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Musings of an Energy Nerd

Another North American Magic Box

Like the CERV, the new Minotair Boreal is a balanced ventilation system with a built-in air-source heat pump

The Minotair Boreal 12000 looks like any other HRV. However, the appliance conceals an air-source heat pump inside its white aluminum case.
Image Credit: Image #1 and #3: Karl Audet

Over the past few years, GBA has published several articles on “magic boxes” — a type of combination appliance that functions as a ventilation system, heating system, and cooling system. Most recently, I wrote about the CERV, a magic box manufactured in Illinois. Now a Canadian manufacturer has come out with a magic box that resembles the CERV.

The new device, the Boreal 12000, is manufactured by Minotair, a small company in Gatineau, Quebec. Like the CERV, the Minotair Boreal 12000 includes an air-source heat pump. All of the heat pump’s components, including both the condenser coil and the evaporator coil, are located indoors. Like a heat-recovery ventilator (HRV), the Minotair Boreal 12000 has four duct connections, including a fresh air duct that pulls outdoor air into the appliance and an exhaust duct that delivers stale air outdoors. During the winter, the exhaust air from the house passes over the heat pump’s evaporator coil, allowing the heat pump to scavenge some heat from the exhaust air. Since the condenser coil is located in the fresh-air duct, the Boreal 12000 delivers heat to the incoming ventilation air.

A motorized damper adjusts the airflow paths depending on whether the unit is in ventilation mode or recirculation mode. During the summer, the heat pump removes heat and moisture from the incoming outdoor air stream and delivers heat to the exhaust air stream, thereby lowering the temperature and humidity level of the incoming ventilation air.


The main purpose of the Minotair Boreal 12000 is to provide mechanical ventilation for a home in a way that pays close attention to the indoor humidity level. While the device appears capable of doing an excellent job of ventilation, it can also provide up to 9,400 Btu/h of space heating and up to 8,700 Btu/h of cooling. While that’s not…

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  1. GBA Editor
    Martin Holladay | | #1

    Response from Karl Audet of Minotair
    I received an e-mail from Karl Audet, the president of Minotair. His e-mail included a response to Cosgrove's opinion; I am posting Audet's response below.

    "Concerning Emmanuel’s arguments about the cost of our unit vs a combo HRV mini split: First, there is no such thing as an excellent air exchanger as it should be able to manage moisture in summer and winter, but none has that capability. In summer, you can't use an air exchanger to manage moisture to prevent damp basements. Whether it’s an HRV or an ERV, it can't dehumidify. As a result, it brings a lot of moisture the wall-mounted heat pump will remove later by working harder and longer, and that is not energy efficient. This is also why owners shutoff their HRVs in summer, depriving themselves of fresh air (this is perhaps energy efficient, but not very healthy ...).

    "In winter, an air exchanger will tend to dry the air of homes since the cold air that is entering does not contain much moisture. On this point the MINOTAIR faces the same problem and manages best with intermittent ventilation modes to reduce the phenomenon. The MINOTAIR also uses its humidistat to adjust the relative humidity winter conditions, ie the colder it gets, the more it will decrease the humidity to avoid frost on the windows (but without ever going below 30%, which would be detrimental to the health of occupants).

    "An 'excellent" air exchanger will cost between $1,200 and $2,400 plus installation. Same for a mini split. Of course there are cheaper systems but we’re talking high-end here. So a combined price between $ 2,400 and $ 4,800 plus installation. A MINOTAIR Boreal 12000 retails around $3,900 plus installation or $4,200 with the HEPA filter and wall-mounted control. Yes it is generally more expensive, but we’re talking of an integrated system with much more than a combination of characteristics to the room: integrated management of ventilation, temperature and moisture, autobalancing airflow and even helping generate a slight positive pressure to reduce infiltration, adaptive defrost, HEPA filtration, no condensing unit to install outside, etc. In fact, I would say the MINOTAIR offers great value for its price. Is it that much more expensive in the end? I am the first who wants to see the lowest price but high quality parts and manufacturing in Quebec makes it difficult.

    "Regarding the performance of a wall-mounted mini split versus a Boreal 12000, it is certain that strictly speaking in terms of BTU the mini split has a larger capacity. However, the mini split is located in a particular room, typically the living room or the dining room, thus not servicing other rooms. Not to mention that they require significant space and are unattractive on people's balcony. With its moisture management, the MINOTAIR creates a very comfortable environment. In the summer, a lower moisture content allows a higher temperature setpoint for the same comfort. And don't forget that there is no outdoor unit to install and no refrigeration contractor to hire for the installation.

    "That said, the MINOTAIR is not for everyone either ... If people approach us strictly for summer air conditioning, then our air exchanger is not for them. Furthermore, new owners often have little experience and are rarely aware of all the little details that affect indoor air quality. The majority of our customers are owners who come to us with a specific problem to solve, mainly related to moisture management. Often their air exchanger plays an important role in the cause of their problem. We also experienced owners who have acquired a good understanding of the operation of a house as a system, as a sum of its parts, and understand the advantages offered by an integrated system. And what about the potential of passive or tiny houses? A Boreal 12000 with a 3000-W electric coil will become a central system that can take care of all the ventilation, heating / air conditioning and moisture management needed in such a house. But make no mistake, we have systems installed in 3,600 sq. ft. homes too; it's really a question of application and offering the right solution for a need or specific problem.

    "Indeed, our systems are not certified EnergyStar nor HVI. But it's not for lack of trying. When we approached HVI 3-4 years ago, they were not sure how to go about evaluating our product. The fact that the motors are at constant air flow and the unit includes a compressor worried them, I think it's out of their comfort zone. Finally, faced with their balking, we put it all on ice. However, this lack of HVI certification never causes any reluctance among our potential customers, but I can understand that it can in the case of an organization like Écohabitation. In addition, it must be remembered that the evaluation committees of organizations such as HVI are often composed of members from the manufacturers of traditional air exchangers, and perhaps (pure speculation on my part) they are less open to a new technology that could make theirs seem the least attractive. We could perhaps approach HVI again if we felt a sense of openness on their part to our technology; it's 4 years ago, and time might have changed things."

  2. DavidAlex | | #2

    The Boreal is more efficient?
    Mr. Audet's statement, "As a result, [the heat exchanger] brings a lot of moisture the wall-mounted heat pump will remove later by working harder and longer, and that is not energy efficient," is confusing to me. On what basis does he claim that the dehumidification of the Boreal is more efficient than via a mini split?

  3. KarlAudet | | #3

    Response to David Hicks
    I assume you are asking your question based on the premise that if both solutions bring in, say 100 CFM of fresh air full of moisture, then both the HRV/mini-split combo and the MINOTAIR should require the same amount of energy to remove such moisture. And if so, then how is it that the MINOTAIR is more efficient than the HRV/mini-split combo?

    The quick answer is that with the HRV/mini-split combo, not only do you have two units that consume energy but the HRV/mini-split combo will require longer run periods to remove the same amount of moisture contained in the fresh air because the mini-split is localized in a specific area of the house. It will take time for all that moisture to make its way from all the HRV supply grilles to the mini-split head, which translates not only into longer run time (i.e. more energy) but also discomfort to the occupants who happen not to be within close proximity of the mini-split. The MINOTAIR removes moisture at the source, well before the fresh air – cooled-down and dehumidified – reaches the supply grilles.

    The long answer is that the MINOTAIR Boreal 12000 humidity management is more efficient (from an energy and/or a comfort point of view) than the HRV/mini-split combo for the reasons discussed next:

    1. In Summer:

    o HRV/mini-split combo: By the way, why do we even associate a mini-split with a HRV in the summer? Because one cannot rely on the HRV to take back the brought-in heat and moisture contained in the fresh air. In other words, fresh air gets diluted with the ambient air and what gets exhausted through the stale air outlet is only a fraction of what got inside in the first place. As a result, moisture and heat build up over time, thus the need for the mini-split. Even if you used an ERV, the same would apply (mind you at a slightly slower speed) because neither of the HRV or ERV has the ability to dehumidify. So why is the HRV/mini-split combo not efficient? Because the HRV brings in moisture (and heat) to ALL the rooms it supplies fresh air to. The mini-split being local to a specific room, won't be as effective at removing moisture (and heat) from these other rooms in which it is not present. Therefore, not only will these other rooms not feel comfortable but the mini-split will be required to run longer to have an effect on them, if at all, and at the risk of over-cooling the room it is located in. The HRV always works against the mini-split by increasing the cooling/dehumidification load.

    o MINOTAIR: when functioning as a HRV, the Boreal removes moisture at the source (i.e. fresh air intake) before distributing it – colder and dryer – to the rooms it supplies fresh air to. Less humidity and less heat equals better comfort. And when functioning in recirculation, there is no heat/moisture intake, thus allowing for all the unit's BTUs to be applied to the cooling/dehumidification load generated by the occupants daily activities. As for potential lack of fresh air while the unit is functioning in recirculation, note that the MINOTAIR ventilation speed increases when bringing in fresh air which compensates for the time it couldn't. However, the software always guarantees a minimum of 10 minutes of "cool and dehumidified" fresh air (at high speed) per hour.

    2. In the warmer period of Spring and Fall:

    o HRV/mini-split combo: when it is not likely that a mini-split would cool (because the cooling set point is already met), there is no dehumidification capability at all. However, Spring and Fall are two seasons where a lot of moisture is present in the outside air. The HRV will let in a lot of moisture in the house that won't be removed by the mini-split. As a result, the occupants will endure a humid house.

    o MINOTAIR: it will switch to recirculation and cooling at low speed to dehumidify. Low speed because the goal is not to cool the house, but to remove moisture. If this process takes too long and ends up cooling the house below the heating set point, then the Boreal 12000 will switch to heating to bring the temperature back up a bit, and will then revert to dehumidification at low speed. True, this process will add to the energy bill, but contrary to the HRV/mini-split combo, humidity is being managed.

    3. In the colder period of Spring, Fall and during Winter:

    o HRV/mini-split combo: it will tend to dry out the house, unless, perhaps, your house happens to be super-airtight built to the Passivhaus standard. Otherwise, one is likely to require a humidifier, which will add to the energy bill.

    o MINOTAIR: it can detect dryness conditions and can also detect sudden moisture peaks, such as when someone is having a shower. In this scenario, the Boreal can recirculate the moisture generated by the shower and help regain some relative humidity percentages. Often times, this is enough to refrain from having to install a humidifier. If on the other hand there is no dryness condition upon detecting someone is having a shower, then that moisture is simply exhausted outside and won't be recirculated. At all time, bathroom timers, if installed, will override the "shower detector" and will force moisture and odours out the house.

    In my opinion, a MINOTAIR unit provides a comprehensive IAQ solution. It is an integrated solution that not only brings in fresh air and exhausts pollutants, but one that also brings humidity management to the next level, ahead of any HRV/ERV-based solution known to date.

  4. DavidAlex | | #4

    Response to Karl
    Thanks for your very thorough explanation, Karl!

  5. srivenkat | | #5

    Winter Humidity Management

    I live in an ICF home that has high Humidity levels even in the winter. A couple of questions:

    1. Does the Minotair Boreal bring in the typical dry winter air in to reduce the indoor humidity?
    2. If it has snowed and the snow is melting causing outdoor humidity to go up, will the Boreal then run as a dehumidifier with the heat exhausted to the indoors?

    Also, would it be possible to trigger the Ventilation mode thru a Honeywell CO2 monitor, to bring CO2 monitoring into the equation. As you might know, the CERV monitors CO2 as well.



  6. srivenkat | | #6

    Also, I am wondering what the noise specifications are. Thanks.

  7. GBA Editor
    Martin Holladay | | #7

    Response to Venkat
    Q. "Does the Minotair Boreal bring in the typical dry winter air in to reduce the indoor humidity?"

    A. Yes. As the article notes, "Like a heat-recovery ventilator (HRV), the Minotair Boreal 12000 has four duct connections, including a fresh air duct that pulls outdoor air into the appliance and an exhaust duct that delivers stale air outdoors. ... The main purpose of the Minotair Boreal 12000 is to provide mechanical ventilation for a home in a way that pays close attention to the indoor humidity level. ... “The way it works, you set the humidity set-point to your liking,” said Audet. “By default, it is set at 45% for the winter. The ideal humidity level throughout the year is 45%, so that is the default. But you are free to play with that — to lower it or increase it.”"

    Q. "If it has snowed and the snow is melting causing outdoor humidity to go up, will the Boreal then run as a dehumidifier with the heat exhausted to the indoors?"

    A. As I hope you know, cold air can't hold as much moisture as warm air. Just because snow is melting, doesn't mean that outdoor contains a lot of moisture. The outdoor air might be at 40 degrees or 45 degrees -- warm enough to melt snow -- and the air can still be very dry -- dry enough to lower indoor humidity levels with ventilation air.

  8. srivenkat | | #8


    Thanks for explaining the snow/humidity scenario. Are you aware of any Minotair installations in the US and if so what their experience has been.

    I will wait to hear from Mr. Audet on the possibility of a CO2 hookup and the noise specs.

    Thanks again,


  9. srivenkat | | #9

    EER 10
    Also, I am intrigued by the low SEER especially in the Air Exchange mode. Shouldn't it be much higher since the exhaust air would be much cooler in Air Exchange?

  10. GBA Editor
    Martin Holladay | | #10

    Karl Audet responds to Venkat's questions
    Karl Audet of Minotair just sent me an email that included answers to Venkat's questions.

    Karl Audet wrote:

    "In terms or airtightness and insulation, ICF homes are somewhat similar to Passive House homes. Therefore, the following explanations apply to both types of homes.

    "HumiWatch365 is the Minotair subsystem responsible for managing humidity all year round. Whether it will choose to ventilate using dry outside air or run in recirculation/cooling mode is dependent upon the outside and inside dew points. During winter, ventilation will normally be used to reduce inside humidity. During summer, however, recirculation/cooling mode will be favoured. As for the most difficult periods of the year, i.e. the shoulder seasons, it will be a mix of both depending on the actual dew points and whether the house requires humidity or needs to be dehumidified.

    "Removing humidity with the Minotair is achieved in two ways:
    1) Ventilate with outside air if the outside dew point is less than the inside dew point, or
    2) Use recirculation/cooling mode.
    Adding humidity with the Minotair is achieved in three ways:
    1) Ventilate using outside air if the outside dew point is greater than the inside dew point,
    2) Recirculate moist air when people take showers, thanks to our integrated shower detector (note: bathroom timers will override the shower detector as required), and
    3) Add humidity via the use of a third party humidifier connected inline with the air distribution main duct.

    "To answer the question about melting snow that could increase outside air humidity, and by the same token increase inside air humidity once allowed in, one needs to remember that any outside air temperature below 50°F (10°C) at 100% humidity will have a dehumidification effect on inside air set for 70°F (21°C) and 50% humidity. This is because such humid outside air, once heated to the 70°F inside temperature will see its 100% humidity level shrink to about 50%. This is the point of equilibrium if you will, so any outside temperature falling below 50°F and 100% humidity will dehumidify the inside air over time. Therefore, whether it rains or snows, as long as the outside temperature is below 50°F (10°C) and the inside setpoints are 70°F (21°C) and 50% humidity, one will get a dehumidification effect simply by allowing outside air in. Of course, the closer the outside air gets to 50°F (10°C), the less of a dehumidification effect one will realize. On the contrary, combined with normal household activities (breathing, showers, laundry, cooking), inside humidity would tend to increase and one could no longer rely on ventilation to bring the humidity down unless the outside air temperature starts to fall below the 50°F and 100% humidity level. In the situations where ventilation alone cannot dehumidify, the Minotair will switch to recirculation/cooling mode at low speed since the idea is not necessarily to cool the house but to dehumidify it. And should the recirculation/cooling mode end up cooling the house anyway, the system will switch to heating for a few minutes to bring the temperature back up, and then would resume its dehumidification activity. But this would only really happen at temperatures above 50°F since most of the time outside humidity is well below 100%, allowing for recirculation/cooling to engage realistically more in the range of 60°F (16°C) and above. Considering most of our household activities generate heat, a bit of cooling while dehumidifying in recirculation mode is normally welcome anyway.

    "So this pretty much sums up the HumiWatch365 subsystem.

    "A somewhat related question that often gets asked is whether the optional wall mount control has sensors in it or not. Well, as all of our sensors are integrated inside the main unit, the answer is simply that there are no sensors in the wall mount control. In fact, the wall mount control is nothing more than a dumb terminal that remotely replicates the controller's display integrated with the machine. However, the majority of people chose to install the wall mount control for convenience so as to avoid having to walk to the machine to get actual readings about ventilation, temperature and humidity. As a matter of facts, most will install it in the hallway leading to the main bedroom.

    "About CO2 and VOC sensors, we support any third party make and model as long as they can provide a dry contact (e.g. a simple SPST relay output) which will be connected to the Minotair the same way one would connect our bathroom timers. When the CO2 or VOC sensor goes past the set threshold, the dry contact will close and will force the Minotair to ventilate. Once the dry contact is no longer closed (i.e. CO2/VOC back to desire levels), the Minotair will resume its normal operations.

    "As for the unit sound level, it should be below 60 dB when standing 3 feet away from the unit and when operating at high speed (250 CFM) with compressor on and with no ducts connected. With ducts of the proper diameter and length, it should be closer to 50-55 dB at high speed, and you can hardly hear it at speeds below 180 CFM. But it all depends on the quality of installations. Installations realized following HVAC best practices are quiet even when operating at 250 CFM. However, installations done poorly will start to be noisy at airflow > 180 CFM but will be just fine at lower speed. This is why we have introduced a setting for the not-so-optimal installations that will limit the airflow at 180 CFM. This setting is also beneficial when replacing existing ERV/HRV with the Minotair where we are sometimes forced to reuse the existing and undersized duct installations. While the setting will reduce ventilation noise, this will be at the cost of reduced heating/cooling capacity in the order of 20-25%.

    "Dehumidification won't be affected, however, as it is done using airflow of less than 180 CFM. All in all, it is always best to follow our installation guide and contract out the work to HVAC tradespeople that have good ventilation skills and reputation. This way, you'll not only get a quiet installation but you won't have to compromise the machine's heating & cooling capabilities since it will be allowed to work at 250 CFM when required. True, the do-it-yourselfers can also get very good results doing the installation themselves, but they will be more prone to make beginners' mistakes, sometimes costly ones, that the pros just won't make."

  11. srivenkat | | #11

    Boreal control of Central HVAC
    Thanks to Mr. Audet for explaining the above. A few more questions:

    1. How does integration with a Central HVAC system work when it's a variabe speed unit that will likely run continuously at modulated speeds according to the load. Wouldn't giving control of such a system to the Boreal, cause the Boreal to cycle the HVAC system on/off?

    2. Is there a "stand-by" mode where if the cooling-HVAC is running (which could be a pretty long run in the case of a variable speed system) and there's no call from the CO2/VOC/Bathroom, the Boreal will NOT run the fans nor the compressor and thus conserve energy?

    3. Must the Boreal be hung from the ceiling or can it be placed on its shipping legs at an elevated height so the drain could be connected underneath?

  12. GBA Editor
    Martin Holladay | | #12

    Karl Audet responds once more to Venkat's latest questions
    Karl Audet of Minotair sent me another email that with still more answers to Venkat's latest questions.

    Karl Audet wrote:

    "Question 1. When one wants to use the Minotair to control a central HVAC system, the Minotair becomes no different than a traditional wall mount thermostat that provides heating and cooling calls to the said system. In the case of variable speed central HVAC systems, the variable-speed logic is normally integrated in the HVAC control board, not the thermostat. Also, when the Minotair is interlocked with a central HVAC system, it has precedence over the HVAC system itself in that it will be the first unit to try to satisfy the load, and then based on outside/inside temperatures and humidity levels, will call the central HVAC system for help only when needed. This interlock feature helps save energy since all the HVAC components suddenly start working as a coherent whole.

    "Question 2. Contrary to other manufacturers, the Minotair does not promote a standby mode. It is our belief that the constant distribution of a minimum airflow, be it fresh air or recirculated air, should always be in effect even when there is no request from the CO2/VOC/Bathroom sensors. While continuously filtering the air, a minimum airflow helps homogenize the inside temperature and humidity. Otherwise, one would end-up with pockets of air of uneven temperature and humidity that might generate discomfort and air quality issues that can go unnoticed in the rooms not serviced by the CO2/VOC sensors. While saving energy is a noble goal, we believe that the energy required to maintain a minimum airflow is an investment in health and comfort rather than a plain and simple expense. Solely relying on CO2/VOC/Bathroom sensors is not the one-size-fits-all answer to achieving indoor air quality and comfort in our view. Such sensors should only act as watch dogs of last resort in case the normal ventilation operations become insufficient for whatever reason.

    "Question 3. The Minotair can either be hung from the ceiling or stand on its legs on a shelf or square brackets bolted to the wall. If you are going to make it stand on its legs, however, ensure the legs are placed on vibration absorber pads to avoid vibrations to transmit to the house structure. Also there should be a minimum height permitting the access panel to open fully and the drain to be connected with a P-trap."

  13. GBA Editor
    Martin Holladay | | #13

    Response to Venkat
    After Karl Audet has very graciously answered your first 7 questions in great detail, you have proposed 7 more questions.

    My suggestion is that you use your telephone to call the technical help phone number at Minotair (819-777-2454), since it appears that you have a need for an in-depth consultation with the manufacturer of this equipment.

  14. srivenkat | | #14

    Info might be of value to this blog

    I very much appreciate Mr. Audet's responses in the above. Indeed he was very much generous in painstakingly explaining the functions. I complement him on the design and development of this product.

    I agree some of my questions are installation specific, but I think you would agree that questions 1, 4, 5 and 7 in my last post are about the product's "Green"-ness which I believe would be of interest to many on this site. Also, to the extent others online have similar questions about this product, they will benefit from the info as well and thus take some of the response burden off of Mr. Audet besides also perhaps helping Minotair setup a FAQ page on their site with responses to these sort of questions.

    I found the answer to question 3 in the user guide. I contacted them about 2 days back (via both voice mail and email) and have yet to hear back from them. Perhaps they aren't setup to deal with individual owners like me and their time would be better spent dealing with builders and contractors that specify multiple units. Although I am excited about the product and have serious interest in it, the inability to communicate with the company directly is a serious hindrance now that could also prove problematic in the future if and when service of the equipment is needed.

    Thank you,


  15. srivenkat | | #15

    HVAC control
    Thanks again for the response from Mr. Audet. A few more follow-on questions.

    1. In regard to question 2 above, the contention is that if the Central HVAC is running, then there's already mixing/distribution of the air happening, which could be a long time in the case of a variable-speed system, which is almost constantly running, in which case, the Boreal also running the fans to try to do the same would be redundant, right?

    2. Do I understand correctly that the Boreal uses the Central HVAC for temp control only in the Heat Pump and Smart modes?

    3. How long does the Boreal try to heat/cool on its own before calling on the Central HVAC?

    4. Once started, is the Central HVAC left running uninterrupted until the temp is satisfied or is it periodically interrupted, say for the 10 minutes per hour ventilation that the Smart mode entails?

    5. After calling on the Central HVAC to cool (and dehumidify), does the Boreal also try to supplement with its own cooling/dehumidification?

    6. Also would appreciate how the "G" terminal connection works. In this case, is the Boreal controlled by the Central HVAC?

    7. Is the compressor in the Boreal inverter-driven, i.e., does it modulate its output according to the load?


  16. srivenkat | | #16

    Conversation with Mr. Audet
    Mr. Audet called me back yesterday and again this morning to answer my questions. Both times, Mr. Audet took a lot of time to patiently explain the various modes and workings of the Minotair Boreal and to answer all the questions I asked. They would prefer that home owners deal with their dealers as first points of contact but will welcome direct contact if the dealers aren't responsive. They have a 72-hour turn around on most calls, and service calls are normally handled the same day via their network of authorized dealers.

    Here's a brief summary:

    1. Recirculation mode would consume the least energy and in this mode, when the Boreal is connected to Central Heating/Cooling, the Central Heating/Cooling will be triggered to run if the home temperature diverges from the set point. Essentially this is the recirculation + thermostat mode. Built-in compressor is NOT used in this mode to heat/cool, which is good if Central Heating/Cooling would be less costly. Dehumidification by the Boreal is not available in this mode. While in recirculation mode, CO2/VOC/Timers will enforce ventilation mode, however, and for that period of time the compressor could be required and used as needed.

    2. In all other modes (Air Exchanger, Heat Pump and Smart modes), the compressor is available and will be used as the primary way to heat/cool as well as to dehumidify; central heat/cool will be called to *additionally* run according to the parameters specified via the wall/microcontroller display.

    3. If Central heating/cooling is called to run, Air Exchanges as programmed/expected will still occur in parallel to Central heating/cooling being run.

    4. The Boreal does modulate the output by varying the fan speed.

    5. Regarding the low EER/SEER, the Boreal is a multi-function device that's optimized for air exchange and dehumidification. While it does operate as a Heat Pump as well which might satisfy the needs of a Passivhaus, for larger heating/cooling loads, it's *normally* (*normally* because some houses with big cooling loads are still very comfortable in the summer simply by removing humidity) expected that dedicated heating/cooling devices will be installed.

    6. Dealers are expected to be the first point of contact for all service calls.

  17. ethan_TFGStudio | | #17

    Riversong, Minotair, and Durability
    OK, maybe it is too late to be reading GBA, but after perusing some of Riversong and Holiday's comments on durability over here...

    ...and then reading this complicated post about an amazing!, technically advanced, combined ERV and Heat Pump with a scary spider looking machine that would scare me every time I opened the utility room door... I see a way to connect the durability question with the technology question...

    While it is important to contemplate durability as well as sustainable sourcing of materials... it may be most important to make sure that the Structure is not overly dependent upon the continued functioning of any particular mechanical System. We should "model" or "contemplate" how our house will perform with zero electricity. Is there redundancy? Is there resiliency? Companies come and go... technology is replaced or becomes obsolete... we don't want mold forming in our roof sheathing just because the ERV/dehumidifier stopped working...

  18. GBA Editor
    Martin Holladay | | #18

    Response to Ethan T
    I have noted the same point in the past: If you are designing a thermal envelope that is at risk of failure when the interior RH gets too high, then you are depending on future homeowners' operation of the ventilation system to prevent envelope failure. Do builders sleep well at night under these circumstances?

    Ideally, our envelopes should be robust enough to survive a little homeowner abuse.

  19. ethan_TFGStudio | | #19

    Robust envelopes and napkin calculations...
    Martin, I agree with you... I think ventilation and dehumidification will be for occupant health and comfort in a CLT+wood fiber or other vapor open home... and if the parts wear out on a fancy Magic Box it can be replaced by two simple DC powered solar fans running in either direction. I think shrink wrapped homes with mandatory ventilation requirements to prevent mold are another story...

    Now to my rough napkin sketch cost/value calculations. The Minotair is about $5k, plus maybe $3K installation. A Panasonic Intellibalance is about $1K plus the same exact ducted installation cost as the Minotair, so lets say $3k. Now a Panasonic 1 ton Minisplit will be about $1.5k plus maybe another $2k installation. So this puts the installed Minotair around $8k and the Minisplit+ERV at about $7.5.

    But then you don't have dehumidification function on the Minisplit/ERV combo, and you don't have the benefit of the system being integrated... so the Minisplit and ERV will be in a bad marriage... at worst fighting and at best not talking to each other (and you aren't getting what they call "Free Cooling" which I don't 100% understand).

    All of the above assumes that the home is able to be heated exclusively with the Minotair or perhaps the Minotair running the $500 add on resistance heat periodically (not all winter).

  20. GBA Editor
    Martin Holladay | | #20

    Response to Ethan T
    Ethan T,
    It's rare to find a house with heating and cooling loads that are low enough to be entirely satisfied by a Minotair unit. But for the rare home that falls into that category, the cost of the Minotair seems easy to justify.

  21. user-995931 | | #21

    Minotair Experiences
    I just completed a "pretty good house" and my heating/cooling loads calculated were pretty close to the capacity of the Minotair (plus inline heating coil) so I decided to go for it. I purchased the 3KW inline duct heating coil as well, and put a cadet baseboard heater in each of the bedrooms just to be on the safe side.
    The company has been good to work with, they're very responsive and helpful. However, the unit I received seems to have a bad compressor, so it's turned into a money pit - they're going to repair the unit for free and even perform some upgrades, but I'm having to pay the shipping both ways, to canada. They've also offered to send me a new compressor completely free of charge, but the local HVAC repair shops are leery of doing the work and are quoting me fees in the $2000 dollar range to swap compressors.
    In the mean time,we've been relying on the heat coil and cadets alone for heat this winter and it's been costly in terms of energy usage as well.
    Bottom line, I'd recommend the Minotair to you if you're close to a dealer (east coast, canada, or alaska locations listed). Otherwise, you'd probably be wise to steer clear.
    It's also worth mentioning that I didn't get the advantage of canadian vs. USD, they charged me $3950 USD. With the wall control, heating coil add on and shipping, it's more like $5000. Comparatively, you can get an Ultimateair 200DX for $2500 and a MR Cool DIY 24K btu mini split for around $1650 from Home Depot for a total of $4150.
    Now I'm trying to figure out if I should double down on the Minotair and pay hundreds/thousands in shipping or if I should junk it and buy an ultimateair + mini split and hopefully have something a bit more reliable (or at least, repairable) and possibly more efficient (heating would be from a heat pump entirely vs. half resistance half heat pump). Any thoughts?

    1. barkingeater | | #26

      Im not sure of your location but it seems Pretty Good House envelope would require a larger heat engine than just the minotair? my feeling is that if the minotair is to be used as primary it would need to be in PH levels of a house? that would explain the high use of the resistance heat?

      1. Expert Member
        Michael Maines | | #27

        Tim, the Minotair unit can connect (electronically) to a Mitsubishi mini-split to give you all the heating and cooling you would need in a PGH.

  22. GBA Editor
    Martin Holladay | | #22

    Response to Zac Blodget
    I'm very grateful that you are sharing your experience. It's a valuable cautionary tale.

    After reading your comment, I double-checked the advice I gave in my article. In that article, I wrote:

    "Early adopters of this technology face a few risks:
    • Will this small manufacturing company provide adequate technical support in the future?
    • Will this appliance provides years of trouble-free operation, or will it require frequent maintenance?
    • Will local HVAC contractors be able to perform future repairs?
    As with any relatively new appliance, time will tell."

    Unfortunately, I can't offer you any advice on your dilemma -- whether to double down on the Minotair or throw in the towel and start from scratch.

    Good luck.

  23. user-995931 | | #23

    Response to Martin
    Yeah, I gambled and lost for sure.
    To be clear, the Minotair folks are offering great service and support, but shipping costs are a huge factor. If you're close to a dealer, I'd still recommend it.

  24. GBA Editor
    Martin Holladay | | #24

    A comment from Karl Audet of Minotair
    Karl Audet, the founder of Minotair, just sent me the following email:

    "I recently stumbled across a discussion on your blog with a certain Mr. Blodget. While I understand the point of view, it only shows half the story. We did fix his machine and upgraded it to the best extent possible (better silencer/muffler, no more vibration, better performance), which should make a difference in his perception of the product. Yes, he needed to pay for transport, but that wasn't thousands like he wrote. A couple of hundreds each way. Besides, he got a revamped and better machine that he could not have had otherwise, easily 800 USD value for only the cost of shipping. I'd say he got a happy ending.

    "It would be great if you could ask him how the machine performs now and whether he was pleased and satisfied with customer service. We may still be a young company, but I'd say we deliver to at least if not more the level of a major.

    "Best regards!
    "Karl Audet"


    I wanted to comment on the posts regarding the idea that we should build houses that can survive with zero electricity. (This is also about the Miontair in the end...) This is my one goal in life and it has been my biggest struggle over the last 15 years. As a sustainable architect who builds new, Net Zero and Passive Houses and also does a lot of Deep Energy Retrofits (DERs) I have seen the hard parts of this issue up close.

    It is easy to build a Passive House or simple a really good house NEW that has very few problems with moisture. Your biggest problem if the power goes out for a long time will be build up of indoor humidity and the lack of fresh air as you have pretty much sealed the house from out door humidity in every direction (roof, walls, basement, slab. ). However you cannot live for long in a sealed box. Its true. I have tried. I lived in our sealed box for a couple of weeks when our ERV was down and it was not fun. We all felt it badly. Humans NEED fresh air.

    So, then you can crack the windows and get fresh air in the winter. But if its really cold out this is tough because you then loose the contained heat of your awesome PH enveloped house. In the summer you can open the windows for ventilation but then you have outdoor humidity in the house. Both are survive-able for a while but not forever.

    With DERs in Lower New England this problem is huge. Most people with existing houses can only do so much and cutting off moisture from the basement into the house is often really impossible to do thoroughly. I am talking moisture vapor up through the slab and through not being able to seal the walls well enough. Think ruble foundations and uneven half dirt basements etc. (Yes you can tell me the 100 solutions to doing it but the reality of physics and money and space are often insurmountable for the average person. I have tried them all . It is SO not that easy....) So with a DER if you encapsulate a house with an awesome envelope above a half-assed basement you WILL have a lot of humidity and a lot of problems.

    If the house only has radiant heat (no forced air system or AC) then you have really big problems. You have to put a bunch of dehumidifiers in and you have to get some sort of ERV in there for fresh air if you have really sealed the envelope well. Your energy bills for running this operation are really high. You start to question whether you should have done those energy efficiency envelope upgrades in the first place. Because your house sat for 50 years with zero humidity problems (because of that super leaky envelope you had) and now the floors are warping and doors wont close because inside your sealed box is now very humid.

    This is perhaps the biggest problem I face as a DER architect. This moisture retrofit problem. It may be specific to my little micro climate of southern New England where the humidity is killer and we have a lot of houses that have not yet gotten ducted central air. (even tho in the last 30 years it has become a fact that we for sure need AC.)

    So even though ALL I want is to build houses that do not need electricity to survive I cannot find a way to build a super energy efficient one that doesn't. (hence my obsession with passive ventilation. But it still does not tackle humidity.)

    In the mean time...

    This is where the Minotair seems like a godsend! Humidity control and fresh air all in one! I talk to Alex about buying one all of the time for my own DER house and this s the year, Alex, this is the year.

    1. Nicolas_Bertrand | | #28

      Very interesting viewpoint about the problems a DER can cause. Never looked at it that way, but it makes a lot of sense. Though the retrofit is done to save and make the house easier to heat/cool, it does cause a lot of problems when it comes to air circulation and humidity.

      Interested to hear if you have tried the Minotair yet and if you had any results to share?

    2. alan_from_dc | | #29

      Elizabeth: This is about M. Audet's Minotaur product, and your comments. About 3 years ago you described for New England the challenge we face here in Alexandria VA. This place is humidity city. (I grew up in Michigan.).

      We own a twice-rehabbed 1968 mid-century modern glass house. The first story is built into the marine clay hill. Two Carriers heat and cool the original 30 x 40 foot structure. We have just added a 12 x 20 tower to one end -- 3 stories, with the first built into the hillside, with two walls serving as an over-engineered retaining wall system to keep the clay hill from pushing in one end of the house.

      The tower will be seriously insulated. (Well, except for the glazing.). We were going to heat & cool the tower structure with Mitsubishi ductless units, adding an ERV to the walkout basement. I was thinking that our planned cutting a door between the "old" building and the tower would give us a reasonably healthy air exchange for the new two floors, given an internal staircase. We will super foam the new envelope, and then peel off the 12-year old membrane of the larger building's roof, sister the joists for more depth, and spray foam a 10-inch roof stratum.

      After reading the Minotaur discussion, I see that our planned HVAC may simply add to our humidity challenges.

      Have you, or anyone, experienced the Quebec technology since the last entry here?

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