Instruction manual

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P/N HN-IOM-1 82-0331 Copyright 2009 Mestek, Inc.
Finned copper tube gas boilers & water heaters – Control manual
Table 9 Setup menus — parameter explanations (continued)
Menu item Under . . . Explanation
Master FIRST
ADVANCED SETUP
FIRING MODE
Set this to “ON” to always start the master boiler first, regardless of the rotation scheme
selected.
SENSOR#
ADVANCED SETUP
SENSORS
The HeatNet control can be connected to up to six sensors: OUTSIDE, SUPPLY, RETURN
HEADER, and two user-selectable inputs (number 5 or number 6).
TYPE
ADVANCED SETUP
SENSORS
For each sensor, select either TYPE Z (10K), ON/OFF, or NONE.
Type Z is a thermistors sensor (as supplied by RBI). Type Z sensors are NTC thermistors,
10Kohms at 77 °F, 335.67 Kohms at -40 °F, 185 Kohms at 150 °F, +/- 1 °F,
-40 to 140 °F.
ON/OFF looks for an external dry contact closure.
NONE means no sensor is connected to the terminals.
CALIBRATE ?
ADVANCED SETUP
SENSORS
Use this function only if the response to a sensor indicates the control calibration may be off.
Calibrate Type Z sensors inputs by attaching a 10Kohm precision resistor across the sensor
terminals.
Select “YES” after “CALIBRATE.”
The control will measure the resistance and establish a trim value (in ohms) for the sensor
input.
The control display will show the trim value setting.
The trim value must not exceed +/- 200 ohms. If it does, verify that the resistor is correctly
connected. If so, the sensor input is bad. Contact RBI for recommended action.
If the trim setting is acceptable, press the SELECT key to accept.
The display will show, “TRIM VALUE SET!”
After a slight delay, the display will return to the sensors menu.
4mA SETPOINT
20mA SETPOINT
ADVANCED SETUP
4-20mA INPUT
ADVANCED SETUP
4-20mA INPUT
The 4mA SETPOINT and 20mA SETPOINT establish the temperature range when the boiler/
system is operated with a remote 4-20mA setpoint.
Set the 4mA SETPOINT to the starting temperature.
Set the 20mA SETPOINT to the maximum desired temperature (at max signal of 20 mA).
Any signal between 4 and 20 mA will change the setpoint proportionally between the upper
and lower temperature values.
Example: 4mA SETPOINT = 140 °F / 20mA SETPOINT = 200 °F — If the signal is at 4 mA, the
setpoint temperature will be 140 °F; at 20 mA, the setpoint temperate will be 200 °F.
At 12 mA, the setpoint temperature will be:
140° + (200° – 140°) x (12mA – 4 mA)/16mA = 140° + (60° x 8/16) = 140° + 30° = 170 °F.
At 15 mA, the setpoint temperature will be:
140° + (200° – 140°) x (15mA – 4 mA)/16mA = 140° + (60° x 11/16) = 140° + 41° = 181 °F.
NOTE: Under SETUP | SETPOINTS, the SETPT SOURCE must be set to 4-20mA. The current
must be above the BOILER START value, the 4-20mA ENABLE contact must be closed for
remote setpoint operation to function.
BOILER START
ADVANCED SETUP
4-20mA INPUT
This sets the signal current at which the boiler will start/shut off. The boiler will start when the
current is approximately 0.10 mA above the setting. The boiler will shut off if the current falls
below the setting. Example: 4mA SETPOINT = 3.8 mA — the boiler will start at 3.9 mA and
shut at or below 3.7 mA.
Control menus and adjustments (continued)
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