LAARS HEATING SYSTEMS
Page 18
Table 8. Troubleshooting Analysis.
#
Symptom
Cause
Remedy
1.
Pump not
A. No power
A. Check circuit breakers and power source.
operating
B. Pump defective
B. Replace.
C. Incorrectly wired
C. Recheck wiring diagrams.
2.
Pilot outage
A. Inlet gas pressure too low
A. Consult gas utility company. Inlet gas pressure to boiler
should be 5.5" to 10.0" water column on natural gas. 11.0" to
14.0" on propane gas.
B. Inlet gas pressure too high causing
an unstable blowing pilot
B. Pressure should be regulated within limits shown above.
C. Weak or defective thermocouple
C. Replace thermocouple.
D. Damaged pilot or thermocouple
D. Replace.
E. Dirty pilot
E. Blow dust or lint out of pilot.
F. Plugged or undersized pilot orifice
F. Clean or replace pilot orifice.
3.
Flame roll-out
A. Blocked flue
A. Remove blockage.
on start-up
B. Pilot out of position (delayed ignition)
B. Correct pilot position.
C. Blocked heat exchanger or flue
C. Clean and correct as necessary.
D. Refractory tile out of place
D. Correct or replace tile as necessary.
E. Altered draft diverter
E. Install factory-provided draft diverter.
4.
Spillage at
A. Cold chimney
A. Allow boiler to operate 5 minutes to create draft action.
draft hood
B. Vent pipe pitches down to chimney
B. Reinstall vent pipe to pitch up from boiler to chimney.
C. Blocked chimney
C. Remove blockage.
D. Draft hood altered
D. Install factory-provided draft diverter.
E. Pre-fabricated chimney with incorrect cap
E. Install U.L. listed vent cap.
5.
Flame has
A. Low primary air
A. Correct manifold pressure according to rating plate. Correct
lazy yellow tip
orifice size if necessary (see parts list). Clean burner ports if
dirty.
6.
Not enough heat
A. Inadequate gas supply
A. Gas meter too small. Gas line from meter to boiler too small.
B. Low manifold gas pressure
B. Gas pressure on boiler manifold, with Modusnap valve wide
open. Should be adjusted to 4.0"W.C. natural gas, 9.0"W.C.
propane.
C. Boiler size inadequate
C. Replace with boiler of higher input.
7.
Pump noisy
A. Air in volute
A. Bleed air from volute. Check pump alignment.
B. Worn coupling or bearings
B. Replace worn parts.
8.
Boiler pounding
A. Too low water flow through boiler
A. Check temperature rise between inlet and outlet boiler piping.
or knocking
15°F to 25°F temperature rise is recommended. If temperature
rise is over 25°F, increase pipe size or pump capacity or
locate obstruction. Check for stuck closed zone valves.
Check for zone pumps not operating. Check for closed valve
in system.
9.
Boiler condensing
A. Low water temperature
A. Flue product moisture will condense at the start-up until the
boiler water temperature reaches the normal operating
conditions.
10.
Pump cavitates
A. Defective fill valves or pressure regulator
A. Replace.
or low water
B. Oversized expansion tank
B. Replace.
pressure at boiler
C. Expansion tank piped incorrectly
C. Repipe expansion tank to suction size of pump.
gauge or bubbles
in system at high
temperature
11.
Pressure relief
A. Water-logged expansion tank
A. Drain
2
/
3
of the water from the expansion tank.
valve opens
12.
Pilot is lit but main
A. Gas valve not at "on" position
A. Turn knob to "on" position.
burners will not
B. Boiler off on hi-limit control
B. Check for low water flow or hi-limit setting.
come on
C. Boiler incorrectly wired
C. On single or multiple zone systems with zone valves, room
thermostat should be wired to R & W terminals. For multiple
zone systems with zone pumps, thermostats for extra zones
should be wired to R & A terminals.
D. Boiler off on blocked vent switch
D. Remedy as in symptom #4. Reset the manual reset switch.
E. Boiler off on flame roll-out switch
E. Remedy as in symptom #3. Reset the manual reset switch.
F. Broken wire in thermostat circuit
or defective thermostat
F. Check continuity through thermostat circuit with wires
disconnected from R & W.
13.
Boiler short cycles
A. Heat anticipator in room thermostat
set too low
A. Increase setting (1.0 is usually satisfactory).
B. Low water flow through boiler
B. Increase size of pump or increase piping size.
C. Hi-limit switch may be set too low
C. Increase setting to at least 20°F over outlet water temperature.
