House oil being used up faster than before

[TMo1980]

We have an issue with our oil tank that's driving me nuts! The oil is burning faster than it did this time last year and I cannot work out why this is happening.

Our setup includes:
- 2500 ltr oil tank with Apollo Ultrasonic meter reader
- a Camray Quartet oil boiler which has dual zone (central heating radiators upstairs and underfloor heating downstairs)
- A Joule hot water tank
- two oven Aga

The Apollo monitor used to tell me that one bar (250 ltrs'ish) would last around three weeks in the winter, whereas now I am only getting between 10 days to two weeks use. The setup is the same and our usage hasn't changed - in fact, it should be better as I replaced an old programmable unit with a Nest smart thermostat which is actually coming on for less time during a 24 hour period.

So for the obvious things - I've checked the oil tank for cracks, odours, discoloration on the ground etc and found nothing. The pipes that lead to the house are underground so there could be an issue there, but as I say there's no evidence to suggest that. I have tried switching off the Aga to see if that was the issue, but that doesn't seem to be draining the oil more than it should. There might just simply be an issue with the Apollo monitor and it's giving me the wrong readings, but I have tested the level manually with a stick and it the levels seem to match up.

I'm just a bit stumped at this point - the only change from a year ago is that we now use Nest but I can't see why this would be the issue. It's not firing up the boiler more than before, so where is all this extra oil going?

I think I may need to hire an oil specialist to investigate this, but any other advice that could me troubleshoot this would be most welcome - thank you!

 

[oilhead]

What shape is your tank?
How does the level compare with last year's?
Your Apollo, as will all sight indicators, will indicate the lwevel of oil in the tank. Depending on the shape of your tank, each bar will represent a different quantity of oil. Fror instance, on a round tank, the volume of oil for one bar of you gauge will be greater than at the top and bottom, so you cannot assume that one bar is 250 lts/ish. Without a flow meter, the only way to measure consumption is to measure replenishment quantities from a consistent level mark.
How are you sure that your Nest is running the boiler less than your previous controls? Just because your old programmer was possibly set for longer periods, does not mean the boiler was actually running for longer periods.
Do you feel you are warmer than under the old regime?
Is your hot water hotter or more plentiful than last year?
If so, then this is where you oil is going.

 

[TMo1980]

Thanks (or tanks) for getting back to me so quickly!
The tank is the ribbed kind - the top bar went a lot quicker than the rest and so you're absolutely right about it not being equal throughout. That's obviously not the most accurate way for me to gauge the oil levels, except to say that they are going down more quickly than last year. Last year I was averaging a 1/3 more use from the oil before it lost another bar. That's the only yardstick I have to measure it by as we only moved in back in December 21, so I only have two years of data.
The issue with the previous programmer was that it didn't have a built in thermostat, so the only way to control the temperature in the rooms was via the TRV radiators. And because Nest is controlled via the app and I can set the temp controls, I just assume that it is working more efficiently - although I have no way of knowing for sure, except that the history of usage on the Nest app ranges between a few hours on mild days and up to 8 hours on a cold day.
The hot water seems the same as do we in terms of warmth, but as you say this must be where the extra litres are going. There's nothing else that I can think of!

 

[Exedon]

Are you sure that you haven't gone for gone for a bit more comfort level now system is easily to control?
I would always suspect the Aga we look after quite a few but they do have a justified reputation for been thirsty beasts.

 

[TMo1980]

Hi Exedon!
I don't think so - I check the history on the app and it's not firing up the boiler anymore than before. At least not to the point where I would notice such a change in oil consumption.
But you may be right on the Aga - they are hungry buggers! Although we had the same setup last year with the Aga on.
I think I may just have to accept this as there's certainly nothing blatant that I've missed. It's probably just a combination of everything!

 

[oilhead]

Aga's are thirsty beasts, but are consistent as long as you're not leaving lids up or ovens open for extra heat.
Are you cooking more on it?