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Above is a video about ERV systems in general, but the video features the centralized, ducted type, which is not the same as the OpenERV.   

Fundamentally, the outgoing air surrenders >91% of it's sensible heat and ~45% of it's water vapor to the heat exchanger media, and then the airflow through the heat exchanger is reversed, with fresh air picking up the heat and water vapor on the way in.   The units must always work in pairs.  One always sucks air while the other blows air.  If this is not done, hot air escapes from the building or cold air is drawn in, greatly reducing real-world de-facto system efficiency.   

This type of heat exchanger is called a fixed matrix regenerator.

The OpenERV is an Energy Recovery Ventilator, which means it recovers at least some of the latent heat (water vapor). Under testing for Toronto weather, it recovered an average of 45% of water vapor over the season.  This is better than an HRV, which does not recover water vapor.  This occurs because when the outgoing air gets below the dew point, water vapor condenses onto the regenerator media.   When flow is reversed, it evaporates back into the airstream.   The efficiency of latent heat recovery changes when the temperature differential and humidity changes, while sensible efficiency stays about the same, even when it is extremely cold out.  


FAQ

There is a True HEPA filter option that can be purchased separately.   It is effective in removing pollen and wildfire smoke during summer.  You must choose between the Automatic Storm Valve add-on and a filter, at any given time.  You can switch from one to the other at the right time of the season.  The filter is usually used only in warmer weather, outdoor air in winter does not generally need to be filtered. 

The filters are standard, widely available filters intended for use in car cabin air filtration systems.   You do not need to buy new filters from us at a high markup, and you do not even need exactly the right size of filter. 

 However, for maximal flow rate and ease of use, it is recommended that you use the Filter Attachment Kit, and the filter it is designed for.  This is just two parts that hold the filter slightly away from the intake to improve airflow, and screw onto the outdoor plate, under the vent hood.

Any filter reduces the air flow rate.  In Summer Mode, maximum net provided fresh air flow rate with the HEPA filter is 40 CFM in one direction, per unit, so 80 CFM per pair.  


  See the spreadsheet below.  You can save a copy of it, and then edit it, to enter the figures for your region for electricity and fossil fuel prices, etc. and see for yourself that the payoff period is much shorter than for a photovoltaic panel installation in many areas.


Yes, there is a 5 year Warranty against defects in material or workmanship on all our products. It is important to note that in reality, almost all conventionally made products include what's called planned obsolescence - they are deliberately made to break soon after the warranty expires, and we have all come to expect this.  And when they do break, they cannot be fixed.  The openERV is not like that.  There is no planned obsolescence.  It is made to last as long as the fundamentals of technology allow.  This improves the investment properties substantially.  Doing things right is better than any warranty.


If you live in an area where storms occur with enough severity to force air or water through the unit, and the unit is not installed in a sufficiently sheltered area, you should use the Automatic Storm Valve add-on module.  This will close the intake when the system detects extreme wind, and prevent the intrusion of air and rain during a storm.  If you are talking about a hurricane, you need to take all precautions to prepare in accordance with logic and good practice.  It's not meant to stand a hurricane without some help.  You should probably remove the outer hood and valve or filter, and put a plate of plywood or metal over it, securely.


Yes, but we can't/it is not economical to try to honour the warranty on units that have been modified, there are too many things that could go wrong and it's just too complicated, and labor intensive, unfortunately. 


Open source has valuable, beneficial implications for the long term return on investment, and real-world reliability of the system.

When a system is made from common, widely available parts, and you have the blueprints, you will never be at the mercy of any one company, which may keep you waiting for long periods or charge too much for replacement parts or service.   All conventional companies engage in what's called Planned Obsolescence.   They design things to break and in such a way that you have to come back to them for parts and service - and then they eventually stop supporting a product or go out of business, leaving the product an expensive piece of trash, and leaving you without a properly, fully working home, while you solve things.

If you want to amortize the cost of a product over a long time period, it has to last a long time.  25 or even 50 years, for a building element.  Open source and standard parts really helps with that.

Open source also provides a certain inertia and staying power, and is more respectful of the user in many ways.  

The design can be seen and criticized by anyone, helping prevent the existence of problems at an early stage.

For a rare few of us, the ability to modify, reprogram and enhance the unit, or shimmy it into a different role, is valuable. 

Environmental friendliness also shakes out of this designed-to-last approach.  It's less stuff, way less stuff, in the trash, and less stuff produced means less pollution. 

Hopefully some community will form around this machine, which is a common part of the open source paradigm.  After the development costs are paid off, the code may be released for anyone to use for any purpose, which could make it an interesting sociological phenomena with broad community support.  

We support the Right To Repair movement.  This is especially important for farm equipment and other basic infrastructure, such as housing and building technology, which we all depend on and form a major part of the cost of living.

Consider: fans never last more than a few years of continuous operation.  If you purchase a conventionally made unit, will you be able to find a replacement fan when the time comes, several years from now?  What if the company is out of business? If not, there is a serious problem as it is expensive, and built into your wall.  

What happens if something gets damaged, due to a lighting strike/power surge, fire, severe storm, or just careless mechanical trauma?  Kids or pets? How much will it cost to rectify?  These are part of life for a building element.  With the OpenERV, these things can all be solved relatively quickly and cheaply.


 All the other ductless ERV and HRV units on the market are prone to getting an excess of air blowing through them, which greatly reduces real world efficiency.  The efficiency they advertise is merely under laboratory conditions with no wind, and is not realistic.  The OpenERV automatically monitors the fan rpm and power level relationship to ascertain if there is any wind pressure, and precisely measure how much.  The fan is used as an anemometer, basically.

This improves comfort by helping prevent drafts, and improves the return on financial investment.  It also allows the fan to reduce it's speed during calm conditions, reducing noise levels.

 Turn the power level control knob to the full position and back to the minimum position three times within ten seconds.  The unit will enter Summer Mode.  The middle position of the power level control knob becomes the Fan Off position.  What used to be the maximum power level position causes the fan to blow air into the house, and you can adjust the power level.  Full the other way causes the fan to suck air out of the house.  The follower unit will act the same way as the leader.


  We should ask this question of any appliance.  Dust can be blown out with compressed air, whenever desired.  If the unit gets dirty due to unusual conditions, you can remove it from the wall and clean it, but that should not be needed.  The HEPA filter may need to be cleaned or replaced, it should be good for at least one season, depending on pollution levels.

After several years, the motor bearings will need to be replaced.  This process of wear has some randomness to it and depends on usage levels.  When that happens, you can replace the motor, they are widely available for about $15 USD.  It is a standard 2805, 14 mm thick brushless DC motor.  Or, you can actually dismantle the motor and just replace the bearings.  The motor can be dismantled and just the bearings removed and replaced.  See the manual for details.

In fact, as a bit of a gimmick to promote the paradigm of this undertaking, we include a free pair of ABEC-5 bearings.  These are top notch, precision bearings.  They may be taped to the inside of the electronics area, so they don't get lost some time in the next few years.

If it is damaged due to extreme weather, mechanical trauma, or a power surge or lighting, the relevant parts can always be sourced and replaced, either with identical 3d printed parts, or commodity, standard parts.   Even the electronics can be replaced with standard modules.

  Not yet.  The WiFi is only used to synchronize the two modules right now.

In the future we may release a firmware update that gives internet of things functionality, and allows you to control the unit(s) in your home from your phone as a google Matter device.   However, we can't do that right now as the Matter standard has not been released yet.  

  Ductless ERV manufacturer's frequently indicate a laundry list of supposed standards the units are compatible with.  Some even claim inapplicable standards, such as those made for fans or ducted ERV units.  They claim the units are suitable for X many square feet of floor area. 

 Fundamentally, the efficiency, flow rate and efficiency of the fan in terms of watts per CFM is what determines compatibility with these standards.  The OpenERV unit is RoHS and WEEE compliant, meaning it does not contain any of a laundry list of toxic substances, such a lead.   Almost all modern appliances are. 

 By most building codes, the OpenERV is suitable for about 700 square feet of interior space.

Some manufacturer's claim compliance with DIN 1946-6.  This is merely a standard for the amount of ventilation air for a building.  A ventilator unit cannot itself be compliant, only a building with adequate ventilation can be compliant.  The OpenERV can be used to make a compliant building, certainly.

DIN 308 is a legitimate standard for measuring the efficiency of Energy Recovery ventilators and Heat Recovery Ventilators.  But it does not apply to ductless units, only conventional ducted units.  The testing protocol is specific to ducted units.  It also does not  factor in the impact of wind pressure on efficiency.  With ducted systems, this is reasonable as the fans are powerful and high pressure (and therefore use a lot of electricity).  In ductless units, this does not make sense as wind has a very large impact on units that do not have compensation systems.  See FAQ #7, on the subject of the built in efficiency optimization system the OpenERV features.  

The OpenERV has not yet been evaluated by an accredited laboratory, and it would not be very useful if it had been, because, as mentioned, their testing protocols are not applicable to these new ductless units.  

We have leveraged additive manufacturing to produce the quietest fan blades that are physically possible,  and use the best quality motors and electronics, as well as many features to passively absorb sound.    This includes viscoelastic rubber isolators, and fiberglass.  This provides a profoundly quiet unit, which at equal flow rates and efficiency levels, we believe is the quietest ductless ERV in the world.   The fan is also located in the middle of the tube, which helps reduce the radiation of sound energy, compared to putting it on the indoor side, or fully inside the room.

We have chosen to include the acoustic cover by default, because although most people will consider it overkill, we take pride in doing really good work. 


  There seems to be some slip in what the term "silent" means these days.  Silent means truly, actually inaudible.  It is not perfectly inaudible if you are in the same room and there is zero other background noise, and neither is any other fan in the world.  It will be drowned out by a typical computer fan, most refrigerators, an open window with the typical background roar of the city, a forced air furnace, etc.    It is extremely quiet. 


Quantitatively, see the specs on the main product page for details.  It gets about 0.2 sone, about as close as any moving machine can be to silent, when on the low setting (~8 cfm).  All fans make more noise when they are turned up to maximum.   The OpenERV gives you options, and among these is a relatively high flow rate, but that means maximal noise production is also higher.   There are limits to how quiet a fan can be, unfortunately, and anyone who says otherwise is being dishonest.  It can be used in a bedroom or office.  It is quieter by far than most computer case fans.

We did experiment with Roots blowers and other interesting mechanisms that have potential to eliminate the last of the noise that a fan makes, but they are unfortunately not economical to make. 

No, it is designed and tested to work all year round, including during Canadian weather at -30 degrees C.  


OpenERV financial and carbon impact reckoning

Installation

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 450 mm, you need a new SDR-35 tube.  The one that comes with the unit is only long enough for a 450 mm wall, but you can get tubes of practically any length.  Standard 6 inch SDR-35 PVC pipe can be used, or any of many other pipes of approximately that size available through typical construction supply channels.

Having a contractor install it is advisable.

The unit needs power.  It requires a 24 volt DC, 20 watts capability, regulated, input. The default option for the power supply is the hard wired power supply module that is to be built into the junction box in a wall.

 You can also choose to use a so called wall wart or other 24 V DC power supply to just plug into a nearby outlet and power the unit without any wiring hassles.  Any regulated DC power supply of 24 Volts and at least 20 Watts power capability should work fine.  You can buy one from us.   There are solutions for low voltage DC power supply lines that you can paint over, usually for speakers, but these details are the responsibility of the installer.

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 24 volt wires go to the unit from the power supply.  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. 

For the ducting, 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 cover can be painted with any primer, and then any interior paint to give the same color as the wall, or you can leave it as-is.

Configuration is fully automatic.  The machines are paired and programmed at the manufacturing facility.  The Leader will start it's own WiFi network, and the Follower will connect to it, search for and find and synchronize with the Leader unit with the same Pair ID on the network.  They continue to constantly communicate and keep their clocks synchronized.  In the even of power loss, they recover and synchronize automatically.  If you wish, you can connect via the USB port and change the configuration.   Power level/ventilation flow rate is controlled by the knob on the top of the leader unit.  For longer range, you can connect the device to your home WiFi network by plugging into the USB port and entering the configuration information.

If you wish for home automation functionality, for now you can use a smart switch or smart plug compatible with your favourite home automation system to turn the unit on and off on a schedule, connect it to your phone's GPS, a humidity or CO2 sensor, etc.  Smart switches and plugs are also legitimate options for relocating the control switch without doing a lot of wiring.