Operating instructions

The above is an example of a typical 1-pipe system. For larger systems or other types of systems such as 2-pipe systems or systems with convectors
or fan coil units, pressuretrol settings need to be determined on a system-by-system basis.
The cut-in setpoint is determined by system pressure drop to furthest radiator or terminal unit. Double the system pressure drop as a safety factor,
resulting in the rule that cut-in setting should never be less than twice the system pressure drop.
The differential setpoint is the steam pressure required at terminal heating units.
Boiler now operates in correct pressure range. It maintains enough steam pressure to send steam out to furthest radiator, and not go over optimum
steam pressure required at radiators.
PROCEDURE 5—CHECKING CONTROLS
A. Low Water Cut-Off (LWCO)
To check LWCO, turn power off to boiler or adjust thermostat to lowest setting. Drain water to below visible bottom of water gauge glass. Turn
power on and adjust thermostat to call for heat. Gas valve should not open on a call for heat when water is low.
If boiler is equipped with optional WF-2U-24 water feeder, keep thermostat calling for heat after LWCO recognizes low water condition. After
a 1-minute time delay, water feeder should start feeding water to boiler. The feeder should feed for 1 minute and then go into another 1-minute
waiting period. This cycle of alternately waiting and feeding should repeat until:
MODEL 67D-1 FLOAT-TYPE LOW WATER CUT-OFFS
As water level raises the float above burner cut-off switch level, burners should ignite. The water feeder remains powered until water level raises
the float to water feeder switch level satisfying water feeder.
MODEL PS-802 PROBE-TYPE LOW WATER CUT-OFFS
The water level rises until water in boiler makes contact with probe satisfying water feeder and igniting burners.
In either case, there should be between 1 and 2 in. of water visible in gauge glass when both the water feeder is satisfied and the burners are allowed
to ignite.
The time delays in feed cycles are designed to prevent boiler from flooding due to slow return lines.
B. Pressure Limit
To check pressure limit, run boiler until pressure reaches system demand. Then turn pressure screw and drop pressure setting until boiler shuts
down. This shows that pressure limit is operating properly.
Refer to control manufacturer’s instructions (enclosed) for more information.
C. Thermostat
Check thermostat operation. When set above temperature indicated on thermometer, boiler should ignite. Make certain thermostat turns boiler off
when room temperature reaches selected setting and starts boiler operating when room temperature falls a few degrees.
Finally, set thermostat for desired temperature. Special conditions in home and location of thermostat govern this setting.
CLEANING BOILER
It is very important to clean a new steam boiler after it has been installed and put into continuous operation. This must be done to remove any
accumulation of oil, grease, sludge, etc. that may be present in system. These substances may cause boiler water to foam and surge, producing
a very unsteady water line, throwing water into steam header, and possibly preventing steam generation. Follow the procedures below in order to
remove these contaminants:
PROCEDURE 1—SKIMMING
New boilers must be skimmed at the time of installation to remove threading oil and other impurities that float on surface of water.
1. Remove plug from skimmer tapping and pipe to a floor drain or bucket.
2. Raise water level to skimmer tapping.
3. Fire boiler to maintain a water temperature of 180-200°F.
4. Feed water to boiler to maintain water level. Adjust water feed rate to keep water continuously flowing out of skimmer tapping without
water level going above or falling below tapping. Cycle burners to prevent boiling.
5. Continue skimming until water runs clear. This may take several hours.
PROCEDURE 2—BLOWDOWN
1. Float-type low water cut-offs must be blown down after skimming. The float chamber of the low water cut-off must be flushed clean and
maintained clear of sediment to allow free movement of float. This must be done frequently during initial operation of boiler and at least
once a week thereafter. Follow instructions on tag attached to control.
Probe-type low water cut-offs require no maintenance at this time.
2. After blowing down low water cut-off and before blowing down boiler, fill boiler to water line. Fire burners and allow normal steam
pressure to build up. Run a connection from boiler blowdown valve to a nearby sewer or floor drain or to a safe discharge point outside.
SHUT OFF GAS BURNERS, open blowdown valve, and allow all water in boiler to drain out. Close blowdown valve. Allow boiler to cool
thoroughly, then slowly refill boiler to water line. Repeat this item as many times as necessary until blowdown water is clear.
3. Following final blowdown, allow boiler to thoroughly cool, then add fresh water slowly up to normal water line. Start burners and maintain
at least 180°F for 15 minutes to remove dissolved gases from fresh water. Shut off burners.
Now let boiler steam for a few days to give the majority of the system dirt a chance to work its way back to boiler. Check water in gauge glass.
The gauge glass should be dry above water line. The water line should not bounce more than 1 in. when boiler is steaming. If water droplets carry
over from top of gauge glass or excessive bouncing of water line occurs, boiler needs further cleaning. Take a water sample and boil it on stove
to see if it foams. If it does, this also indicates boiler needs to be cleaned.
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