How To Survive A Wet Bulb Event

Territories across the northern hemisphere are suffering through record-breaking heatwaves this summer. Climate scientists are publishing graphs with red lines jagging dangerously upwards as unprecedented numbers pour in. Residents of the southern hemisphere watch on, wondering what the coming hot season will bring.

2023 is hinting at a very real climate change that we can’t ignore. As the mercury rises to new heights, it’s time to educate yourself on the very real dangers of a wet bulb event. Scientists predict that these deadly weather conditions could soon strike in the hottest parts of the world. What you learn here could end up saving your life one day.

Hot Bodies

The body has methods of maintaining a set temperature. Credit: Wikimedia Commons, CNX OpenStax, CC BY-SA 4.0

To understand the danger of a wet bulb event, we must first understand how our bodies work. The human body likes to maintain its  temperature at approximately 37 °C (98.6 °F). That temperature can drift slightly, and the body itself will sometimes move its temperature setpoint higher to tackle infection, for example. The body is a delicate thing, however, and a body temperature above 40 °C (104 °F) can become life threatening. Seizures, organ failures, and unconsciousness are common symptoms of an overheating human. Death is a near-certainty if the body’s temperature reaches 44 °C (112 °F), though in one rare case, a patient in a coma survived a body temperature of 46.5 °C (115.7 °F).

Thankfully, the body has a host of automated systems for maintaining its temperature at its chosen set point. Blood flow can be controlled across the body, and we instinctively seek to shed clothes in the heat and cover ourselves in the cold. However, the bare naked fact is that one system is most crucial to our body’s ability to cool itself. The perspiration system is vital, as it uses sweat to cool our body via evaporation. Water is a hugely effective coolant in this way, with beads of sweat soaking up huge amounts of heat from our skin as they make the phase change from liquid to vapor.

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Ventbot fans with 3D printed brackets and control circuit board with ESP32 breakout and multicolored 3D printed cases

Ventbots Are Fans Of HVAC And Home Automation

[WJCarpenter] had a common HVAC problem; not all the rooms got to a comfortable temperature when the heater was working to warm up their home. As often happens with HVAC systems, the rooms farthest from the heat source and/or with less insulation needed a boost of heat in the winter and cooling in the summer too. While [WJCarpenter] is a self-reported software person, not a hardware person, you will enjoy going along on the journey to build some very capable vent boosters that require a mix of each.

Ventbot control circuit board with ESP32 breakout in a red 3D printed case

There’s a great build log on hackaday.io here, but for those who need more of a proper set of instructions, there’s a step-by-step guide that should allow even a beginner hardware hacker to complete the project over on Instructables. There you’ll find everything you need to build ESPHome controlled, 3D printed, PC fan powered vent boosters. While they can be integrated into Home Assistant, we were interested to learn that ESPHome allows these to run stand-alone too, each using its own temperature and pressure sensor.

The many iterations of hardware and software show, resulting in thoughtful touches like a startup sequence that checks for several compatible temperature sensors and a board layout that accommodates different capacitor lead spacings. Along the way, [WJCarpenter] also graphed the noise level of different fans running at multiple speeds and the pressure sensor readings against the temperatures to see if they could be used as more reliable triggers for the fans. (spoiler, they weren’t) There are a bunch of other tips to find along the way, so we highly recommend going through all that [WJCarpenter] has shared if you want to build your own or just want some tips on how to convert a one-off project to something that a wider audience can adapt to their own needs.

Ventbot graphing of temperature, pressure, and fan noise

See a video after the break that doesn’t show the whole project but includes footage of the start-up sequence that tests each fan’s tachometer and the customizable ramp-up and ramp-down settings. Continue reading “Ventbots Are Fans Of HVAC And Home Automation”

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Hackaday Links: June 11, 2023

As Tom Nardi mentioned in this week’s podcast, the Northeast US is pretty apocalyptically socked in with smoke from wildfires in Canada. It’s what we here in Idaho call “August,” so we have plenty of sympathy for what they’re going through out there. People are turning to technology to ease their breathing burden, with reports that Tesla drivers are activating the “Bioweapon Defense Mode” of their car’s HVAC system. We had no idea this mode existed, honestly, and it sounds pretty cool — the cabin air system apparently shuts off outside air intake and runs the fan at full speed to keep the cabin under positive pressure, forcing particulates — or, you know, anthrax — to stay outside. We understand there’s a HEPA filter in the mix too, which probably does a nice job of cleaning up the air in the cabin. It’s a clever idea, and hats off to Tesla for including this mode, although perhaps the name is a little silly. Here’s hoping it’s not one of those subscription services that can get turned off at a moment’s notice, though.

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A thermostat unit and a replacement PCB for it

Custom Thermostat PCB Connects Boiler To Home Assistant

Thanks to Home Assistant, automating the various systems that run your home is easier than ever. But you still need to make a connection between those systems and your Home Assistant setup, which can be tricky if the manufacturer didn’t have this use case in mind. When [Simon] wanted to automate his home heating system, he discovered that most Home Assistant-enabled thermostats that he could find didn’t support his two separate heating zones connected to a single boiler. The easiest solution turned out to be to design his own.

The original heating system consisted of two control boxes that each had a 230 V mains connection coming in and a “request heat” control line going to the boiler. [Simon] considered replacing these with a simple off-the-shelf ESP8266 relay board and a 12 V power supply, but figured this would look messy and take up quite a bit of space. So he bought a neat DIN-rail mounted enclosure instead, and designed a custom PCB to fit inside it.

A Home Assistant screen showing two thermostatsThe PCB holds a Wemos D1 Mini connected to two relays that switch the two heating circuits. The D1 runs ESPhome and needs just a few lines of configuration to connect it to [Simon]’s home network. There’s no separate power supply — the 230 V line is connected directly to a 12 V DC power module mounted on the PCB, so the new system is plug-and-play compatible with the old.

Complete PCB design files are available on [Simon]’s website and GitHub page. There are several other ways to make custom thermostats for your home, with an Arduino for example. If you’re interested in repairing your own heating system, or want to optimize it even further, there’s a whole community out there to help you.

Is This The Oldest Open Source HVAC Project In Existence?

Homebrew HVAC systems are one of those projects that take such a big investment of time, effort and money that you’ve got to be a really dedicated (ideally home-owning) hacker with a wide variety of multidisciplinary skills to pull off an implementation that can work in reality. One such HVAC hacker is [Vadim Tkachenko] with his multi-zone Home Climate Control (HCC) project that we covered first back in 2007. We now have rare opportunity to look at the improvements fifteen years of part-time development can produce, when a project is used all day, all year round in their own home. At the start, things were simple, just opening and closing ventilators with none of those modern MQTT-driven cloud computing stuff. Continue reading “Is This The Oldest Open Source HVAC Project In Existence?”

ESP8266 Smart Vents Keep Tabs On Home Temps

Have you ever found that, despite having a central heating and air conditioning system, that not all the rooms in your home end up being the temperature you want them to be? Maybe the dining room gets too hot when the heater is running, or the bedroom never seems to cool off enough in the summer months. If that sounds like your house, then these motorized “smart vents” from [Tony Brobston] might be exactly what you need.

The idea here is pretty simple: an ESP8266 and a servo is built into the 3D printed vent register, which allows it to control the position of its louvers. When connected to your home automation system via MQTT, the vents allow you to control the airflow to each room individually based on whatever parameters you wish. Most likely, you’ll want to pair these vents with an array of thermometers distributed throughout the house.

While [Tony] says the design still needs some testing, he’s released smart vents in a range of sizes from 2×10 to 6×12 inches. He’s also provided excellent documentation on how to print, assemble, and program the devices. It’s clear that a lot of care and thought went into every element of this project, and we’re excited to see how it can be developed further by the new ideas and contributors that will inevitably pop up now that it’s gone public.

Want to add some automation to your HVAC, but don’t have a fancy central unit? Don’t worry, as long as your heater or air conditioner has an infrared remote, you should be able to wedge a WiFi-enabled microcontroller in into the equation.

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The Benefits Of Displacement Ventilation

The world has been shaken to its core by a respiratory virus pandemic. Humanity has been raiding the toolbox for every possible weapon in the fight, whether that be masks, vaccinations, or advanced antiviral treatments.

As far as medicine has come in tackling COVID-19 in the past two years, the ultimate solution would be to cut the number of people exposed to the pathogen in the first place. Improving our ventilation methods may just be a great way to cut down on the spread. After all, it’s what they did in the wake of the Spanish Flu.

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