Communications and Displays, Specifications

COMMUNICATIONS AND DISPLAYS

Two modes of communications are available to the R7910.

1.The R7910 has two RS485 communication ports for ModBus that allows for interfacing to one or all R7910s of a system and presents them individually to the user. The S7999B System Operator interface is a color touchscreen displays used for configuration and monitoring of the R7910A. Control Operation and display status in both test and graphical modes can be shown along with the ability to setup. The R7910 can also be remotely reset through the S7999B display.

2.Either ModBus RS485 communication port can be used to allow configuration and status data to be read and written to the R7910. Support a Master S7999B or a Building Automation master to control the R7910 to respond to a single ModBus address to service the requests of the ModBus master in a Lead/Lag arrangement.

The local S7910 Keyboard display, the S7999B System Operator interface, and the S7999C Local Operator Interface are optional components.

The S7999B (or the DSP3944 which is a portable S7999B) or is required configuration of the parameters of the R7910 but is not needed for the operation of the system once configured.

SPECIFICATIONS

1.Electrical Ratings: Operating voltage

•24VAC (20 to 30 VAC, 60 Hz ±5%)

•30 amps (Single Heat Exchanger)

•60 amps (Double Heat Exchanger)

Connected Load for Valve and annunciator functions:

•24VAC, 60Hz

•120VAC (+10%/-15%), 60Hz (±5%)

•Model Specific

2.Corrosion:

•R7910A must not be used in a corrosive environment.

3.Operating Temperature: -4°F to 150°F (-20°C to 66°C)

4.Storage/Shipping Temperature: -40°F to 150°F (-40°C to 66°C).

5.Humidity:

•Up to 95% Relative Humidity, noncondensing at 104°F for 14 days. Condensing moisture may cause safety shutdown.

6.Vibration: 0.0 to 0.5g Continuous (V2 level)

7.Enclosure: Nema 1/IP40.

8.Approvals:

Underwriters Laboratories, Inc. (UL): Component Recognized: File No. MP268 (MCCZ)

•R7910 is certified as UL372 Primary Safety Controls.

•The R7910 is certified as UL353 Limit Rated device when using part number 50001464 dual element limit rated NTC sensors.

CSD-1 Acceptable.

Meets CSD-1 section CF-300 requirements as a Primary Safety Control.

Meets CSD-1 section CW-400 requirements as a Temperature Operation control.

Meets CSD-1 section CW-400 requirements as a Temperature High Limit Control when configured for use with 10 kohm NTC sensors.

Federal Communications Commission, Part 15, Class B. Emissions.

BURNER CONTROL OPERATION

SAFETY SHUTDOWN OF BURNER CONTROL FUNCTIONS

Safety Shutdown (Lockout) occurs if any of the following occur during the indicated period:

1.INITIATE PERIOD:

a. A/C line power errors occurred.

b. Four minute INITIATE period has been exceeded.

2. STANDBY PERIOD:

a. Flame signal is present after 240 seconds.

b. Preignition Interlock is open an accumulative time of 30 seconds.

c. Interlock Start check feature is enabled and the Interlock String (including Airflow Switch) is closed for 120 seconds with the controller closed. (jumpered or welded Interlock).

d. Main Valve Terminal is energized. e. Internal system fault occurred.

3. PREPURGE PERIOD:

a. Preignition Interlock opens anytime during PREPURGE period.

b. Flame signal is detected for 10 seconds accumulated time during PREPURGE.

c. Purge Rate Fan RPM or High Fire Switch fails to close within four minutes and fifteen seconds after the firing rate motor is commanded to drive to the high fire position at the start of

PREPURGE.

d. Light off Rate Fan RPM or Low Fire Switch fails to close within four minutes and fifteen seconds after the firing rate motor is commanded to drive to the low fire position at the end of

PREPURGE.

e. Lockout Interlock (if programmed) does not close within 10 seconds.

f. Lockout Interlock opens during PREPURGE. g. Pilot Valve terminal is energized.

h. Main Valve terminal is energized. i. Internal system fault occurred.

4. PRE-IGNITION TIME

a. Lockout Interlock opens.

b. IAS Purge and Ignition enabled and the Interlock opens. c. Preignition Interlock opens.

d. Pilot Valve terminal is energized. e. Main Valve terminal is energized.

5. PILOT FLAME ESTABLISHING PERIOD (PFEP):

a. Lockout Interlock opens (if enabled). b. Pilot Valve terminal is not energized.

c. No flame is present at the end of the PFEP, or after programmed number of retry attempts.

d. Main valve terminal is energized. e. Internal system fault occurred.

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