# How low to let oil tank go before filling it up



## newseeker1 (9 Mar 2010)

How low is it safe to let oil level in home heating oil tank go before filling it up again without running risk of airlocking the system 

Oil tank isnt sitting on ground but is off ground sitting on about 3-4 cavity blocks 

Thanks


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## Billo (9 Mar 2010)

I usually let it go to about 6 inches from bottom before filling up.


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## woodbine (9 Mar 2010)

check the level at which the pipe comes out of the tank. Some are higher than others. You can use an old sweeping brush handle then to check the level in the tank and compare the two. 

Also keep in mind that over the years you will get a sludgy build up deposited in the end of the tank and it's best not to allow that muck into the burner. 

so try not to let it run out, and if it does don't tilt the tank.


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## NorfBank (9 Mar 2010)

woodbine said:


> Also keep in mind that over the years you will get a sludgy build up deposited in the end of the tank and it's best not to allow that muck into the burner.



On that note, is it just a matter of time before that build up gets to the same level as the pipe? Should you get it emptied before then or what?
My tank is around 3 years old and there's a fair but of muck at the bottom.


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## runner (9 Mar 2010)

If the base of the tank is at a higher level to the input to the boiler, then you can let it go down to a few inches- its driven by gravity only. Beware of silt and dirk in bottom as mentioned.


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## PyritePete (9 Mar 2010)

so try not to let it run out, and if it does don't tilt the tank.[/QUOTE]

We tilted the tank as we were close to running out over a weekend with no delivery possible, no problems with this. Just be careful not to dislodge/knock the feed pipe.


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