This is a *pair* of TW4 (Through-Wall-4) OpenERV Energy recovery ventilator modules. Some assembly is of course required during installation. I think of a pair as a single ERV, but each module (half of the pair) is identical in hardware. The firmware is also identical except for the configuration file - one is the "Leader" and the other is the "Follower". They are meant to always work in pairs. See the learn more page for more information.

You need to agree to documenting the installation process to buy this pair at this price. It shouldn't take too much work, just pictures and a document like a blog post.

This is a special sale with tax included, to simplify things, because it is a unique prototype at-cost, and we are engaged in a collaboration to verify things/do beta testing.

The expected eventual retail price of this product is $1300 + tax, and that compares extremely favorably with units like the Blauberg Vento, which are $1700 + 15% tax = $1955 CAD or so for a pair. It also gets far superior performance, with much higher flow rate, efficency, lower noise, are equipped with high quality pressure sensors to regulate pressure in the face of static pressure and wind (increasing real world efficiency), and have a far better lifespan expectation, all of which improve the rate of return on investment greatly. It has many other qualitative advantages, as described in the manual and the learn more section.

There is the option of the heavy duty sound attenuator, but this is optional and has not yet been field tested. See manual for details. This would have to be arranged manually by contacting me, I was not really expecting anyone to want it.

You can see the layer lines in the printed parts, but the interior cover is sanded and painted, reducing the appearance of the lines. MPLA (Modified PLA) is used, which does not crack with time or exposure to water. It is not suitable for a service temperature above 55 degrees C, however, so not good for very hot areas.

I am discounting it greatly because a) It's in beta and b) Part of the agreement must be that you document the install process, producing a blog post or document that can be shared, with pictures and optionally videos. This is important to encourage others to undertake the process, because they know what to expect more. It doesn't have to be a lot of work, just take some pictures and notes during the process and write things down.

The sensible efficiency is 85% at a full 60 CFM, higher at lower flow rates. 60 CFM indicates the actual net total fresh air that is provided. These have both been tested with instrumentation, the efficiency has been tested with thermistors and data logging equipment, and the flow rate verified with a hot wire anemometer (HVAC contractor quality). Third party testing is ongoing. You can verify functionality with an infrared thermometer, instructions in the manual.

Latent efficiency is expected to be about 50%, average over the season. Water vapor condenses and then re-evaporates each cycle. These heat exchangers do not have silica gel adsorbent, which would increase that figure by adsorbing and desorbing water vapor, rather than employing condensation. I am experiencing some turbulence with the details of the coating process, so silica gel coated ones are not available right now.

Noise level for each module in the pair is only 40 dBa after installation, at full power. Lower at lower power, of course, to the point of being essentially inaudible (~25 dBa) on low power (~15 CFM).

The pair can be controlled over MQTT, only power level changes are possible right now. This allows them to be controlled with an app on a phone (there are many suitable apps, I recommend MyMQTT).

For more details, including information on the installation process, see the manual.

Chose between hard wired or wall wart type power supplies using the product options. See the manual for the difference and implications for each. The wall wart type is shown in the pictures. This is recommended because no electrical work is needed, which can complicate things and cost more.

Measure the thickness of your wall by using the area near a door or window to estimate pipe length you need. If you need pipes longer than 360 mm, you should select the "no pipes" option, and buy them separately, because shipping pipes longer than 360 mm is costly, because there is not enough space in the standard box. It is SDR-35 PVC pipe, which can be purchased at hardware stores, sometimes in short segments cheaply. The SDR-35 PVC label means precise dimensions and acceptable variation from those specified dimensions.

The ecwid functionality for shipping is very primitive. I have set it to a reasonable intermediate, flat rate, suitable for most of the US and Canada, but this won't work if you are very far away and shipping is very expensive. There would have to be an extra charge if it is very expensive.