"Michael Walsh" wrote in message
m...
Hi

Thanks for the info. I will have a look at the Flue to-night for soot.

Your suggestion about a weak mixture might well be right, The fan was
wire-brushed and alot of muck was removed from it so it may well be
supplying more air at this stage.

The valve I talked about is part of the 'pump' which is mounted on the
end of the motor. The oil feed line comes in one side and there are
two hex-nuts on it. One of them is used to bleed the pump when I run
out of oil and I have an air lock. The other hex nut (about 10-12mm in
size) has a screw in its centre about 4mm with a screwdriver slot in
it. I took it out once and there is a small spring inside it so I
guess it is probably the oil pressure adjuster.

What should I do to fix a meak mixture? I will get the make and model
of the boiler also when I get home and post it later on to-night, I
think it is a Riello but I will check to make sure.


Riello make a couple of basic models of burner. The old faithful which has a
grey plastic control box sitting on top of the motor and is available in a
range of outputs with slight detail changes for the various ranges, or the
recently introduced RDB range with a black plastic control unit mounted to
the left as you look at the burner from outside the boiler.
Assuming your unit is the earlier of the two since it has needed a motor
bearing then you can adopt the following procedure bearing in mind that this
will need test gear to do it right.

1. Isolate the electrical supply and close off the oil supply valve Check
the oil filter and renew paper filter elements.
2. Open up the flue access plate/doors to gain entry to the combustion
chamber and flueways.
3. With brushes and a scraper clean all surfaces, removing any baffles or
retarders to allow access to do this.
4. Vacuum out any deposits (soot and sulphur) you have dislodged.
5. Check the inside for corrosion or defects.
6. Reassemble, making sure all seals are in good condition and make a seal
but do not overtighten and distort the joints.
7. Remove the burner from the mounting flange by undoing the retaining nut
at the top of the mounting flange.
8. Withdraw from the boiler (on some boilers this may require you to
dismantle some casing)
9. Loosen the blast tube retaining screws located at either side of the
blast tube into the cast burner casing and remove the blast tube from the
burner. This will expose the nozzle and electrodes for cleaning. Note
carefully the position and clearances of the electrodes with respect to the
nozzle, compare with the settings given in your manual.
10.With a nylon pan scourer clean up then electrodes and nozzle mount. etc.
Renew the nozzle with one of the same capacity and spray angle (this is
stamped on the flats of the old nozzle for typical example 0.65 US GPH 60
degree spray angle). Removal of the nozzle may require you to loosen the
electrode block so be sure you know where to put it back again.
11. Clean out the aperture in the casing which you see behind the blast tube
and note the photocell lens is clean
12. Reassemble the blast tube and secure with the two screws. (You did put
the electrodes back didn't you?)
13. Undo the three screws holding the fan volute casing in place and expose
the fan for cleaning with a stiff bristle brush. (Some models have a
hydraulic ram which operates an air shutter over the air intake and this may
need the mounting screws removing first to allow the volute casing to be
removed). Clean the volute casing and the air intake apertures also then
reassemble.
14. It is not normally necessary to remove the oil pump unless there is
obvious sign/sound of bearing or coupling wear however if it is judged to be
necessary then loosen the two (sometimes three) screws which clamp the pump
into the end of the motor, remove the solenoid from the top of the pump,
disconnect the oil pipe nuts and gently rotate the pump a little to
disengage the oil pipes and withdraw it from the end of the motor. Check the
bearings and the condition of the plastic drive dog which transmits rotation
from the motor shaft to the pump. The motor bearings are sealed but a little
light oil may be applied to inhibit corrosion.
15. Reassemble and check your oil joints.
16. At three yearly intervals renew the oil flexible pipe, sooner if it
shows damage.
17. Obtain a suitable pressure gauge reading 0 to 250/300 PSI. Remove the
hexagon plug below the pump pressure adjuster and fit the gauge to this
port.
18. Refit the burner to the boiler and open the oil supply valve. Check for
leaks and rectify if necessary.
19. restore power and set the controls to call for heat. The motor should
start up and run for a few seconds before opening the oil solenoid with an
audible click and the burner should fire. If it does not fire the controls
will register lack of flame and the unit will shut down and go to lockout,
lighting the lockout alarm lamp under the reset button.
20. Check the pressure gauge and adjust to the specified pressure given in
the boiler/burner data sheets using the adjusting screw on the pump. Once
set this screw should NOT be touched again.
21. Situated (usually on top of) the boiler shell you should find a flue gas
sampling point. When the boiler has warmed up insert a smoke tester
(Baccarach pump) and draw a smoke sample. This should be zero on the
Baccarach scale in most cases (no smudge visible on the filter paper the
sample is drawn through)
22. Insert an analyser probe into the sample point. Either an electronic
tester or a Fyrite/Briggon wet tester sample pump tube. If you haven't got
either of these you will be unable to go further and should seek
professional assistance. Draw the sample into the tester and read the CO2
content of the flue gases. Adjust the air slide/shutter to give a figure in
line with that given in the boiler specification sheet.
23. Recheck the smoke is still within tolerance
24. Insert a thermometer into the flue sample point - this may be included
in the analyser probe if you are using an electronic set. Allow the reading
to stabilise and record. By reference to tables or from your analyser set
the nominal efficiency of the boiler can be obtained.
25. If the boiler has a conventional flue insert a draught gauge and record
the flue draught for comparison with previous recordings which will indicate
any possible problems developing in the flue integrity.
26. Remove all test gear, Check for leaks, Close up and clean down

It is a useful exercise if a firestop valve with a capillary sensor is
fitted to test this by putting the sensor into a cup of hot water in excess
of 65 degrees C

Typical flue gas analyser readings
Smoke 0 to 1 Baccarach
CO2 10 to 13 percent
Flue gas temperature 190 to 230 degrees C
Flue draught 0.02 to 0.05 inches water gauge or equivalent

HTH