Hah... luckily I survived this year in TX. I had a scare when the pool temp dropped to 31 and ice started forming on the surface. I decided to try my JXI 400N heater to warm it to 42 and it was throwing all kinds of codes. After cleaning the sensors and clearing the codes ("All 3 buttons for 5 seconds), the codes cleared and it fired right up. My buddy was having the same issue, with his 400N and was able to replicate what I did. After that, the pool sat at 42. Yesterday afternoon I shut down the system once it hit 40 outside temp (after 96 hours).
Just a few minor leaks that I have been fighting for a year now, nothing major (mainly just Drain plug leaks and a hairline crack on my heater manifold from when it cracked 3 years ago and I epoxy'd it back together). The one advantage of the freeze is that you see any small leaks. I have a spare heater manifold and gasket set for it, took a year to acquire it, but I am waiting till it is needed.
