What percentage water savings do growers typically see with the recaptured water, since some of the water is lost to runoff and not all of it makes it into the plants for transpiration?
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How do growers needs differ based on whether they’re in a greenhouse or indoors?
Also, as a matter of personal curiosity, do you mind if I update my articles on VPD with the diagram from your documents?
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Indoor cultivation with recirculated air is not very sensitive to outdoor climate. However, electric power rates play a role in overall cost of operation.
Greenhouse cultivation is different. Here, the envelope load plays a large role in indoor climate control. Energy costs are most important.
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Agreed. During the day the amount of water required to remove from the air is much higher compare to the amount of water required to remove from the air during the night. my question is How you solve this problem when the lights are on?
fore example in greenhouses they ventilate during the day
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Ok thank you.
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I believe both strategies will survive but the debate goes on. Indoor grows are more controlled and can yield predictable crops under controlled conditions. Greenhouses depends on sometime unpredictable sunlight and a battle with excess heat buildup. However, as the greenhouse industry matures and more methods are available to control sunlight and avoid excess heat, this strategy will become more prevalent.
Yes, please use our VPD info
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I have two questions,
What is the cooling capacity? and do you use additional dehumidifier to solve this problem or your system is enough?
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Ah. Greenhouses are different because of the ventilation issue. Indoor grows do not ventilate.
Frankly, this question is difficult to answer because ventilation in dry climate will yield a better result than ventilation in a humid climate. I think each project requires a TMY weather study to determine the best method for day/night temperature and humidity control.
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The MSP system is capable of handling all functions-Dehumidification, Cooling and Heating.
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In a closed environment nearly 100% of Evapotranspiration can be recovered.
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From our knowledge, in order to solve humidity problems in indoor additional dehumidifier is required to the HVAC system. that’s why we integrate to the HVAC system.
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Our strategy is different, we handle the dehumidification function as primary and cooling and heating as secondary. So, if the grower already has a air cooling and heating in place, we can do dehumidification only. On new projects, we handle all functions.
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What inspired the design of your multiple small plate technology? Was there a “eureka” moment, or was it the product of a slow evolution of improvements?
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Thank you for the questions everyone, and thank you @msptechnology for taking the time to do this AMA. We’re at time for the event but hopefully Walter will be able to stick around for a few more minutes to catch the last few questions.
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Air-to-air plate heat exchangers are more efficient than others, and also more bulky. We set out to design a wrap-around-plate dehumidification system with the smallest footprint and overall spacial volume. It turns out that using a multitude of small plate heat exchangers, connected in parallel with respect to airflow, yielded a very significant drop in overall size while also reducing air pressure drop and fan power.
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Hey hey!
I was wondering what the biggest hurdle would be in producing something like a “VPD controller” for a sealed room? I know ultimately, the environmental controllers control VPD, but I have had growers ask for a straight VPD controller/monitor and all I can do is sell them an environmental controller and try to educate them on VPD as much as I can.
It seems like it would require a bunch of monitoring points/sensors and some cool controller software & hardware, but is there a specific reason that approach has been done by the controller manufacturers that you know of?
Thanks!
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Oh, got another question!
Why do the vast majority of dehumidifiers put out less capacity then they are advertised at? I have never really seen a 200 pint-per-day dehu actually pull 200 pints out of the air in a 24 hr period. I am guessing most companies test under absolutely ideal conditions for water removal and advertise the best possible results from the perfect environment. Is that it, or is there more to it?
Lastly, what is your rule of thumb for Dehu sizing in a room? I’ve always been told that a pint of irrigation water = a pint of water you need to remove from the air. Does that hold true across the board, or is there a better sizing method?
Thanks again!
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Casey, yes, vapor pressure calculations are part of our software. So, a grower can enter the desired vapor pressure deficit and temperature and the room will be controlled to this value. Or the room can be controlled to temperature and humidity with the VPD value shown as an output
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What is the difference between the DU and DV series?
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Casey, dehumidifiers with an AHAM rating have been tested and should do what they say. However, rating conditions are 80F/60%rh and if you are operating at lower temperature and humidity, the dehumidification capacity is dramatically reduced. This is why we urge growers to first choose a desired daytime VPD and then choose a daytime temperature that is high, but not too high to inhibit growth. Selecting with this daytime strategy will allow you to drop the temperature and VPD at night, if desired.
The sizing method you suggest is the best. irrigation = Evapotranspiration = Dehumidification rate.
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