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APPENDIX A: LOW WATER CUT OFF (LWCO) ON HOT WATER BOILERS
(continued)
A 24 VAC LWCO is used primarily for gas fired boilers
where a 24 volt control circuit exists within the boiler.
However, a 24 VAC LWCO can only be used if the
boiler manufacturer has provided piping and wiring
connections and instructions to allow for this
application.
How to Test
Shut off fuel supply. Lower water level until water
level is BELOW the LWCO. Generate a boiler demand
by turning up thermostat. Boiler should not attempt to
operate. Increase the water level by filling the system.
The boiler should attempt to operate once the water
level is above the LWCO.