Instruction manual
61
SECTION XII: OPERATING (CONTINUED)
c. Low Limit (LL_)
The Warm Start Boiler Control is factory
programmed with a Low Limit Setpoint of
110°F. On falling temperature the boiler
turns “on” and the “ZC” terminal and System
Circulator outputs are de-energized when the
boiler temperature is less than the Low Limit
Setpoint less the differential. On a rising
temperature when the boiler temperature is above
the Low Limit Setpoint the boiler turns “off”,
the “ZC” terminal output is energized and the
System circulator is enabled to respond to a call
for heat. The Low Limit Setpoint is adjustable
between 110°F and 220°F.
d. Low Limit Differential (Ldf)
The Warm Start Boiler Control is factory
programmed with a Low Limit Differential
Setpoint of 10°F. The Low Limit Differential
is the number of degrees the boiler temperature
must decrease below the Low Limit Setpoint
before the Warm Start Boiler Control takes
actions to warm the boiler. These actions include
starting the burner and stopping water ow
through the boiler. The Low Limit Differential is
adjustable between 10°F and 25°F.
e. Circulator Overrun Time (OR_)
Circulator Overrun Time (also called “circulator
off delay” or “circulator post purge”) continues
circulator operation after a call for heat has
ended, sending excess heat from the boiler into
the priority zone. Ensure system piping and zone
panel settings allow water ow to the priority
zone after the call for heat ends. The Circulator
Overrun Time has a factor setting of 0 minutes
and is eld adjustable between 0 and 10 minutes.
f. Circulator Pre-Purge Time (PP_)
When the boiler is warm [boiler water
temperature higher than 140°F (adjustable using
Start Temperature parameter)] and there is a
thermostat call for heat, the system circulator
is started and boiler ring is delayed pre-purge
minutes. If the temperature drops below 140°F or
there is a DHW Call for Heat the boiler is started
without delay. Additionally, the boiler is started
without delay if the thermostat call for heat is
initiated when the boiler water temperature is
less than 140°F. This feature helps save energy
by satisfying home heating needs with residual
boiler heat rather than cycling the boiler. The
Circulator Pre-purge time has a factory setting of
2 minutes and is eld adjustable between 2 and
20 minutes. Refer to Table 6.
The Warm Start Boiler Control Pre-purge Time is
factor set to 0 minutes.
Cold Start Boiler Control
Adjustment Mode Options
HL_ 140-240°F Adjust High Limit Setting
HdF 10-30°F Adjust High Limit Differential
ZC_ dh, ZR or ELL ZC and ZR Terminal Function
Or_ 0-10 minutes Pump Overrun Time
PP_ 2-20 minutes Pump Pre-purge Time
t_ 140 - 180°F Start Temperature
Pt_ On or Off Priority Time
f-C F or C Select degrees F or C Mode
bac Back to Operating Mode
Warm Start Boiler Control
Adjustment Mode Options
HL_ 140-240°F Adjust High Limit Setting
LL_ 110-220°F Adjust Low Limit Setting
Ldf 10-25°F
Adjust Low Limit Differential
Setting
ZC_ ZR or dh ZC and ZR Terminal Function
Or_ 0-10 minutes Pump Overrun Time
PP_ 0-20 minutes Pump Pre-purge Time
t_ 140 - 180°F Start Temperature
Pt_ On or Off Priority Time
f-C F or C Select degrees F or C Mode
bac Back to Operating Mode
c. Press the Up ñ and Down ò keys to adjust the
displayed setpoint to the desired value.
d. To return to the normal operating mode from
the Adjustment Mode, when the "bc” option is
displayed, press either the Up ñ or Down ò key.
If no keys are pressed, after ve (5) minutes the
Boiler Control will automatically return to the
Operating Mode.
6. More Information about Adjustable Parameters
a. High Limit (HL_)
The Boiler Control is factory programmed with
a High Limit Setpoint of 180°F. The boiler turns
"off" when the boiler water temperature (bt)
is above this value. The High Limit setpoint
is adjustable between 140° and 240°F. The
Operating Setpoint (P) will equal the High
Limit Setpoint.
b. High Limit Differential (HdF)
i. The Cold Start Boiler Control is factory
programmed with a Differential of 15°F.
The Differential is the number of degrees
the boiler temperature must decrease below
the Operating Setpoint before the boiler
can restart. The differential is adjustable
between 10° and 30°F.
ii. On Warm Start Boiler Control the High
Limit Differential is not adjustable and is
xed at 10°F.