Slant/Fin EM-10 Installation - Manual (Page 6)

STAGING MODE (STGMODE)
The control can operate up to four stages in order to
supply the required target temperature. The method of
staging used by the control is either P (proportional) or
PID (Proportional & Integral & Derivative), and is selected
using the STGMODE item in the Adjust menu.
Proportional & Integral & Derivative (PID)
PID staging allows the control to determine when the next
stage is required to turn on. After a stage is turned on in
the firing sequence, the control waits a minimum amount of
time (Stage Delay) before turning on the next stage. After
the minimum time delay between stages has expired, the
control examines the control error to determine when the
next stage is to fire. The control error is determined using
PID logic.
Proportional logic compares the actual operating sensor
temperature to the boiler target temperature. The colder the
temperature, the sooner the next stage is turned on.
Integral logic compares the actual operating sensor
temperature to the boiler target temperature over a period
of time.
Derivative logic determines how fast or slow the operating
sensor temperature is changing. If the temperature is
increasing slowly, the next stage is turned on sooner. If
the temperature is increasing quickly, the next stage is
turned on later, if at all.
STAGE DELAY (STG DLY)
The stage delay is the minimum time between firing first
to second stage, second to third stage, and third to fourth
stage and is determined by the Stage Delay setting. It can
be manually set, or it can be set to automatic in which the
boiler mass determines the stage delay time.
BOILER MASS (BOIL MASS)
The boiler mass setting allows the installer to adjust the
control to the thermal mass of different types of heat sources
used. The boiler mass setting automatically determines the
stage delay on, stage delay off, minimum on time and
minimum off time of the stages. A higher thermal mass
setting provides slower staging, while a lower thermal mass
provides faster staging.
Proportional (P)
Proportional staging, also known as step staging, is based
on manually adjusted settings that determine when the
next stage is required to turn on. These manual settings are
based on temperature and time. The interstage differential
sets the temperature drop at which the next stage turns on.
However, in order for a stage to fire, the interstage delay
on and minimum off times must first elapse.
Interstage Differential (STG DIFF)
The interstage differential is the temperature drop at which
the next stage will turn on. Once a stage turns on, the
next stage cannot turn on until the temperature drops
the interstage differential below the temperature at which
the previous stage turned on. The interstage differential
is adjustable through the STG DIFF setting in the Adjust
menu.
Interstage On Delay (ON DLY)
The interstage on delay is the amount of time that must
elapse before turning on the next stage. Once a stage turns
on, the next stage cannot turn on until the interstage delay
on time elapses. The interstage on delay is adjustable
through the ON DLY setting in the Adjust menu.
Interstage Off Delay (OFF DLY)
The interstage off delay is the amount of time that must
elapse before turning off the next stage. Once a stage turns
off, the next stage cannot turn off until the interstage delay
off time elapses. The interstage off delay is adjustable
through the OFF DLY setting in the Adjust menu.
Minimum On Time (MIN ON)
The minimum on time is the minimum amount of time that
a stage must be on before it is allowed to turn off. Once a
stage turns on, it cannot turn off until a minimum on time
elapses. The minimum on time is adjustable through the
MIN ON setting in the Adjust menu.
6 EM-10-40 Operation and Instruction Manual
175°F
170°F
180°F Setpoint
Proportional Staging
185°F
190°F
155°F
150°F
145°F
140°F
160°F
165°F
Stage 4
Stage 3
Stage 2
Stage 1
water
temperature
droop
water
temperature
droop
water
temperature
droop
175°F
170°F
180°F Setpoint
P.I.D. Staging
very little
temperature
droop
185°F
165°F
Stage 4
Stage 3
Stage 2
Stage 1
P.I.D. = Proportional + Integral + Derivative