Things are getting cold.

[Kiwi_Jezza]

Hey growers!

My grow has currently been reduce to a large cabinet in the garage but as its winter things are getting a little cool in there with lights off temperatures getting down to 14 and 15 degrees celcius and it hasn't really even started getting cold.

Currently 2 Sonoff switches are doing the monitoring and through one of these I'm able to track the temperature and humidity which is why I've noticed the drop.

The cabinet measures 2 metres tall, 1.2 wide and about 600mm deep. Two or three zones operate within the cabinet depending on whats going on.

What solutions are there to safely heat the space without risking burning anything to the ground?
Space is VERY tight in the cabinet so contact with leaf is highly likely which makes me tentative about typical space heaters.

[Jolly Green Giant]

my first thoughts, is the cabinet insulated? ( does your reflective material help) reflective ( or white) insulation foam on the inside ( and or outside) could help over just any reflective material..

electric seed heating mats could help keep root zone temps up.. they also make small tabletop fans, that can also blow heat.. something like that...

making sure your well insulated, and keeping the root zone temps up will help a lot! that was one thing I learned early in small closet grows during the winter.. ( during February we can average -17C here )

[Nuggie]

Germination heat mats like mentioned above, made for this type of environment. I found a space heater calculation for reference, take the square footage of area and multiply it by 10 to get the wattage needed for an 8 foot ceiling. So if you had a space that was 2 wide x 4 long x 5 high you would take 2x4 = 8 sqft x 10 x 5/8 = 50W. If a germ. mat isn't enough try a heat lamp for about $12 but you may have to get creative to keep direct heat away from plants and keeping your cabinet frame cool so it doesn't go up in smoke. I would try mounting the bulb/shroud face down just above a small concrete pad like the kind for foot paths that is laid most of the way across the bottom of the grow area. This way the heat is being directed into a non-flammable surface and the concrete will act as a heat sink and if your plants are on it, it will heat up your plants pots. Heat will also be non-direct and won't act to dry out your plants like a fan heater would.



The shroud for bulb:


Come to think of it I think I am going to try this as currently I have a dyson heating up my area but I think the heat lamp would be less energy and more effective as it would conduct heat thru to roots rather than convect heat thru the air. Being infrared and only $11 in would come in handy during flower too.

[ATPinMotion]

+1 for heat mat on a paving stone. Can't get much safer than that - just make sure you float the concrete block on some insulation to provide a thermal break between it and your garage floor.

I've floated some pretty big slabs and decks on Extruded polystyrene (rigid pink insulation). It's got a surprising amount of compressive strength, and doesn't break down even when exposed to water.

I've also floated stuff on hockey pucks, and tennis balls cut in half. My expertise is in acoustics, but thermal transfer follows the same principles.

[Nuggie]

Hockey pucks, lol Canadian eh? I've got a few of those from the rink next door, should work well. I just thought of the heat lamp and watering. Make sure fixture is out of the splash zone.

[Steveb123321]

I used an arduino, dht sensors and relay to control an exhaust fan, lights and small heater. Mine is a 2x4x8 foot space.

Probably not the safest, I did have a few relay issues. Especially for one light.

I think I'll replace the heater, which is simlar to Jolly Green's post, with a heat pad and thermal mass for next fall.

[unkle_psycho]

You need to create insulation before heating makes sense. Once you have insulation and heating, your biggest factor is what the exchange air is like. If you are pulling freezing air into a small space you might need timers that have more resolution then normal. The delicacies of replacement air are discussed under the term 'lung room'.

[unkle_psycho]

Perhaps I'm sinning, saying this in the LED forum, but I would definitely consider small HID's as an alternative to the heatlamps. I guess a heatlamp and LED combo = HID.
I have some separate farm buildings, and used to do a spring grow in those cold unheated spaces. In my experience a 1000w heater left the room cold, but 2x400w HIDs kept things moving, as long as buckets didn't touch the floor. There is something about the infrared heat penetrating plant tissues that does wonders against cold.