Outdoor Air Reset Option; Additional Temperature Controls - Lochinvar SOLUTION 260000 Installation & Service Manual

5
Electrical connections

Outdoor Air Reset Option

For boilers ordered with the Outdoor Air Reset option, there
is an additional control (FIG. 5-5). There are three setting
knobs for Shutdown, Outdoor Air Max., and Ratio. There is
also a switch to turn the outdoor air shutdown feature On or
Off. An O.A. Sensor is also included.
(c)2002 L.C. (c)2002 L.C.
55
50 60
CN7 CN7
45 65
CN8 CN8
VR3
40 70
W1 W1
SHUTDOWN
55
50
60
45
65
VR1
40 70
CN1 CN1
O.A. MAX.
160 160
200 200
8 8
140 140
7 7
220 220
6 6
120 120
240 240
DIFFERENTIAL DIFFERENTIAL
OFF OFF
SETPOINT SETPOINT
Figure 5-5_Optional Outdoor Air Reset Control
Shutdown
The Shutdown knob specifies the outdoor air lockout
temperature at which the control would prevent the unit from
operating.
Outdoor Air Max (O.A. Max)
The O.A. Max knob allows a reset up to the maximum
outdoor air temperature specified by this knob setting. When
the outdoor air temperature is above the specified setting, the
unit will not function in the O.A. Reset Mode, but will
continue to run at the selected set point temperature.
Note that the set point knob will now indicate the "minimum"
boiler temperature. Target temperature is determined by the
ratio and outdoor air temperature below the O.A. Max
setting.
Ratio
The Ratio knob allows control over the reset ratio to be used
during Outdoor Air Reset. The allowable ratios are as low as
0.5:1 or as high as 1.5:1.
Selecting the 0.5:1 ratio will increase the set point 0.5° for
every 1.0° drop in outdoor air temperature up to the
maximum set point temperature.
Selecting the 1.5:1 ratio will increase the set point 1.5° for
every 1.0° drop in outdoor air temperature up to the
maximum set point temperature.
38
CN1
CN2 CN2 CN3 CN3
O.A. SENSOR
CN4 CN4
ENABLE
ON
SW1
DISABLE
CN5 CN5
O.A. SHUTDOWN
1.0
0.9 1.1
CN6 CN6
1.2
0.8
1.3
0.7
W3
1.4
0.6
VR2
0.5 1.5
W1 W2
RATIO
10
11 11
9 9 10 10
12 12
15 15
5 5
13 13
14 14
VR2 VR2
VR3 VR3
5 5 15 15
(F-)0 (F-)0 20 20
HIGH-FIRE HIGH-FIRE
OFFSET OFFSET
TST2314 TST2314
If the outdoor design and boiler design temperatures are known,
the Ratio setting can be calculated using the following formula:
Ratio = (boiler design temperature - operator set point)
(O.A. Max. setting - outdoor design temperature)
Note that the reset set point cannot exceed the maximum set
point of the boiler thermostat.
These settings are illustrated graphically in FIG. 5-6.
OJ1 OJ1
OJ2 OJ2
CN9 CN9
Figure 5-6_Outdoor Air Control Example Chart
Outdoor Air Shutdown Enable/Disable Switch
The Outdoor Air Shutdown Enable/Disable switch turns the
outdoor air shutdown feature On and Off. Disabling the
Outdoor Air Shutdown feature allows the unit to operate
regardless of the outdoor air temperature. This is needed for
indirect domestic hot water systems for example.

Additional Temperature Controls

High Water Temperature Limit Con trol
The appliance is supplied with a fixed setting, auto-reset high
water temperature limit control. The setting of this control
limits max i mum discharge water tem per a ture.
temperature exceeds the setting, the limit will break the con trol
circuit and shut down the appliance. The limit control will only
be reset after the water tem per a ture has cooled well below the
setting of the limit. The auto-reset high water temperature limit
control is mount ed in the outlet side of the front header.
Installation & Service Manual
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