30. Steady heat operation
It is possible to use boilers for slow-burning operation, i.e. keeping the fire up overnight without
the necessity to heat-up during the day. This is only permitted during wintertime. This operating
method however decreases the boiler service life. Prepare the boiler for slow-burning operation in the
following way:
- place several (4 – 6) larger logs on a glowing layer of partially combusted fuel
- turn the mixing valve down
After the valve has been turned down, the boiler water temperature increases to 80 - 90 °C.
- the control flap valve /8/ operated by the FR 124 Honeywell draught regulator automatically
shuts down and the ventilator switches off (DC15E excluded) – the boiler operates in maximum
output mode
In boilers prepared as previous, the fuel burns for 8 – 12 hours. The actual slow-burn combustion
time depends on the amount of fuel placed in the boiler and on the actual quantity of consumed heat.
Even if the boiler operates in the slow-burn mode, it has to keep the output water temperature
ranging between 80 - 90 °C and returning water minimum temperature 65 °C.
31. Boiler cleaning
It is necessary to clean the boilers regularly and thoroughly every 3 to 5 days because the flue
cinder accumulated in the fuel storage tank together with tars and acids dramatically decreases the
boiler’s service life and output and insulates the heat transfer surface. If excessive amount of cinder
in the lower chamber is left to form, then the burn-off area is insufficient and damage to the ceramic
nozzle handle or the boiler may occur. Carry out the cleaning procedure by first switching the ex-
traction ventilator on (except for DC15EP), then open the loading door /2/ and sweep the cinder down
through the slot into the lower chamber. Leave long pieces of wood which has not fully combusted
(charcoals) in the hopper for the next time the boiler is used. Open the cleaning lid /15/ and clean the
rear duct with a brush. If the brake valve is inserted in the duct (corrugated sheet), it must be removed
before cleaning. Remove all the soot and cinder after opening the lower lid /15/. Open the lower door
/3/ and clean the lower chamber from cinder and soot. Remove the layers of dust on the side walls of
the lower combustion chamber with a poker or a brush. If there is a roof in the lower combustion area
which contains a breaker (corrugated sheet – DC30SX, DC40SX, DC50S, DC75SE), it is necessary
to remove the breaker when cleaning and removing the ash. The cleaning interval depends on the fuel
quality (wood moisture content), heating intensity, chimney draught and other factors. We recom-
mend cleaning the boilers once a week. Do not pull out the fireclay shaped piece /10/, /14/, /38/, /39/
when cleaning. At least once a year clean the extraction ventilator rotating wheel and via the cleaning
hole, inspect the state of the primary to secondary air ratio regulation. For boilers DC50SE, special
sheets are placed on the sides next to the gasification nozzles; the sheets improve the combustion
quality. Area underneath these sheets must be cleaned regularly once per 7 to 14 days. Boilers DC70S
must be checked at least 2x a year and the compressive ventilator and the air duct may need cleaning.
If necessary, clean the area behind the heating area rear screen from tars and ash /41/, /19/.
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