Lochinvar KNIGHT 400 - 801 - Manual (Page 10)

1
Service
10
Service Manual
1
Service
General Operation
How the boiler operates
The Knight XL 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 Knight XL 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 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.
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 (reference the Parameter Table -
Table 1-4 on pages 15 - 18 of this manual)
Please note that the brackets ([]) denote
screen status.
NOTICE
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.