CATALYST
It is recommended that the catalytic converter is inspected for signs of damage and dirt during routine serv-
icing procedures. The expected life of the catalyst is in excess of 11,000 hours (10 years of normal use).
After this time the catalytic converter should be replaced.
If there are any deposits of dirt or soot on the catalyst they should be cleaned with a soft brush and a vac-
uum cleaner. If removed for cleaning ensure the seals are in good condition before replacing the catalytic
converter. New seals will usually be required.
The performance of the catalyst may be checked using an analyser as follows. Any analyser used should
conform to BS7927 : 1998 + A1 : 1999 or BS EN 50379-3.
Important: The temperature of the gases emmited by the catalytic converter is in excess of 400
o
C.
Measuring gas of this temperature may damage some types of gas analysers. If in doubt consult the
equipment manufacturer.
Position gas sample probe directly in front of the catalyst underneath the hood, in the centre of the upper
firebox. Ignite the fire as per the operating instructions, and run at high setting for 15 minutes. Record the
carbon dioxide (CO2) concentration and then the carbon monoxide (CO) concentration as displayed by the
analyser - also noting the units in which the values are expressed.
Most analysers display carbon dioxide (CO2) 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/CO2) 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 car-
bon dioxide (CO2) to obtain the appliance combustion ratio.
The combustion ratio of the gasses emitted by the catalytic convertor should not exceed 0.0015.
If replacing the catalytic converter, remove the
hood, front fret/facia and the grille (as shown in
figure 22). The catalytic converter retaining
clamp is secured with 4 nuts and slip proof
washers, located on the inside of the firebox, at
the top, remove these nuts and the clamp can be
removed. Withdraw the clamp, followed by the
catalytic converter and its seals from the firebox
and discard.
Refit a new catalytic converter and seal in
reverse order.
TESTING FOR FIREBOX LEAKAGE
Appliances that are several years old or have been extensively dismantled should be checked for sound-
ness. 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 quan-
tities of smoke may be seen in corners of joints and gasket faces etc without affecting safety when the
fire is in operation.
9.4
9.5
CO (%)
CO2 (%) = ratio
Figure 22
14
©
2009 Focal Point Fires plc.
