What does a flat cool towards? Not the outside air
Seven hours with no heat in the circuit, and the question of how far to preheat. The answer hung on a figure I had assumed wrongly at first.
Topic
Heating and cooling
Thermostats, stove, air conditioning — and the question of what a flat actually cools towards.
12 articles
What a radiator thermostat measures is not your room
Three homes, three ways to a radiator: tado over HomeKit, Shelly over Zigbee, and once no valve at all. What each gives you — and what none of them can do.
The stove obeys again — for 55 instead of 299 euros
The pellet stove accepts heat level and target temperature again. It took a 32-euro converter, the right baud rate, and one line of code in the right place.
tado integrated locally — then six weeks of wrong diagnoses
The local route to tado runs through HomeKit, and HomeKit allows only one controller. What followed: four plausible diagnoses, all of them wrong.
Three rooms cooled down — and nobody had a window open
A home-built detector spotted ventilation in an empty flat. The interpretation was wrong, and the real reason called a whole measurement series into question.
Four buttons for six heating zones — the stove counts too
In winter it is always the same four states. Clicking each one by hand across six zones is the kind of work where you forget half — usually the toilet.
The switch says requested, not running
The pellet stove has no network. The relay only reports that heat was asked for — whether it is burning is revealed solely by the ignition spike in the power draw.
The model with more physics was the worse one
Four years of gas use reconstructed from 71 meter readings. My temperature model was physically sound — and off by 110 cubic metres.
Vienna: three integrations in one day, and a dead file
The second installation was the first to profit from the first. And on the same morning it wrote a configuration that never had any effect.
35 minutes of cooling, zero degrees colder — the proof run
The air conditioner ran and did not cool. "Cools badly" is not a finding. How a complaint became a measurement series the engineer confirmed.
The calendar knows in advance, the phone knows now
No tracker can predict an arrival, no calendar can safeguard a departure. Why both are needed — and where the eight and ten hours come from.
Six valves move house — and the radio network improved
The radiator heads spoke Bluetooth through two gateways. The same hardware can do Zigbee — and after removing the gateways the weakest link got better.