Grow Room Outbuilding Winter Setup Questions

[Subaroot]

Hi all, sorry if this is a bit long

I'm a new grower, haven't begun yet, still collecting equipment. I have my set up mostly planned, but there are a few decisions that I would appreciate some advice on; mainly to do with temperatures (I'm in the UK and will be starting my first ever grow in the heart of winter).

My set up:
- Cinderblock outbuilding, flat roof (structural chipboard and felt), approx 8x6' inside, fully sealed excluding intake and extraction points.
- 75mm PIR roof insulation
- 2x4 tent
- HLG 300L R-spec
- 6" carbon filtered extractor from tent to outside.
- 6" silencer & combi ducting
- 8" passive intake into the outbuilding, filter box & G3 filter, volume control damper.
- 8" acoustic ducting
- Oscillating circulation fan
- AC Infinity controller

My ideals:
- I will be growing auto's to begin with (until I get a veg tent). Ideally don't want to run a 24hr light cycle simply to maintain temperatures. Will likely run 18/6.
- I would like to keep the room warm, as well as the tent, so that I can keep water/nutes/soil etc out of freezing temps.
- I'm reluctant to plumb the passive intake directly to the tent. I could place a heater in the tent, but this will take up precious space, won't warm the outer room(?), and will the freezing air stunt the plants(?).


Possible solutions:

1. Partially or fully close the intake vent which will reduce cold air entering.
- Would the lack of fresh air "suffocate" the plants?
- Would no intake prevent my extractor from running effectively?

2. Thermostat controlled oil heater in the room, which will allow intake air to mix with warmer air before it is sucked into the tent.
- How low can room temp be during lights off?
- How long after lights off before tent temps become critical?
- If it's freezing outside, what wattage heater would happily keep the room at minimum safe temp with me chonky roof insulation?
- Will it be madly inefficient with the cold air being taken in?


Any advice much appreciated

 

[Bob's Auto's]

First off... to AFN, @Subaroot
Loads of really nice people here and lot's of information to be found. Do use the advanced search as you can filter the results.

- I will be growing auto's to begin with

Nothing wrong with auto's brother. I grown nothing else

Ideally don't want to run a 24hr light cycle simply to maintain temperatures.

You will probably have to do that unless you are going to heat the shed (from now on, called 'lung room').

I would like to keep the room warm

Good idea, but with the cost of energy I really do suggest isolating the lung room so you won't break the bank trying to keep the room at 16°C / 60°F

I'm reluctant to plumb the passive intake directly to the tent.

In your situation I would suck air out of the tent, directly outside. That way you get rid of humid air, which is your enemy for the most part of your grow.
Negative presure will suck air into the tent from nooks and crannies. The same goes for the lung room. Negative presure always want's to regulate, so you won't have to plumb anything to take air in. But you do for the outtake. With a long drill, a good hammerdril and some time you can make a hole to the outside. On the outside a nice vent so it looks 'official' and inside the hole in the wall a check valve so cold air doesn't blow in when you are not using the extraction fan.

How low can room temp be during lights off?

Under a certain temperature the plants seize their activity. Don't know exactly the temperatures (maybe someone else does), but I don't like to go beneath 21°C inside the tent at all times. But then I do run my Mars Hydro TS-1000 24/7, just to keep temperatures stable.

How long after lights off before tent temps become critical?

Temperatures are always critical to plant activity. The higher the temperature the faster everything goes, to a certain limit of course.

If it's freezing outside, what wattage heater would happily keep the room at minimum safe temp with me chonky roof insulation?

I would really invest in isolation. If you can't afford to isolate the entire lung room, then try to make a smaller lung room inside the shed and isolate that. Just make sure it has about 2-3 times the volume of the tent. That way the heater doesn't have to be that big and all the heat is used for growing plants and not to heat up your 'chonky' roof.


Regards,

Bob

 

[Subaroot]

First off... to AFN, @Subaroot
Loads of really nice people here and lot's of information to be found. Do use the advanced search as you can filter the results.


Nothing wrong with auto's brother. I grown nothing else



You will probably have to do that unless you are going to heat the shed (from now on, called 'lung room').



Good idea, but with the cost of energy I really do suggest isolating the lung room so you won't break the bank trying to keep the room at 16°C / 60°F



In your situation I would suck air out of the tent, directly outside. That way you get rid of humid air, which is your enemy for the most part of your grow.
Negative presure will suck air into the tent from nooks and crannies. The same goes for the lung room. Negative presure always want's to regulate, so you won't have to plumb anything to take air in. But you do for the outtake. With a long drill, a good hammerdril and some time you can make a hole to the outside. On the outside a nice vent so it looks 'official' and inside the hole in the wall a check valve so cold air doesn't blow in when you are not using the extraction fan.



Under a certain temperature the plants seize their activity. Don't know exactly the temperatures (maybe someone else does), but I don't like to go beneath 21°C inside the tent at all times. But then I do run my Mars Hydro TS-1000 24/7, just to keep temperatures stable.



Temperatures are always critical to plant activity. The higher the temperature the faster everything goes, to a certain limit of course.



I would really invest in isolation. If you can't afford to isolate the entire lung room, then try to make a smaller lung room inside the shed and isolate that. Just make sure it has about 2-3 times the volume of the tent. That way the heater doesn't have to be that big and all the heat is used for growing plants and not to heat up your 'chonky' roof.


Regards,

Bob

Thanks for the warm welcome Bob.
The cannabis community is a big family

The shed's pretty small and very well sealed, and kind of a man cave. In fact, I forgot to mention that the shed will be used to dry bud so overall I'm willing to pay to heat it. Just like to calculate what it's gonna cost me so I can halve it and report that to the Mrs

So an intake into the shed isn't required? I was worried about reducing extractor fan efficiency. The mechanic in me says that if you block a car's intake then the exhaust can't kick any air out

I'd like to fit an intake channel anyway, as I plan to grow in summer, and this year's was a belter.

Regarding extraction to outside, the outbuilding has a small window on the side that faces into my garden (only I can see it). The glass has fogged anyway so I have a PVC infill panel to blank it out, makes cutting the hole a lot easier, and a vent to outside with a check valve built in.