The attendant walked the round and wrote the readings onto a ruled sheet. The law requires such a log, but paper does not look at what you write on it: a value outside its limit looks exactly like one inside it.

By the time anyone noticed, it was the next round — or the moment something stopped heating. And a round nobody walked leaves no trace on paper, just an empty line no one looks at.

A GSM unit texts in its readings on a set period — anywhere from once a day to every half hour. The server parses the message, stores it, and checks every quantity against its upper and lower bound.

When a value falls outside, an SMS and an e-mail go to whoever has each channel switched on, and a second message follows when the value comes back. Quiet hours are set per weekday and per quantity, so an alarm at three in the morning has a reason.

The log stayed a log: the attendant writes notes and signs them with a finger on a tablet, and the month closes with three PDFs that replace the paper sheet outright.

The system has run since 2023 and HEATING PRO sells it under its own brand on a monthly plan. It is not one company's internal tool but a product with customers of its own.

Efficiency calculation from monthly meter readings, reminders for readings nobody filed, and remote control of the unit came later — period, limits and reset are all set from the browser.