Boiler Cutting Out

Discussion in 'UK DIY' started by Neal Harwood, Oct 25, 2004.

  1. Neal Harwood

    Neal Harwood Guest

    I have a Potterton Profile 50e boiler, and lately the (thermal?)
    cut-out has started tripping. This results in the pump going
    continuously, but no hot water.
    It happily resets manually, and starts up again.
    It seems to trip 4/5 times a week, at different times/conditions - no
    obvious pattern.

    Any ideas?

    Obviously I am not going to take the boiler apart (unqualified), but
    if the cause is elsewhere in the system, I beleive I could fix it.

    Neal
     
    Neal Harwood, Oct 25, 2004
    #1
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  2. Neal Harwood

    Set Square Guest

    In an earlier contribution to this discussion,
    Neal Harwood <> wrote:

    > I have a Potterton Profile 50e boiler, and lately the (thermal?)
    > cut-out has started tripping. This results in the pump going
    > continuously, but no hot water.
    > It happily resets manually, and starts up again.
    > It seems to trip 4/5 times a week, at different times/conditions - no
    > obvious pattern.
    >
    > Any ideas?
    >
    > Obviously I am not going to take the boiler apart (unqualified), but
    > if the cause is elsewhere in the system, I beleive I could fix it.
    >
    > Neal


    This normally happens when the boiler and pump are turned off by a room
    stat - and the residual heat in the boiler's heat exchanger continues to
    heat the water to the point where the overheat stat trips.

    Boilers which are susceptible to this usually control the pump directly -
    and have an over-run stat which continues to run the pump for a while after
    the boiler stops firing - in order to dissipate the residual heat.

    Clearly, the water must have an available circulation path during this
    over-run period - often requiring a by-pass loop, depending on the exact
    setup.

    The first thing to check is whether your boiler has a pump over-run stat
    and, if so, to make sure that it is wired up correctly.

    If you still have problems, come back with further details of your system
    setup. Does it look like one of the "plans" described in
    http://content.honeywell.com/uk/homes/systems.htm ?

    --
    Cheers,
    Set Square
    ______
    Please reply to newsgroup. Reply address is invalid.
     
    Set Square, Oct 25, 2004
    #2
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  3. In article <>,
    raden <> writes:
    > In message <>, Neal
    > Harwood <> writes
    >>I have a Potterton Profile 50e boiler, and lately the (thermal?)
    >>cut-out has started tripping. This results in the pump going
    >>continuously, but no hot water.
    >>It happily resets manually, and starts up again.
    >>It seems to trip 4/5 times a week, at different times/conditions - no
    >>obvious pattern.
    >>
    >>Any ideas?
    >>

    > The impeller of the pump hasn't broken off the shaft has it ?


    or as happened to a friend of mine, the blades had all fallen
    off the impeller (and were nowhere to be found).

    --
    Andrew Gabriel
     
    Andrew Gabriel, Oct 25, 2004
    #3
  4. Neal Harwood

    Set Square Guest

    In an earlier contribution to this discussion,
    raden <> wrote:

    > In message <>, Neal
    > Harwood <> writes
    >> I have a Potterton Profile 50e boiler, and lately the (thermal?)
    >> cut-out has started tripping. This results in the pump going
    >> continuously, but no hot water.
    >> It happily resets manually, and starts up again.
    >> It seems to trip 4/5 times a week, at different times/conditions - no
    >> obvious pattern.
    >>
    >> Any ideas?
    >>

    > The impeller of the pump hasn't broken off the shaft has it ?


    I don't think the system would run for between 1/5 and 1/4 of a week if it
    had!

    I think it's something to do with sets of circumstances which occur now and
    again where the pump can't effectively overrun. Maybe it's not wired to do
    so, or maybe there isn't a by-pass and it gets caught out when all the TRVs
    are shut.
    --
    Cheers,
    Set Square
    ______
    Please reply to newsgroup. Reply address is invalid.
     
    Set Square, Oct 25, 2004
    #4
  5. Neal Harwood

    Neal Harwood Guest

    raden <> wrote in message news:<>...
    > In message <>, Set Square <>
    > writes
    > >In an earlier contribution to this discussion,
    > >raden <> wrote:
    > >
    > >> In message <>, Neal
    > >> Harwood <> writes
    > >>> I have a Potterton Profile 50e boiler, and lately the (thermal?)
    > >>> cut-out has started tripping. This results in the pump going
    > >>> continuously, but no hot water.
    > >>> It happily resets manually, and starts up again.
    > >>> It seems to trip 4/5 times a week, at different times/conditions - no
    > >>> obvious pattern.
    > >>>
    > >>> Any ideas?
    > >>>
    > >> The impeller of the pump hasn't broken off the shaft has it ?

    > >
    > >I don't think the system would run for between 1/5 and 1/4 of a week if it
    > >had!
    > >

    > You have a point there - I'll try to read threads better in future




    Thanks for the replies so far
    I believe the pump is fine, because it DOES work most of the time,
    just cuts out occasionally.
    It has also only started doing this recently. It used to happen VERY
    occasionally (2 times per year), but recently it is much more
    frequent.

    This 'cut-out due to residual heat' sounds very feasible
    I will try and work out the circuit type (thanks for the link) and get
    back to you

    Neal
     
    Neal Harwood, Oct 26, 2004
    #5
  6. Neal Harwood

    Neal Harwood Guest

    "Set Square" <> wrote in message news:<>...
    > In an earlier contribution to this discussion,
    > Neal Harwood <> wrote:
    >
    > > I have a Potterton Profile 50e boiler, and lately the (thermal?)
    > > cut-out has started tripping. This results in the pump going
    > > continuously, but no hot water.
    > > It happily resets manually, and starts up again.
    > > It seems to trip 4/5 times a week, at different times/conditions - no
    > > obvious pattern.
    > >
    > > Any ideas?
    > >
    > > Obviously I am not going to take the boiler apart (unqualified), but
    > > if the cause is elsewhere in the system, I beleive I could fix it.
    > >
    > > Neal

    >
    > This normally happens when the boiler and pump are turned off by a room
    > stat - and the residual heat in the boiler's heat exchanger continues to
    > heat the water to the point where the overheat stat trips.
    >
    > Boilers which are susceptible to this usually control the pump directly -
    > and have an over-run stat which continues to run the pump for a while after
    > the boiler stops firing - in order to dissipate the residual heat.
    >
    > Clearly, the water must have an available circulation path during this
    > over-run period - often requiring a by-pass loop, depending on the exact
    > setup.
    >
    > The first thing to check is whether your boiler has a pump over-run stat
    > and, if so, to make sure that it is wired up correctly.
    >
    > If you still have problems, come back with further details of your system
    > setup. Does it look like one of the "plans" described in
    > http://content.honeywell.com/uk/homes/systems.htm ?


    Having just read some old (c1998) posts (I Love GOOGLE Groups),
    someone else suggested problems with an airlock in the CH system
    We HAVE had to drain the system a couple of times over the last year
    (to move some pipes and rads in the basement).
    Is it possible I have an airlock of some sort? Where would it be?
    Would it cause my symptoms? And of course, HOW do I get rid of it?
     
    Neal Harwood, Oct 26, 2004
    #6
  7. Neal Harwood

    Set Square Guest

    In an earlier contribution to this discussion,
    Neal Harwood <> wrote:

    >
    > Having just read some old (c1998) posts (I Love GOOGLE Groups),
    > someone else suggested problems with an airlock in the CH system
    > We HAVE had to drain the system a couple of times over the last year
    > (to move some pipes and rads in the basement).
    > Is it possible I have an airlock of some sort? Where would it be?
    > Would it cause my symptoms? And of course, HOW do I get rid of it?


    I doubt if it's that. An air lock after re-filling can prevent any primary
    circlation (I've had one!) but once you've got circulation going, any
    residual air will usually park itself somewhere where it doesn't do any
    major harm - probably in one of the radiators. I don't think an air lock is
    likely to cause an intermittent circulation failure.

    Of course, I could be wrong . . .
    --
    Cheers,
    Set Square
    ______
    Please reply to newsgroup. Reply address is invalid.
     
    Set Square, Oct 26, 2004
    #7
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