Lochinvar knight 399 - 800 User Manual

User’s Information Manual 

Please read before proceeding

The Knight XL Installation and
Operation Manual along with the
Knight XL Service Manual are for use
only by a qualified heating
installer/service technician.  Refer only
to this User’s Information Manual for
your reference.  Improper installation,
adjustment, alteration, service or
maintenance can cause property
damage, personal injury (exposure to
hazardous materials) or loss of life.
Installation and service must be
performed by a qualified installer,
service agency or the gas supplier (who
must read and follow the supplied
instruction before installing, servicing,
or removing this boiler.  This boiler
contains materials that have been
identified as carcinogenic, or possibly
carcinogenic, to humans).

Failure to adhere to the guidelines on
this page can result in severe personal
injury, death, or substantial property
damage.

• To avoid electric shock, disconnect electrical supply 

before performing maintenance.

• To avoid severe burns, allow boiler to cool before 

performing maintenance.

• Do not block flow of combustion or ventilation air to 

the boiler.  This boiler is equipped with a control which 
will automatically shut down the boiler should air or 
vent be blocked.  If vent or air blockage is easily 
accessible and removable, remove it.  The boiler should 
attempt to restart.  If blockage is not obvious or cannot 
be removed, have the boiler and system checked by a 
qualified service technician.

• Should overheating occur or gas supply fail to shut off, 

do not turn off or disconnect electrical supply to the 
circulator.  Instead, shut off the gas supply at a location 
external to the appliance.

• Do not use this boiler if any part has been under water.  

The possible damage to a flooded appliance can be 
extensive and present numerous safety hazards.  Any 
appliance that has been under water must be replaced.

• Thoroughly flush the system (without boiler 

connected) to remove sediment.  The high-efficiency 
heat exchanger can be damaged by build-up or 
corrosion due to sediment.

• Do not use petroleum-based cleaning or sealing 

compounds in the boiler system.  Gaskets and seals in 
the system may be damaged.  This can result in 
substantial property damage.

• Do not use “homemade cures” or “boiler patent 

medicines”.  Serious damage to the boiler, personnel, 
and/or property may result.

• Continual fresh make-up water will reduce boiler life.  

Mineral buildup in the heat exchanger reduces heat 
transfer, overheats the stainless steel heat exchanger, 
and causes failure.  Addition of oxygen carried in by 
makeup water can cause internal corrosion.  Leaks in 
boiler or piping must be repaired at once to prevent 
makeup water.

• NEVER use automotive antifreeze.  Use only inhibited 

propylene glycol solutions, which are specifically 
formulated for hydronic systems.  Ethylene glycol is 
toxic and can attack gaskets and seals used in hydronic 
systems.

When calling or writing about the boiler
– Please have the boiler model and serial
number from the boiler rating plate.

Consider piping and installation when
determining boiler location.

Any claims for damage or shortage in
shipment must be filed immediately
against the transportation company by
the consignee.

Factory warranty (shipped with unit)
does not apply to units improperly
installed or improperly operated.

 WARNING