LWCO error E12 on Burnham Freedom

Here is some help from Burnham

The MCBA control Low Water Cutoff strategy is to place the boiler in a Hard Lockout whenever it senses a low water condition in the supply outlet tee of the boiler. generally this may occur in the fall when the system has sat dormant all summer and air collects in the remote and physically higher parts of the system. As this air flows through the boiler, It can create a low water condition with the LWCO before it has a chance to be removed by the system piping Air Elimination device.

 

Another cause involves piping an Indirect Water Heater directly to the boiler supply and return piping as the flow to and from the indirect is not flowing through the air elimination device which is generally installed in the system flow piping. A remedy for this involves removing the relief valve from the top port of the supply cross tee and installing a close nipple, black tee, street elbow, 3/4" x 1/8" bushing and float vent into the top port of the cross tee. The close nipple and 3/4" tee go into the cross tee with the street elbow into the branch of the tee and the relief valve into the street elbow. The bushing goes into the top of the tee and the float vent into that. This will remove air as it flows through the boiler before it has a chance to become a larger air bubble.

 

The probe could also require cleaning but I usually focus on captive air as the culprit as systems are generally never manually purged of air on a regular basis. The boiler needs annual service to ensure proper operational efficiency and purging the system should be part of that service procedure. The yellow light would normally only illuminate if the probe has no water on it which would be a very momentary event with a large bubble of air coming through the boiler and would go back off when the bubble moves past it just before the E12 error occurs.