I have a house with a 275 gallon oil tank, and a forced air oil fired furnace (Thermopride). Standard oil burner setup. A single line has always fed both the furnace and an oil fired water heater. The furnace burner sits about 18 inches off the floor. The water heater burner is at floor level, the oil tank about 7" above the floor. Early this winter the furnace was losing prime and the oil company thought maybe it was a leaky fitting, and also recommended getting the line above slab level and therefore up to code. They ran a single overhead line to both burners...no tiger loop.
The furnace continued to get airbound (within days), so they installed Tiger Loops on both burners. After several months, the furnace (only) is quitting again. It happens when two conditions exist... warm weather (furnace sits for a long time) and a relatively low tank level (a few inches lower than the burner level).
Any ideas on this one would be much appreciated!