Oil central heating boiler problem

Discussion in 'UK DIY' started by Thomas, Apr 18, 2004.

  1. Thomas

    Thomas Guest

    Hi

    I wonder if anyone here can throw any light onto a problem I have with a
    new replacement oil central heating boiler.

    The boiler is a Potterton and the burner is a Riello.

    After installation the technician switched on the boiler and I noticed
    it was smoking badly from the chimney. He then proceeded to set up the
    oil pressure and air adjustments using a pressure gauge and analyser.

    The boiler then seemed to work just fine, no smoke from the chimney and
    the boiler efficiency was, according to the technician, as per the
    manufacturers specification.

    Everything was fine for a few days then I noticed that the chimney was
    smoking badly and there was a smell of kerosene from the boiler after it
    had finished a cycle.

    I checked the air adjustment and was surprised to see it set at zero.
    The manufacturers optimum setting was 2.4.

    Out of interest I altered the air adjustment to see if I could effect
    the combustion characteristics of the burner but to no effect.
    Increasing the air to the boiler reduced the size of the flame but had
    no effect on the smoke coming from the chimney.

    The flame at all air adjustment settings seemed to me to be very yellow
    and not the bright perky sort of flame I seem to remember seeing through
    the peep hole of the old boiler.

    Obviously I will be calling back the guy who did the commissioning but
    wondered if anyone here could throw any light on what the problem could
    be.
    --
    Thomas
     
    Thomas, Apr 18, 2004
    #1
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  2. Thomas

    John Guest

    "Thomas" <> wrote in message
    news:...
    > Hi
    >
    > I wonder if anyone here can throw any light onto a problem I have with a
    > new replacement oil central heating boiler.
    >
    > The boiler is a Potterton and the burner is a Riello.


    Fortunately Potterton oil boilers are not so far suffering the same decline
    of reputation that their gas models suffered in the shapre of the Puma et al
    (IMHO)
    >
    > After installation the technician switched on the boiler and I noticed
    > it was smoking badly from the chimney. He then proceeded to set up the
    > oil pressure and air adjustments using a pressure gauge and analyser.
    >
    > The boiler then seemed to work just fine, no smoke from the chimney and
    > the boiler efficiency was, according to the technician, as per the
    > manufacturers specification.
    >
    > Everything was fine for a few days then I noticed that the chimney was
    > smoking badly and there was a smell of kerosene from the boiler after it
    > had finished a cycle.
    >
    > I checked the air adjustment and was surprised to see it set at zero.
    > The manufacturers optimum setting was 2.4.


    "optimum" subject to variances of flue draught and other site variables!

    >
    > Out of interest I altered the air adjustment to see if I could effect
    > the combustion characteristics of the burner but to no effect.
    > Increasing the air to the boiler reduced the size of the flame but had
    > no effect on the smoke coming from the chimney.
    >
    > The flame at all air adjustment settings seemed to me to be very yellow
    > and not the bright perky sort of flame I seem to remember seeing through
    > the peep hole of the old boiler.
    >
    > Obviously I will be calling back the guy who did the commissioning but
    > wondered if anyone here could throw any light on what the problem could
    > be.


    The zero setting of the air intake is worrying. Was it loose? The shutter
    adjustment should be fixed after adjustment or commissioning and if not it
    may have vibrated closed.
    Which model of Riello burner do you have as there are a variety of models.
    Early ones were easily identifiable because the grey plastic control box
    with red reset button sits on top of the unit. This model mutated into a
    balanced flue version enclosed in a cast Aluminium enclosure with spigot for
    air inlet hose on top. In both cases the air adjustment is via a rotating
    disc with apertures which cover or expose the fan inlet. This is secured via
    a locking screw (sometimes a nut). An alternative adjustment flap was later
    used either on its own or with a hydraulic ram operator linked to the oil
    pump so as to close the air inlet when the burner is not running.
    While rare it is not unknown for the oil pressure adjustment to fail and you
    could have a problem there but on balance I'd suggest the first thing to
    check is the air setting as you have done. I'd then take a look at the swirl
    plate in the burner blast tube. If the air supply had shut off to nearly
    nothing this swirl plate could easily have carboned up thus limiting the
    airflow when the air adjustment is opened up again. Cleaning it and putting
    the airflow right is fairly trivial to do but you will need a combustion
    analyser or a Fyrite kit and a smoke tester.
    Riello moved on to the RDB range of burners which are good but not as easy
    to work on as the earlier ones in some respects. The principles remain the
    same however except the air adjustment is a bit more finicky and most of the
    spares are not compatible with the earlier models (how amazing! or is this
    part of a sales drive for the spares stockists?).
    Other things to check:-
    Oil nozzle is not loose and allowing unatomised leakage into the blast tube.
    Any air inlet routes remain clear (no kinked intake snorkel tubes etc)
    If a two pipe oil system is in use the return pipe is not restricted since
    the pressure regulator relieves into the return pipe and blockage will
    result in a pressure rise.

    HTH
     
    John, Apr 18, 2004
    #2
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  3. Thomas

    Thomas Guest

    In article <c5uc7l$5gr$>, John
    <> writes
    >
    >"Thomas" <> wrote in message
    >news:...
    >> Hi
    >>
    >> I wonder if anyone here can throw any light onto a problem I have with a
    >> new replacement oil central heating boiler.
    >>
    >> The boiler is a Potterton and the burner is a Riello.

    >
    >Fortunately Potterton oil boilers are not so far suffering the same decline
    >of reputation that their gas models suffered in the shapre of the Puma et al
    >(IMHO)
    >>
    >> After installation the technician switched on the boiler and I noticed
    >> it was smoking badly from the chimney. He then proceeded to set up the
    >> oil pressure and air adjustments using a pressure gauge and analyser.
    >>
    >> The boiler then seemed to work just fine, no smoke from the chimney and
    >> the boiler efficiency was, according to the technician, as per the
    >> manufacturers specification.
    >>
    >> Everything was fine for a few days then I noticed that the chimney was
    >> smoking badly and there was a smell of kerosene from the boiler after it
    >> had finished a cycle.
    >>
    >> I checked the air adjustment and was surprised to see it set at zero.
    >> The manufacturers optimum setting was 2.4.

    >
    >"optimum" subject to variances of flue draught and other site variables!
    >
    >>
    >> Out of interest I altered the air adjustment to see if I could effect
    >> the combustion characteristics of the burner but to no effect.
    >> Increasing the air to the boiler reduced the size of the flame but had
    >> no effect on the smoke coming from the chimney.
    >>
    >> The flame at all air adjustment settings seemed to me to be very yellow
    >> and not the bright perky sort of flame I seem to remember seeing through
    >> the peep hole of the old boiler.
    >>
    >> Obviously I will be calling back the guy who did the commissioning but
    >> wondered if anyone here could throw any light on what the problem could
    >> be.

    >
    >The zero setting of the air intake is worrying. Was it loose? The shutter
    >adjustment should be fixed after adjustment or commissioning and if not it
    >may have vibrated closed.

    The air adjustment is via an allen key on the front of the unit. I have
    moved the adjustment a bit and will monitor to see if it changes. The
    adjustment friction seems to me to be high enough to render this
    unlikely.

    >Which model of Riello burner do you have as there are a variety of models.

    It's a Riello RDB1 with the inlet hose on the top. The boiler flue
    gasses vent into a conventional chimney.

    >Early ones were easily identifiable because the grey plastic control box
    >with red reset button sits on top of the unit. This model mutated into a
    >balanced flue version enclosed in a cast Aluminium enclosure with spigot for
    >air inlet hose on top. In both cases the air adjustment is via a rotating
    >disc with apertures which cover or expose the fan inlet. This is secured via
    >a locking screw (sometimes a nut). An alternative adjustment flap was later
    >used either on its own or with a hydraulic ram operator linked to the oil
    >pump so as to close the air inlet when the burner is not running.



    >While rare it is not unknown for the oil pressure adjustment to fail and you
    >could have a problem there but on balance I'd suggest the first thing to
    >check is the air setting as you have done. I'd then take a look at the swirl
    >plate in the burner blast tube. If the air supply had shut off to nearly
    >nothing this swirl plate could easily have carboned up thus limiting the
    >airflow when the air adjustment is opened up again. Cleaning it and putting
    >the airflow right is fairly trivial to do but you will need a combustion
    >analyser or a Fyrite kit and a smoke tester.
    >Riello moved on to the RDB range of burners which are good but not as easy
    >to work on as the earlier ones in some respects. The principles remain the
    >same however except the air adjustment is a bit more finicky and most of the
    >spares are not compatible with the earlier models (how amazing! or is this
    >part of a sales drive for the spares stockists?).
    >Other things to check:-
    >Oil nozzle is not loose and allowing unatomised leakage into the blast tube.
    >Any air inlet routes remain clear (no kinked intake snorkel tubes etc)
    >If a two pipe oil system is in use the return pipe is not restricted since
    >the pressure regulator relieves into the return pipe and blockage will
    >result in a pressure rise.
    >
    >HTH
    >
    >

    Many thanks for the reply John. I will check the points that you have
    raised.
    --
    Thomas
     
    Thomas, Apr 18, 2004
    #3
  4. Thomas

    John Guest

    "Thomas" <> wrote in message
    news:...

    SNIP

    > >Which model of Riello burner do you have as there are a variety of

    models.
    > It's a Riello RDB1 with the inlet hose on the top. The boiler flue
    > gasses vent into a conventional chimney.
    >


    It would be worth checking that the conventional chimney has a liner fitted.
    Older oil boilers had a much higher exit temperature than the current
    increased efficiency models and condensation in an unlined existing flue is
    almost guaranteed. Take a look at the installation and service booklet for
    guidance.


    SNIP

    > >Riello moved on to the RDB range of burners which are good but not as

    easy
    > >to work on as the earlier ones in some respects. The principles remain

    the
    > >same however except the air adjustment is a bit more finicky and most of

    the
    > >spares are not compatible with the earlier models (how amazing! or is

    this
    > >part of a sales drive for the spares stockists?).
    > >Other things to check:-
    > >Oil nozzle is not loose and allowing unatomised leakage into the blast

    tube.
    > >Any air inlet routes remain clear (no kinked intake snorkel tubes etc)
    > >If a two pipe oil system is in use the return pipe is not restricted

    since
    > >the pressure regulator relieves into the return pipe and blockage will
    > >result in a pressure rise.
    > >
    > >HTH
    > >
    > >

    > Many thanks for the reply John. I will check the points that you have
    > raised.


    I'd be very wary if the air setting was zero on an RDB1. I agree it is very
    unlikely that the adjustment would move accidentally. Did you get a written
    record of the combustion readings and smoke content of the flue gases?
     
    John, Apr 20, 2004
    #4
  5. Thomas

    Thomas Guest

    >
    > SNIP
    >
    > > >Which model of Riello burner do you have as there are a variety of

    > models.
    > > It's a Riello RDB1 with the inlet hose on the top. The boiler flue
    > > gasses vent into a conventional chimney.
    > >

    >
    > It would be worth checking that the conventional chimney has a liner fitted.
    > Older oil boilers had a much higher exit temperature than the current
    > increased efficiency models and condensation in an unlined existing flue is
    > almost guaranteed. Take a look at the installation and service booklet for
    > guidance.
    >

    It has a SS liner but there is no insulation installed between the
    liner and chimney brickwork. I think you are absolutely right here;
    what I am seeing is condensation and not smoke. It is only visible
    during cold weather. The installation manual indicates that
    insulation is required so I guess I need to introduce some form of
    insulation between the liner and chimney. Any ideas as to what I need
    to do?
    >
    > SNIP


    > I'd be very wary if the air setting was zero on an RDB1. I agree it is very
    > unlikely that the adjustment would move accidentally. Did you get a written
    > record of the combustion readings and smoke content of the flue gases?


    No unfortunately I didn't get a record from the technician who did the
    adjustment. As you indicated in your previous post that I should
    check the fuel nozzel installation I purchased a replacement from the
    local plumbers merchant just to be on the safe side and set the air
    adjustment back to the manufacturers nominal setting. The unit seems
    to be functioning in a satisfactory manner now. I am however, after
    my experience, somewhat wary about letting an 'expert' tweak my
    boiler. Is it possible to hire a flue gas analyser in order to do my
    own set up.

    Many thanks

    Thomas
     
    Thomas, May 4, 2004
    #5
  6. Thomas

    John Guest

    "Thomas" <> wrote in message
    news:...
    > >
    > > SNIP
    > >
    > > > >Which model of Riello burner do you have as there are a variety of

    > > models.
    > > > It's a Riello RDB1 with the inlet hose on the top. The boiler flue
    > > > gasses vent into a conventional chimney.
    > > >

    > >
    > > It would be worth checking that the conventional chimney has a liner

    fitted.
    > > Older oil boilers had a much higher exit temperature than the current
    > > increased efficiency models and condensation in an unlined existing flue

    is
    > > almost guaranteed. Take a look at the installation and service booklet

    for
    > > guidance.
    > >

    > It has a SS liner but there is no insulation installed between the
    > liner and chimney brickwork. I think you are absolutely right here;
    > what I am seeing is condensation and not smoke. It is only visible
    > during cold weather. The installation manual indicates that
    > insulation is required so I guess I need to introduce some form of
    > insulation between the liner and chimney. Any ideas as to what I need
    > to do?
    > >

    It depends on the "cooling" of the liner within the old chimney. If the
    chimney is in good order and restricts the convected cooling air currents
    then the practicalities of the matter are that you will not suffer from top
    end corrosion of your boiler. If the old chimney is leaky and excessive
    chilling does occur condensate will appear inside the top of the boiler with
    corrosion of the mild steel following close behind. If this occurs you will
    have to find a way to fill the void around the flue with vermiculite or
    similar, possibly via a hole cut into the masonary :-(

    > > SNIP

    >
    > > I'd be very wary if the air setting was zero on an RDB1. I agree it is

    very
    > > unlikely that the adjustment would move accidentally. Did you get a

    written
    > > record of the combustion readings and smoke content of the flue gases?

    >
    > No unfortunately I didn't get a record from the technician who did the
    > adjustment. As you indicated in your previous post that I should
    > check the fuel nozzel installation I purchased a replacement from the
    > local plumbers merchant just to be on the safe side and set the air
    > adjustment back to the manufacturers nominal setting. The unit seems
    > to be functioning in a satisfactory manner now. I am however, after
    > my experience, somewhat wary about letting an 'expert' tweak my
    > boiler. Is it possible to hire a flue gas analyser in order to do my
    > own set up.
    >


    I don't know of any hire service for analysers but you could enquire of a
    large hire company such as HSS.
    A "proper" OFTEC registered technician will have demonstrated his/her
    competence and be able to do the job right. What area did you say you lived
    in?
     
    John, May 5, 2004
    #6
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