General Operation; Access Modes; Sequence Of Operation - Lochinvar FTxl 500 Service Manual

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Service Service

General Operation

How the boiler operates
The FTXL uses an advanced stainless steel heat exchanger
and an electronic control module that allows fully
condensing operation. The blower pulls in gas and air and
pushes flue products out of the boiler through the heat
exchanger and flue piping. The control module regulates
blower speed to control boiler firing rate. The gas valve
senses the amount of air flowing into the boiler and allows
only the right amount of gas to flow.
How the control module operates
The FTXL control module receives input from boiler
sensors. The control module activates and controls the
blower and gas valve to regulate heat input and switches
boiler, DHW, DHW recirculation, and system pumps on
and off as needed. The user/installer programs the module
to meet system needs by adjusting control parameters.
These parameters set operating temperatures and boiler
operating modes. Boiler operation can be based on boiler
outlet water temperature, boiler return water temperature
or system supply temperature, depending on the parameter
setting.

Sequence of operation

Table 1-1 shows control module normal sequences of
operation for space heating and DHW operation. The
combined operation sequence is for a typical application,
programmed to provide DHW priority.
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Service Manual

Access modes

User
The user can adjust space heating and tank target temperatures
by pressing the NAVIGATION dial when "SETPOINTS" is
flashing at the bottom of the display. The date and time, and
the temperature units can also be changed.
Installer
Most parameters are available only to the installer, accessible
by entering the installer password (5309).
Saving parameters
Table 1-4 on pages 16 - 19 of this manual)
Please note that the brackets ([]) denote
NOTICE
screen status.
To save parameters and exit programming:
Press the RIGHT SELECT [SAVE] key and then press the
RIGHT SELECT [HOME] key.
To enter a parameter and continue programming:
Press the RIGHT SELECT [SAVE] key 1 time to return to the
parameter listings; press again to return to the menu listings.
Remember to press the RIGHT SELECT [HOME] key when
finished programming in order to save the changes made.
(reference the Parameter Table -