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8.0 GENErAL OPErATING INSTruCTIONS
8.1
CONTrOL SySTEm - wOOd FurNACE
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Control of the woodburning section of the furnace is by adjustment of the primary air control located on the
top rear right corner of the Hmf150/200. This control operates in two set positions - "full open" allowing
maximum combustion air delivery to the fire box and "Closed", providing minimum primary air to the fire
box to assist the development of secondary or gasifying burn in the top of the fire box (note that secondary
combustion air enters through two inlets on the front of the furnace either side of the ash lip tray and is not
adjustable).
IN NO WAY SHALL THE pRIMARY AIR CONTROL SYSTEM BE ALTERED TO INCREASE COMBUSTION
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in the automatic mode the adjustment of primary air is accom-
plished using a shutter connected to a small servo motor. The
control circuitry will energize the motor if it detects the room
thermostat is calling for heat and the high limit sensor in the sup-
ply plenum has not been surpassed (greater than 250°f (121°C)).
The primary air shutter will be fully opened and will remain so
unless the room temperature has been satisfied or too much heat
is detected in the plenum.
8.1.1 POwEr OuTAGE OPErATION
HIgH TEMpERATURES CAN BUILD IN THE DUCT WORk, TO ENSURE AIR CIRCULATINg IN A gRAv-
ITY METHOD REMOvE AIR FILTER FROM FURNACE. ENSURE ALL SUppLY AND RETURN AIR
gRILLS ARE FREE FROM HOUSEHOLD OBjECTS OR DEBRIS, AND ENSURE ANY MANUAL DAMp-
WITH THE MANUAL DAMpER LOCkED IN OpEN pOSITION, THE FURNACE MUST BE MONITORED
NEvER BUILD FLASH FIRES DURINg A pOWER OUTAgE OpERATION. SEE SECTION 8.9.
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In the case of a power outage it is possible to increase the output of the firebox by manually adjusting
the primary air control shutter. on the front face of the primary air control box a control arm protrudes out.
To increase combustion push down on this handle, moving it towards the bottom of the clearance slot,
keep the control arm down by swinging the clasp (also mounted to the front of the primary air control box)
over top of the control arm. This will continuously maintain the maximum combustion air being fed into
the fire box (furnace must be monitored to prevent over firing). Although the blower fan will be inoperable
in a power out situation, convection air flow through to the house will move under gravity circulation.
The air filter must be removed from the filter rack when operating in a power out condition to help promote
gravity circulation and prevent excessive heating of the duct work.
W415-1013 / A / 06.05.12
AIR FLOW gREATER THAN THE FACTORY pRESET MAxIMUM.
ERS IN THE DUCT NETWORk ARE FIxED IN A FULL OpEN CONDITION.
TO pREvENT OvER FIRINg.