The boiler, when installed, must be electrically grounded in accordance with requirements of the authority having jurisdiction, or in the absence
of such requirements, with the NEC. Run a 14 gauge or heavier copper wire from boiler to a grounded connection in service panel or a properly
driven and electrically grounded ground rod.
PROCEDURE 2—INSTALLING THERMOSTAT
The thermostat location has an important effect on the operation of boiler system. BE SURE TO FOLLOW INSTRUCTIONS INCLUDED WITH
THERMOSTAT.
Locate thermostat about 5 ft above floor on an inside wall. It may be mounted directly on wall or on a vertically mounted outlet box. It should
be sensing average room temperature so avoid the following:
DEAD SPOTS:
Behind doors
Corners and alcoves
HOT SPOTS:
Concealed pipes
Fireplace
TV sets
Radios
Lamps
Direct sunlight
Kitchens
COLD SPOTS:
Concealed pipes or ducts
Stairwells—drafts
Doors—drafts
Unheated rooms on other side of wall
Set heat anticipator at 0.7 amps for boilers equipped with standing pilot and at 0.9 amps for boilers equipped with intermittent ignition. The 24-v
thermostat leads shall be connected to the 2 wires tagged "24 volt thermostat" on boiler. For boilers with 67D-1 float-type low water cut-off, both
wires are black. One wire is located on secondary of 24-v transformer. The second wire is located on pressure limit control. For boilers with PS-802
probe-type low water cut-off, 1 wire is green and is located on terminal B of the PS-802. The second wire is black and is located on pressure limit
control.
PROCEDURE 3—ELECTRONIC THERMOSTATS
Certain types of electronic thermostats may lose their memory or shut down. With PS-802 probe-type low water cut-offs, this may occur each time
the low water cut-off detects a low water condition. With 67D-1 float-type low water cut-offs, this may occur each time thermostat calls for heat,
due to the internal circuit in vent damper. If this is the case, an isolation relay is required for thermostat circuit. A 24-v single-pole single-throw
(SPST) normally open (N.O.) relay is required such as Honeywell R8222A or equivalent. See Fig. 16 or 17 and wire as shown.
PROCEDURE 4—VENT DAMPER
The boiler is equipped with a factory-wired harness with a 4-pin Molex plug which plugs into 4-pin Molex receptacle inside vent damper operator.
The vent damper must be connected for boiler to operate.
CAUTION: Label all wires prior to disconnection when servicing controls. Wiring errors can cause improper and
dangerous operation. Verify proper operation after servicing.
Fig. 16—Isolation Relay Wiring for Steam Boilers
with 67D-1 Float-Type Low Water Cut-Off
and Using Electronic Thermostat
A96054
4
1
2
3
PRESSURE
LIMIT
24 VOLT
TRANSFORMER
FIELD WIRING
TO LWCO &
IGNITION SYSTEM
BL
BL
BT
BR
O
O
Y
ELECTRONIC
THERMOSTAT
ISOLATION RELAY 24V
SPST N.O. HONEYWELL
R8222A OR EQUIVALENT
t
°
VENT DAMPER
4 PIN
MOLEX PLUG
Fig. 17—Isolation Relay Wiring for Steam Boilers
with PS-802 Probe-Type Low Water Cut-Off
and Using Electronic Thermostat
A96055
4
1
2
3
B
PRESSURE
LIMIT
TERMINAL B
OF LWCO
24 VOLT
TRANSFORMER
FIELD WIRING
VENT DAMPER
4 PIN
MOLEX PLUG
TO LWCO &
IGNITION SYSTEM
BK
BK
BT
G
W
BR
O
O
Y
ELECTRONIC
THERMOSTAT
ISOLATION RELAY 24V
SPST N.O. HONEYWELL
R8222A OR EQUIVALENT
t
°
—18—
