Operating Information General - Lochinvar FTXL 400 Installation & Operation Manual

11
Operating information
General
How the boiler operates
Th e FTXL uses an advanced stainless steel heat exchanger
and electronic control module that allows fully condensing
operation. Th e blower pulls in air and pushes fl ue products
out of the boiler through the heat exchanger and fl ue piping.
Th e control module regulates blower speed to control the
boiler fi ring rate. Th e gas valve senses the amount of air
fl owing into the boiler and allows only the right amount of
gas to fl ow.
How the control module operates
Th e SMART SYSTEM control module receives inputs from
boiler sensors and external devices. Th e control module
activates and controls the blower and gas valves to regulate
heat input and switches the boiler, Domestic Hot Water
(DHW), DHW recirculation, and system pumps on and off
as needed. Th e user programs the module to meet system
needs by adjusting control parameters. Th ese parameters set
operating temperatures and boiler operating modes. Boiler
operation can be based on boiler outlet water temperature,
boiler inlet water temperature, system temperature, a 0 - 10V
signal, Modbus, or BACnet, depending on the parameter
settings.
Control inputs and outputs
Room thermostat
Th ere are three (3) heat/loop demand connections available
on this control. Th ese inputs tell the boiler to provide water
for space heating. Each demand connection has its own set
point and outdoor air reset curve. When multiple demands
have a call for heat the control will give priority to the
demand with the highest set point.
Example: Assume that both heat/loop demand 1 and heat/
loop demand 2 have a call for heat. Demand 1 has a set point
of 110°F. Demand 2 has a set point of 140°F. Th e boiler will
regulate the system temperature to 140°F until Demand 2 has
been satisfi ed. Once Demand 2 has been satisfi ed the boiler
will provide 110°F water to the system.
When multiple temperature loops are
CAUTION
used, mixing valves are required for the
protection of any low temperature loops.
64
Installation & Operation Manual
SMART SYSTEM Multi-temp loop control
Th e FTXL boiler is capable of producing up to three (3) set
point temperatures to meet diff erent space heating demands.
Th is device controls the temperatures of up to three (3) separate
loops, based on the settings for the three (3) heat/loop demands
(reference Lochinvar kit 100167843).
0 - 10V input (set point or power)
Th e FTXL can be controlled by a Building Management System
(BMS) using a 0 - 10 VDC signal. Th e control can be confi gured
by the installer to use this signal to either control set point or
fi ring rate.
Th e FTXL can also be programmed to accept a call for heat
from a 0 - 10V signal, reference the FTXL Service Manual for a
detailed explanation of this procedure.
DHW priority
Th e SMART SYSTEM control allows the connection of a DHW
thermostat or tank sensor to the low voltage connection board.
When a tank sensor is connected, the DHW thermostat input
is ignored. When a boiler is programmed for DHW Normal
Mode, the maximum fi ring rate can be limited to match the
input rating of the indirect tank coil.
DHW / space heating (SH) cycling
If a DHW call for heat is received while a space heating call is
in progress, and the DHW is in Normal Mode, the control will
start the DHW pump and shut the boiler pump off . Th e system
pump will remain on. For stand-alone boilers, if the space
heating call is still active while the DHW call is in operation,
the control will wait for 30 minutes (time adjustable by installer)
then it will switch back to the space heating demand. Th ere is
a timer to switch from space heating to DHW and a timer to
switch from DHW to space heating. Th e control will switch
back and forth until one of the heat demands end. Th is function
does not apply to cascade systems.