CYCLONE Xi COMMERCIAL GAS WATER HEATER
BTH 120 thru 500 SERVICE HANDBOOK
A.O. Smith – Technical Training Department 36 Ash
land City, Tennessee © 2009
Servicing should only be performed by a Qualified Service Agent 316586-000
HOT SURFACE IGNITER / FLAME SENSOR / CONTROL TIMING
HOT SURFACE IGNITER
This water is equipped with an electric hot
surface igniter. The igniter material is
silicone carbide and should not be handled
with bare hands because of possible damage
to the igniter.
The normal ohm reading at 77°F is listed
between 40 and 70 ohms. The minimum
igniter current monitored by the CCB is 2.7
amps. Once this threshold is met a check
mark will appear by the igniter icon in the
UIM (display).
FLAME SENSOR
This water heater is equipped with an
electronic flame sensor. The flame sensor
senses flame by passing a small electric
current through the burner flame. This type
of flame sensing is also known as flame
rectification. The CCB is looking for a
minimum current of .7 micro amperes for the
water heater to operate. Once this current is
established the UIM will display a flame icon.
CONTROL TIMING
Pre-purge 25 seconds
Igniter Warm-up 17 seconds
Trial for ignition
Gas Control Open
5 seconds
Inter/Post Purge 30 seconds
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