TROUBLE-SHOOTING
CHIMNEY FIRE
If your stove has been installed correctly and you have
also operated it correctly and regularly carried out the
recommended routine checks then it is unlikely that
you will ever experience a chimney fire, which can be
highly dangerous.
Chimney fires can be detected by an unusual roaring
sound and / or unusual vibrations coming from the
chimney breast or the stove itself. The sound is not to
be confused with the gentle ‘rushing’ sound you may
normally hear when a stove has a well performing
up-draught. During a chimney fire you may also see
sparks or flames exiting from the chimney terminal
outside.
• Prevention
If you suspect a chimney fire then immediately close
the Primary and Secondary Air controls, as well as the
Thermostat Control, evacuate the building and call
the Fire Service.
Never
open the stove door as this will
make the chimney fire worse by providing additional
combustion air. Do not re-enter the building until you
have been advised by the Fire Service that it is safe.
Do not re-light the stove until the flue system has
been thoroughly inspected by an approved installer or
chimney sweep and any necessary repairs have been
carried out.
•
Causes: Inadequate cleaning
Chimney fires occur when soot and creosote have
built up to such a level that they ignite. It is important
therefore that your flue system has as many cleaning
access points as practicable to enable comprehensive
removal of soot, creosote and other debris. This will
also minimise the amount of time it takes for a
qualified sweep to clean the system making the
system safer and its cleaning more cost-effective in
the long run.
•
Causes: Continuous low burning
To discourage the potential for such soot and
creosote build-ups, long periods of consistent
‘slumber’ or overnight burning should be avoided
or that these should at least be compensated for by
regular burning on full output for short periods (eg 30
minutes per day) to help burn off any likely deposits
before they become problematic.
•
Causes: Poor fuel choice
As previously mentioned
unseasoned or damp wood or fuel should always be
avoided as these produce excessive soot and creosote.
This is particularly problematic for boiler stoves where
the fire chamber temperatures are much lower than
in a non-boiler stove and therefore the potential to
promote the conditions for dangerous deposits from
damp fuel is much greater.
SYSTEM BALANCE
With all wood burning and multi fuel boiler stoves,
given their particular heat cycle and the natural gravity
fed flow, it is extremely important that the radiators
are balanced to ensure an efficient distribution of heat
as well as an even heat balance from one radiator to
the next. The idea is to reduce the flow to the hottest
radiators so that more hot flow is available to heat the
coolest ones. The system is ‘balanced’ when there is a
good hot water flow through every central heating
radiator.
To undertake this, all of the system valves should be
set to open (including any lock shield valves (LSVs)
on the heat leak radiator) and the circulation pump
adjusted to the correct flow speed. Thermostatic
radiator valves (TRVs) should also be set to maximum
to ensure that these are not activated during the
balancing process. All radiators should be fully bled
of air and the system should be at full operating
temperature. Please note it could take the system 2
– 3 hours, depending on the size of the system and
the fuel loads, to reach full operation.
The objective is to get a consistent temperature
difference of approximately 10ºC between the flow
(80ºC) and the return (70ºC) on each radiator. If the
circulating pump flow rate is set too high then the
temperature drop between flow and return will be
less than 10ºC. Balancing the system means adjusting
all of the various thermostatic valves, thermostats,
lock shield valves on each radiator and the circulating
pump speed to give the desired temperature in each
room for the least amount of fuel used. This can be
a time-consuming process, but is well worth it, and
therefore is best left to an experienced installer.
With the system at full operating temperature and
all of TRVs fully open, if the temperature drop is
different from 10ºC but consistent across all of the
radiators then it will be a simple matter of adjusting
the circulating pump flow to achieve the desired
10ºC drop. Slow down the pump flow to increase the
drop difference and speed it up to reduce it. In reality
it does not matter if some radiators have a slightly
smaller temperature drop, hence a higher flow, so
long as there is enough flow to get all of the radiators
at a desirable temperature.
Fortunately, a balanced system does not mean
that all of the radiators have to be set at the
same temperature. How hot a radiator is once the
thermostatic valve is operating will depend on many
variables including the size of the room, how high the
TRV is set and how big the radiator is. Radiators are
likely to be slightly hotter at the top than the bottom
but this will vary from system to system and the
design of the radiator itself. Provided the temperature
difference from the top to the bottom of the radiator
is no more than the 10ºC flow and return difference,
then this is not generally an indication of a system
problem.
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