The OpenERV is a ductless ERV. The above video explains the general concepts of ERVs, but does not talk about ductless units, which are a newer technology that's still catching on. A ductless unit just goes in a hole in the wall to access the outdoors directly. There is no need to install or interface to ductwork in your building.
Each OpenERV TW4 module has a reversible, ultra-quiet, fan and a heat exchanger in a 6 inch pipe, that goes through a wall. The hot, polluted air from inside goes out for 20 seconds, and the heat from it is stored in the heat exchanger.
Then, the fan reverses direction, moving clean air from outdoors to the indoors. On it's way in, it picks up that heat from the heat exchanger. This type of heat exchanger is called a regenerator.
The OpenERV TW4 modules are made to always work in pairs. One always sucks air while the other blows air. This must be done, or hot air would be pushed out from the building through the walls during the ingress phase, causing a great deal of heat loss. Beware cheap units that don't do this. The different modules can be located anywhere in a home, even some distance away from each other. You can have many units per home. They communicate over the WiFi network, they can start their own if they cannot connect to the main one.
There are several critical features:
Very long life span/lack of planned obsolescence.
Commodity parts and Open Source design (both are needed to ensure maintainability and remove the incentive and capacity to use planned obsolescence).
Wind compensation, which improves the quantity of heat re-captured per season by roughly 25% (see detailed discussion).
A better heat exchanger, enabled by additive manufacturing.
A better fan, high pressure, high flow and extremely quiet. Noise is a form of pollution, like indoor air pollution, and it makes no sense to pay money to just replace one form with another. The bearings are standard and replaceable, so it will last practically forever.
Wireless synchronization and flexible power supply options simplifies installation.
The efficiency and flow rate determines how much energy is saved. Both are higher for several reason than the next best units available. The superior fan allows a shorter period for flow direction reversal, which helps efficiency. The fan also pushes more air.
Smart home connectivity, as a generic, highly compatible WiFi-connected MQTT device. This allows for any combination of remote switches, central control, humidity and CO2 level controls, time of day scheduling, etc. through AdafruitIO Google Nest, Amazon Alexa, and compatible devices and similar platforms.
Modular, durable design using quality materials and approaches.
Also works as a quiet, powerful supply or extractor fan (Not warrantied for use as a bathroom fan due to the water spray).
Far superior return on investment, and uptime. Return on investment is many, many times better than any other ductless ERV unit. It is also more than twice that of a typical photovoltaic panel installation in the region of Toronto, however this depends on the climate in your area. See spreadsheet.
Real time, quantitative efficiency monitoring and optimization using 2 built in humidity/temperature sensors.
There are 3 accessory kits:
The storm valve kit, which prevents the intrusion of air during high winds. This may not be needed, depending on where it is installed, which side/area of the house, and the typical weather patterns. The system automatically detects high winds, and also closes the valve when turned to zero flow rate.
The HEPA filter kit. HEPA filters are the best filters, equivalent to approximately MERV-13 and remove greater than 99.97% of all particulates from the air, including smoke, smog and pollen. Great for allergies or areas with problems from wildfire smoke or smog. A range of widely available filters can be used, so you will not get stuck unable to source compatible filters.
Bug mesh kit. Almost no bugs can get past the fan and heat exchanger anyway. You can use any type of bug mesh, including very fine mesh to exclude very small bugs such as no-see-ums.
Note: it is not warrantied for use in areas like a desert that get above 40 Deg C. The combined effect of intense direct sunlight and very high ambient temperatures could damage components.
Video coming soon. See the installation section of the manual for details.
The unit can be installed in a wall of any thickness, but if the wall is thinner than 230 mm, the unit will stick out slightly, indoors or outdoors. If the wall is thicker than the tube you purchased with the unit, you need a new SDR-35 tube. You can get tubes of practically any length. Standard 6 inch SDR-35 PVC pipe is what it is designed for, but there are many other types of pipe that are commonly available and will fit, but you need to check the dimensions closely.
Although made to be as DIY friendly as possible, in reality it still takes skill and equipment to install. Having a contractor install it is advisable, if you can find a reasonably good one, otherwise you can DIY.
The unit needs power, 24 volts DC, 0.7 amps. The unit comes with a power converter module, you can chose which type you want.
You can chose when you buy the unit which option you want for the power supply: the type that is hard wired into your wall, or the type that uses a so-called wall-wart, which you can just plug into a nearby outlet.
There are solutions for low voltage DC power supply lines that you can paint over, to avoid drywall work, usually for speakers.
To hard wire the power supply and get the best cosmetic result, you need to tap into a nearby electrical wire, put a junction box around the junction, and you need to install a switch and the power supply module in the junction box. Then, low voltage DC wires transmit the power from the power converter module to the unit. Or you can run the AC power wire somewhere else to another junction box and put the switch and power supply there. The wires, junction box and switches are not included.
Electricians have techniques such as fishing, which allow wires to sometimes be run cleverly without removing the drywall, if you are retrofitting a building.
For the pipe, you need to bore a hole with a standard 162 mm core drill, or you can cut it out through other means. A core drill is recommended for a clean hole.
The interior cosmetic matches typical white semi-gloss interior walls (the most common gloss for interior white paint), but if you wish it can be painted any interior paint to give the same color etc as the wall. It is primed.
Configuration is takes only a minute. Each device is programmed as a Leader upon first boot. You turn one on, it will start a wifi network, you connect to it and enter the configuration information you want. Do the same with the other of the pair, but tell it is a Follower and enter some information so it can find it's designated Leader (we are trying not to use slave/master terminology). They continue to constantly communicate and keep their operation synchronized. Multiple leader/follower pairs can be used on the same network, see manual for details.
The leader can be configured to connect to AdafruitIO or CloudMQTT or any other MQTT broker.
If you wish, you can connect via the browser of your phone or the USB port with a laptop or Android device and change the configuration. See manual for details.
Power level/ventilation flow rate is controlled by the knob on the side of the units, or over the Wifi network by accessing the device through a browser on a phone (you can bookmark the page). Smart knobs can be used as well through, for instance, the AdafruitIO system. Google home and Alexa can also interface to the device, but they require some configuration. Matter will be supported when it's more developed.