Testing For Firebox Leakage; Catalysts - Smeg P23 LINEAR Installation & User's Instructions

10.3 CATALYSTS

If there are any deposits of dirt or soot on the catalyst they should be cleaned with a soft brush and a vacuum cleaner. If removed
for cleaning ensure the seals are in good condition before replacing the catalyst. New seals will usually be required.
The performance of the catalysts may be checked using a combustion gas analyser as follows. Any analyser used should conform
to EN 50379-3.
Ignite the fire as per the operating instructions, and run at maximum setting for 15 minutes. Position gas sample probe directly
over the catalysts via the outlet grille, on top of the appliance. Record the carbon dioxide (CO 2 ) concentration and then the car-
bon monoxide (CO) concentration as displayed by the analyser - also noting the units in which the values are expressed.
Most analysers display carbon dioxide (CO 2 ) concentrations in percentage (%) terms and carbon monoxide concentration in
parts per million (ppm) terms.
In order to calculate the combustion ratio for the appliance (CO/CO 2 ) it is first necessary to express both gas concentrations
in terms of percentage. To convert from parts per million (ppm) to a percentage (%) divide the ppm figure by 10,000. Examples :
35ppm = 0.0035%, 15ppm = 0.0015%, 5ppm = 0.0005%. Now divide the concentration of carbon monoxide (CO) expressed in
percent by the concentration of carbon dioxide (CO 2 ) to obtain the appliance combustion ratio.
The combustion ratio of the gasses emitted by the catalytic convertor should not exceed 0.0015.
If replacing, firstly, remove the decorative frame/glass facia (as described in section 8.3) and outer casing. The catalysts are locat-
ed on the top of the internal firebox and can be removed by unscrewing the retaining nuts securing the clamping plates. Remove
the catalysts their seals and discard. Refit the new catalysts and seals in reverse order, ensure the catalysts and the glass door have

10.4 TESTING FOR FIREBOX LEAKAGE

good seals.
Appliances that are several years old or have been extensively dismantled should be checked for soundness. It is important that
all the products of combustion pass through the catalytic converter at the top of the firebox before leaving the appliance.
The firebox is heated by lighting for a few minutes to provide a flow through the firebox. The burner is then shut off and a
smoke pellet or match introduced at the base of the fire underneath the burner tray. Large quantities of smoke will emerge
from the top of the appliance, but none should emerge from the joints or gasket faces, especially around the door.
It is important to note that the appliance can never be expected to be 100% smoke tight and small quantities of smoke may be
seen in corners of joints and gasket faces etc without affecting safety when the fire is in operation.
CO (%)
= ratio
CO 2 (%)
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2012 Smeg (UK) Ltd.