1
Service
Service Manual
1
Service
LOW OUTDOOR
TEMPERATURE
(Default = 25°F)
HIGH OUTDOOR
TEMPERATURE
(Default = 70°F)
SET POINT AT
HIGH OUTDOOR
TEMPERATURE
(Default = 70°F)
SET POINT AT
LOW OUTDOOR
TEMPERATURE
(Default = 180°F)
(SH)
SET POINT
(Default = 125°F)
WATER
TEMPERATURE
SET POINT
OUTDOOR AIR
TEMPERATURE
Figure 1-1 Outdoor Air Reset Curve
Outdoor Reset
Knight Wall Hung boilers are equipped with outdoor reset,
a feature that saves energy by reducing the boiler water
temperature as the heating load decreases. In accordance
with the United States Energy Policy and Conservation
Act, boilers with inputs less than 300,000 Btu/hr must use
either outdoor air reset or an external energy management
system. To use the outdoor reset feature, the outdoor
sensor provided with the boiler must be properly installed.
For better zone control, three (3) individual outdoor resets
for low outdoor temperatures are available. If multiple
zones are calling for heat, the highest set point has priority.
Each curve is created using four (4) adjustable parameters:
low outdoor air temperature, high outdoor air temperature,
set point at low outdoor air temperature, and set point at
high outdoor air temperature. The set point is calculated
using the individual curve for each zone.
Outdoor (1 - 3) Low
This parameter specifies the low outdoor air temperature.
When the outdoor air temperature drops to this point, the
zone set point 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). If the
outdoor air temperature drops further below this setting,
the set point will continue to increase. This parameter can
be changed by the installer by accessing the
Outdoor (1-3)
Low
parameters. The temperature range is -39°F (-39°C) to
high outdoor air temperature set point. The default value
is 25°F (-4°C).
Outdoor (1 - 3) High
This parameter specifies the high outdoor air temperature.
When the outdoor air temperature rises to or above this
point, the water temperature set point will be at
Set point
(1 - 3) at High Outdoor Temp (1 - 3)
parameters (FIG. 1-1).
This parameter can be changed by the installer by accessing the
Outdoor (1-3) High
parameters. The temperature range is low
outdoor air temperature set point to 104°F (40°C). The default
value is 70°F (21°C).
Set Point (1 - 3) at Low Outdoor Temperature
When the outdoor air temperature drops to the
Outdoor (1
- 3) Low
parameter, the set point will be at this setting (FIG.
1-1). However, the outdoor reset curve is limited by the
SH
(1 - 3)
Set Points
. If
SH1, SH2,
and
SH3
are set lower, the water
temperature will be at these set points instead. If the outdoor
air temperature continues to drop below the
Outdoor (1 - 3)
Low
parameter, the set point will continue to increase above
this setting until
SH1 (1 - 3) Set Point
is met. These parameters
can be changed by the installer by accessing 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. The temperature
range of this parameter is 68°F (20°C) to 180°F (82°C). The
default value is 180°C (82°C).
Set Point (1 - 3) at High Outdoor Temperature
When the outdoor air temperature rises to or above the
Outdoor (1 - 3) High
parameter, the calculated set point will be
at this setting (FIG. 1-1). These parameters can be changed by
the installer by accessing 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
.
The temperature range of this
parameter is 68°F (20°C) to 190°F (88°C). The default value
is 70°F (21°C).
Outdoor Air Shutdown (SH1 - SH3)
The
Outdoor Air Shutdown
parameter specifies the outdoor air
temperature at which there is no longer space heating demand.
When the outdoor temperature rises above this point, the
control will block all SH demands (DHW demands will still
be active). These parameters can be changed by the installer
by accessing the
Outdoor Air Shutdown SH1, SH2,
and
SH3
parameters. The temperature range of this parameter is 32°F
(0
°
C) to 104°F (40°C). The default value is 70°F (21°C).
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Содержание WH 399
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