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Matrix Installation and Operation Instructions
9.3 Outdoor Sensor Operation
The outdoor sensor is connected to the terminal board on the left side of the matrix. The two terminals are labeled ‘OUTDOOR
SENSOR’.
When the Outdoor sensor is not used, or the outdoor temperature is below 0°F, the Matrix operates at a boiler water temperature
equal to the HYD or HI setpoint during a call for Hydronic or Emergency Heat respectively. When the sensor is used and the
outdoor temperature is above 0°F, the Matrix boiler control automatically reduces the operating temperature of the boiler during
those calls. Using the following formula, the control factors in the current outdoor temperature, control setpoint (HYD or HI), and
the RES (reset) setpoint, in determining the appropriate operating water temperature.
Figure 9.2 Outdoor Reset Calculation
Formula:
Operating Temperature = {(RES – Outdoor Temp) x (HYD – RES) / RES} + RES
Note: Substitute HYD for HI during a call for Emergency Heat.
Example:
•
There is a call for Hydronic heat; therefore the control uses the HYD programmed
setting.
•
The HYD is programmed to be 160°F.
•
The RES is programmed to be 85°F.
•
The outdoor temperature is 40°F.
Operating Temperature = {(85 – 40) x (160 – 85) / 85} + 85 =
125°F
The following chart illustrates the effect of changing outdoor temperature on the boiler operating
temperature for the above example.
Reset Curve for Res=85 & Setpoint=160
70
90
110
130
150
170
-10
0
10
20
30
40
50
60
70
80
90
100
Outdoor Temperature (deg.F)
Water Tem
p
. (F)
