We have ‘used’ 600 litres of heating oil in 8 days!

lohr500

As you say, by turning off the boiler you can check for leaks if you keep an eye on the tank by manually checking it with a dipstick. If you discover it is leaking then there should be a stopcock on the tank outlet. Shut the valve as soon as you have established it is leaking. At least if the leak is in the pipework somewhere that should prevent further leakage.

Apodemus

No one has mentioned the possibility that it could be a bunded tank...

Reed_Richards

cannugec5 said:

On Monday they filled up with the full 1200 litres. 

....

Today I checked the tank again and we are down below half! 

Are you absolutely sure that the tank capacity is 1200 litres and it really was full on Monday?  Because possible explanations are that you got less oil than you think or that the tank holds more oil than you think so 1200 litres did not fill it.

Also, if you do have a leak then turning the boiler off may not help.  There should be a valve where the oil comes out of the tank that you can turn off (edit: oh, as @lohr500 stated already).

cannugec5

Apodemus said:

No one has mentioned the possibility that it could be a bunded tank...

Unfortunately not. 

cannugec5

Reed_Richards said

Are you absolutely sure that the tank capacity is 1200 litres and it really was full on Monday?  Because possible explanations are that you got less oil than you think or that the tank holds more oil than you think so 1200 litres did not fill it.

It was full. Both on manual check and on the Watchman. 

Because the previous delivery didn’t last as long as anticipated we took careful note. 

Unfortunately, Sod’s law the ‘tap’ or stopcock has seized so we cannot turn it off. 

It has not dropped any further today ( so far) 

Apodemus

I presume that the flue isn't showing signs of poor combustion?  The exhaust gas is clear, with no visible soot?

ccluedo

cannugec5 said:

The tank is above ground. It’s on a concrete plinth. 

I think it’s plastic. It is was installed in - about - 1999, before we bought the house. 

Even if tank itself isn't leaking, circa 23 years is long time in the single skin plastic tank world. I think average life is 12 -15 years give or take so might be an idea to budget for a new bunded tank in the near future.  Have u ever had the oil tank itself serviced?

cannugec5

Apodemus said:

I presume that the flue isn't showing signs of poor combustion?  The exhaust gas is clear, with no visible soot?

No, combustion was fine ( until we switched it off yesterday). We are imagining that burning that quantity of fuel would have had black smoke billowing out and/or the house as hot as toast! 

cannugec5

ccluedo said:

 Have u ever had the oil tank itself serviced?

To be honest I don’t know. I have always left such things to my husband. 

Certainly the boiler has always had an annual service, but whether the heating engineer touched/checked the tank I don’t know. 

I guess I didn’t know there were any serviceable parts on the tank. 

I will find out. 

cannugec5

With the oil level having dropped another 3 inches in the past 24 hours ( approx 120 litres) 
it was decided to further attempt to use the stopcock. With a hammer and brute force they have managed to switch it off. There is maybe 250 litres left in the tank. 

Heating engineer is coming on Sunday. 

Boiler has been ‘checked’ at the annual boiler service. The stopcock was fully functional at the last ‘check’ in March ‘22.