How much heating oil is used for a bath / shower?

Oil tank almost empty, moving house in a few weeks so don’t want to order 500 litres.

Can get 20L refills from oil supplier. Central heating not on but 2x showers + 2x baths daily. Any idea how many litres this would use a day?

Just pick the tank up one end and put some blocks underneath it as the outlet will not be on the very bottom. Should give you enough oil for a few weeks.
Also if you’ve got a hot water cylinder use immersion heater?

No immersion unfortunately and didn’t really want to tip the tank as I’d need to take the bricks out when we left and new owners would be out if oil

I used to reckon on about 100l per month in the summer. Few weeks, so 60-80l?

Diesel has an energy density of 9.7kWh/l.
To heat 1m3 (approx 10 baths) of water to 41degC is 37kWh.
So I make 1L of oil around enough to do 3 baths. apologies if the maths is shonky.

Diesel has an energy density of 9.7kWh/l.
To heat 1m3 (approx 10 baths) of water to 41degC is 37kWh.
So I make 1L of oil around enough to do 3 baths. apologies if the maths is shonky.

…adjusting for the mains water temperature and the efficiency of the boiler.

Just fill it half way. It’s traditional that the new owner buys the contents of the tank at the going rate.

…adjusting for the mains water temperature and the efficiency of the boiler.

It’s a rough calc. I don’t have either of these variables. Either way, it won’t deviate a huge amount despite what the boiler manufacturers tell you. You could also take into account the heat losses due to the length of pipework run, construction and insulation but that would be silly.

I was running low ,awaiting pay day to fill up and was surprised how little the level dropped using showers and even putting the heating on for a couple of hours as house felt damp couple evening when the mist was down.
So go get 2x20l n that will last you.

Our Rayburn uses about 5-6 litres a day. It is on permanently, does all the domestic hot water, keeps the kitchen warm and does all the cooking. Even if you were to work on half that, a conservative 2.5l a day, then I reckon 40 litres would be plenty for 2-3 weeks

It’s a rough calc. I don’t have either of these variables. Either way, it won’t deviate a huge amount despite what the boiler manufacturers tell you. You could also take into account the heat losses due to the length of pipework run, construction and insulation but that would be silly.

Sure, but I’d allow another 25% for boiler, pipework & standing losses.

25% is a lot of loss but it’s always best to assume the worst so 2.25 baths per litre of oil.

you bathe in heating oil ?

…. I guess it depends how much you put in the bath then… 🙂

IGMC….

so many variables…….

how deep/hot is your bath?
how long do you shower?
what is your shower type – mains/pumped or gravity?
how old is your boiler?

here’s some standard answers that we used when i was designing hot water tanks. I’ll assume a mains/pumped shower.

bath – 80 litres of hot water
5 min shower – 6l/min hot water = 30 litres/shower

total daily use for 2 x bath/2 x shower = 220 litres.

220 litres heated from 5-60 degC requires (220 x 55)/858 kwh of energy = 14 kWh approx.

oil has 10 kWh/l so you need 1.4 litres if boiler was 100% efficient. assuming 75% efficiency means you need 1.4/.75 = 1.9 litres of oil per day.

HTH

The jet in my oil boiler has a flow rate of 2.1 litres/hr. Typically, during the winter, it’s on for about 15% of the time, but that’s doing the heating as well. Just hot water I’d expect it to drop to 5% approx, but that is to maintain a temperature. So 20 litres should be enough, assuming it’s enough to reach the exit in the tank.