NTI INSTALLATION MANUALS

Part 9 - Controls

I. Type of Temperature Control

(e.g. Parameter 4.2.1 for Zone 1) 0 = Fixed Outlet Temperature - When operating for central heating, the boiler operates at a xed supply temperature equal to the setting of pa rameter 4.0.2, which is adjustable via the CH + and - buttons on the home screen, with a range de ned by parameters 4.2.5 and 4.2.6. The supply temperature is xed and does not change due to indoor or outdoor temperature conditions.

1 = Basic Temp. Control - The boiler uses the ON/OFF condition of the room thermostat to boost/reduce the boiler target temperature. With a starting* ( rst time) boiler target temperature of 136 o F (4.2.0 = 1) or 95 o F (4.2.0 = 0), the function boosts the target temperature by 7 o F every 16 minutes** a call for heat is continuously active. Similarly, the target temperature is reduced 7 o F every 16 minutes** that the heat call is continuously inactive. The temper ature will boost/reduce a maximum of 3 times (21 o F)*** for a given thermo stat ON/OFF cycle. *NOTE: The boiler starting target temperature can be manually o set up or down via the Parallel Shift setting (4.2.3), which is adjustable from the home screen via the CH + and - buttons. **NOTE: The default boost interval of 16 minutes can be adjusted via param eter 2.4.4. ***NOTE: The boiler supply temperature is limited upwards by the xed max imum temperature (4.2.5) and downwards by the xed minimum temperature (4.2.6).

Figure 66 - Basic Temp. Control Example (4.2.0 = 1)

2 = Indoor Temp. Reset - The boiler target temperature automatically adjusts between the Min and Max Temperature Settings (4.2.6 and 4.2.5), based on the input temperature provided by an optional NTI Room Sensor, in accordance with the following formula:

Boiler Target Temp = Min Temp (4.2.6) + Room Sensor In uence (4.2.4) X [Room Setpoint - Room Temp] + Parallel Shift of Reset Curve (4.2.3)

3 = Outdoor Temp. Reset - The boiler target temperature automatically adjusts between the Min and Max Temperature Settings (4.2.6 and 4.2.5), based on the input temperature provided by the included Outdoor Sensor (or Internet Weather via WiFi connection), in accordance with the following formula:

Boiler Target Temp = Min Temp (4.2.6) + Slope of Outdoor Reset Curve (4.2.2) X [Room Setpoint (4.0.0) - Outdoor Temp] + Parallel Shift of Reset Curve (4.2.3) Where: Room Setpoint, in the absence of an NTI Room Sensor, defaults to 66 o F and is adjustable via parameter 4.0.0.

4 = Indoor and Outdoor Temp. Reset - The boiler target temperature automatically adjusts between the Min and Max Temperature Settings (4.2.6 and 4.2.5), based upon the input temperatures provided by an optional NTI Room Sensor AND the included Outdoor Sensor (or Internet Weather via WiFi connection), in accordance with the following formula:

Boiler Target Temp = Min Temp (4.2.6) + Slope of Outdoor Reset Curve (4.2.2) X {Room Sensor In uence (4.2.4) X [Room Setpoint - Room Temp] + [Room Setpoint - Outdoor Temp]} + Parallel Shift of Reset Curve (4.2.3)

J. Slope of Outdoor Reset Curve (e.g. Parameter 4.2.2 for Zone 1)

179 °F

The boiler control adjusts the supply temperature according to the outdoor temperature. The lower the outdoor temperature, the higher the boiler supply temperature, and vice versa. The supply temperature needed to e ciently satisfy a call for heat from a thermostat depends on the heating system and building conditions (building materials, insulation, etc.) The Slope of the Outdoor Reset Curve may be adjusted to adapt the boiler supply temperature to installation conditions. NOTE: The boiler supply temperature is limited upwards by the xed maximum temperature (4.2.5) and downwards by the xed minimum temperature (4.2.6).

120 °F

Target CH supply temperature Target CH supply temperature 179 °F 120 °F

65 °F

80 °F

20 °F

Outdoor temperature

0,4

1,3 3,5

Default

Outdoor temperature

Figure 67 - Adjusting the Slope of the Outdoor Reset Curve

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