Proper operation and maintenance of your boiler and its distribution system can save significantly on energy bills. Since many boiler systems operate at an average efficiency of only 65 percent to 75 percent, the remainder of your heating fuel bill is going up the chimney or down the drain. The following low-cost or no-cost items will typically pay for themselves in less than one year and should be incorporated into your regular operations and maintenance programs.
Have your service company perform a detailed analysis of your system. The
check should include analysis of firing rate, flue draft, air/fuel ratio,
stack temperature, combustion air setting, flue carbon dioxide and oxygen
readings, and control calibrations.
Adjust, repair or recalibrate controls and settings as needed. If the proper
air/water level is not marked on your sight glass (if present), have it marked.
Scale (mineral deposits) inside the boiler reduces the efficiency of the
boiler and may lead to stress problems and leaks. Proper chemical treatment
of boiler water will reduce scale build-up and control condensate water pH
and corrosion potential. When the boiler is shut down, inspect for scale deposits,
accumulation of sediment or boiler compounds on the water-side surfaces.
Stack flue gas temperatures should be no more than 150° greater than the
steam or water temperature. Clean and scrape fire-side tubes to remove soot
and scale if the desired temperature split is exceeded. Add stack thermometer
if necessary.
Check boiler insulation, refractory, brick work, and boiler casing for hot
spots and air leaks; repair and seal where necessary.
Replace boiler door gaskets if they do not provide a tight seal.
Proper combustion air intake ensures maximum safety as well as efficiency.
Interlock combustion air intake with burner operations.
If your boilers are large, a daily log of boiler operation may be helpful.
Chart boiler pressure, temperature, CO2, O2, steam or condensate flow, and
other data from the boiler. Variations from normal can indicate the need for
tube and nozzle cleaning, pressure or linkage adjustments, and related air/fuel
or draft adjustments.
Small, frequent boiler blowdowns are more effective than larger, less frequent
blowdowns. Schedule blowdown when needed as indicated by regular boiler water
tests, rather than by a fixed schedule. Inspect nozzles or cups of oil-fired
burners on a regular basis and clean if needed. Inspect oil line strainers
and replace if dirty.
Eliminate gas pilots and install intermittent ignition electric pilots.
In steam systems, inspect steam traps on a regular basis. The inspection
must be performed when the equipment is actually operating.
Shut off equipment or steam valve, wait a few minutes and then restart.
Listen to the trap to hear whether it opens and closes as expected.
Inspect condensate tank vents. Steam plumes from the roof vents are
an indication of one or more defective traps in the condensate return
system.
Use a surface pyrometer to check condensate line temperature surface
downstream of trap while equipment is operating. This line should be slightly
cooler than the steam line feeding the equipment. If it is lukewarm or
cold, the trap is allowing condensate to pass through, probably because
of a flooded float or worn-out thermostatic element. If the condensate
line is about the same temperature as the entering steam line, the trap
is probably passing steam and should be replaced. This situation can be
caused by dirt and sediment or by defective or worn valves and seals.
Malfunctioning traps may be rebuilt for future use.
Clean radiators, fin tube convectors, and coils. Check perimeter radiation
units for blockage of air passages by objects placed on top of or in
front of radiation covers. Maintain a one-foot clearance in front of convectors,
radiators or registers when possible.
Maintain the lowest steam pressure that is adequate to meet space heating
or process demands. Reduce steam pressure during low-demand periods. Where
high pressure steam is required for turbines or other processes which
operate only a portion of the year, reduce the system steam pressure for
the rest of the year. Shut down boilers when their heating function is
unneeded, but don't cut back heating levels in areas where there is a
possibility that freezing damage could result. Boilers that are shut down
should be properly drained and dried out to prevent the possibility of
freezing or corrosion.
Oversized boilers short-cycle and waste fuel during startup and shutdown periods. If the boiler is oversized, adjust or modify the firing
rate to better match building load. Time the on and off periods of burner
operation to get a better handle on cycle periods. Take outside air temperature
into account. For multiple-boiler plants, make sure one boiler is loaded
to the maximum before a second boiler is put into service.
When outdoor temperatures are moderate, switch boiler control to manual
low-fire setting. The boiler will operate longer between cycles at a higher
overall efficiency. Shut one boiler down during mild weather to improve
operating efficiency.
Tag all drained, disconnected, or idle equipment that might be unsafe
or harmed by inadvertent use or operation.
Don't disregard safety in the interest of saving energy. Maintain adequate
ventilation and combustion air. Maintain proper lighting in boiler areas
and machinery spaces.
