CONTROLS AND ACCESSORIES
PROCEDURE 1—RELIEF VALVE
The relief valve should open automatically if boiler steam pressure exceeds pressure rating of valve (15 psig). Should it ever fail to open under
this condition, shut down boiler. If valve discharge occurs or valve fails to open as described above, contact an authorized contractor or qualified
service technician to replace relief valve and inspect heating system to determine the cause as this may indicate an equipment malfunction.
Run a pipe from safety valve outlet (pipe must be same size as outlet, and open end must not be threaded) to an open drain, tub, sink, or other
suitable drainage point not subject to freezing.
CAUTION: Failure to do so may cause water damage or injury should relief valve release. Do not cap off drain line from
this valve!
PROCEDURE 2—STEAM PRESSURE GAUGE
Every system should have a pressure gauge installed in boiler. This gauge enables monitoring of pressure in system. If safety devices fail to shut
off boiler at proper settings, notify service technician immediately.
PROCEDURE 3—WATER LEVEL GAUGE
The water level in boiler can be seen through glass tube in water level gauge at side of boiler. Correct cold boiler water level is stamped on side
jacket panel. The water level should be checked regularly for proper level.
PROCEDURE 4—STEAM PRESSURE CONTROL
The steam pressure limit control (pressuretrol) shuts off gas to main burners when steam pressure in boiler reaches cut-off setpoint (the sum of
cut-in and differential set points). Burners refire when stream pressure drops to cut-in setpoint. System pressure requirements are based on size
and condition of pipes and load.
PROCEDURE 5—LOW WATER CUT-OFF (LWCO)
On right side jacket panel of boiler, there are 3 holes for glass water level gauge. The top hole is common for both types of LWCOs and is used
for upper gauge glass fitting. The middle hole (9 in. down from top hole) is used for bottom gauge glass fitting for the Model 67D-1 float-type
LWCO. The lowest hole (12-1/4 in. down from top hole) is used for bottom gauge glass fitting for the Model PS-802 probe-type LWCO. The hole
that is not being used is covered with a sheet metal knockout.
A. Model 67D-1
This is a float-operated switch which shuts down gas burners if water falls below visible bottom of gauge glass.
B. Model PS-802
This is an electronic probe-type LWCO. The probe is located inside boiler. The LWCO shuts down burners if water loses contact with probe for
a period of 10 sec.
Refer to manufacturer’s instructions (enclosed) for more information.
PROCEDURE 6—WATER FEEDER (OPTIONAL)
The model WF-2U-24 water feeder may be used with either of the available low water cut-offs. The water feeder’s job is to maintain a safe
minimum water level. It is used to keep boiler running by compensating for minor evaporative steam leaks and to prevent freeze-ups if the
homeowners are away and a return line springs a leak.
McDonnell and Miller Model 101 water feeders may be used; however, the water feed rates are too high and need to be regulated or throttled,
and wiring must be revised. Consult boiler manufacturer before using these or any other non-standard types of controls.
The automatic water feeder is a safety device not a convenience item. It is not designed to maintain a "normal" water line. The water feeder does
not take the place of a responsible person monitoring and maintaining normal water line. Steam boilers require personal attention.
PROCEDURE 7—VENT DAMPER
This is an automatic, motorized stack damper developed to increase efficiency of heating systems by reducing standby losses from boiler and
conditioned air space. The damper closes chimney vent when burner is off and fully opens it when combustion is required.
PROCEDURE 8—ROLLOUT SWITCH (FLAME ROLLOUT SAFETY SHUTOFF)
The rollout switch is a temperature-sensitive fuse link device. It is located on boiler base just outside fire box. In the event of heat exchanger
flueway blockage causing flame to roll out of fire box, the fuse blows shutting down flow of gas to main burners. The fuse does not change in
appearance when blown.
If rollout switch blows, it must be replaced with an exact replacement. Check heat exchanger flueways for blockage when restoring system to
operating condition. Do not operate system without a rollout switch.
PROCEDURE 9—SPILL SWITCH (BLOCKED VENT SAFETY SHUTOFF)
The spill switch is a manual-reset disc thermostat with a fixed setpoint (280°F) and normally-closed contacts. It is located at relief opening of draft
diverter. In the event of chimney or venting system blockage causing products of combustion to spill out of relief opening, the spill switch disc
heats up and spill switch contacts open shutting down flow of gas to main burners by removing power to gas valve.
In the event that spill switch contacts open, the reset button on back of switch pops up. The spill switch must be reset manually, after the switch
has cooled off, by pushing the reset button down. Check venting system and chimney for blockage when restoring system to operating condition.
DO NOT operate system without a spill switch.
FOR YOUR SAFETY READ BEFORE OPERATING
WARNING: If you do not follow these instructions exactly, a fire or explosion may result causing property damage,
personal injury, or death.
A. Some boilers are equipped with an intermittent ignition device which automatically lights the pilot. Do NOT try to light pilot by hand.
Some boilers are equipped with a continuous pilot and must be lit manually. See lighting instructions in Continuous Pilot Boiler section. A match
holder is included in parts bag.
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