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Low Water Cutoff (LWCO)
Internal of the Combi Boiler
The Noritz Combi Boiler is equipped with a factory installed, pressure sensor type low water cutoff device.
The lowest operation pressure for this device is 8 psi. (operation pressure = (default valve 12 psi) - (4 psi))
• The Combi Boiler performs water replenishment automatically when the built-in water pressure sensor
detects insufcient water level in the Combi Boiler system.
External of the Combi Boiler
• Low water cutoffs shall comply with the Safety Standard for Limit Controls, ANSI/UL 353, or the Standard for
Temperature Indicating and Regulating Equipment, CAN/CSA C22.2, No. 24, as applicable. The following
illustrates example of typical LWCO installation.
• Install the probe above the minimum safe water level.
NOTE: This may be in a tapping on the Combi Boiler or in the Combi Boiler supply or return piping.
• Install the probe to extend into the Combi Boiler cavity or piping to make contact with the water.
•
Low water cutoffs shall be located so as to provide adequate access for cleaning, repairing, testing and inspection.
• Remove the factory installed jumper on the LWCO terminals (CN234) prior to connecting the LWCO.
• The Combi Boiler supplies 24 VAC from the terminal (CN231) (see below illustration).
LW
above the top of casing.
[CN234]
LWCO
[CN231]
24VAC
OUT
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