Hello! I am trying to troubleshoot my Roth Dual Oil tank setup and why they are not equalized. In the 5 years I have lived in the house, they have always been exactly equal or tiny tiny differences - so I'm sure whatever is going on is not a design or installation issue - it is a failure of something somewhere.
Tank A currently reads 3/4 full. Tank B is at or slightly below 1/8 full. When I went down to check the oil I was expecting both to read somewhere around 1/2 full. Knowing how low tank B is and how full tank A is, this has been going on for quite a long time (it's been warm weather and no heat used other than hot water up until a month ago). I suspect the problem happened about a month after my last fill.
First question (see attached picture): What is this valve called?
It is very clear that it has an inlet for fuel that is drawn from the other tank, as well as drawing fuel from the tank it is located on top of. It has a single outlet for fuel that goes to the furnace, and a return inlet (outlet?) that is unused. The lever on the top is in the up position currently. I believe it should be in the down position, and might actually be the root of my entire issue. If I am correct that it should be in the down position, what could cause it to move to the up position without any outside disturbance?
Second question: Is it safe to have my tanks filled, and will they be equalized after the fill?
Third question: if the answer to the first question does not provide my fix, what should I be looking at as the issue? What is the order of steps in troubleshooting?