Emerson 36H User Manual

   Gas Valve Cross Reference

The thermostat calls for heat and energizes the HSI control. If 

system is equipped with prepurge, the purge fan is energized and 

power will be delayed thirty seconds before application to the Hot 

Surface Ignitor. If prepurge is not selected, the ignitor is powered 

within one second. The ignitor heats up and at the end of the 

heating period, the redundant and main valves are opened. A 

flame must be detected within a fixed time period or both valves 

close, the ignitor is turned off and the HSI control locks out unless 

the system is equipped with retry. Retry indicates the ignition 

sequence will be repeated for a total of three tries if flame is 

undetected or lost within 30 seconds of ignition.

The thermostat calls for heat and simultaneously energizes the 

DSI control module and gas valve solenoid. Sparks at the ignition 

electrodes ignite the gas at the main burner. Flame is sensed 

through the electrodes by the flame detection circuit and shuts off 

the sparking. If flame is not established within a fixed time period 

(lock-out time) main and redundant valves close, sparking ceases 

and the control module locks out.

M

V

2

T
R

G
N
D

T

H

M

V

1

L

2

F

P

L

1

H

S

1

THERMOSTAT OR

CONTROLLER

ALTERNATE 

LIMIT

L

1

(HOT)

L

2

LIMIT

CONTROLLER

FLAME 

PROBE

RED

ADAPTER

BLUE

HOT

SURFACE

IGNITER

MV

2

MV

1

BURNER

GROUND

H

S

2

TRANSFORMER

GAS

VALVE

M

P

C

External

Jumper