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Bimetal Tyranny

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After eventful flights, including an unannounced stopover to Milwaukee, I finally reached Denver, Colorado. Just to continue the day’s theme, my hotel was overbooked and they bumped me into the neighboring, brand new Hyatt. All good around 1am.

Having been awake for 32 hours, I was expecting a good night’s sleep before the meeting marathon the next day. Now the day had been quite warm, so I turned on the (also brand new) air conditioning system.

Boom. Crackle. Humm. The box started and my papers flew around the room. Yes, this machine was built in 2017, not 1917.

I set the thermostat to 65 Fahrenheit, as I like to sleep in a bit colder air. I fell into sleep in some 10 minutes, just after the box went quiet.

Boom. Clonk. Crackle – waking up after 15 minutes as the box again geared revolutions like a V8 from the 60s. After this happened the third time, I had no other choice than shutting it down, in order to get at least some sleep.

A typical air conditioning machine like this has a simple bimetal thermostat, which switches the power on and off after warming or cooling to a threshold set by a spring. An invention of the early 1900s, it is bad for the electricity grid (sharp power spikes), bad for the coolant pumps and motors, and even worse for the user like me, who can’t use ear protectors due to sensitive ear membranes.

With an investment of less than $20, the bimetal relic could be replaced with a frequency-controlled drive with smooth, variable control. Add a couple of dollars, and the room would be equipped with an array of sensors to balance the air temperature for maximum comfort.

The reason these relics still exists is that no data (or my angry feedback) is collected by the air conditioning manufacturer, or by the hotel. If the machines where spimed, an upgrade would be underway immediately just for the energy savings. But it takes a bit of time to adjust away from the fire-and-forget business models.

//Pasi

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