Pilot Operation Testing - Bock Water heaters 38W-155 Service Manual

W-Series
120 Volt Exposure. To avoid personal injury,
use caution while performing this procedure.
Condition
Pilot will not light.
Ignition module LED is "ON".
Reset heater by turning
power "OFF." Wait 5 seconds and
turn power "ON." When LED of
ignition module turns "ON" does
ignition module send "spark" signal
(buzzing or clicking sound)?
Y
Is there spark at the pilot?
Y
Is there 22-27 VAC output
across terminals "MV/PV" & "PV"
of ignition module? Disconnect
wires and check across terminal of
module. (see photo 11)
Y
Is there 22-27 VAC input
across wire leads "MV/PV" and
"PV" at gas valve?
(see photo 12)
N
Check continuity across ECO
(RED) leads of lower thermister.
(see photo 13)
Is continuity okay?
Y
Check wire harness for damage
or loose connections. Repair or
replace as needed.
8
DANGER
N
Replace ignition module.
Check for:
Loose or damaged ignition wire,
N
grounded pilot electrode,
damaged pilot.
N
Replace ignition module.
Loosen pilot tubing connection
Y
at the gas valve and soap test.
Is there pilot gas flow out of the
gas valve?
N
Tighten pilot tube connection at
the gas valve. Check incoming
gas pressure to water heater.
If okay, replace gas valve.
ECO Specifications
Opens between 181°F/201°F
Closes between 160°F/100°F
Service Procedure 24- II

Pilot Operation Testing

CAUTION
Be careful when making voltage
measurements or jumping terminals
not to damage or deform connectors or
connector pins.
11
12
Check for clogged or kinked
Y
pilot tube, clogged pilot orifice.
Clean or replace as needed.
(see page 13)
13
Check across
"MV/PV" and "PV" terminals.
Check across
"MV/PV" and "PV" wire leads
to gas valve.
Check across RED
wire leads of lower
thermister (ECO).