HONEYWELL 7800 series combustion controller

Terminal function and load capacity

1. EC/RM7830A key terminals

Rated value of terminal marking function (RM7830A)

3 AL alarm output (normally open) 1A, 10A surge

4 FAN fan/burner motor 4A, PF=0.5, 20A surge

5 L1 power input 120 Vac

6 RT limit and burner control 1mA

7 LD2 wind pressure switch input 5A

8 PV1 ignition valve 1 (interrupt type) 4A, PF=0.5, 20A surge

9 MV main fuel valve 4A, PF=0.5, 20A surge

10 IGN ignition transformer 2A, PF=0.2

21 PV2 ignition valve 2 (continuous) 4A, PF=0.5, 20A surge

2. EC/RM7850A additional modulation terminal

Rated value of terminal marking function

12 HI high fire position output 0.5A, PF=0.5

13 COM modulation common terminal 0.5A, PF=0.5

14 MOD modulation output 0.5A, PF=0.5

15 LO low fire output 0.5A, PF=0.5

18 ES1 low flame switch input 1mA

19 ES3 high flame switch input 1mA

Static inspection program

Before installing the relay module, a static inspection must be performed to verify that the wiring base and external devices are properly connected. The inspection requires the use of a voltmeter (sensitivity ≥ 1M Ω/V, range 0-300V) and insulated jumper wires.

1. Key points for static inspection of EC/RM7830A

Test jumper voltage measurement in normal condition

1 without 5-L2 terminal 5 with line voltage

2 without 17-L2 terminal 17 with line voltage

3 5-16- Alarm turned on

4 5-16, 2-20 20-L2 locking circuit limit closure

5-16, 2-6 6-L2 cycle limit closure

6 5-16, 5-4, 2-7 7-L2 fan starts, terminal 7 has voltage

7 5-10- Ignition spark appears

8 5-8- Ignition spark appears, ignition valve opens

9 5-21- Ignition spark appears, ignition valve opens (main valve during DSI)

10 5-9- Main fuel valve open

2. EC/RM7850A additional modulation test

Test jumper voltage measurement in normal condition

11 12-13 18-L2 low flame switch closed (voltage returns to zero after motor is turned on)

12 12-13 19-L2 high fire switch closed

13 14-13 19-L2 motor drives towards low flame, terminal 19 voltage returns to zero

14- Change the controller settings and modulate the corresponding actions of the motor

Important reminder: After each test is completed, the main switch must be disconnected and all test jumpers must be removed, otherwise the equipment may be damaged.

Operation sequence and safety interlock

The 7800 series relay module controls the burner according to precise timing, with strict safety monitoring at each stage.

1. Initial Stage

After the module is powered on, it enters the InitiatITE sequence for 2 seconds

If the voltage or frequency exceeds the tolerance range, the module enters a hold state and locks after a maximum of 4 minutes

Monitoring items: power interruption, line noise, low voltage

2. Standby phase (STANDBY)

When the control input sends out the "heating demand" signal, the module is ready to start

Check the burner switch, limit, operation control circuit, and all microprocessor monitoring circuits

If the flame signal appears for more than 40 seconds, it will be locked

3. PurGE stage

The blowing time can be selected through the blowing timing card (2 seconds to 30 minutes)

Fan output (terminal 5) power supply, start blowing

EC/RM7850A type drives the modulation motor to the high flame position at the beginning of blowing

The wind pressure switch must be closed within 10 seconds, otherwise it will lock

The pre ignition interlock must remain closed

4. Ignition test stage

Pre ignition: The ignition transformer (terminal 10) supplies power for 3 seconds

First Safe Time (SAFETY1):

The ignition valve (terminals 8 and 21) is powered simultaneously with the ignition transformer

EC/RM7850A type requires low flame switch to be closed

The flame must be established within the first safe time, otherwise it will be locked

Stable ignition period (PILOT TAB.):

After the flame is established, the ignition transformer is powered off

Lasts for 5 seconds

Main Trial Period:

Main fuel valve (terminal 9) power supply

The main fire test time can be selected as 3 seconds or 5 seconds

If the flame goes out, the module will lock within 1-2 seconds

5. Running phase (RUN)

Modulation motor adjusts combustion load based on controller signal

Continuously operate until the heating demand disappears or the limit is disconnected

6. Post blowing stage (POSTPUGE)

Power off of main valve and continuous ignition valve

Modulate the motor drive to the low flame position

Continue running the fan for 2, 15, or 30 seconds (depending on the model)

Return to standby mode after blowing is completed

On site configuration of jumpers and test switches

1. On site configurable jumpers

The relay module provides three on-site configurable jumper options, and users can cut off the corresponding resistors according to their application needs:

Jumper function not cut (default) cut off

JR1 first safety time 5 seconds 3 seconds*

JR2 main fire test time 5 seconds 3 seconds

JR3 wind pressure switch without wind pressure switch with wind pressure switch

*Note: EC7850A1148/RM7850A1035 type, uncut for 3 seconds, trimmed for 2 seconds

Important: When the cumulative operating time of the main valve exceeds 200 hours, the module will lock the jumper configuration to the internal memory. If the jumper is modified afterwards, the module will be locked (Code 110) and cannot be reset, and the module must be replaced. This design ensures tamper proof configuration and enhances security level.