Smith Cast Iron Boilers GB250 SERIES - Manual (Page 7)

7
STEP 3: INSTALLING HYDRONIC COMPONENTS
A low-water cutoff must be installed to protect the unit
from dry-fire.
Screw extension nipple into 3/4" tapping on top of the
absorption unit and install relief valve into top of nipple
with the spindle in the vertical position (i.e., with the
valve discharge in the horizontal)(See Figure 2.4).
Most localities require the discharge piping to terminate
within 6" of the floor. Check local code requirements if in
doubt. Discharge piping must be of same size or larger
than the relief valve outlet and should be run as short
and straight as possible. Elbows in the discharge piping
should be placed as close to the valve as possible. If
valve discharge is to be drained away, the discharge
piping must not be hard-piped to the drain piping (i.e.,
an open funnel or similar arrangement must be used).
PRESSURE
RELIEF VALVE
PRESSURE RELIEF
VALVE DISCHARGE
PIPING
FIGURE 2.4
STEP 4: VENTING BOILER
Install draft hood on boiler. If the draft hood shroud has a
hole near the relief opening for installing a spill switch,
mount draft hood so the hole faces to the front of the
boiler. Spill switches are provided on Model GB250-5L,
GB250-5H, and GB250-6 boilers.
Applicable boiler is equipped with a factory-mounted
spill switch harness/mounting bracket assembly; spill
switch is provided in plastic bag. See Figure 2.5. Install
mounting bracket on outside surface of draft hood
shroud with screws provided (HARNESS MUST BE ON
OUTSIDE OF SHROUD). Install spill switch in hole in
shroud (on outside surface) with screws provided. Plug
wiring leads from harness/bracket assembly onto flat
terminals on spill switch.
NOTE: Boiler will not operate unless wiring leads to
spill switch are connected.
INSTALL
SWITCH
IN OPENING
ON DRAFTHOOD
CONNECT
WIRE
LEADS
INSTALL
MOUNTING
BRACKET
ON DRAFTHOOD
FIGURE 2.5
If vent damper is supplied with boiler, it must be installed
between the top of the draft hood and the flue pipe. See
“Installing The Vent Damper” instructions.
Connect draft hood to chimney or Class B vent. Flue
pipe must be same diameter as the draft hood outlet.
WARNING: No Valve of any type may be installed
between the boiler and the relief valve to prevent
accidental explosion from overpressure.
DANGER: Drafthood, vent outlet and vent damper as
supplied must not be altered in any was as proper
boiler operation would be jeopardized. Flame
rollout, fire or carbon monoxide poisoning will
result.
CAUTION: Piping must be installed from the relief
valve discharge so there will be no danger of
scalding personnel.