stroke in a manner that has already been described blade section 78 of spacer bar 72 will be wedged in between stop 58 and the angled plate 50 in effect causing stop 58 to commence pushing against inner surface 122 angled plate 50 earlier than otherwise causing plate 46 in hopper 20 to start moving outwardly sooner during such outbound stroke and as a result pushing plate 46 a further distance rearwardly out of hopper 20 spacer bar 72 is thus automatically pivoted into such position when solenoid 84 is energized which energization takes place whenever the set temperature 98 of thermostat control 90 is greater than the room temperature 96 in effect therefore by temporarily inserting blade section 78 of spacer bar 72 between stop 58 and the inner surface 122 of angled plate 50 the linear distance or stroke length of the device is increased automatically as should now be evident insertion of blade section 78 between stop 58 and angled plate 50 causes reciprocating plate 46 to move a greater distance out of coal hopper 20 thereby allowing more coal to fall downwardly into the space created along the leading edge 110 see fig1 of plate 46 and then upon an inbound stroke forcing more coal into furnace 12 and generating more heat once the actual temperature 96 in the room or other interior environment rises to the set temperature 98 thermostat control 90 will automatically deenergize solenoid 84 allowing blade section 78 of spacer bar 72 to pivot upwardly due.