Lochinvar KNIGHT 399 - 800, Service Manual

Page: 31 / 44

3
Troubleshooting
(continued)
Service Manual
31
Table 3E
Troubleshooting Chart - Noisy System
FAULT CAUSE CORRECTIVE ACTION
Noisy
Operation
- Supply gas problem. Natural gas pressures
should be between 4 inches w.c. (1.0 kPa)
and 14 inches w.c. (3.5 kPa). LP gas
pressures should be between 8 inches w.c.
(2.0 kPa) and 14 inches w.c. (3.2 kPa).
• Refer to Section 7 - Gas Connections of the Knight
XL Installation and Operation Manual for detailed
information concerning the gas supply.
- Gas/air mixture problem. • Refer to the Gas Valve Adjustment Procedure on
page 41 of this manual for the proper gas valve setting.
Verify that the vent/air intake lengths do not exceed the
maximum listed in the General Venting section of the
Knight XL Installation and Operation Manual.
- Dirty/damaged burner. • Refer to page 26 in this manual for the burner removal
and inspection procedure. Clean or replace the burner
as necessary.
- Low water flow through the heat exchanger. • Refer to Section 6 - Hydronic Piping of the
Knight XL Installation and Operation Manual for
minimum flow rates. Verify that the boiler is piped in a
primary/secondary fashion and that the boiler and
system pump are running on a call for heat.
- Air in the piping system. • Properly purge all air from the piping system.
- Low system water pressure. • Verify system pressure is a minimum of 12 psi
(82.7 kPa).
No Pump
Operation -
Boiler Pump
System Pump
or
DHW Pump
- Blown fuse.
• Replace fuse F5 on the control board, see page 28 of
this manual.
- Faulty pump. • Replace pump.
- Internal fault on control board.
• Replace main control board.
- Faulty pump relay.
• Replace relay.
Relief Valve
Opening
- System pressure exceeds relief valve
setting.
• Lower the system pressure below the 50 psi
(344.7 kPa) rating of the supplied relief valve or replace
the standard relief valve with a higher rated valve up to
the maximum pressure of the heat exchanger.
• Improperly sized expansion tank.