Monitor Oil Fired Boiler (Hydronic) Fuel Consumption

During Maine winter on 2021 and 2022 I wanted to understand my oil consumption related to daily average temperature. The Sense Flex prob was ideal for this application since the user can adjust the Flex prob Standby to On Threshold to any desired level. After monitoring the Boiler for a few days I noticed levels greater than 150 Watts indicated my boiler was on and using oil. Level between 65 and 150 Watts indicated by circulator pump was active. At 60 Watts the Boiler system was in standby.

Using my Boiler fuel nozzle rating of 0.625 to 0.65 GPM (Gallons per Minute) and the Sense Device usage per day Total Time On I was able to estimate my daily oil consumption (GPM * Minutes of Use). Latter I purchased a Smart Oil Gauge and was pleased to see I was my estimated vs. actual daily oil usage was close 0.65 vs. 0.76 GPM. I suspect the difference between the two readings is the nozzle flow rate (GPM) is based on a calibrate oil pressure of 100 psi. My oil pressure is set to 150 psi. I confirmed this assumption during this writeup using the following reference, Effects of Pressure on a Nozzle Flow Rate A nozzle with a 1 GPM @ 100 PSI has a 1.26 GPM at 160 PSI.

I hope this helps someone.

@drose, thanks for your input! Your post reminds me of this one, even though the fuel is different:

I have a native detection for the pump on my natural gas-powered boiler, and my natural gas-powered water heater is on a KP125. This gives me a some idea of daily usage, although it misses the kitchen range and the basement space heater. My natural gas service is billed monthly, so I can’t do the daily comparison that you did.

My boiler system has standby usage of 4 Watts, measured with a traveling HS-110. I believe my standby energy is consumed to power the thermostat. I’m curious what your system does in standby to use 60 Watts.

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