Setting up a sealed room for winter - any advice?

Discussion in 'Grow Room Design & Setup' started by Sam&Max, Nov 16, 2017.


    Sam&Max Active Member

    what do you guys think of my setup, any advice? I am planning to build in one big room, two rooms with drywall side by side sharing a wall of 15 feet. One room will be for flowering and be 15x7.5x8 feet which is 900 cfm.The second room will be one third smaller than the other room and be around 600 cfm. It will be used for two motherplants, clone rooting and drying harvest. I will insulate the flowering room with styrofoam and seal it. (The two rooms are side by side and will share one wall of 15 feet. I will not insulate this wall, as I hope to share some warmth of the flowering room with the motherroom)

    Room for flowering:

    I plan to operate three 4x4 ebb and flow tables with a 100 gallon reservoir and a solenoid valve so that only one table at a time gets flooded. (Water is unfortunately not unlimited available). As a medium I will use rockwool.

    I will operate three 750 Double ended Gavitas. One Gavita per table.

    Outside, now in winter, it will have minus degrees and high humidity. So I plan to seal the room and use the heat of the lamp fixtures and also heat a bit by using a CO2 generator with propane (with the heat generated, I can save on electric heating a bit).

    In summer, I plan to add a minisplit AC for cooling. Also instead of CO2 by propane (which create heat), I might switch to CO2 tanks directly.

    Because of the sealing, the floodtables, the many plants and the burning of the propane, there will be a lot of humidity.

    So I will put in a dehumidifier. I am not sure actually, how much humidity I will have to deal with. I thought maybe a 120 pint /24 hours dehumidifer would be alright. I did read overkill is the way to go. You will get your room much faster under control.

    And of course I will use a fan with charcoal filter.

    Room for mothers, clones and drying:

    Here I would grow two mothers in soil or DWC under T5 lights. I would take around 100 - 150 clones every two months.

    Also I would dry the harvest in that room.

    I would put a charcoal filter and a dehumidifier in that room and hope that this room gets good warmth of the flower room.

    I try not to heat with electric heaters as it seems expensive.

    What do you guys think of the setup? Any advice?

    And actually I have some questions:

    - What would be roughly a recommended size of dehumidifier for that size of the room, if you dont have an AC (will add AC later in summer)?

    - Some dehumidifieres have an ionisator which claims to clean the air. Could this ionisation thing be something I dont want in the growroom?

    - Should I vent the flowerroom at least once a day? If yes, why? ( I could build in sealed electronic dampers, so the room would still be sealed)

    - Do I need to inject CO2 in to the motheroom or vent it? In summer I can vent the motherroom, but in winter it is very cold outside and the humidity is high. If I dont vent the motherroom and if I dont inject CO2, I am not sure if the mothers will react badly, because the CO2 levels might go too low.... Actually I don't want to buy another CO2 generator, as they seem too expensive for basically just some sort of gas oven.

    - Do you think I will need to heat a lot? The building is very very good insulated, but nobody lives there so it isn't heated. Outside it will be minus degrees but because of the insulation the temperature will even without heating never drop to zero. I will insulate the drywall rooms also with styrofoam, so that the heat of the lamp fixtures, the dehumidifier and the CO2 generator will stay in the small rooms.
    Last edited: Nov 16, 2017

    PsychoDad New Member

    Hi there , first post here ... I'm on my second grow so more on the noob side with the plants but i'm fairly good at other technical stuff.

    One thing I see about your plan ... thing is , when temps go below 0 Celsius RH drops to 0 so all the humidity will be generated inside .
    Another thing , the maximum amount of water in the air is dictated by the air temperature , same quantity of water in the air will give different RH readings at different temp .. that's why it's called relative .

    Just keep that in mind.

    Also , I don't think you will be able to cool heat generated from 3X750W gavitas with 900cfm, maybe in the winter , venting and CO2 seems a bit counter productive but I didn't experiment that yet, for me it looks like a waste of co2 if the room cooling is venting to outside.

    An AC unit will also dehumidify air, if you don't vent you need to cool the room with AC
    Sam&Max likes this.

    Sam&Max Active Member

    Ahhh... I just read the following... The humidity capacity of air at 0 °C is about 1/10th the capacity at 35 °C.
    So even if I have outside now 90 % humidity, it is not much absolute humidity and will be low relative humidity inside.

    The 900 cfm (EDIT: I mean cubic feet, it is also wrong written in my first post, but can't edit it anymore) is my room volume. Not a fan or something. I don't worry so much about cooling issues now in winter. More about heating. I wouldn't vent for cooling in winter... Only to have clean new air. Maybe only once a day when lights are off. If it is timed right, I can't imagine it will be a waste. But I don't know if it is even necessary...
    Last edited: Nov 17, 2017

    PsychoDad New Member

    900 cfm ... cubic feet pe minute... nvm

    even with minimal insulation and no air exchange 3x750W hids will need some cooling unless you have very high ceilings

    about humidity ...any water surface exposed to room air will evaporate and rase rh, also the plants will create a lot of humidity, if you defoliate you'll see a drop in rh.
    You will need a good dehumidifier, the ones that have the ioniser or other crap in them are way too small , that's good for a bedroom or something, what you need is a unit that's used in construction , the bigger the better but it gets expensive , with those you can use an RH controller that will automate the process , the home owner units beside being too small have setting that get reset when you unplug them(use a controller)

    I learned this the expensive way , my room is very similar to yours , took me almost one full year to refine it , I still can't get temps as low as I want ... but winter is coming :)

    Sam&Max Active Member

    Sorry, I mean cubic feet. It is 900 cubic feet!!!

    A friend did grow there before and he didn't made the ceilings lower but used the full 11.5 ft height. He operated 3 x 600 Watt hids and needed to heat to get to something like 20 degree celcius only. He said, if it is outside around 10 degree celcius, he didn't need to heat. So I just guessed, that if I make the ceilings a bit lower by building a drywall romm, insulate the drywall, and use CO2 with propane, I will have a more energy efficient situation. So now you say, that I need the high ceilings...

    Do you use a dehumidifier? How many pints? The one with 120 pints on amazon is pretty good rated and it seems like that the bulky ones for construction site don't do much more than this one...
    Last edited: Nov 17, 2017

    chemphlegm Well-Known Member

    No ions inside the grow room. exhaust is fine
    Sam&Max likes this.

    Sam&Max Active Member

    What is the thing with the ions???

    And is an exhaust beneficial in any way?

    PsychoDad New Member

    probably he ment heating the space when lights off , or that space is not at all that well insulated or there's some air movement

    reviews you read are probably from people that use that dehumidifier in their bedroom ...or small grow rooms , or vented ones.
    you will need a construction type dehumidifier at least in flower , there's no way around it you can take the info or buy the home unit and then the construction one when the smaller doesn't make it, maybe use the smaller in the flower room.

    I have no ideea what 120 pints means and too lazy to google it sry

    Sam&Max Active Member

    120 pints is around 55 Liters. 55 Liters per 24 hours. Actually people say it is too noisy for bedroom. They use it for example to keep their basement dry.

    I am not sure about the heating times.... He might had to heat only when the lights were off.... An option would be to have the lights on at night, when the temperatures are lower. But actually the place is good insulated and I don't think that day or night will make lot of difference.

    I also asked my friend if there would be any situation that it might get to hot and he said no... :-S

    I looked on the Gavita homepage and there it says ...

    Safe average values for cooling the Pro-line complete fixtures are:

    • Pro 600 - 2600 BTU
    • Pro 1000 - 4000 BTU
    If you know the type of insulation and the air temperature, is it possible to calculate with the BTU the effect of the lamps on the room/air temperature?

    Weed-noob Active Member

    Save money buy 2x3’s, acoustic seal, vapour barrier, zip and panda film on amazon
    Sam&Max likes this.

    ttystikk Well-Known Member


    Weed-noob Active Member

    Yeah man, frame that with 2x6 and make er’ R20 value
    ttystikk and Tyleb173rd like this.

    Tyleb173rd Well-Known Member

    Are you going to fill all three tables at once or run a perpetual?
    Sam&Max likes this.

    Sam&Max Active Member

    Perpetual. I think rez is too small for all three. Also I just figured out that I probably need to put the rez outside of the room if I use CO2, as it seems too drive the ph up. Wanted to aerate the rez solution by flooming.

    Sam&Max Active Member

    I still have plenty of drywall and aluminium frames around. I will also use styrofoam, as it is cheap and insulates better than rockwool.
    Weed-noob likes this.

    zep_lover Well-Known Member

    if you have a dehumidifier in the grow room,when the humidity spikes at lights out,the dehumidifier helps keep your temps warm.i exchange air between my veg and flower room.i have a mini split in flower room and and the dehumidifier also.
    i am running 1800 watts of led lights in my flower room and 200 watts of led in the veg room.6 plants in veg and 6 plants in flower.
    my grow is in a unheated garage that is insulated.i built the two grow rooms inside the garage and insulated with r13 fiberglass.the walls are 1/2 inch osb wood on both inside and outside walls of grow
    my flower room is 8 x10 x8 foot veg room is 6 x8x8 foot high.i have my co2 generator in the veg room.i have 2 6 inch vortex fans one going from each room into the other exchanging air constantly.the mini split is set to cool only and my low temp is 68 .have the mini split set at 77 .my thermometer says low of 68 high of 73 and humidity is set at 50%. it is in the intake from flower room to veg room.i only run 1 200 watt led light in veg for 6 mini split is a 18k unit.i live in michigan so it gets pretty cold in the winter.i collect the water from the dehumidifier in a 55 gallon drum and use that to mix with my dry nutes.i also collect the water from the mini split in another 55 gallon drum and also use that for mixing my nutes.if you are planning on drying in your veg room ,you might want to make it a little bigger.
    Last edited: Nov 18, 2017
    Sam&Max likes this.

    Sam&Max Active Member

    Thank you for that interesting post!!!

    I just looked up in the temperature over the year in michigan and it seems that your climate is a bit colder in winter (both mostly single digits below zero) and a bit warmer in summer and you have less rainfall than me.

    So with your 1800 watts of LED, your grow room size with insulation, and CO2 generator you don't need additional heating (lowest temp 68 )?

    You also say that your high is 73 and you have your mini split set at 77. Does that mean that you also don't need to cool, because the temperature stays itself below 77?

    What model of Co2 generator do you use?

    Also what is the electric bill for the mini split (especially in summer)?

    I don't know exactly how much space I would need for drying the harvest. The veg/clone/mothers room will be around 35 % smaller than flowering room 15x7.8 x8 feet. But depending on how I position the two rooms in my big room, I later will be able to make one of the two rooms longer which will result in a increase in that room of 35%. I wonder if I should set it up so that, if I need it, I can increase later the flowering or the veg room. For me it seems like a waste of space already to keep only two mothers in a room of around 15x5x8, which will share the room two weeks with clones after that ten days with harvest and will remain then more then 30 days by themself in that room. To me it sounds better to increase the size of the flower room afterwards.

    Sam&Max Active Member

    Actually there is something that I am really wondering about....

    If you have two rooms and you want a constant air exchange between them, then do you need to fans, each one pulling air into the other room, or is one fan sufficiently?

    I am just thinking if I just buy a big Systemair Revolution fan with a controller and adapt that one to my needs to distribute and scrub the air of both rooms. It is an EC engine fan, which seems to be very efficiently to regulate with a controller. Like that I would save on buying two AC fans (two EC fans would be to expensive) and would be able to have a fan which I can regulate from 1% to 100% without wasting engergy. (Although it seems like EC fans seem to loose a bit of efficiency if you regulate them down a lot.)

    zep_lover Well-Known Member


    zep_lover Well-Known Member

    i would recommend 1 fan going from each room to the other.i have varying temps in each does help stabilize temps but i still have 3 oscillating fans moving air around in flower room and 1 in veg.i have each fan connected to light proof baffles also which impedes air flow.i built the baffles inside the wall between the two grow light leaks between the rooms.i did insulate the wall between the rooms except for the two cavities where the fans move the air.

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