koosjr

Well ja. I have load shedding 24/7. Only a solar system to run from. It will take quite a bit of thinking to make my setup viable, if at all. Things like fans will have to be selected with the utmost care. Easy peasy to make a wrong selection and double your consumption for the same flow. That said, I don't think you need 6 fesh air changes per minute at night time to control humidity. What about you can do a lot less on less on that side and only keep the box ventilation on? Jsut enough fresh air to keep humidty down? Is humidity your only issue at night time? Apart of course from temperature control?

Just for interest sake, what potency is possible from a well grown outdoors plant?

Prom, Thanks for an excellent post. The information in there is exactly the kind that I can work with. Thanks for the offer to help calculate the room consumption. Luckily I can do that to a T. Energy simulations still is some of the primary work I do for my customers, usually just on a MW scale. So, I am planning a 2.4x2.4 room for one reason only: So that I can in the beginning have walking space inside. Grow space will be no more than 2 m2. I certainly consider a type of hydronponic or autopot setup. I do like what I see form the Autopot. The 6 fresh air chages per minute is something I did not expect. That is a SERIOUS amount to cool or heat. For cooling, I just won't have the power for AC, but I do have a bore hole so I can do it geothermally. I have almost 20 meters of water column which gives me a few kilowatts of cooling. With 6 air changes per minute cooled geothermally, I should be able to stay below 26°C, but I will have to have a custom coil made. Yes, I know the TD-series fans well. We use them all the time. They are certainly some of the better products out there. So, are the air changed needed 24/7, or only when the lights are on?

Many things said here that agree with. Yes, I not going for a moon landing, but I do want to have a good chance to get the best plants I can in the shortest time. The climate is obviously important - and there I tried to get some direction on another thread - about if and how one can mitigate the problem of say running above 30 °C for some lenght of time. The suggestion to say that then you avoid growing in the hottest months, is practical at least. Perhaps not always the answer one wants, but practical. Growing indoors without Eskom is a huge challenge. That is already evident on this forum. The problem for many here is that they have made their setups in a time where load shedding was not such a big problem is. Now it is and it will not get better. With that in mind, it would be foolish not to put in an effort now to see how one can deal with it. Again. If I do not have much power at night, what should I do? Reduce the power to half the level and hope it works? Sounds like high change for poor results. Lights is THE major issue to get right. It makes the heat which in winter is good and in summer is bad. It makes the light. 5000K works better for veg and 3000k for flower. I have 25 years of experience with heat load calculations. This is by far the highest heat load from lights that I ever had to work with and I can tell you, from my perspective this will be an issue regardless of the application not only for a cannabis room. If I just buy the fist light, good or bad, then I still have no possibility for reconfiguration if I need to. With the light I want to design myself here, I very much want the flexibility. So, if I grow plants, it does not go well, I post pics and the problem is perhaps a common one with a solution - like changing the shape of the light, I want to be able to do that on the spot. If I buy a light with all the dimmer functions etc I am going to pay through my ears for it. A good light is at the very least R 20 per watt or more. I can build that myself however because I am well fluent with PCB design. For me to put in the circuitry needed to dim the light is not that big a deal. I will rather want to find out that I dont have to use it, than not having it and needed it. Lets say then I can have it done for R 7 per watt, power supply included and it ends up begin good. That will be a good deal if one wants to expand further. Right. Air changes. 6 air changes per minute is already something to work with. However, that probably does not mean 6 FRESH air changes per minute? Just recirculation I suppose? And then, when the new range of LEDS come, all I need to do is change a component and order a new batch. The rest will be sorted.

What reluctance to accept help? You have yet to provide any proper data of your lights. I did so I know hat I work with. Rather the devil you know. I was simply discussing the problem and brain stormed a bit. Me think you need to go and smoke a joint. You sound way to tense. But that said, this happened on other forums before. I got into a topic and made a nice thread where the ideas was developed. Got lots of appreciation from some for it and then of exactly the same reaction like yours from those like who apparently feel threatened that some oaks wants to figure out things with developing the theory first. Same story. Told me how stooopid I am as an engineeeer who cannot understand these basic topics that one apparently learned on school. Simply could not follow the discussion. Told me theory and practice does not meet bla bla bla. Eish. And one should not dare mention the Dunning-Kruger effect because that they like to try and throw that back at you. You can see that everywhere. Mechanics thinks they know better than the engineer who designed the engine in front of them. That is now the engine and ALL the tooling and technology to built it. So mechanic think just because is able to make it faster, he did better - yet he is unable to design and make the engine for starters. Too stoopid to think that perhaps the engineer could also do what he did, but he did not because there was many other things to consider. On one forum I documented the remapping of the ECU of my TD5 Land Rover. I started knowing nothing about engine mapping. I documented everything from knowing nothing to the final result and covered the improved measurements during the exercise, in detail. I ended up with probably on of the most balanced and polished maps ever done anywhere for this vehicle, because I did my research and I can make things work in practice. You can ask anyone who have my engine map on their car today. It ended up with a super smooth vehicle, nice power, vastly improved shift quality on the auto gearbox, improved traction control in low range, improved engine protection - all of which "experienced" engine tuners (with no engineering degrees mind you), bypass. They just moer the fuel map because that is how they did it all the years. Worst place ever to scratch around in an ECU map. And they have broken maaaany motors with their approach. A few really bright guys stuck with me there and we could generate some great ideas - and we had to ignore the others who were annoyed when we got good results. I honestly doubt that you of all can teach me anything about heat exchange and inefficiencies. Sorry Sir. I am perfectly aware of the problem of running lights at day. Said that even before you did. But you should know by now why I need to consider it. I only have solar power. No eskom. Can't run a gennie here all the time. If that reason is not ligit enough for you, then why waste time here? It is a damn good reason. Do you perhaps have clever ideas of how to get through a night other than buying fat batteries? Or running a noisy gennie? I bet you don't. Neither have I. Option 1: Look at a major heat source and see if I can do something about that. And the lights, regardless how good they are will dump at least 40% of what ever watts goes into the room, as raw heat if it is not removed by other means. It does not matter how they are put together. Option 2: Grow Outside. Not for now.

Jip, those references helps, but the point is I will not know until I have the first prototype on my table. And that is what design is about. I now need to make the best guess I can based on the best information I can get, order the stuff and see if my expected calculations managed to reflect in practice. Design is about not having to try 50 times. It is first guess and perhaps try 2 or 3 times.

Hey buddy, no need to get excited. Obviously a kak led will give off more heat than a good one. I never said it would not. Good LED or KAK LED, a heat sink does not make the heat less. It simply spreads it - and that I have learned prevents foxtailing The lm/w is a great indication of the efficiency of the light. There is a theoretical maximum that a 100% efficient source can deliver. Some of us likes to get technical. You have a problem with that? If you just want to draw on your experience and no more, good for you. Me wants to understand the theory and connect it to practice. I am quite comfortable with heat transfer. Don't have to prove that to anyone. I have also designed plenty of electronics by now and I can assure, we to have to deal with the heat from components. You cannot just leave it.

Also have a look at this. Make a full cover for your tent. This should help a LOT. Alububble-Data-Sheet-2906_2019-final-no-crops.pdf

I do see that winter heating is quite a challenge for those with grow tents. This is a suggestion only. You can make a cover for your box with this product and perhaps remove it again in summer. Alububble. I have used this on hanger type structures and the R-value is really great for the thickness. A typical tent will have a U-value of about 6 W/m^2K. This means that a 1.2x1.2x2m tent with an exposed area of about 11m^2 will have a heat loss of 66W for each degree of temperature difference between the box inside and the ambient. With this Alububble, the U-value will drop to below 1 W/m^2K so your loss will be about 10W for each degree difference. Perhaps something to consider. Long tie since I got new prices so I don't know what a roll currently goes for, but I do think it will easy pay for itself within a few weeks if you are dependant on direct electrical heating. Alububble-Data-Sheet-2906_2019-final-no-crops.pdf

Jip. Many things to consider. I may even consider wood since I do have sawmill at home. But that is quite an effort better suited for something permanent.

What you seems to be unable to grasp is that regardless how cool the fitting runs, it still dissipates the same watts as heat rejection. If that watts are dropped in your room, then the room gets hot. As simple as that. And it gets the very same hot regardless how cool the surface feels to your hand. I fully understands why you would want to reverse the light cycle to night time - that is the obvious solution if you have ESKOM power. If you don't, then it has to be run from batteries. At R 25 000 for a 5.2 kWh Lithuim, of which you would probably need at least 2 then, it can become rather steep. If this problem can be solved in an elegant wat, then I can assure you it will be to the benefit of many others who will be ever ore plagued by load shedding.

Well, the big problem is I will not be able to change my light cycle to work at night when it is cool... I simply will not have the power for that. My power is in the day when the sun is shining. Regardless of that, I would like to see your light design that does not give off any heat. LEDs, even the best of them is about 50% efficient - unless you can show me products where this is not the case. Shit, I have looked at many data sheets of components and there just ain't that magic one in there. Sorry, it simply is impossible. A 1W LED will give off about 0.5W of heat minimum and if that LED is inside your room, it is room load. I am not trying to be wiseguy here. This is just plain and simple realities of engineering. I have never come across a 100% efficient device. As said, the fact that your hand does not feel the heat, does not mean there is not the same heat. It is just spread over a larger area. I also see people are struggling to heat up boxes in winter - and yet a simple layer of good bubble wrap sheets around the box will probably more than half the heat one would need to keep it hot. In that case, the light alone will be enough to heat it up.

OK, so I do understand better now what you say - but you are mixing up your 3000K and 5000K again hehehehe.. For this discussion, I have attached the data sheet of the LED as it will help a lot to explain a few points. Your input is based on experience and it helps me a lot to build this puzzle quicker. Thanks a lot for that. Yes, my light will indeed be such that if I use the 5000K channel it will be enough light without using any 3000K and vice versa. Regarding the heat though, there I have to differ from you completely. My day job is HVAC so I have been doing heat load calculations for buildings for the past 20 years. Any device, regardless if you can "feel" the heat or not, if it dissipated say 20W of heat, it is done - it does not matter if it was done at a surface temperature of 40°C or 60°C. You can't reverse it. Heat from a device (and even humans) is basically transferred in two ways to the room. Convention and radiation. If that heat was transferred to the room air either way, eventually the room air heats up the same amount and you have to remove it via the AC unit or otherwise. However, a higher surface temperature does make a difference with regards to how heat is transferred as the higher it is, the larger a portion of the heat will be transferred via radiation. Radiation can be a very bad thing because that is the thing that can literally burn your plant leaves from a distance. Spreading out the LEDS on the panel to lower the surface temperature therefore will reduce that radiation component - but not only that, it spreads the light out better. What you are trying to suggest is that if you run a LED at a lower output, it will be more efficient. I did not thought about making those calculations, but yes it does bring up the efficiency slightly. If I work on 90% of the rated lumens, then I go up from 137 lm/w to 151 lm/w and at 75% lumens it reach 160 lm/W. That said, the difference in heat rejected between 137 lm/w to 160 lm/w is not that much. I can however see the advantage in longevity clearly. What is also tells me is that controlling the LED means I basically need a current controller - not a voltage controller. Since in a room like this, lights are the major source of heat, it can be a big advantage if one can capture that heat and get it out of the room before it is transferred to the room air. All in all, we can get to a very good answer here. An affordable, reliable light that does not dump heat into the room. 2009021504_HONGLITRONIC-Hongli-Zhihui--HONGLITRONIC-HL-A-5730D1W-S1-08-HR3-LY_C210347.pdf

Yes, basically it is two different lights on one panel so although the total power of a panel will be say 200 W, I will be using only 100W for Veg and 200W for flower. I surely have no intention to use both spectrums all the time. I also want it dimmable because if I run from solar, then some days I might have to compromise and tune down the light to the minimum level possible for the hours that I have limited or no solar. I do not want to get too technical though. Where I don't follow you well is with regards to the heat rejection in the box. Event he 165 lm/w Samsung LEDS have almost 50% energy loss in heat. So, if you power 100W, then 50W is heat. Do I miss something there?

Do you have access to burning some wood? I have lots where I am, so I am planning to have a plain old Donkie and heat it up with sticks. If you have a 200 litres insulated tank at 60 or 70°C you can pull it down no nearly 30°C with a properly selected heating coil. That will give you already about 9kWh of heat - and you can even store then with your solar system with an element during daytime if you have any access.

Thanks Sir! Nice to have a view from someone who has both. I think perhaps rather Budbox for me. I think where I am a stronger construction is probably gong to be needed more.

I am reading as much as I can here, and it seems that optimal temperature for indoor growing is 18-26°C. However, we need to be realistic that load shedding is not going to get better and this will for sure kill many indoor setups. I will be running from a solar system, and it will simply not be possible to run an AC unit from batteries. 'n Gennie perhaps, but fuel cost will be rough. I am high up in KZN and at least we have exceptionally mild weather. I have yet to see summer temperatures over 33°C and even on cold winter nights we might perhaps get 10°C. Right now we are sitting at 19°C - mid May 7:00 in the morning and we will probably hit no more than 24°C for the day - actually great temperatures to work with. So, what happens if summer comes and you have many hours of 33°C? What are the ways to mitigate that other than AC? After all, the plants outdoors grow in that heat and they do very well. Since this is a very small space, I can in fact get some cooling from my borehole for which the water is always about 21°C - then I run a pipe loop in and out and circulate that through a coil in the room. I will probably be quite comfortably get below 28°C I think. Then all input I will have is a pump and a small fan.

I think my first post is clear enough what I want to achieve. Yes, I am going to have a light with both 3000K and 5000K such that either can provide the full power needed for veg and flower. I will then have each circuit to be fully modulating - which is easy enough to do so I can go 50% of the one and 50% of the other if I want to. It seems to save manufacturing costs, I need to limit my panel sizes to 400x100mm - not a bad length and I am still playing with ideas of how to assemble it. I want use aluminium PCB's as it will help a lot to remove heat from the LEDS and hopefully will at least make them last better. My thinking starts leaning towards having a dedicated plenum system for the lights where the air in/out is a separate circuit to that of the airflow for the box - so this means that almost the entire heat load of the lights can be removed from the box.

Nope, ventilation for the room through the light fitting will probably not work as well as I hoped. I ill have to get that heat out separately which means extraction and I doubt that ill give much leave movement. Some good ideas on this forum help shaping my ideas.

Which one would you choose? Budbox does claim that the white inside is better than Mylar, and it does seems like even a slightly better construction. These two seems to me stronger than the cheaper alternatives and it can hang quite a bit more.

OK, so I found that LED light efficiency is about 40%, which means that in this room I will have a heat gain of nearly 300W. So, if I do blow air through my light fitting it means at least a 3°C increase if the air passing through the fitting. That will give me problems in summer but in winter this will be advantageous. I need to think a little about it... I won't have enough power to use an AC unit, but I do have other options. Maybe some geothermal...

Question: What if I incorporate the light fitting and the ventilation? Make it a low density 400x400 light fitting with perforations through which one can then also have a very nice downward flow through the plants? 4 fittings on a 1.2x1.2m tent.

Look, it is not a matter of simply disregarding your figures. A "wrong" value is not bad if it is at least accurately wrong all the time. You het my drift? We often have to work with what we have. The actual driving force as you have mentioned, is indeed vapour pressure. Most people - engineers included - have no idea that this is the fact. However, difference in vapour pressure is not something one can measure easily - most of that eventually is determined empirically.

https://migrolight.com/blogs/grow-light-news/cheap-par-meter-hack-use-a-lux-meter-to-measure-par-accurately Perhaps not a bad ay of doing it initially.

Being an HVAC designer, Psychrometrics is my forté and I had at one stage a commercial biltong drier on the market that worked on the refrigeration principle. So at least I can follow this discussion. To get down to 40% is very rare in natural conditions so I highly doubt your figures. What I suspect is that you used one of these electronics Temperature/humidity meters to give an indication. However, electronic humidity sensors - even the good ones - are far less accurate than what the data sheets claim. Even very expensive sensors gave me erroneous readings on high and low values. Usually below 50% they start to runaway to the low side, and above 90% they start to run away on the high side. I have seen this over and over especially in laboratories where I had to do full humidity control. At least though the runway is fairly accurate, but all it is then is a figure that you can use as reference for the meter you have. The most accurate way for me is still the old dry bulb / wet bulb thermometer. Nothing can fool that. It is perfectly reliable anywhere in the range. I have to agree that high humidity will cause you trouble within the hour. We also had that in the biltong rooms. If the system goes down you need to take immediate action.