Heating grow room with HPS

[DrPhoton]

Im planning to do a indoor grow this winter and i was wondering if i could use a air cooled hood to heat the room. I plan to use a 600 watt HPS with large air cooled hood. With it i will feedback the heat into the grow room.
I would prefer circulating the heat rather than just using a open hood as it prevents heat spots and buildup around the top of plants. I will have a second duct bringing in fresh air at a very low velocity for fresh co2.

Will this be enough to keep the room warm (13x13x8) through the winter ?. Temps average around 50 during winter days and can dip as low as 32 during winter nights.

[South Sierra Dude]

Nope. I use a 1k hps.

[DrPhoton]

What about for a grow tent. If you could run a feedback, the space should be small enough to raise temps. ?

[South Sierra Dude]

I was talking about a tent

[PigSquishy]

My first thought... the only way you'd even stand a chance would be to have your lights on the 6-hours of light 2-hours of darkness for Veg... then maybe you could grow in the right temp range, but no matter how you start trying to make it work you will run into problems. I say this as someone who has lived at -40 below zero using the heat from light bulbs as my main source of heating a room with my body heat included to bring the room temps up to 80-F and maintain it. So here is what I learned from my experience, it would seriously take 2-4 days depending on the temps outside and inside to get the temps to 80, but I couldn't ever get them warmer inside, despite using plastic sheeting to seal the entire room to the point of being AIR TIGHT, as I was scrubbing out black mold and everything had to be done in sealed conditions, hence why no heaters, even electric heaters could be used, only lights like hallegon's could be to produce the heat I needed to work by. Sealing the room was the only way for me to maintain any heat, but when I made the mistake of turning out the lights a couple of times it seriously took less than 1-hour for the room to drop down into 40-degrees or colder and another 2-4 days to reheat the same room with the lights on 24-7.

Later I would take everything I learned from there to try some other experiments to see if I could do this for an emergency... and what I found is you first you need powerful lights to produce that much heat, and the room has to be sealed airtight, or the air exchange in the room will drop the temps even faster and the room can not be evenly heated, if you can heat it at all with drafts. The other major thing I learned was when those lights (heaters) kick off the temps will drop super fast, if you can't turn off a normal heater (electric, gas, etc...) and expect that room to maintain those temps, don't expect the lighting to be able to do it for you either. Good air circulation is also a very big key to making this kind of thing work, because I was filtering for mold in a sealed room, I had a big air filtration unit in the room with me moving the air around the room to scrub it in the same fashion as a carbon scrubber in a sealed room, which allowed the air to be moved around the lights to more evenly heat the air in the space. If you don't have a fan or some way of keeping the air moving at a large scale, the only air that gets heated is directly around your heat sources (lights) and when they go off the temp drops in those locations will drop even faster yet, than when the entire room was evenly heated.

Humidity will also play a huge part in this issue as well, because at higher humidity it can allow cooler temps in the 40's to even kill your plants with frost on the plants, as you may know from being a gardener and having to have blankets or whatever to cover your crops in the spring and fall of the year to protect them from frosts. As the plants put more humidity into the air, the temps inside the room will become harder to warm up and will become even faster to cool off, as I did more mold cleaning with liquids and water, I would begin to notice this as a huge problem more and more as I had no way to remove the humidity without a dehumidifier, which in turn does add heat to the air, but doesn't work at efficiently outside of a select temp range. So even because it is running at 50-degrees, doesn't mean its producing heat, all it is doing is circulating the air and moving the moist air around until it gets warm enough to work which makes the space seem even colder yet. The humidifiers have a chart showing when they work best and explain the best ways to size them for what room size and what you want them for and the temps they work best at removing the most humidity from the air at.

I hope this helps you get a better understanding of what I learned from my experience heating like this.

[DrPhoton]

Yes very helpful, i pretty much counted on such a response. Even a 600 watt heater would struggle. Saying that i do have confidence that a 4x4x8 tent could be heated by lights with the heat fed back to the bottom. Maintaining a smaller microclimate would be much easier. Although i still need to cycle air, i could do so with intermittent timing like i do with green house grow. Cycling the fresh intake every so often so that fresh air is introduced and does not stay on long enough to cool down the tent.

Anyone with any experience like this ?

[DrPhoton]

So im thinking of running a 600 hps air cooled in a 4x4 tent with the intake air pulled from inside the tent and the exhaust fed back to the bottom. Reusing and cycling the air for even heat distribution in the tent. No hotspots. I will also have a high powered exhaust on the tent wired with a thermostat to run when temps are too high. This will also serve to bring in fresh air from a passive vent when this exhaust is running.

Anyone run their grow tents in winter with just lights ?

[OzBud]

I ran a 2'x3' cupboard last winter, temps down as low as about 25F outside at night, lots of nights below 32F. 600W HPS, open reflector and no hot/cold problems. I was growing autos though and ran my lights 24/0 through the whole grow though

[DrPhoton]

What about during flower when you had to 12-12 ? Im thinking of running the dark 6 hours during the day. Then with flower run the dark 12 from mid day to midnight, running the lights during the coldest 12 hours. It may be that it requires some supplimental heating.

[OzBud]

I was growing autos and they don't need 12/12 to flower. You can get heat bars for tents. Like an aquarium heater but doesn't have to be in water. Have never used them though so don't know how effective they are.

[DrPhoton]

Yea i think il get away with it during veg but i might have to compensate with heaters during flowering. But im confident that i might get away with it.

[South Sierra Dude]

Good luck. My tent is in my bedroom and I have a hard time with temps in feb and jul.

[Chowder]

Hi, I'm using the air tube cooled HPS lights, and recirculating the air into the grow room and it works great! I had beans on dec 3/16, and made it all thru the winter, eastern Canada, using the heated air from the lights during the day, and my heater at night. Yes, there were times that I needed the heat from the lights and a heater during the day, but that was rare, and only had heater on low.
I have 2 x 600 w HPS and a couple LEDs, in a 6x10 grow room, that is in an outside building! With no heat. I pull air in over the lights with two small inline fan outside grow room in storage area and door to building. Each light has its own ducting and its own inline fan outsid growroom where I can rotate the inline to draw in fresh cold air over the lights, or push air over lights with air from storage area room. What works best I found was having one each way, and I could easily regulate heat and humidity inside grow room with my 440 cfm exhaust fan set on a fan speed controller. In my storage prep room with the door to the outside I also have another 440 cfm fan on a controller pushing air from that room into my grow room at a rate equal to my exhaust fan inside the grow room.

so, as I'm sure you know, I pull / push air from outside or storage prep room, depending on the direction of my inline fans. When I pull fresh air over the lights, it is heated by the lamps as it enters the storage prep room, then it is pulled into the grow room by the 440 cfm fan, located low in one corner of the growroom, and then it is removed from the grow room with the other 440 cfm exhaust fan, located in opposite corner of other fan and placed up high. The idea is , low, blow in the cool air, high, suck out the hot air! This has worked extremely well for me this winter, but we have also had a good winter for this part of the country.

im currently in my grow room now and temp is 23 C and RH is 30%, and I am controlling this by my fans only, no heat on during the day when lights are on. I want these numbers as I'm deep into flowering right now and don't want mold.

i also have some side lighting, t5 s x 3, which also proved some heat directly in grow room.

someone else told me that I. May ruin my lights premature with possible condensation build up, but I haven't had an issue with condensation.

good luck with your grow

[South Sierra Dude]

What it's the annual low and high in the room? I use all the techniques described above and my tent is never exposed to extremes. I avoid picky strains as it is.

[DrPhoton]

I think i should do comfortably with my tent then. Your idea is similar to mine. As long as your bringing in fresh air its all good.

Very helpful.