Modeling Home Heating Systems With Circuit Simulation Software

July 1, 2024 by Bryan Cockfield 6 Comments

Electricity flow is generally invisible, silent, and not something that most humans want to touch, so understanding how charge moves around can be fairly unintuitive at first. There are plenty of analogies to help understand its behavior, such as imagining a circuit as a pipe of water, with pressure standing in for voltage and flow standing in for current. But you can flip this idea in reverse and use electric circuits to model other complex phenomena instead. [Oxx], for example, is using circuit theory to model his home’s heating systems.

To build his model, he’s using LTSpice, a free circuit simulation program. Using voltage to model temperature and current to model heat flow, he’s set up a model for his home to compare the behavior of a heat pump and a propane furnace. A switch model already in LTSpice with built-in hysteresis takes the place of the thermostat. Using temperature data for a single day in January [Oxx] can see how each of his two heating systems might behave, and the model for the heat pump is incredibly close to how the heat pump behaved in real life.

The model includes all kinds of data about the system, including the coefficient of performance of the heat pump and its backup electric resistive heater, and the model is fairly accurate at predicting behavior. Of course, it takes a good bit of work to set up the parameters for all of the components since our homes and heating systems won’t be included in LTSpice by default, but it does show how powerful an electric circuit analog can be when building models of other systems. If you’ve never used this program before, we’ve featured a few guides to getting started that you can take a look at.

Thanks to [Jarvis] for the tip!

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Baseboard Heaters Get Automated

April 10, 2024 by Bryan Cockfield 12 Comments

If you’re lucky enough to have central heating and/or air conditioning, with an automatic thermostat, you probably don’t have to worry too much about the outside temperature. But central HVAC is far from the only way of maintaining temperature in a home. From wood stoves to boilers there are many options depending on your climate and home type, and [Murphy’s Law] has a decentralized baseboard system instead of something centralized. An ESP8266 solution was found that was able to tie them all together.

There are other types of baseboard heaters, but in [Murphy’s Law]’s case the heaters were electric with a separate thermostat for each heater. Rather than build a control system from the ground up to replace the thermostats, turnkey smart wall switches were used instead. These switches happened to be based on the popular ESP8266 microcontroller, like plenty of other off-the-shelf automation solutions, which meant less work needed to be done on the line voltage side and the microcontroller’s firmware could be easily customized for use with Home Assistant.

While [Murphy’s Law] doesn’t live in the home with the fleet of electric baseboard heaters anymore, the new home has a single baseboard heater to keep a bathroom warm since the central heating system doesn’t quite keep it warm enough. This system is able to scale up or down based on number of heaters, though, so it’s still a capable solution for the single room and has since been updated to use the ESP32. All of the code for this project is available on GitHub as well, and for those of you attempting to add other HVAC components to a home automation system this project that loops in a heat pump is worth taking a look at as well.

A Raspberry Pi in an enclosure, connected to a stepper motor controller and a UMTS stick

2024 Home Sweet Home Automation: SMS Controlled Heating

March 26, 2024 by Dave Rowntree 23 Comments

Hackaday.io user [mabe42] works during the week away from their home city and rents a small apartment locally to make this life practical. However, the heating system, a night-storage system, is not so practical. They needed a way to remotely control the unit so that the place was habitable after a long winter commute; lacking internet connectivity, they devised a sensible solution to create an SMS-controlled remote heating controller.

The controller runs atop an old Raspberry Pi B inside a 3D-printed case. Seeing such an old board given a real job to do is nice. Connectivity is via a USB UMTS stick which handles the SMS over the cellular network. The controller knob for the heater thermostat (not shown) is attached via a toothed belt to a pully and a 28BYJ-48 5V geared stepper motor. Temperature measurement is via the ubiquitous DS1820 module, which hooks straight up to the GPIO on the Pi and works out of the box with many one-wire drivers.

The software is built on top of Gammu, which handles the interface to the UMTS device. Daily and historical temperature ranges are sent via SMS so [mabe42] can decide how to configure the heating before their arrival. The rest of the software stack is in Python, as per this (German-language) GitHub project.

While we were thinking about storage heating systems (and how much of a pain they are), we came across this demonstration of how to build one yourself.

Automated System Keeps Camper Van Air Fresh And Warm

March 6, 2024 by Lewin Day 22 Comments

Air quality has become a hot topic in recent years. [Ryan Stout] was interested in improving it in his camper van, and set about doing something about it. His solution was an automated system that provided cleaner air and better comfort to boot.

The concept was simple. [Ryan]’s system is based on an Arduino clone, and uses a SparkFun SCD40 as a CO2 sensor, and an MCP9808 for temperature. When the system detects excess carbon dioxide levels, it opens the MaxxAir fan in the camper by triggering it with an infrared signal. Similarly, when it detects excessively low temperatures inside the van, it kicks on a diesel furnace for heating. In a neat addition, to avoid the fan sucking in exhaust fumes, it also closes the fan in order to avoid exhaust fumes entering the camper unnecessarily. All the hardware was then wrapped up in a simple 3D printed enclosure.

With this setup, [Ryan] has managed to cut the buildup of CO2 in his camper at night, and he credits this with reducing morning headaches when he’s out in the camper. We’d call that a win, to say nothing of the additional comfort created by the automatically-controlled heater! If you’re interested in something similar for your home HVAC system, we’ve got you covered.

Feeding The Fire By Robot

January 15, 2024 by Bryan Cockfield 24 Comments

It might seem a little bit counterintuitive, but one of the more carbon-neutral ways of heating one’s home is by burning wood. Since the carbon for the trees came out of the air a geologically insignificant amount of time ago, it’s in effect solar energy with extra steps. And with modern stoves and well-seasoned wood, air pollution is minimized as well. The only downside is needing to feed the fire frequently, which [Anders] solved by building a robot.

[Anders]’ system is centered around a boiler, a system which typically sits in a utility area like a basement and directs its heat to the home via another system, usually hot water. An Arduino Mega controls the system of old boat winches and various motors, with a grabber arm mounted at the end. The arm pinches each log from end to end, allowing it to grab the uneven logs one at a time. The robot also opens the boiler door and closes it again when the log is added, and then the system waits for the correct set of temperature conditions before grabbing another log and adding it. And everything can be monitored remotely with the help of an ESP32.

The robot is reportedly low-maintenance as well, thanks to its low speed and relatively low need for precision. The low speed also makes it fairly safe to work around, which was an important consideration because wood still needs to be added to a series of channels every so often to feed the robot, but this is much less often than one would have to feed logs into a boiler if doing this chore manually. It also improves on other automated wood-burning systems like pellet stoves, since you can skip the pellet-producing middleman step. It also eliminates the need to heat your home by burning fossil fuels, much like this semi-automated wood stove.

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Hackaday Prize 2023: AutoDuct Smart Air Duct

September 15, 2023 by Bryan Cockfield 13 Comments

Modern building techniques are relying more and more on passive elements to improve heating and cooling efficiencies, from placing windows in ways to either absorb sunlight or shade it out to using high R-value insulation to completely sealing the living space to prevent airflow in or out of the structure. One downside of sealing the space in this fashion, though, is the new problem of venting the space to provide fresh air to the occupants. This 3D printed vent system looks to improve things.

Known as the AutoDuct, the shutter and fan combination is designed to help vent apartments with decentralized systems. It can automatically control airflow and also reduces external noise passing through the system using a printed shutter mechanism which is also designed to keep out cold air on windy days.

A control system enables features like scheduling and automatic humidity control. A mobile app is available for more direct control if needed. The system itself can also integrate into various home automation systems like Apple’s HomeKit.

A 100% passive house that’s also as energy-efficient as possible might be an unobtainable ideal, but the closer we can get, the better. Some other projects we’ve seen lately to help climate control systems include this heat pump control system and this automatic HVAC duct booster fan system.

Heat Pump Control That Works

September 4, 2023 by Bryan Cockfield 33 Comments

Heat pumps are taking the world by storm, and for good reason. Not only are they many times more efficient than electric heaters, but they can also be used to provide cooling in the summer. Efficiency aside, though, they’re not perfectly designed devices, largely with respect to their climate control abilities especially for split-unit setups. Many of them don’t have remotely located thermostats to monitor temperature in an area, and rely on crude infrared remote controls as the only user interface. Looking to make some improvements to this setup, [Danilo] built a setup more reminiscent of a central HVAC system to control his.

Based on an ESP32 from Adafruit with an integrated TFT display, the device is placed away from the heat pump to more accurately measure room temperature. A humidity sensor is also included, as well as an ambient light sensor to automatically reduce the brightness of the display at night. A large wheel makes it quick and easy to adjust the temperature settings up or down. Armed with an infrared emitter, the device is capable of sending commands to the heat pump to more accurately control the climate of the room than the built-in controls are able to do. It’s also capable of logging data and integrating with various home automation systems.

While the device is optimized for the Mitsubishi heat pumps that [Danilo] has, only a few lines of code need to be changed to get this to work with other brands. This is a welcome improvement for those frustrated with the inaccurate climate controls of their heat pumps, and since it integrates seamlessly into home automation systems could also function in tandem with other backup heat sources, used in cold climates when it’s too cold outside to efficiently run the heat pump. And, if you don’t have a heat pump yet, you can always try and build your own.