Woday

I have owned a WM97 110,000 BTU boiler for around 3 years. . The boiler works fine but I keep getting a "low water cut-off" readout every several days. At times I can just reset the boiler and it returns to normal. Other times I have to shut the boiler off to reset it. Finally I sometimes have to open the boiler up and reset the low water cut off right on the sensor. There is no way the boiler is in a low water situation as I have it hooked to my domestic with a check and pressure valve included in the line. The boiler works in tandem with a wood boiler attachment to my cookstove upstairs in the kitchen. I have played with the pH and think I have it right. Not sure why it keeps tripping this read out. Also I do shut the boiler off often and just use the wood boiler, could this effect anything? Thanks, W