My P68 provides all the heat for our home. I use a propane fired Rinnai on demand hot water unit for all our hot water needs. We don't need to burn one drop of oil anymore, EXCEPT, emergency back up heat should the pellet stove go down or we leave the house for a weekend or longer. Question: how should we maintain the oil burner to be a reliable backup source? Do we need to fire it up on regular schedule? The unfinished basement does get cold, but never drops below 39 degrees, no matter how cold it gets outside. Last weekend I test fired it up and the air vent over the expansion tank was really springing leaks.