Another North American Magic Box

musingsheader image

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

Posted on Nov 6 2015 by Martin Holladay
prime

Over the past few years, GBAGreenBuildingAdvisor.com 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 pumpHeat pump that relies on outside air as the heat source and heat sink; not as effective in cold climates as ground-source heat pumps.. 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(HRV). Balanced ventilation system in which most of the heat from outgoing exhaust air is transferred to incoming fresh air via an air-to-air heat exchanger; a similar device, an energy-recovery ventilator, also transfers water vapor. HRVs recover 50% to 80% of the heat in exhausted air. In hot climates, the function is reversed so that the cooler inside air reduces the temperature of the incoming hot air. ), 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.


MORE ON MAGIC BOXES

To read an overview article on magic boxes from 2010, see A ‘Magic Box’ For Your Passivhaus.

Three magic box manufacturers are now distributing these appliances in North America:

1. The Minotair Boreal 12000 is described in this article. For more information, contact the manufacturer: Minotair, 45 Rue de Villebois Unit 300, Gatineau, Quebec J8T 8J7, Canada; tel: 819-777-2454; e-mail: info@minotair.com.

2. The Conditioning Energy Recovery Ventilator, or CERV, provides fresh ventilation air while simultaneously exhausting stale air from the building. The CERV also provides a limited amount of space heating and cooling. For more information, see A Balanced Ventilation System With a Built-In Heat Pump.

3. When paired with the optional Cool Breeze unit, the Air Pohoda Ultima240E ERV provides fresh ventilation air while simultaneously exhausting stale air from the building. The Cool Breeze unit provides a limited amount of cooling. For more information, see New Green Building Products — May 2014.


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 BtuBritish thermal unit, the amount of heat required to raise one pound of water (about a pint) one degree Fahrenheit in temperature—about the heat content of one wooden kitchen match. One Btu is equivalent to 0.293 watt-hours or 1,055 joules. /h of space heating and up to 8,700 Btu/h of cooling. While that’s not enough to heat or cool most homes, it might be enough for a very small Passivhaus.

It’s installed like an HRV

Ideally, the Minotair Boreal 12000 is installed like an HRV with dedicated ventilation ducts. In a pinch, though, it can be connected to the forced-air ductwork of a furnace.

According to the manufacturer, “The Minotair is an innovative device used to control the ventilation, temperature and humidity of your house. It filters, dehumidifies, heats, cools and renews the air to provide a healthy and comfortable environment all year round. … [It is equipped with an] innovative motorized damper permitting several operating modes such as air exchanger, heat pump, recirculation. … In addition to standard antimicrobial filters, there is also optional activated carbon filtration for odor removal as well as HEPA filtration for unsurpassed air quality.”

The maximum heat output is 9,400 Btu/h

I asked Karl Audet, the president of Minotair, about the heating output of the Boreal 12000. He responded, “It produces 9,400 Btu/h of heating when the outdoor temperature is at 47 degrees F. That’s the outdoor temperature at which it is rated.” Needless to say, the appliance’s heating output drops as the outdoor temperature drops.

“For colder outdoor conditions, you can attach a 3,000 watt electric coil,” Audet said. “We can set up the system so that the electric coil makes sure that the distribution air [during the winter] is always at 40 degrees C [104°F]. But the prime mission is not to be your central heating or cooling appliance. First and foremost, this is a heat exchanger” — in other words, a type of HRV.

Indoor air: too dry in the winter, too humid in the summer

Audet feels that most HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. systems do a poor job of controlling indoor humidity levels. “We need to get control of indoor humidity,” Audet told me. “HRVs dry out the indoor air too much in winter months, when you have cold air, very dry air, coming in the house — including infiltration through doors and windows.”

Audet noted, “The magic box concept originated in Europe. With the Nilan [a magic box manufactured in Denmark], at low outdoor temperatures your house becomes too dry. The unit didn’t provide a means to recirculate the air. In our [Canadian] climate, that is not acceptable. You need to be able to control it so it doesn’t always exchange the air.”

He continued, “Our unit will stop bringing in outdoor air until the indoor humidity comes up. And in summer we don’t let you go beyond 60% RH. It’s a convoluted machine, but humidity levels are looked at first and foremost.”

The Minotair Boreal 12000 has flexible control options. “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. We just don’t let you go beyond 60% during the summer. The machine changes the algorithm in winter. As the outdoor temperature gets below the freezing point, the machine will lower that set-point automatically.”

Audet continued, “The controller allows several options for cold weather ventilation. It is user-settable. One option ensures that below a certain outside temperature, the unit will no longer do any air exchanging. At very cold temperatures, there is already plenty of natural ventilation occurring through your keyholes. And you have another setting that says that if the indoor air gets too dry, there will be no more air exchange until it gets a little more humid inside. Or, if you prefer, you can set it to intermittent mode, to always provide 10 or 20 minutes of air renewal per hour.”

Lowering indoor humidity during the summer

According to Audet, “This device has a special way of achieving cooling. We have an effect on indoor temperature, but our biggest effect during the summer is reducing the indoor humidity level.”

He continued, “Humidity is the battle that you have to win. Venmar makes air exchangers, but there is no way they can control the humidity in the summertime. For that, you have to use a compressor.”

Power use

  • The appliance has two ECM blowers that can automatically increase fan speed to compensate for a rise in static pressure caused by clogged filters.
  • Each fan motor draws a maximum of 136 watts, for a maximum fan wattage of 272 watts. According to Audet, unless the fans are facing high static pressure, they will usually draw much less than 272 watts.
  • The airflow delivery rate is adjustable from 80 to 250 cfm.
  • The compressor draws up to 725 watts. According to Audet, “The colder it gets outdoors, the easier it gets on the compressor. At -25 degrees Celsius, the compressor draws the least power, because the cold air makes it easier to condense the hot gas. The hotter it gets outdoors, the harder it has to work.”

Comparing the Minotair to the CERV

The specifications of the Minotair Boreal 12000 are similar to those of the CERV. Both appliances have a maximum airflow rate of 250 cfm. While the CERV claims to have a maximum heat output of 8,500 Btu/h, the comparable figure for the Minotair Boreal 12000 is 9,400 Btu/h.

One notable difference: the Minotair Boreal 12000 is much more compact than the CERV.

Cost

The cost of the Minotair Boreal 12000 is $4,200 (Canadian dollars), or about $3,213 at the current exchange rate. That’s less than the CERV, which costs $4,500.

Needless to say, it’s hard to estimate installation costs. “If you plug it into a furnace, the cost of installation might be $1,000 to $1,500,” said Audet. “But if you are going to be doing a full ducting job, the installation cost could be $2,000. Each house is different.”

Do you really need a magic box?

Emmanuel Cosgrove, the founder of a Canadian green building web site called Écohabitation, isn’t convinced that the Minotair Boreal 12000 is worth the cost. He wrote, “This type of machine is hard to recommend, especially since its cost often exceeds that of an excellent HRV and a better performing wall-mounted heat pump.”

It seems clear that the Minotair Boreal 12000 does a better job of controlling indoor humidity levels than a typical HRV or ERV. However, 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.

Martin Holladay’s previous blog: “A Backyard Test of Liquid-Applied Flashings.”

Click here to follow Martin Holladay on Twitter.



Image Credits:

  1. Image #1 and #3: Karl Audet
  2. Image #2: Minotair

1.
Nov 8, 2015 6:13 AM ET

Response from Karl Audet of Minotair
by Martin Holladay

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.
Nov 30, 2015 9:56 AM ET

The Boreal is more efficient?
by David Hicks

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.
Dec 1, 2015 1:02 PM ET

Response to David Hicks
by Karl Audet

David,
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.
Dec 2, 2015 7:05 AM ET

Response to Karl
by David Hicks

Thanks for your very thorough explanation, Karl!


5.
Jul 8, 2016 7:04 AM ET

Winter Humidity Management
by Venkat Y

Karl,

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.

Thanks,

venkat


6.
Jul 8, 2016 7:12 AM ET

Noise
by Venkat Y

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


7.
Jul 8, 2016 7:30 AM ET

Response to Venkat
by Martin Holladay

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.
Jul 8, 2016 8:51 AM ET

Thanks
by Venkat Y

Martin,

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,

venkat


9.
Jul 8, 2016 8:09 PM ET

EER 10
by Venkat Y

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?

http://www.minotair.com/wp-content/uploads/MINOTAIR_BOREAL_12000_Specifi...


10.
Jul 11, 2016 2:30 PM ET

Karl Audet responds to Venkat's questions
by Martin Holladay

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.
Jul 12, 2016 8:16 AM ET

Boreal control of Central HVAC
by Venkat Y

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.
Jul 12, 2016 12:07 PM ET

Karl Audet responds once more to Venkat's latest questions
by Martin Holladay

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.
Jul 13, 2016 7:07 AM ET

Edited Jul 15, 2016 10:36 AM ET.

HVAC control
by Venkat Y

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?

Thanks.


14.
Jul 13, 2016 8:16 AM ET

Edited Jul 15, 2016 10:43 AM ET.

Response to Venkat
by Martin Holladay

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.


15.
Jul 15, 2016 10:35 AM ET

Info might be of value to this blog
by Venkat Y

Martin,

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,

venkat


16.
Jul 19, 2016 11:07 AM ET

Edited Jul 19, 2016 1:23 PM ET.

Conversation with Mr. Audet
by Venkat Y

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.
Jun 1, 2017 11:36 PM ET

Edited Jun 1, 2017 11:41 PM ET.

Riversong, Minotair, and Durability
by Ethan T ; Climate Zone 5A ; ~6000HDD

OK, maybe it is too late to be reading GBA, but after perusing some of Riversong and Holiday's comments on durability over here... http://www.greenbuildingadvisor.com/blogs/dept/musings/green-homes-don-t...

...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.
Jun 2, 2017 5:24 AM ET

Response to Ethan T
by Martin Holladay

Ethan,
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.
Sep 14, 2017 8:27 AM ET

Edited Sep 14, 2017 8:49 AM ET.

Robust envelopes and napkin calculations...
by Ethan T ; Climate Zone 5A ; ~6000HDD

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.
Sep 14, 2017 9:17 AM ET

Edited Sep 14, 2017 9:18 AM ET.

Response to Ethan T
by Martin Holladay

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.


Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!