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Operation
Variable Capacity Heat (35% to 100%)
Three-Stage Heat
(35%, 70%, 100%)
Two-Stage Heat (W1 70%, W2 100%)
NOTE - When the SLP99UHV is used with a communicat-
ing thermostat, all indoor blower speed selections and DIP
switch settings are made by the thermostat.
SLP99UHV units are equipped with an integrated control.
This control manages ignition timing, combustion air induc-
er speed, heating mode fan off delays and indoor blower
speeds based on selections made using a communicating
thermostat or the control DIP switches and on-board links.
The control includes an internal Watchguard feature which
automatically resets the ignition control when it has been
locked out.
NOTE - All DIP switches are factory shipped in the
"OFF" position.
Heating Operation DIP Switch Settings -- FIGURE 56
Switch 1 -- Thermostat Selection -- This unit may be
used with either a single-stage or two-stage thermostat.
The thermostat selection is made using a DIP switch
which must be properly positioned for the particular appli-
cation. The DIP switch is factory-positioned for use with a
twostage thermostat. If a single-stage thermostat is to be
used, the DIP switch must be repositioned. See TABLE
16.
Switch 2 -- Operating Mode with Two-Stage Ther-
mostat -- If a two-stage thermostat is used, the furnace
can operate in either variable-capacity or conventional
twostage mode. When variable-capacity mode is select-
ed, the firing rate of the unit is varied to maximize comfort.
Conventional two-stage mode is the factory default set-
ting. See TABLE 16.
Switch 3 -- Second-Stage Heat On Delay -- If a single-
stage thermostat is used, the integrated control can be
used to energize second-stage heat after either 7 minutes
or 12 minutes of first-stage heat operation. See TABLE 16.
Switches 4 and 5 -- Blower-Off Delay -- The blower-on
delay of 30 seconds is not adjustable. The blower-off delay
(time that the blower operates after the heating demand
has been satisfied) can be adjusted by moving switches 4
TABLE 16
Thermostat Selection Switch Settings
Thermostat
Switch 1
Two-Stage
Off
Single-Stage
On
Two-Stage
Off
and 5 on the integrated control. The unit is shipped from
the factory with a blower-off delay of 120 seconds. The
blower off delay affects comfort and is adjustable to sat-
isfy individual applications. Adjust the blower off delay to
achieve a supply air temperature between 90° and 110°F
at the exact moment that the blower is de-energized. Lon-
ger off delay settings provide lower supply air tempera-
tures; shorter settings provide higher supply air tempera-
tures. TABLE 17 provides the blower-off timings that will
result from different switch settings.
Indoor Blower Operation DIP Switch Settings
Switches 6 and 7 -- Continuous Indoor Fan Operation
Blower Speed -- The unit is shipped from the factory with
the DIP switches positioned for medium low (2) speed
during continuous indoor blower operation. The table be-
low provides the continuous blower speeds that will result
from different switch settings. Refer to tables beginning on
page 44 for corresponding cfm values.
* Percentage of high speed cooling
Page 43
Switch 2
On
Off
Off
TABLE 17
Blower-Off Delay Switch Settings
Blower-Off Delay
Switch 4
(Seconds)
90
120 (factory)
180
210
TABLE 18
Continuous Indoor Blower Operation -- Blower Speeds
Speed
1 - Low (28%)*
2 - Medium Low (38%)*
Factory
Switch 3
Off
2nd stage delay OFF = 7 minutes
ON = 12 minutes 3rd stage delay
10 minutes fixed
Off
Switch 5
Off
On
Off
Off
On
Off
On
On
Switch 6
Switch 7
Off
On
Off
Off
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