Heating oil usage

[Bayrisch_Dude]

Right, question for the hivemind.

We've moved house and into a single family place. The house has four oil tanks in the cellar. At move in, we noted the tanks read, 38, 38, 36 and 34. These are 1000l tanks.

We did not physically move in until the first week of May. Albeit she did. I was still working and transporting things back and forth. I moved in on 29 May.

At one point, I was told that one heater was warm when turned off. Aye, just a wee bit. Repaired it last week.

The past weekend, while in the cellar, I noticed the oil tanks now show 28, 28, 26 and 26. Simple maths tell me we've used 380L of oil in a month! WTF!?

No heating has been turned on since living here. She has been here alone for the better part of a month. Niether of us shower extended lengths.

This cannae be a normal useage amount. Near on 40 years in Germany and I've never had to handle heating oil tanks.

1. Is this normal useage?

2. If not, thoughts on what might be the cause or causes?

3. Is the idea of turning the heating system off during the day a good idea? To me, it seems worse as it would need more energy to completely warm back up.

4. The water temp can be near on scalding if caution is not made. Perhaps lowering the temperature of the water?

Looking forward to wise answers.

[Franklan]

[..] we noted the tanks read, 38, 38, 36 and 34. These are 1000l tanks.

What are these numbers? Percent? Cm height? Liter?

[Bayrisch_Dude]

What are these numbers? Percent? Cm height? Liter?

From what I've read online, it's percentage of what's left in each tank from 1000l.

[snowingagain]

Whatever the actual problem is, lowering the water temperature is a good idea. 55 is supposed to be ok re avoiding Legionella, though in summer I go lower, as our system is very small. I very occasionally want a hot bath, so just whack it up

[Bayrisch_Dude]

Whatever the actual problem is, lowering the water temperature is a good idea. 55 is supposed to be ok re avoiding Legionella, though in summer I go lower, as our system is very small. I very occasionally want a hot bath, so just whack it up

I looked at the system a couple of hours ago. It showed a Kesseltemperature of 64 and Warmwasser temp of 50. I also looked at the Raumtemperatur and showed 20 and 17 at night.

Should I lower the Kesseltemp?

[snowingagain]

Hey, totally absolutely not an expert here. But not sure why your water so scalding hot with those figures.

[Franklan]

From what I've read online, it's percentage of what's left in each tank from 1000l.

Can you take a picture of the tank, incl. the scale/gauge you're reading from, and post it here?
I've never seen a heating oil tank that shows its content in %, tbh.

Do the tanks have a rectangular shape or are the cylindrical?

[HEM]

Our heating oil tank shows cms (not terribly accuratly).

In the "Summer" (like now) we have it just set for hot water; in cooler months also the heating during the day.
Clearly the amount of oil used varies enormously.

[Franklan]

Our heating oil tank shows cms (not terribly accuratly).

That's why I asked about the scale that's used, and the shape of the tank!

Let's *assume* the tank is cylindrical, lying on its side, and its diameter is 100cm:

oil tank.jpg (48.3 KiB) Viewed 138 times

* "Burning" oil from 100cm to 96cm is "4cm of oil burned",
* "burning" oil from 52cm to 48cm is "4cm of oil burned",
* "burning" oil from 4cm to 0cm is "4cm of oil burned".

Look at the picture, the volume associated with "4cm" is different (!!), depending on where we are considering the absolute fill level.

There is not necessarily a linear relationship between the "volume burned" and the "change in fill level"!

Near on 40 years in Germany and I've never had to handle heating oil tanks.

OK, just as a hint, indepentently from your question: Never, ever let the "fill level" get too low. You always have "pulp" in an oil tank, when you let the level get too low, your pump will choke on that (undiluted) pulp. I was taught (a long time ago) that you should fill up the oil tank when you're getting below 15% of the total volume of the oil-tank.

[Bayrisch_Dude]

From what I've read online, it's percentage of what's left in each tank from 1000l.

Can you take a picture of the tank, incl. the scale/gauge you're reading from, and post it here?

Here's a decal scale on the tank. More soon.

20260610_131116.jpg (844.87 KiB) Viewed 39 times

[Bayrisch_Dude]

More photos...

[Bayrisch_Dude]

Last night I looked at the control panel and saw two buttons. Reading the user manual, it seems there is a button for warm water only and a separate one for heating and warm water. The later was on, so I pressed the warm water only.

This solves only a part of the problem. Again, unless I am misunderstanding the readings on the tanks, we used 380L of oil with near on no heating in 4 weeks time.

I feel perhaps I should ring the heating expert to have a wee look

[Franklan]

Here's a decal scale on the tank. More soon.

OK, your tanks are not spherical, more like a cube with rounded corners. Fine.

The four tanks are connected to each other, so their fill level will always be the same. The difference you see is because they're not standing on the same level (uneven ground).

Between 10cm and 140cm, you have a linear connection between the reading of gauge and the volume. It is 7,2l/cm for 1 tank, and 28,8l/cm for all 4 tanks.

The results you presented are a change of 10cm on all tanks, which means you've used 288l of oil in that time span. Multiplying that by 12 results in 3456l/year.

There is a reason why this house has tanks for 4000l.

[HEM]

Our house has a single 4000 or 4400 litre tank (cubic).

Currently I cannot get close enough to read the metal label on the tank. Contents last for more than one year.