Advances in boiler and water-heater designs and control systems give managers and technicians effective tools to meet performance demands.Today’s generation of boilers and water heaters is more efficient, more reliable, and safer than any previous generation. But accidents still occur, and boilers still fail before they reach their rated service lives. Nearly two-thirds of boiler failures result directly from poor operating and maintenance practices, and most unscheduled interruptions of services also are the result of poor operating and maintenance practices.
Effective maintenance can go a long way to improving safety but only if the maintenance program addresses specific safety measures.
Technicians should start with the safety-relief valve, which is the boiler’s last line of defense against overpressure. Scale and other contaminants in the water system or plugged discharge lines can interfere with the valve’s operation. Operators must test these valves each time they start a boiler, and they must perform additional testing at intervals the manufacturer recommends.
Flame-safeguard controls also require regular testing. These controls ensure the boiler lights, operates and shuts down properly. Typical operation includes purging of combustible gasses from the boiler during start-up to reduce the risk of an explosion. The flame-safeguard control verifies all other safety interlocks are closed before ignition.
When a boiler shuts down, it initiates a purge cycle designed to eliminate combustible gasses. Depending on the size and type of boiler, technicians might need to inspect the flame-safeguard control daily or weekly.
Finally, the low-water-cutoff control shuts down boilers in the event of a lost water supply, which can cause overheating and permanent damage. The controls are reliable, but components can fail, resulting in a false indication of the boiler’s water level. Again, depending on the size and type of boiler, operators might need to visually confirm each day that the boiler’s water level is as indicated.
Operators must not simply assume that if a boiler’s safety indicator lights and alarms are normal, everything is okay. Lights burn out, and alarm contacts fail or are disconnected. Most operating panels include a test button for indicator lights and alarms. Operators need to use it regularly.
— James Piper, P.E.
James Piper, P.E., is a national facilities consultant based in Bowie, Md. He has more than 35 years of experience with facility maintenance, engineering and management issues.
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Monitoring and Maintenance To Increase Boiler Efficiency
Smart Specification of Boilers and Water Heaters
Boilers and Water Heaters: Spotlight on Safety
