Hey I have a water furnace 5 series. About 2 yrs old. Thermostat has turned red twice now. Once yesterday morning then again this morning. It is very cold here about -15 with the wind chill. OPEN LOOP Pumps and dumps in the same well. Shallow well only 24ft deep. The error code is E5 - FRZE DETECT FP1 Any ideas? This never happened before. My well pump died 2 weeks ago and I had it replaced. Had a tech out to check the system over because when the well pump died the whole geo system turned off. He tested a bunch of things and couldnt find any reason why ot happened. But now this error code is coming up.