boilers

Gas fired combi boilers (with centrally heated [pumped] cycling water) are pretty much the default in the UK.

Old boilers fed a hot water tank in the loft, but newer ones usually heat water as required.

Did traditional boilers just eject the excess as waste heat (perhaps through a steam pressure relief valve)?

Also, other than the fact that it uses induction, there are many single cup liquid boilers on the market.

It also could be quite a bit on the too dangerous side due to exploding boilers.

Are there modern boilers that adjust the amount of fuel added and/or the burn rate, based on the incoming water temperature?

The NY Times suggests that inefficient boilers in old buildings could be the culprit [1].

Then tell them about how old boilers on trains used to blow up.

That in turn lets us make boilers, and in turn, steam power.

But, having lived in houses with ordinary thermostats and non-modulating boilers and houses with programmable thermostats and modulating boilers I can tell you this: I'm not going back to the old stuff.

Not just modulating boilers, but also multi-stage heating with a heat pump.

To go better than that, you have to have better boilers (ones that don't leak or blow up) and cylinders that don't leak so badly.

Boilers have to be brought up to temp, and do not take well to throttling like a combined cycle natural gas plant.

Boilers are nearly always gas powered (electrical systems are called ‘immersion heaters’).