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

MODE 7 (External Target Temperature Input and Setpoint
with Primary/Secondary Piping)
Mode 7 is designed for an external input signal and
setpoint with primary/secondary piping. The external input
signal can be provided from a BMS, an EMS, or a tekmar
tN4 System Control for space heating. The setpoint can be
used to heat an indirect domestic hot water tank.
The external input signal creates an internal demand and
changes the boiler target according to a linear scale. The
control stages the boiler to maintain the boiler target at the
boiler supply sensor. Refer to section E for a description of
external target temperature operation.
Once a setpoint demand is present, the control stages the
boiler to maintain the boiler target at the boiler supply
sensor. If both an external input signal and a setpoint
demand are present at the same time, the control targets
the higher of the two requirements. Refer to section B for a
description of setpoint operation.
MODE 8 (External Direct Drive Operation)
Mode 8 is designed for an external input signal to directly
control the staging rate of the boiler with either parallel
or primary / secondary piping. The heat demand and
setpoint demand inputs are disabled. Refer to section F for
a description of external target temperature operation.
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.
6 EM-40-SM Service Manual
BTC
Mode 7
0-10 V (dc)
tN4 System
Control
Relay
Factory
Installed
Boiler
Outlet
Sensor
Boiler Inlet Sensor (Optional)
Secondary
Piping
Sensor
(Included)
External
Control
Sensor
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
BTC
Mode 8
External
Control
BTC
0-10 V (dc)
Direct Drive
Boiler
Supply
Sensor
Boiler Inlet Sensor (Included)
External
Control
Sensor
Factory
Installed
Boiler
Outlet
Sensor
Factory
Installed
Boiler
Outlet
Sensor