More boiler / storage analysis - where does the heat go?

[Nofossil]

I wanted to see what happens with my heating system over the course of a 24-hour day - how much heat is produced, how much is used, how much goes into and out of storage, and so on. I modified my efficiency spreadsheet, and here's a first pass.

Not a lot of surprises, but interesting (to me at least).

During the 24 hour period in the graph, the house used a bit over 355k btu. 86% went to space heating, 13% to the hot tub, and 1% to DHW.

During that same period, I had a short fire (just over 4 hours of actual burn) that produced 269k btu (about 67k btu per hour).

The difference between what I used and what I produced came out of storage. The heat in storage was 102k btu less at the end of the 24 hour period.

This is not a perfect analysis. I have no way to actually measure the heat transferred to the living space from the baseboards. I use an equation that takes into account the water temperature, but it's never exact. Also, I only have three storage tank temp sensors, so I can't measure storage energy precisely. Finally, I have no way to measure storage energy that goes into preheating DHW.

In this case, there was a 15.7k btu discrepancy over the 24 hour period. It's not all measurement error - certainly some of it is DHW preheat.

 

[Corey]

Wow - neat! It's interesting to see where all the heat goes. Reminds me of my own project I need to kick off...basically the same thing, but with electricity. Electric bill says I use an average of nearly 40 kWh per day and that just seems astronomical to me, especially considering no one is home 8 hours/day....and I haven't even been welding that much or running the Tesla Coil!

 

[sublime68charger]

yea this is a great read on the heating dynamic's of your system.

are you gonna plot this out over a week or a month at all?

be interesting to compare it to what your outside temps are as well.