[infecto]

The OP was too kind to you. Most furnace efficiency ratings come from calculating the input energy and the output energy. It is pretty obvious from the site that the calculation is a simple, energy in vs energy out calculation.

Maybe you should educate yourself some before writing posts you know nothing about.

[pandora-health]

I see where you coming from and even if the simple calculation is not what it is in real life, it's definitely running more efficiently than it would otherwise. Also, there are other benefits. Mainly, climate control, which means that the room temperature is very precisely at the target level at all times, within 0.3 C degree on average. And when you have constant temperature at all times, it feels very comfortable, and you can't tell whether heating is on or off.

[hn_throwaway_99]

> Maybe you should educate yourself some before writing posts you know nothing about.

Except another commenter, obviously more versed in the field than I, specifically highlighted how this efficiency is calculated differently based on what is specified as the denominator, and the rules are apparently different for the US vs. Europe: https://news.ycombinator.com/item?id=40055464. So perhaps it is you that should educate yourself.

[infecto]

My mistake, I thought it was more common knowledge how HHV and LHV are calculate and equivalents when comparing to heat pumps. I tend to respond too harshly when low level words are thrown. Sorry!