“Smart” oil tank meter

I have an Apollo wireless tank meter on my oil tank.

It’s OK but I would like to be able to get more information about my usage. Daily consumption etc.

I see they do a sort of “smart” version that gives you a lot more detailed information.

Also Watchman have one that works with a phone app.

Anyone have one? Are they any good?

Can I upgrade a dumb one to a smart one? Is the tank sensor the same unit with a different frontend?

Anyone got the Watchman?

If the sensor just measures the depth of oil it will never be smart, as the shape of modern moulded tanks means that the volume of a drop of 1mm isn’t the same at different parts of the tank. It needs to actually measure the oil flow to the house.

What I did was record how long the boiler was on for, and use data for the nozzle in the boiler to work out a flow rate of oil. It worked ok, but the nozzle does get larger over time (mine used to be replaced every service). I’ve gone over to a heat pump now so not a problem.

It’s OK but I would like to be able to get more information about my usage. Daily consumption etc.

I don’t think any of the sonar/radar/whatever they use tank-based ones that measure the gap between the sensor and the top surface of the oil are accurate enough to be able to tell you that, given that you probably use single figure litres, at most, in a day. In a 1000+ litre tank the difference in surface height that would cause would be a matter of millimetres.

**EDIT – it’s also worth considering why you’re measuring it. I started doing it when we first moved in, cos I’d never had an oil boiler before; I was recording when the Watchman dropped another bar, how many days between each drop, comparing to the previous years etc etc, then I realised it was all basically useless information – if we’re cold, or we need some hot water, the boiler goes on. If it’s a colder winter, we’ll use more oil. When we’ve run out, we’ll order more. Knowing exactly how much we’ve used each day/month isn’t actually of any use.

I know it wouldn’t be accurate but at the moment it works in intervals of 100 litres, that’s why the smart was in inverted commas.

Even if I just knew how long it took to drop between the 100 litre intervals it would be useful.

At the moment it’s not practicable to measure this.

@IHN – The reason I want to measure it, is that I have underfloor heating and around this time of year I tend to switch it on and leave it on. It takes a while to warm up and it seems inefficient to be switching it on and off.

I would like to be able to gauge how much oil it is using against the thermostat setting.

Even if I just knew how long it took to drop between the 100 litre intervals it would be useful.

Just keep an eye on it and note the dates it drops, that’s what I (used to) do

What I did was record how long the boiler was on for, and use data for the nozzle in the boiler to work out a flow rate of oil.

This is what I’ve done, basically:

1) Connect a relay to the fuel pump power connections – when the pump starts (which is when the burn starts) it closes the relay

2) The other side of the relay is connected to 2 pins on a Pi zero which continually monitors the pins

3) When the pins sense the relay has been closed (no voltage involved so very safe) it records the start time and then records the stop time when the burn finishes.  It calculates the burn time and thus the oil consumed using the nozzle size.

4) It then uploads that data into a google spreadsheet and to my Initial State dashboard which is then displayed as useful information.

It’s pretty easy to build and has proved to be really pretty accurate (within 20L over a volume of 500L I’d say?).  I really have no excuse to run out of oil now!
Happy to share the code if you want to put one together yourself.

You can put a consumption meter on the oil line if you want.

I’ve just moved into a house with a Watchman thing which doesn’t seem to have moved in nearly two months (hot water and now occasional heating) so I am beginning to doubt its efficacy, and I haven’t seen any sight glasses either.

Doesn’t help you much, I know.

Just looking at the specs for the wireless system, just realised that it must only transmit once or twice a day, as it gets 10 years out of a button battery.

Does anyone know how often it updates the display? There’s nothing in the manual.

I’ve just moved into a house with a Watchman thing which doesn’t seem to have moved in nearly two months (hot water and now occasional heating) so I am beginning to doubt its efficacy, and I haven’t seen any sight glasses either.

Heating hot water uses pretty much sod all oil, so I’m not that surprised it’s not moved

FWIW, this time of year when the heating is turned on occasionally but it’s not “that” cold, we get about three weeks per bar, from a 1000L tank. And that’s in a really not very warm or insulated stone cottage on top of a hill

And if you’re concerned, you can’t beat a dipstick…

I have a Watchman Sensit, works fine, sends an email every day or two with the tank level and the app shows usage etc. My tank is cylindrical so it’s accurate enough, I don’t particularly care that it’s not exact, the main thing is I know the tank is getting low and I don’t run out between Christmas and New Year which has happened in the past…..

I know it wouldn’t be accurate but at the moment it works in intervals of 100 litres, that’s why the smart was in inverted commas.

Even if I just knew how long it took to drop between the 100 litre intervals it would be useful.

At the moment it’s not practicable to measure this.

Ours is plugged into the kitchen socket, I just note when it drops a ‘number’.

Been doing it +10 years.

When it get’s to 1 it flashes (constantly) – I order more.

It’s a permanently on AGA, uses 3000l per year and we’ve a 1200l tank.

When it get’s to 1 it flashes (constantly) – I order more.

You’re braver than me, I generally order when it’s on two or three :-)

I’ve got a Watchman Sensit.  New tank last year so it came as part of the package.  Works well.

Having a tank sensor display plugged in the kitchen (with an oil-fired Rayburn) in one place I owned was a profoundly depressing experience.

Having a tank sensor display plugged in the kitchen (with an oil-fired Rayburn) in one place I owned was a profoundly depressing experience.

Having an oil-fired Rayburn was a profoundly depressing experience. Loud, inefficient, massive, crap for heating, crap for cooking. We got shot and replaced it with an external boiler.

A swift Google shows a few options for flow meter/usage on pipe, eg.

https://www.flowquip.co.uk/flowmetertechnologies/smart-flow-meters/

Having an oil-fired Rayburn was a profoundly depressing experience. Loud, inefficient, massive, crap for heating, crap for cooking. We got shot and replaced it with an external boiler.

We just moved house!

Moved into a house with oil heating and AGA and a non-functioning Watchman, so early on we found a length of wood, marked off inches and do a dipstick every now and then.

Oil flow meters, that are accurate for a couple of litres an hour, were very expensive when I looked.

I have a sight tube on my tank, and spreadsheet calculation that accounts for the mixed cylindrical / cubic shape of the tank.

Using burner run time as sharkbait does works well. You could use a small 12V power supply, fed from the mains power to the burner, then 12v hour meters are readily available and cheap (eBay). You might have an 12V wall wart psu from an old router or set top box kicking about. You might find a 240V ac hour meter if you’re lucky.

You need more accuracy than an hour meter can give you though really.

Which is why a fairly simple system that is triggered by the fuel pump starting/stopping works so well.  I get burn times, effectively, down to the second.

All that said I do also have an old broomstick [roughly] marked off in 500L sections!

To go back to my earlier point though, those of you who are doing clever things to measure oil consumption really accurately, er, why?

I

I did it because I’m a bit of a geek. I just like data.

 er, why?

1) Wot Richmars sed

2) ‘Cos oil can be very expensive so it’s good to know how much is being used and when.  It’s no different to GaS about the fuel consumption of your car!

3) It can show issues before they become worse

4) It’s way better than having a Watchman type thing

5) ‘Cos I can

:)

1) Wot Richmars sed

I mean, that’s fair enough

2) ‘Cos oil can be very expensive so it’s good to know how much is being used and when.  It’s no different to GaS about the fuel consumption of your car!

But why would you need to know the daily MPG of your car (apart from ‘see 1’)? (although, full disclosure, I don’t really GaS about the fuel consumption of my car, I just put fuel in it when it needs it)

3) It can show issues before they become worse

I mean yeah, in theory, but this is pretty tenuous

4) It’s way better than having a Watchman type thing

It’s only better if it allows you to do something of practical use that the Watchman doesn’t

5) ‘Cos I can

I think this is the real reason, so just own it :-)

,I don’t really GaS about the fuel consumption of my car, I just put fuel in it when it needs it

Did you buy it irrespective of its fuel consumption? Do people not care how much it costs to heat their house?

It’s only better if it allows you to do something of practical use that the Watchman doesn’t

– It’s way more accurate

– supplies a record of usage over time [that can be compared with outside temperature at the same time …. which I’m now doing just out of interest]

– if I wanted it would automatically send an email to my oil supplier when the level got to a certain point

– it cost less than £10 to implement (and that was for the relay I already had)

– doesn’t look shit

TBH I did it to see when I need to order more oil as I’m not cash rich and usually can’t afford to buy large amounts of oil each time, so it helps to know when I need to order more as my wooden dipstick approach isn’t that good!
I’m struggling to see why you seem to have an issue with why anyone would spend a little time creating something that’s much cheaper and better than an £80 Watchman but, whatever.

A swift Google shows a few options for flow meter/usage on pipe, eg.

https://www.flowquip.co.uk/flowmetertechnologies/smart-flow-meters/

Those will cost more than the entire oil heating system and multiple years of oil.

@sharkbait – I’ve sent you a DM.

– It’s way more accurate

Undoubtedly, but we’re clearly going to have to agree to disagree on the usefulness of this

– supplies a record of usage over time [that can be compared with outside temperature at the same time …. which I’m now doing just out of interest]

This is just geekery. I’m not saying that’s a bad thing, but it’s just geekery

– if I wanted it would automatically send an email to my oil supplier when the level got to a certain point

Fair do’s, I’ll give you that one

– it cost less than £10 to implement (and that was for the relay I already had)

Ah, I assumed you already had a Watchman. If you didn’t, and this cost you miles less than a Watchman, then, again, fair enough,.

– doesn’t look shit

This is marginal, the Watchman thing is not exactly obtrusive

Do people not care how much it costs to heat their house?

Of course I care, I don’t just burn £50 notes in the grate to keep warm, but the crux of it is that we heat the house to what we think is a reasonable temperature (although my wife would disagree) for what we think is a reasonable period period per day (ditto) and then basically it costs what it costs.  I know that a full tank will pretty much, at a push, last a whole winter, and ideally we can wait until July when prices are lower to fill it, but if it needs filling/topping up in March/April, then so be it, and whenever we fill it it’ll cost whatever the oil price happens to be. I don’t need to know it cost me £3.26 today, £2.82 yesterday, £14.27 for the whole of last week or whatever, it’s irrelevant really.

I’m struggling to see why you seem to have an issue with why anyone would spend a little time creating something that’s much cheaper and better than an £80 Watchman but, whatever.

Honestly, I don’t, I’m just interested in why when there’s no fundamental need to. If it is, basically, for the data geekery and the “cos I can” then I absolutely have no problem with that.

Undoubtedly, but we’re clearly going to have to agree to disagree on the usefulness of this

OK – I have a 2500L tank.  A Watchman seems to have 10 ‘lines’, so each one will represent 250L.  If I put in 500L it will display just two lines – what happens when there’s 200L left* …. does it show one line or none.  What about when there’s 100L left?  In this use case you’re better off with a wooden stick (or something that ‘works’!)

 but if it needs filling/topping up in March/April, then so be it, and whenever we fill it it’ll cost whatever the oil price happens to be.

I’m happy that your life seems easier than mine.

I’m just interested in why when there’s no fundamental need to.

That question could be applied to many, many things in life but we all do them anyway.

* (not that I expect it can measure the quantity in a cylindrical tank that accurately using ultrasonics)

I’m happy that your life seems easier than mine.

I apologise if I seemed overly dismissive, I know that the generally fairly big lump sums of cash needed to pay for oil heating, rather than the year-round drip feed into an account that a ‘normal’ gas/leccy customer can benefit from, is not ideal for many people.

That question could be applied to many, many things in life but we all do them anyway.

True.

To go back to my earlier point though, those of you who are doing clever things to measure oil consumption really accurately, er, why?

I don’t measure it to any great accuracy, just looking at the general trend and more importantly for when the tank needs filling.

But, the reason I do is that neighbours had a leak on the oil pipe going into the house, they never noticed (as it was in the wall).  It eventually leaked that much that they had to move out for a while as the insurance job needed had to remove/replace the entire outer wall, as the oil had ‘rotted’ out the mortar (stone build)…

what happens when there’s 200L left* …. does it show one line or none.

It’ll show one, flashing, bar. I suppose in my case I’ll know that I’ve got “about a week or so” to get some more, as I know roughly how long each ‘bar’ lasts. You, knowing your typical daily usage, will be able get that to more a specific number of days.

We heat the house to what we think is a reasonable temperature (although my wife would disagree) for what we think is a reasonable period period per day (ditto) and then basically it costs what it costs.

I look at my (gas) smart meter to decide how much effort to put into turning the heating on / off in different rooms, and helping to decide what a reasonable temperature is. When it’s just me in the house during the day the heating is off in all the rooms apart from the one I work in. If I see a big number on the smart meter I make more of an effort to get all the rooms off and my room temperature down. If I couldn’t quickly see the results of this working to reduce costs then I might not bother.

Seeing as heating is a fairly big contributor to CO2 then I would have thought we should all be thinking about it’s use a little bit more.

Re using hour meters, I can see on ebay 240Vac that are mechanical counters, and so will tot up the briefest of burner firings, and shows to 1/100’s of an hour. About £7. Plenty accurate if you’re not into stringing PIs and stuff together.

My 23kW boiler is 1.94 Kg/hour fuel use, or 2.425 litres per hour.

As to why record fuel use, yeah, partly geekery, and it nice to know efforts to save money / the planet are effective. In the 20/21 winter (pandemic year) I used 1475 litres, then after the price peaks qfter the ukraine invasion, various tweaks got me down to 846 litres last winter. In both years I was WFH.

I can see on ebay 240Vac that are mechanical counters

That sounds better than nothing, but I don’t know how you would power it.

The only power feed I could find that only runs when the boiler is firing is the oil pump – and that’s 24v on a Riello burner.