Designer Guide

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LOCHINVAR, LLC
300 MADDOX SIMPSON PKWY
LEBANON, TN 37090
www.lochinvar.com
Designer’s Guide / Knight XL Boiler
The Knight XL Boiler 400-801 has a 1” gas pipe connection. Logically, the gas pipe size from the
meter to the boiler may be larger than the appliance connection.
The table below lists the Minimum and Maximum Inlet Gas Pressures.
INLET GAS PRESSURE
Model
NATURAL GAS
L.P. GAS
Number
Max. w.c.
Min. w.c.
Max. w.c.
Min. w.c.
Knight XL 400-801
14”
4”
14”
8”
L.P. GAS MODELS
Knight XL models are typically shipped ready to fire on natural gas. The Knight XL boiler may be
easily field converted to L.P. gas by either an orifice change or a gas valve pressure adjustment.
See the Knight XL Installation and Operation manual for details.
GAS PRESSURE REGULATORS
Lochinvar recommends the use of “Lock-Up Type” gas pressure regulators on the system gas
supply. A Lock-Up Type gas pressure regulator features a seat that seals the regulator orifice
when the appliance is off and there is no demand for gas. The seat will seal against the orifice,
shutting off the flow of gas to the appliance.
A standard regulator without a Lock-Up mechanism could allow the system pressure to reach the
boiler when it is off. The system pressure can “creep up” pressing against the appliance gas train
with excessive system pressures. This can damage the components in the gas train.
HIGH PRESSURE GAS REGULATORS MUST BE THE LOCK-UP VARIETY AND MUST BE INSTALLED NOT
LESS THAN 10 EQUIVALENT FEET FROM THE BOILER TO PROVIDE AN ADEQUATE VOLUME OF GAS.
Important