Steffes DLF40B - Manual (Page 9)

SUMMER/WINTER OUTDOOR AIR CHARGE kW INPUT (MAX) CORE TEMP.
SWITCH POSITION TEMP. (ºF) LEVEL DLF30B DLF40B ºF (Nominal)
Winter 55* 1 9.6 12.8 500
Winter 35 2 19.2 25.6 900
Winter 15 3 28.8 38.4 1,350
Summer 35 1 9.6 12.8 500
Summer 15 3 28.8 38.4 1,350
Operating the Furnace
(cont'd)
8
HOW TO TURN THE FURNACE “OFF” AND “ON”
Since heat calls are unlikely during the summer months, you may wish to turn the furnace "OFF". To do so,
switch all 60 amp core charging breakers located on the front of the furnace’s electrical panel to the "OFF"
(down) position. (See Figure 1 for reference to the location of the breakers on the furnace.) The 15 amp
breaker should remain "ON" at all times as this breaker operates the blowers and all other controls in the furnace.
It MUST remain "ON" if using the furnace in conjunction with an air conditioning system. To turn the furnace
"ON", switch the breakers to the UP position.
For users who prefer to maintain a reduced heating capacity during summer months rather than shutting the
system off completely, the SUMMER/WINTER toggle switch should be set to the SUMMER position. In
standard configuration, a SUMMER switch setting enables automatic brick core charging but at a reduced level.
The outside temperature must drop below 35
o F before core charging will occur. (Refer to Table 2, Brick Core
Charging Schedule, in this manual for more information on charging levels in relation to outdoor temperature and
the furnace control panel settings.)
* If during off­peak hours the wall thermostat calls for heat and the outdoor temperature is above 55 o F, 1/3 of
the elements will be energized for the duration of the heat call.
BRICK CORE CHARGING SCHEDULE
Table 1
During brick core charging, the heating elements are staged "ON" and "OFF" in 6.4kW increments (maximum).
4
The AUTO/HIGH/LOW toggle switch on the furnace control panel will allow the user to override the automatic
charge control system of the furnace. In normal operation, this switch is set to the AUTO postion. Regardless of
the position of this switch, the brick core charging system in the furnace is designed to respond to the coldest
temperature signal it is receiving. As a result, if the toggle switch is set to LOW and the outdoor sensor is calling
for a higher brick core temperature setting, the furnace will respond to the sensor signal. Or, should the charge
level 1 sensor fail to respond to outdoor temperature, the charge level 2 or 3 sensors will initiate core charging.
This feature provides control redundancy which reduces the chance of having an uncharged or undercharged
brick core during cold weather.