Originally Posted by bryanlaws
I guess the key phrase here is "if you don't drain it prior to freezing"? Did yours crack like after having drained it in freezing temps or is that while "full"?
You are absolutely correct. I did not drain prior to freezing; it was full. This is the single wall unit before SMB realized they had a problem and before there was a way to drain it (without disabling your entire water system).
So, you know the drill- freeze/thaw = expansion and contraction and eventually you'll break it.
When I talked to the people at Flatplate when this whole fiasco started, they told me that I should absolutely not let water freeze inside it or it will break (like it did). They recommended that I replace it with a double wall "for more buffer" but they also said that a double wall will _also_ eventually break if you let water freeze in it, it'll just take longer.
So those of you with double wall units: You still gotta drain it and not let it freeze!