So I’ve knocked up a bit of an app that hopefully gives me an idea of how much oil I’m burning.
A Raspberry Pi stuck inside the cover of my massive (old) boiler listens once a minute for it running via a £4 USB mini microphone.
When the sound level is above a certain level (i.e. the boiler is running) if fires off a webhook message to IFTTT which adds a row to a google spreadsheet – it fires another message when the sound drops below a certain level (i.e. the boiler has shut down).
This gives me the burn duration from which I get the oil used (a 1.35kg nozzle uses 5.11L of kero per hour).
On my phone I have an app that gets data from the spreadsheet, filters it and makes it look better – it also gives me a total volume used and the associated cost.
There will be some error as the pi might have run the script just before the boiler fires up, but it l could also miss the boiler shutting off by 1 minute also so it kinda evens out a bit!
After 10 days it’s working well.
It’s giving me a daily usage that is subtracted from a rough-ish starting volume and will email/bug me daily once the oil level falls below a certain level.