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Maintenance
12.3 Trouble Shooting Guide
Required tools: electrical diagram on page 69 and a
multimeter with 120 VAC and 24 VAC scales.
Start
Turn gas supply off.
Supply power to the boiler
LED light up on boiler
(aquastat).
Turn thermostat to call for heat.
(10 F above room
temperature).
Turn thermostat on aquastat to
call for heat (min. 10 °F above
boiler temperature).
Does fan motor starts?
We reserve the right to make any changes due to technical modifications!
Installation, Operation and Maintenance Manual Sealed Combustion Gas Boiler Logano GA244 • Issue 02/2004
•
Checking of aquastat and transformer.
* Check for line voltage (120 V) at N and L at plug X1.
NO
If no voltage present, check incoming line voltage.
•
* Check if 120 V at L1/L2 and L1X/L2X on aquastat.
If no 120 V present, check wiring.
If wiring is fine, replace aquastat.
•
* Check for 24 V between terminals C and R on aquastat
If no voltage present, check wiring.
If wiring is fine, replace transformer.
•
Checking thermostat and its wiring.
* Put jumper between R and W terminals of aquastat
If boiler starts, check thermostat and thermostat wiring.
•
Performing self diagnostics on aquastat.
* Check LED light on aquastat.
Light blinks 2x: check aquastat sensor contacts S1 and S2 and sensor wiring. If
it all looks fine, replace aquastat sensor.
Light blinks 3x or 4x: internal aquastat failure, replace aquastat
LED light off: aquastat is RESET mode, wait 5 minutes for automatic reset
•
Check for 24 V between terminals B1 and B2 of aquastat.
NO
If no 24 V, replace aquastat.
•
Checking the fan relay and the fan motor.
* Check for 24 V between terminals 1 and 4 of "terminal of boiler block" strip
("terminal strip").
If no 24 V, check wiring between aquastat terminals B1/B2 and terminal strip.
If 24 V between terminal 1 and 4, check for 120 V between terminals L3 and N of
plug X3.
If no 120 V, check wiring between terminal strip and relay and between relay and
terminal plug X1 (incoming power).
If wiring is fine, replace relay.
If 120 V is present between terminals L3 and N of plug X3, check wiring of the fan
blower.
If wiring is fine: replace fan blower
Buderus Heiztechnik GmbH • http://www.heiztechnik.buderus.de
12
45
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