Home Heating Oil Tank never more than 1/2 full

[stejus]

I put in a wood insert last winter and I expect my oil usage to be about 350 gallons or so a year. If I only 1/2 fill the tank a few times a year, will there be an issue with the top half empty all the time. The tank is in my basement which is very dry. I'm thinking in terms of gas tanks and moisture here....

 

[rowerwet]

fill the tank with diesel if you have to, keeping a tank full gets rid of a huge amount of problems. Water and rust being the biggest, also ending up with a tank of critters that live on hydrocarbons isn't fun either. (yes folks there are lots of bacteria that live on HHO, kero, diesel, etc. and they love the water that pools in your tank from the air) get a bottle or two of the additive for HHO tanks from HD or wherever it will help with these problems. Jet aircraft have the same issues (jet-A is kerosene) and use lots of additives to keep growth under control and to keep the suspended water in the fuel from freezing up at 40,000 ft (it is VERY cold up there) and clogging the fuel system.

 

[DaveH9]

your oil tank should be sloped towards the feed line going to the boiler, that way if any water does condensate and falls to the bottom it will be "burned" as the boiler is fired. I think the slope is a 1/4 inch per foot of tank. If it is not sloped properly the tank warrentee is not valid. Most supply houses sell the tank legs at all the same size, so many of these have been installed incorrectly.

 

[pybyr]

your oil tank should be sloped towards the feed line going to the boiler, that way if any water does condensate and falls to the bottom it will be "burned" as the boiler is fired. I think the slope is a 1/4 inch per foot of tank. If it is not sloped properly the tank warrentee is not valid. Most supply houses sell the tank legs at all the same size, so many of these have been installed incorrectly.

Absolutely, it should be sloped- some modern tanks have legs that are threaded pipe, and you can adjust the legs on the outlet and far ends to get the pitch- as Dave says, a little bit of H20 at a time will just go through the burner nozzle, as long as it does not get a chance to build up.

If you don't have adjustable legs on your tank - carefully jack the end away from the outlet, and put some shims under it that can take the weight under the legs at the far end.

If you're compulsive, get some "Diesel 911" (which contains biocide) treatment at a fuel station that serves truckers, and put some of it in, open one of the spare top ports on the tank, and swish it around with a clean stick in order to mix it.

Old tanks (like the one from the 1950s that was here when I bought my 1840 farmhouse 12 years ago) had the outlet on the lower side/ end, and thus did not allow water to go out to the burner no matter how you pitched the tank. Those are disasters waiting to happen, as they will rust from the inside and fail without warning due to moisture accumulation in the bottom of the tank. If the outlet on the tank is on the lower side of the tank and the belly of the tank has an oily sheen, you want to do something soon, before it really lets go and pees its contents all over.

[disclosure- I am not a pro, just a DIY-er who keeps ears open and tries to learn from my and others' bad experiences]