Service manual

SERVICING
50
Power to System
Thermostat calls for heat
Control board applies power to
Air circulating blower (ACB)
cooling speed. Pilot and Igniter
are locked out.
"Smart Valve" checks Igniter
circuit and valve
System shuts down..
"Smart Valve" powers Igniter,
opens pilot valve.
Pilot Lights, Flame Rod
Senses Flame
Igniter Off
Main Valve Opens
Main burner Lights
Smart Valve sends signal
(24V) to control board.
Thermostat Ends "Call
for Heat"
Main and Pilot Valves Close
Control board times out.
De-energizes power to
blower (ACB)
Igniter stays on
Pilot valve remains
open
Main valve closes
Pilot and main valves
close.
System shuts down.
Start
Self Check
Ignition
Main
Burner
Operation
End
Limit(s) open
Igniter
Missing
or Broken
Limits closed
No
Flame outage
occurs during
run cycle
Igniter
opens
Board checks limit circuit
Igniter and gas
valve check OK
Yes
Control board times out,
applies power to blower
(ACB) heating speed.
Honeywell Smart Valve Sequence of Operation
SV9500