Yes, the cold was a real issue, Tom. We had to warm the tank multiple times, but it needed to be done anyway as the system was low from the previous leak and had no chance of keeping up without getting it reasonably close to where it needed to be. He was supposed to be there a couple days earlier, but some work situations at the "day job" made that impossible. He agreed to come back (he doesn't live far away) in a couple of months or so once it's warmer and check it again. He was actually impressed with the systems features and intelligence. His time and materials was less than it would have cost me to buy just the small 28 oz canisters of the "stuff", too.
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While it's Christmas day, when the daughters and the younger's SO leave after our brunch, I'm going to fire up the Big Orange Power Tool and once it's not flipping me the bird for asking it to run when it's so cold, I'll move the pallets of miscellaneous stuff into the shop building so things are ready to move the machines tomorrow. The sun is out and while it's currently 20ºF, there's no wind, so I might as well take advantage of that.
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The most expensive tool is the one you buy "cheaply" and often...