
4
The Controller - Overview
Cemline CEM-TROL control module is a solid state controller designed to control temperatures and
limit(s) on Cemline Packaged Water Heaters.
The CEM-TROL is supplied with a LED backlit LCD display. LED pilot lights are supplied to
indicate On-Off, primary high limit temperature, and secondary high limit temperature. The CEM-
TROL control module allows the owner to set the operating temperature, primary high temperature
limit and the secondary temperature high limit on the display screen. The CEM-TROL control
module has over temperature alarm lights and an alarm horn with built in alarm silence relay. The
CEM-TROL control module is supplied with dry contact closure outputs to indicate to building
automation system (BAS): power on, primary high temperature, secondary high temperature, and
any alarm. The CEM-TROL control module allows the BAS to turn the Cemline Packaged Water
Heater on or off through a remote relay suitable for 24 VAc, 1 amp. The control module allows the
BAS to remotely monitor the operating temperature and remotely set the operating temperature.
The control module is supplied with an on-off switch and is mounted in a NEMA 4 enclosure.
Built in remote start stop: This feature allows the Packaged Water Heater to be started or stopped
from a remote location. Typically this would be accomplished from the Building Automation
System (BAS) . Requires a dry contact suitable for 24 VAc and 1 amp. Terminal block P1
terminals 1 – 2 on the panel is where the BAS on-off is wired.
Built in On-Off Switch: Allows for local on-off and is convenient for service in the unlikely event
service is required. This switch is mounted in the side of the panel.
Built in Alarm Horn: The alarm horn will sound and LED will light red on primary high
temperature limit and/or secondary high temperature limit. If either high temperature limits are
exceeded the alarm horn will also sound and the alarm light(s) will light red. The CEM-TROL also
features an alarm silence relay which will silence the alarm but not the fault light when the
generator is being serviced. When the fault is cleared both the alarm and fault light(s) will
automatically reset.
Built in PID controller: The PID control in the CEM-TROL allows the user to easily select the
operating temperature set point of the water heater. The controller reads the temperature of the
heated water from a temperature sensor in the water heater. Based upon the water temperature, the
controller then sends a 0 –10 VDC output signal to the control valve to open or close the valve
accordingly. In order to use this functionality of the CEM-TROL must be wired to either a
pneumatic control valve with an I-P transducer or an electronic control valve. This feature is not
functional when using a pilot operated valve with a self-contained temperature pilot.
The CEM-TROL is designed with the P-I-D control logic.
P is proportional. The proportional is used to handle the present. Proportional is a constant used to
send a signal to the output. Proportional control with a set point of 140 oF and a proportional band
of 10 would have a 100% (10 VDC) output at 130 deg F, 50% (5 VDC) output at 135 oF and 10%
(1 VDC) output at 139 deg F oF.