Outdoor Reset - Lochinvar FTxl 500 Service Manual

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Service
(continued)
Tank Minimum Set Point
This setting controls the minimum tank set point for the tank
temperature. The installer can adjust this by accessing the
Tank Minimum Set point parameter. The minimum setting is
60°F (16°C) and the maximum setting is the maximum tank
set point (Tank Maximum Set point parameter). The default
value is 60° (16°C).
Tank Maximum Set Point
This setting controls the maximum tank set point for the tank
temperature. The installer can adjust this by accessing the
Tank Maximum Set point parameter. The minimum setting
is the minimum tank set point (Tank Minimum Set point
parameter) and the maximum setting is 190°F (88°C). The
default value is 190°F (88°C).
Fan Speed Limiting for Indirect DHW Tank
This parameter determines the maximum fan speed (and
therefore the maximum rate) to be used when heating an
indirect DHW tank. This setting may be used when the tank
is unable to accept all of the BTU's available from the boiler.
This parameter may be adjusted by the installer by accessing
the Fan Speed Limiting for Indirect DHW Tank parameter.
The default value is the maximum fan speed for that model.
DHW Type
This parameter determines whether the FTXL boiler treats
the indirect DHW tank as a separate load, or as a zone on
the primary loop. When programmed as a separate load,
the boiler will turn on the DHW pump and then turn off the
boiler pump when an indirect DHW demand begins. When
programmed as a zone, the boiler will turn on the DHW
pump, leave the boiler pump on and change the system set
point to the DHW boiler set point (DHW Boiler Set point
parameter).
This setting may be changed by the installer by accessing the
DHW Type parameter. The choices are NORMAL and ZONE.
The default setting is NORMAL.
SH/DHW Switching Time
When a boiler has a space heating demand and it receives
a DHW demand, it will immediately switch to the DHW
demand and start a timer. Once the timer has expired, the
boiler will switch back to the space heating demand and start
another timer. Once this other timer expires, it will switch
back to the DHW demand. The installer can adjust the
length of time the boiler will service the space heating demand
by accessing the SH/DHW Switching Time parameter. The
minimum setting is 0 minutes and the maximum setting is 55
minutes. The default time is 30 minutes.
Service Manual
DHW/SH Switching Time
When a boiler has a DHW demand and it receives a space
heating demand, the SMART SYSTEM control will start a
timer. Once the timer expires, it will stop the DHW demand
and service the space heating demand. The installer can adjust
the length of time the boiler will service the DHW demand
by accessing the DHW/SW Switching Time parameter. The
minimum setting is 0 minutes and the maximum setting is 55
minutes. The default setting is 30 minutes.
DHW Forces Sys Pump
When the indirect DHW tank is connected as a zone on the
primary loop, the DHW Forces Sys Pump parameter tells the
system pump if it must run when there is a DHW demand.
To have the system pump constantly running during a DHW
demand, set the DHW Forces Sys Pump parameter to YES (the
parameter DHW Blocks Sys Pump must be set to NO). If this
parameter and the DHW Blocks Sys Pump parameter are both
set to NO, the system pump operation will be based strictly on
the System Pump Type parameter setting. The default setting of
this parameter is YES.
DHW Blocks Sys Pump
When the indirect DHW tank is connected as a zone on the
primary loop, the DHW Blocks Sys Pump parameter tells the
system pump if it is allowed to run during a DHW demand.
To force the system pump to turn off during a DHW demand,
set the DHW Blocks Sys Pump parameter to YES. The default
setting is NO.

Outdoor Reset

The option of controlling up to three (3) different outdoor
resets for low outdoor temperatures is available.
Outdoor (1 - 3) Low
When the outdoor air temperature drops to this point, the water
temperature will be at the Set point 1 at Low Outdoor Temp 1, Set
point 2 at Low Outdoor Temp 2 and Set point 3 at Low Outdoor
Temp 3 parameters (FIG. 1-1 on page 24). If the outdoor
air temperature drops further, the set point will continue to
increase above this setting. This parameter can be changed by
the installer by accessing the Outdoor (1-3) Low parameter. The
temperature range of this parameter is -39°F (-39°C) to high
outdoor temperature set point. The default value is 25°F (-4°C).
Outdoor (1 - 3) High
When the outdoor air temperature rises to or above this point,
the water temperature will be at the Set point 1 at High Outdoor
Temp 1, Set point 2 at High Outdoor Temp 2 and Set point 3
at High Outdoor Temp 3 parameters (FIG. 1-1 on page 24).
This parameter can be changed by the installer by accessing
the Outdoor (1-3) High parameter. The temperature range of
this parameter is low outdoor temperature set point to 104°F
(40°C). The default value is 70°F (21°C).
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