Troubleshooting; Xv. Troubleshooting - Crown Boiler MWC Series Installation Instructions Manual

Turn off power to boiler before replacing fuses or working on wiring.
CONDITION
Boiler does not run, no lights are on or fl ashing
Lamp 1 fl ashes every two seconds, but boiler does not
respond to a call for heat.
Combi boiler does not respond to a call for domestic hot water
(DWH).
Combi boiler responds to a call for DHW, but hot water output
is inadequate.
Boiler responds to a call for heat, but room temperature never
gets high enough to satisfy room thermostat
Boiler short cycles AND heat (or DHW) output is inadequate

XV. Troubleshooting

WARNING
Table 15.1: No Error Code Displayed
• No 120VAC Power at boiler. Check breaker and wiring
• Fuse on main PCB is blown (Figure 15.2). Check for short in
• Problem with thermostat or zone wiring
• Domestic draw less than 0.5GPM
• Defective fl ow switch (LED inside fl ow switch will glow red
• Inlet and outlet connections reversed.
• Draw rate is in excess of that shown in Table 2.2
• Inlet and/or manifold pressures incorrect (see Start-up
• Plate heat exchanger is fouled.
• DHW fi lter is dirty
• Air in radiation
• Inlet and/or manifold pressures incorrect (see Start-up
• No fl ow, or insuffi ent fl ow, through system.
• Boiler is undersized.
• Insuffi cient radiation
• Flue gas recirculation into combustion air
• See causes for inadequate heat or DHW above
Figure 15.2: Fuse Location
66
POSSIBLE CAUSES
between breaker panel and boiler
boiler wiring, then replace with an idenitcal 4.0A fuse.
when it resonds to a call for DHW).
Section).
Section).