I'm looking for a sensor to monitor the level in my heating oil tank.
There are a couple of solutions that keep coming up but they are all hard linked to some vendor's cloud platform that isn't open AND they want to charge me a monthly charge to use them... and at some point no doubt they will end the service (knowing cloud only too well!)
I am after being able to track reasonably accurately my heating oil use - a level sensor would be fine, I don't need a metering one on the outflow.
I have a couple sensors measuring water tank levels using an ultrasonic sensor with arduino board and hubduino. Built a custom device handler to let you know the percent full it is. But takes a bit of tinkering to build the sensor.
Thanks @ritchierich but thats a bit heath robinson for me - or rather I'd be no good at building it!
@johnrob burner on time is a good idea - how would you measure that? I guess the consumption rate is flat so it is a good call.
@kampto yes I actually have an ultrasonic sensor that displays remotely. However its a dumb device that just shows a LCD display with 10 bars of fill level. The cloud metering solution I mentioned is the same device but with some sort of wifi module plugged into it. Reading reviews its hardly stellar and costs a lot of money.
I use smart oil gauge (https://www.smartoilgauge.com/) and I wrote a driver to pull from their web interface. It's a bit rough, but it works. I haven't had time to clean it up and post it but I'm happy to share it. Also not sure its available outside the US.
It's a bit fragile as it depends on them not changing their login logic. I've captured their iOS app flow and may switch to that at some point.
The ultrasonic sensors are somewhat inaccurate above about 80%, so you'll see fluctuations.
I also have a water tank and use a pressure sensor (https://a.aliexpress.com/_mORqGeM) which works really well with a Shelly uni. I would think it would work in this case as well, however I haven't researched it and putting even small voltage into an oil tank seems like not a great idea...
Your intuition is correct, however its not as bad as it seems. I still don't recommend it for a hobbyist.
Automotive diesel ( and I assume home heating fuel) can become stochiometric between 20 and 25 °C. When stoichiometric there is a finite amount of energy needed to initiate combustion. If the energy allowed into the tank is below the required level the design is intrinsically safe.
Regarding the pressure sensor. My first thought is the bottom of a fuel oil tank is full of sludge and may be tough to keep a pressure tube clear and empty. However I was thinking of my system and I could put a pressure sensor at the filter tap. I might have to only take readings when the burner is off but it may be easier than building an ultrasonic sensor.
I think after a lot of thought and some of your comments that the best bet is to try and detect the boiler firing, record that and do some maths on the flow rate of the nozzle.
Not quite sure how to pick up the firing though - although I had planned to use a zwave room thermostat to trigger the heating (or rather use the receiver part for HE to trigger it based on other sensors) that still leaves the hot water that could call for boiler ignition.
Maybe a power use sensor on the mains cable to the boiler itself?
While it think this is the best approach, sensing is problematic.
I'm an engineer so my options are braoder than most. If your comfortable with circuits pls let me know.
Otherwise you might try this current sensor module.
I've never used one of these but they would seem to fit the bill. I would guess the output contacts could go to a contact sensor with provision for external contacts.
Another thought that would not use your HUB. You might consider a timer. Search Amazon for "elapsed time meter". One of these with the above sensor will simply cumulate burner time. I realize it won't have a fancy Hub interface but it will work and it is non invasive to the burner.
John
Below is data from my boiler. Data taken with a custom DAQ setup, recording only when something has changed. Perhaps it will help you get a feel for what you will be getting.
I read someone's blog that said about using the elapsed time meter approach. Its a good approach but being less of an engineer and more of a computer geek I sort of wanted to push for a digital solution.
What about one of these clamp type sensors on the power cable to the boiler?
Remember you only need to measure ON Time.
I suggested the non contact current current switch because personally I would not break the burner wiring to pass it through a low cost device.
An engine hour meter that accepts line voltage is what I've used in the past. Your burner nozzle and oil pump pressure will give you the flow rate. Then multiply that by your hour meter. This is a dumb setup but works.
The last time I had to deal with an oil furnace was in my parents' home 50 years ago. I know the oil delivery companies estimated oil usage using a calculator for heating degree days based on average daily temperature readings. In the US and Canada that data is readily available and there is a calculator that makes the estimation quite easy. I do not know if the UK has something similar. Once you determine the historical fuel oil usage for your home, it is easy to estimate when you need to refill the tank.
This could work whenever it comes out (been a while since it was announced, says Fall 2022 but I doubt it since 2022 is almost over), but you will need to buy the FLRG48 float level gauge that Sinope will sell for use in fuel tanks. Might want to reach out to them and ask more details and ETA?
I'm now back to the idea of simply using a dumb level sensor (well its a remote one in my house) and doing some flow rate calculations based on flow rates defined by the nozzle size (from the OEM) and the number of run hours the boiler is on for (I now have the on/off controlled by Hubitat).
Its funny with this stuff, you start out with one concept of how to do things then jump to a different one after musing it for some time!
I have a Tank Utility, by Generac, wifi gauge on my large propane tank. The batteries are holding up so far and it's been working. They say if you get a similar remote ready gauge for your fuel oil tank, which is kind of industry standard, you can make it work. Although there's a Hubitat integration, it's still in the cloud.
