home hacks

1941 Articles

Dumpster-dived Window A/C Becomes Ground-Source Heat Pump

September 22, 2026 by 21 Comments

Heat pumps are great, because they pump heat around, and we often don’t want heat where it is. Need it somewhere else? Pump it! It’s great. It’s also a bit pricey if you’re buying new, but [Craftsman Chris] over on YouTube realized that the window air conditioning unit he found in a dumpster is, in fact, a heat pump. Normally it’s an air-source heat pump, but with a delightful series of hacks, he gets it automated and hooked into a ground loop in his latest YouTube video.

The heat sink is provided by a bunch of PEX tubing [Chris] buried in his back yard. After experimenting with using the water loop for cooling directly, he realized that pumping heat out of his house into the cold ground would go much better with a heat pump. That’s where the window A/C came in. After cleaning and servicing it, it was time to convert it to dump heat into water rather than outside air. To do that, [Chris] welded up a tank made of scrap metal around the existing heat exchanger. It’s designed for air, sure, but water takes its heat just fine. The nice thing about this is that by keeping the internals of the air conditioner mostly stock, he doesn’t let out any of the tasty, tasty CFCs that may be hiding inside.

Connecting this unit to his thermostat is equally hacky– he takes an old Programmable Logic Controller that looks fit to run a small factory, and hooks it to a single linear actuator to poke the A/C unit’s stock power button. Is it elegant? No. Does it work? Yes. Is it a hack? Indubitably!

We’ve seen window units pressed into whole-house A/C service before, but adding the water loop is a great hack. We saw a window A/C used as a ground-source pump before, too, but that was a Canadian project and so sensibly turned the machine around to provide heating for the maple mansion.

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Ski Lift Removes Mice From Chicken Coop

September 20, 2026 by 46 Comments

Getting rid of rodents like squirrels, mice, or groundhogs is a lot like digging a hole on the beach. No matter how much you remove, it’ll always fill back in. So, while [Super Valid Designs] could keep trapping and “removing” the mice in his chicken coop, more will always work their way back in. His theory is that removing them live from the chicken coop and placing them some distance away will be more effective, and with this semi-automated ski lift that traps them and carts them off, it might end up being less work too.

The build comes to us in roughly two parts. The first is the gondolas, which not only cart the mice down the hill to freedom but also double as the mousetrap themselves. They are placed in the chicken coop, and a trap door on the ceiling with bait causes the mice to fall inside. 3D printed with acrylic windows, they are a luxurious way for a mouse to travel. At the bottom, another trap door opens onto a pile of brush, releasing the mice. The second part is the lift, built hastily out of wood and other parts lying around. After much hiking up and down the hill, [Super Valid Designs] eventually got it working properly and reliably toting the mice and automatically releasing them at the bottom of the hill.

It’s a bit too early to tell if this method is more effective than more traditional methods of dealing with mice. But it was at least a fun way to deal with the problem while he also works on more effective methods of preventing the mice from getting into his buildings in the first place. There are some simpler catch-and-release mousetraps out there as well if a ski lift is out of the question for whatever reason.

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A Cheap And Easy Control Screen For Home Assistant

September 16, 2026 by 17 Comments

Home Assistant is a great way to rig up and manage your smart home and its many and varied devices. You can of course control the system from your smartphone or a computer, but you might like to have a dedicated interface too. In that regard, [Max Gramser]’s project may come in handy.

At heart, it’s a Home Assistant control screen that you can lay out yourself. It’s intended to run on ESP32 hardware. Most specifically, it’s built to run on the Cheap Yellow Display which combines an ILI9341 display with an XPT2046 resistive touchscreen, or a Guition ESP32-S3-4848S040, which has a ST7701S RGB display combined with a capacitive GT911 touchscreen. You merely need to load the firmware on to one of these units, and you’ll have a configurable and customizable touchscreen interface for your own Home Assistant setup.

The GUI used is clean, attractive, and flexible. You can have it display weather, time, and date widgets, populate the screen with buttons for activating lights and appliances, or even command a compatible robot vacuum. Whatever you might want to do with Home Assistant, you can almost certainly create a quick control for it on the display so it’s always on the wall, ready to go when you need it.

If you’ve always dreamed of your house having a futuristic control panel like we used to dream of in the 1980s, well… now it’s a reality. You just need to drop a few bucks on a touchscreen ESP32 rig and you’re ready to go. There’s plenty more you can do with a Cheap Yellow Display, too, so don’t hesitate to check out some of the previous builds we’ve featured with it!

Dramatically Increasing Usable Closet Space

September 13, 2026 by 28 Comments

As any science YouTuber or first-year physics student is quick to point out, the universe is mostly empty space. Not just space itself, but the amount of “empty” space between nuclei and their electrons is also huge. Getting rid of this empty space results in all kinds of interesting phenomena like degenerate matter and black holes. But the concept can be extrapolated into our daily lives as well; many things are so filled with air that we can get a lot more usable storage space by compressing them down a little bit. [Super Valid Designs] took this concept to a coat closet, building one that can hold an impressive number of coats.

He started by looking at an existing closet, which could hold around 21 coats but only if someone used two hands to cram the coats into the space. After a trip to a store which sells rugs, he saw a much better design that lets all the rugs pivot like the pages on a book, and took this idea to his closet using a similar mechanism designed for storing large blueprints instead of rugs. The closet he built around this mechanism has two hinged doors which allow a person easy access to the coats, and when opened the blueprint hangers pivot out like a book, allowing the coats to not only be easily accessed without disrupting the other coats, but also allow them to be compressed down by the closet door for storage.

For comparison, the original closet could only hold 10 coats when restricted to single-hand operation and 21 when using both. The new closet design is smaller, and can hold 24 coats with a single hand and over 30 when using both, a dramatic improvement of closet efficiency. To top it off, a set of cupboards on top and bottom allow for storing shoes and hats as well, and there’s even a garage for a robotic vacuum cleaner. Surprisingly, we don’t see many closet optimization builds around here. The closest we can come is another traditionally small space, a college dorm.

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Exploring The Downsides Of Cooling Roof Paint

September 3, 2026 by 34 Comments

The idea of painting a roof or wall white in order to reflect sunshine and keep the building’s insides cool is hardly a new one, and even in the loosest interpretation of the word ‘white’ it generally works pretty well. This is also what [NightHawkInLight] found after using an off-the-shelf silicone-based coating for his shed’s tin roof, though with a few caveats.

One might say that this is mostly a problem for people who live in non-desert climates — like Michigan in this case — yet it’s undeniable that having a cooler indoors in a high-humidity climate will inevitably lead to a higher indoor humidity level. This was the first issue that was encountered, though it mostly meant that instead of running an air conditioner eight hours a day, a weekly dehumidifier session was required, which was at least less expensive in terms of kWh.

While the current silicone-based paint on the roof stays above ambient, in a subsequent test both [NightHawkInLight]’s DIY sub-ambient cooling paint and a commercial option get a sample panel down to around ambient temperature, which could cool down the roof even more. Of course, in this case the humidity issues would get worse, with likely condensation forming that would have to be dealt with.

Overall, a cooling paint on the roof is a pretty thing even if you’re not living in the desert, but you have to be able to tame the resulting humidity and condensation issues.

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Defeating Bacteria In Hot Water Systems With A Heat Exchanger

August 31, 2026 by 74 Comments

The average hot water is a relatively simple appliance to understand. It uses gas or electricity to dump energy into water in the form of heat, keeping it at a pleasant temperature for uses like bathing and cleaning. Basic mechanisms are in place to ensure the water stays at a relatively constant temperature, neither too hot where it could cause burns, nor too cold such that it wouldn’t be fit for purpose.

One of the problems, though, is that sometimes storing water at the desired temperature can create the perfect breeding ground for bacteria. However, a neat little trick developed by NIST could solve that problem rather elegantly.

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USB-C Adapted For Legacy Sprinkler Systems

August 31, 2026 by 47 Comments

In the modern world USB has become a truly universal connector, with its inclusion on almost every major piece of consumer electronics. It has even expanded well beyond things that we’d think of as consumer electronics, like the solenoids on automatic sprinkler systems.

This project comes to us from [Ray Wang] at opensprinkler.org who has been working on various ways of controlling the old sprinkler standards, which generally rely on a 24 VAC power supply to drive solenoids. This tests uses the power available from USB-PD and closely examines four methods of energizing the solenoids: unipolar PWM, dual voltage, synthesizing an AC wave from a DC supply, and producing a bipolar square wave. The bipolar square wave had some interesting results, being able to get pretty close to the behavior of a true sine wave while minimizing the dedrmand on power electronics.

For those working on old sprinkler systems, or many other antiquated systems that still rely on 24 VAC, this project shows that USB can deliver a surprising amount of power in unique ways, and the fact that it’s near-ubiquitous and affordable makes it that much easier to adapt into situations it was never really designed for.

These old sprinkler systems have other ways of working on modern systems as well, like this one which replaces the AC source for a DC one, but with a few caveats.