Lighting Winter growing and light heat question

[mjdregba]

I am hoping you guys can help me with a heat question.

My grow box lives in the garage in the UK - and in the winter the box is basically as good as outside in fairly low temperatures 0-5c. The current grow will be finished within the next four weeks, therefore I am thinking ahead to the cold weather.

The box is 2ft*2ft*4ft

So, my last winter grow ended up with me putting in 370w of CFL lighting (120w sides and 250w top) for a 24/7 light cycle and had to turn my exhaust fan off as any cool air intake was bringing the temps down considerably. However as I started in the winter, it got progressively warmer so I could start extracting the air.

My question is; would a 250w or 400w HPS put out more heat than the CFL's and do you think it be viable to have a fan blowing down from the light circulating the warm air below? or could use a cool tube and pipe the air to the bottom - but that would have space limitations I suspect (since they are normally 6" pipes).

Also, what is the minimum height of a grow box using HPS? I have about 3ft grow room which is barely adequate for a CFL grow - am happy to add more height, but it obviously means more warm air is required

And I know I could use heaters, but found lights were just as good for heating and didn't want to waste electric needlessly.

Thanks in anticipation all.

 

[A4]

Hey bro, yes a HPS will put out a lot more heat than CFL. And yes, you can use them to heat the tent. I have an enclosed hood and use an inline fan with no ducting on it to supplement my heater during the winter. I have noticed during the day my heater rarely kicks on. Actually, for your sized tent a 400 may put off too much heat.

Another thing to consider it to keep the pots up off the floor and let air circulate under them. The floor stays cold and will keep your root temps pulled down.

 

[SCARHOLE]

I have grown with light s as heat. 150w hps 145cmh an 100w flouro.
In a 3x2x3 cab.
It couldn't keep up with the winters here.
I used a space heater in the cab awhile, but they are super touchy an a fire danger.

Then I bought the oil filled electric heater.
It ownes!
Just use it to heat your shed or a part of your garage.
Doing this allows the light to help, but dosent rely on them fully
The thermostats are great for night time temp drops.
And are efficient if your area is insulated
My ladies seen -20'F 2 yrs a ago an the shed an my cab were fine.

 

[mjdregba]

Hey bro, yes a HPS will put out a lot more heat than CFL. And yes, you can use them to heat the tent. I have an enclosed hood and use an inline fan with no ducting on it to supplement my heater during the winter. I have noticed during the day my heater rarely kicks on. Actually, for your sized tent a 400 may put off too much heat.

Another thing to consider it to keep the pots up off the floor and let air circulate under them. The floor stays cold and will keep your root temps pulled down.

thanks a420er - was hoping this was the case. Nice advice on the pots, I had a 4w reptile heat mat under the pot, but realize now that raising it an inch or so was probably just as good.

Do you have any pics or a rough drawing of your setup? just having a hard time visualizing how the fan is connected and blowing down.

Also, what is the minimum distance from the plants for an HPS? Just working out if I need to add a ft or 2 in height - and if I did make the box about 6ft*2ft*2ft do you think that would be big enough for the 400w? My exhaust fan and CF are above the light in the top ft of the box so would be about 5ft left to the light, pot and plant. This would be a winter only setup, I would probably revert back to a 250w CFL in the summer months.

 

[Soylent Green]

I believe that if you insulate the cab using 4-6 cm PUR-plates also on the bottom and top and have a 250w hps with a cooltube on 24/24 with the exhaust partially in that cab you should be fine!
But you should build the system and test the temperature inside so you know how much of the air needs to stay in and how much needs to get out!

 

[A4]

Hey, I don't have a picture of my setup during the winter. This is a pic of it during the summer. It doesn't blow down, I just disconnect all of my duct and the fan has enough cfm to circulate the heat in the tent. I also have a couple of small clip on fans that I put in the back of the tent to circulate air as well.

18" - 24" is the recommended distance but with an enclosed hood and 400W you could probably get away with 12". Use the back of your hand to make sure it isn't going to heat stress your canopy and you will be fine.

 

[mjdregba]

guys, many thanks for the responses and much respect.

a420er that is an awesome setup man I am guessing that is just a static height on the light?

soylent - love the avater name (do people make good plant food?), but what are PUR-plates?