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Storage fuel oil tank for boilers, water heaters and furnaces.

Common problems with, boiler oil tanks also known as, furnace oil tanks. Oil tanks are where you store the oil used to run your furnace, boiler or water heater.Furnace fuel oil storage tank
Some oil tanks are buried in the ground, some furnace oil storage tanks are standing outside of the house, and some boiler oil storage tanks are in your basement or crawl space.

Buried metal fuel oil storage tanks, can be a problem, after being under ground for many years, the oil tank can rust through causing a number of problems.
One problem is ground water getting into the oil storage tank, this type of problem will cause your boiler, furnace or water heater to fail, and make a big mess in the oil lines going to your furnace, and your oil filter, your furnace nozzle, your oil pump filter screen and other. as a temporary fix, the water can be pumped out, giving you some time to make other plans.

Another problem with the buried boiler oil storage tank is, oil can be leaking out of the tank, into the ground, not only is this a waste of oil and money, but it is a big environmental no no.
If fuel oil gets into the ground, all of the affected dirt and soil needs to be removed and disposed of according to EPA rules, this can be very expensive.

It is recommended, that you replace the buried old fuel oil storage tank before it leak, other non metal furnace fuel oil storage tanks are available, and new requirements are needed for all buried fuel oil storage tanks. 

I came across an unusable problem with a Dunkirk oil fired hot water furnace, one day.
The Dunkirk oil fired boiler, was brand new, so was the house and so was the buried fuel oil storage tank.
The problem was, the boiler would run for a day or so, then it would shut down, I would bleed the oil line coming from the fuel oil storage tank, and it would run again for a day or so, and shut down again, everything was new so, I did not think there was anything wrong with oil, or filters, this went on a few more times, but never once did I think, to look at the oil tank, I assumed that it was installed correctly, and being buried, what could possible be wrong with the oil tank.
Then I noticed, when I opened the purge valve on the beckett oil burner, it was sucking back hard, when the oil storage tank is lower then the Dunkirk boiler, it is normal for the oil to go back to the oil tank when the bleeder valve is opened, but this was like a vacuum cleaner sucking, not normal gravity sucking back.
So now I need to understand what is causing this problem, I go to the side of the house where the new furnace fuel oil storage is buried, All I expected to see was the 2 pipes coming out of the ground, 1 pipe is the fill pipe, this is used to put fuel oil into the fuel oil storage tank.
The other pipe is a vent pipe, the vent pipe has 3 functions, 1 it allows air, to leave the fuel tank when the tank is being filled, 2 it has an alarm that tells the person filling the tank, it is full, avoiding overflowing of the fuel, and 3 it allows the fuel oil to flow through the oil lines to the furnace, without creating a vacuum.
When I get to the new buried fuel oil storage tank, I only see 1 pipe coming out of the ground, the fill pipe, whoever installed the new oil tank, did not install the vent pipe or alarm.
Not having a vent on the fuel oil storage tank, caused a vacuum in the oil tank, this would allow the boiler to run until the sucking from the Dunkirk oil pump, created a vacuum, pressure in the oil tank that was equel to the the oil pump pressure, then it could not pull any more oil, and the boiler would shut down.