Furnace oil tank question (twin tanks won't equalize)

[Foilist]

I have tandem oil tanks for my furnace. They have separate fill pipes and a common vent pipe. They are connected at the bottom with a copper fuel line.

Usually, the oil levels slowly equalize after getting a delivery. Our last delivery was 150 gallons about a month ago. Well, I looked at the gauges just now and one is on E and the other is at 3/8. What is going on here? Nobody has messed with the valves or anything. Do I have a plugged line or something? Am I worried about nothing? I would sure hate to have a problem with another cold snap coming tomorrow.

 

[taldesta]

Assuming that the tanks are outside and that the exposed lines are not heated? One possibility is that, with the intense cold, the fuel may have 'gelled' in the copper join line, causing a blockage. Perhaps some water, from condensation (on which the oil will float) has frozen in the copper join line at the bottom. Heat applied to the copper might help - hot water is effective. This year I have had to box in the exposed lines with 2" foam and heat with a brood lamp, 175w infra-red.

If dated tanks, perhaps the float for one of the gauges is fuel-logged and has lost its buoyancy and is simply not telling true.

If cold is not the problem, a simple blockage (say ... particles of rust ...) would be suspect.