About 4 years ago, we had two identical XP19 Lennox heat pumps installed within about 6 feet of each other at our estate residence. From the start, one of the units has behaved badly while the other worked as expected. The units were installed by a high-end contractor from Charlottesville who had installed three other (Trane) units at our other properties. Their work was great and their response has exceeded expectation. None of the Trane units have ever given us problems. In contrast, one of Lennox units has worked poorly from the start. It has had board failures several times, repeatedly frozen up, and generally functioned inconsistently. It has repeatedly gone into defrost mode in the winter, lowering the interior temperature 3 to 5 degrees and then shut down or frozen over. Sometimes, it would run and run and generate little or no heat. Other times, it would repeatedly go into 2nd stage, make little heat, and run for hours while the matching unit ran moderately as expected by the weather. Just a few days ago, the faulty unit froze up with 3" of ice on the top and completely ice-filled on the sides – and of course, no heat again. The matching unit sitting beside this defective unit worked flawlessly. Over these four years, our respected HVAC contractor has made numerous trips checking the unit, replacing boards, checking pressures, etc. – all to no avail. After a few weeks, the problems start again. This is just one lousy dog of a unit. Finally, I demanded that our contractor take the faulty unit out and replace it. Apparently, this finally moved the needle so that Lennox agrees to send someone to look (how kind of them). They are arranging to have a Lennox rep here in the next week, but (!) already the Lennox guy is saying it's possibly weather-related. That's simply bunk. If it was weather-related, both units would be affected approximately the same way. Trust me, Lennox, the weather really IS the same when the two units are six feet apart. I am ready to hear all the excuses. The way we see it, we're 100% OK with three Trane systems and hitting a lousy 50-50 with two expensive Lennox units. We'll report what the Lennox guy does (or doesn't) do. Please do look at the photos. Would you really like to see this over and over? George Beker