tellboy1 New Member

    Boiler is about 9yrs old, its been no probs till utilities cut water off, maybe coincidence, yes can fill to 1 bar via loop, remove loop, gauge goes up to around 2bar, no loop inline, it has been suggested that the heat exchanger maybe faulty and thats what is causing banging noises through pipes when ch turned on, it does sound like an old fashion kettle, i tried to upload videos of turning ch on and if gauge creeping up with loop not in line, but failed, i'll try again, serviced last ermmmm its that long ago
     
  9. The Teach

    The Teach Active Member

    IThe 28i junior (not a greenstar) is a basic reliable boiler which does not suffer from diverter valve and plate heat exchanger faults.

    Like any gas boiler With correct installation and periodic servicing they last many years,should be fixable but you need a boiler tech familiar with this type of boiler :)
     
  10. Tellboy1

    Tellboy1 New Member

    I agree, im trying to locate a local plumber via asking neighbours, hopefully one thats been used happily before can be trusted,.
     
  11. Devil's Advocate

    Devil's Advocate Well-Known Member

    Please report back, Tellboy - it's an interesting one.

    Even if the utility company sent a pressure shock through the water mains, it shouldn't have damaged the P2P exchanger (the only part that contains both water systems afaIk) as this - like the rest of the boiler - will be designed to handle 10 bar as an absolute minimum.

    I guess it's possible you just had a weak one from the off, and the pressure change popped it? But surely unlikely.

    Once it's fixed, it'll be interesting to know the cause. If it's a 'blown' P2P with no other signs of corrosion etc, then I think you can pretty much assume it was 'faulty' and susceptible to failure from the time of manufacture.
     
  12. Tellboy1

    Tellboy1 New Member

    I will update once inspected, some other things happening i forgot, orange/cloudy water from hot tap only, upstairs and downstairs, not always but mostly, when hot tap 1st turned on and as the water heats up, also sporadic bursts of airlocked water spitting out of hot tap,upstairs and downstairs, i was worried so got utilities company to inspect, but.... They only check cold water entering house, report back was all was good. So air is getting into hot water too, prv never been activated, has not reached 3bar, cloudy water was bad a one point, had really cloudy bath water(hence call to waterboard). Will keep updated.
     
  13. retiredsparks

    retiredsparks Well-Known Member

    Carp in system.....Diverter valve sticking or damaged...
    see Unphased post a few days ago
    Rs
     
  14. Tellboy1

    Tellboy1 New Member

    Looked at unphased posts, left me a bit confused as i have a boiler prob(combi not the mrs) unphased posts and replies to electrical posts?
     
  15. Devil's Advocate

    Devil's Advocate Well-Known Member

    :)

    If your cold water is clean but your hot is not, then it does reinforce the likelihood of it being contaminated by the sealed system water.

    So bust P2P exchanger is still most likely cause. (ie. I can't think of any other).
     
  16. Tellboy1

    Tellboy1 New Member

    Appreciate your exceptionally fast resonse, as soon as one of these plumbers gets in touch to arrange an appointment at least i wont be blindsided,
     
  17. Tellboy1

    Tellboy1 New Member

    Is the p2p another name for plate heat exchanger?
     
  18. Tellboy1

    Tellboy1 New Member

    Plate 2 plate?
     
  19. retiredsparks

    retiredsparks Well-Known Member

    Look on plumbers forum...
    RS
     
  20. retiredsparks

    retiredsparks Well-Known Member

    feb4th ...this plumbers forum.
    Rs
     

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