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Chapter 6
Problem
SHUTDOWN OCCURS
DURING FIRING
EXCESSIVE RUST ON
TUBES
WATER ON BASE
6-4
7.
Improper air/fuel ratio (lean fire).
A. Slipping linkage.
B. Damper stuck open.
C. Fluctuating fuel supply.
1). Temporary obstruction in fuel line.
2). Temporary drop in gas pressure.
8.
Interlock device inoperative or defective.
1. Condensation of the flue gases on cool tubes is causing rust.
A Change system so return temperatures are above 120
assure water temperatures entering boiler are above 120
2. Open stack or condensate running down stack or breeching.
A. Stack should be offset. Insulate and drain stack.
3. Frequent cold starts.
A. Reset controls for less cycling.
1. A cold environment and/or intermittent firing may allow inner casing to heat up above
the condensation temperature of the flue gasses.
A. Increase temperature of the cold boiler room if possible.
B. Verify insulation is in place between inner and outer casing and replace if missing.
C. Reset controls for less cycling to allow boiler to run for longer periods of time to heat
inner casing above condensation temperature.
2. Cold system startup.
A. Any time a boiler is started with a cold system, it will produce condensate until
internal surface temperatures exceed 130
once a boiler has warmed up. Condensate will dry up after a short time. Limit number
of cold starts.
3. Cold return temperatures.
A. Return temperatures below 120
return temperatures above 120
4. Gasket leaks allow gases to escape and condense on relatively cool base.
A. Gasket may need to be replaced or inner casing not installed per instructions. Install
inner casing and gasket.
Solution
F. Internal condensation will not be produced
F. will continually produce condensation. Raise
F.
Troubleshooting
F or install blend pump to
F.
750-364
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