Crown Bermuda Installation Manual

36
36
Troubleshooting Chart for BSI Boilers Equipped with McDon-
nell & Miller #67 Low Water Cut-offs and Vent Dampers
Caution: Read page 33 before attempting to use this chart
START
Thermostat
calls for heat
24 volts across
blue and yellow
wires inside
junction box?
120 volts across
black and white
transformer
leads?
* Power off
* Blown fuse or
tripped
breaker
* Miswired or
loose 120 volt
connection
N
Y
* Defective
transformer
See Note #6 on
page 33
N
Y
* Bad connection in
thermostat wiring
* Defective thermostat
* Thermostat miswired or
misapplied
N
N
24 volts
between terminal #
1
on 67 LWCO and
yellow tranformer
connection?
24 volts present
between each
pressure limit
connection and
yellow transformer
connection?
* Boiler off on pressure limit
* Defective pressure limit
Is 24 volts
present across
brown and
yellow leads on
R8225 relay?
Disconnect
thermostat and
temporarily jump
boiler thermostat
connections
together
* Loose
connection
between
transformer
and R8225
coil
* Defective
R8225
See Note #7
on page 33
* Boiler off on low water
24 volts present
across blue lead on
R8225 and yellow
transformer leads?
* Defective R8225
Y
Y
N
N
Y
Y
Y
N
N
Y
Y
N
Is there an audible
click as R8225 relay
pulls in when the
thermostat calls for
heat?
Does relay
pull in now?
Vent
damper
open?