Cheap and Easy Thermostat

You donâ??t have to spend $200 or $300 for a fancy name brand â??atmospheric controllerâ?� to regulate the temperature of your grow area. I rigged up a simple thermostat and heat lamp to keep my seeds warm during germination, which comes on if temperatures drop to 71. It stays on until 81, but just too make sure things donâ??t get too hot too fast, it has a duty cycle of 3 minutes on and 12 off. Additionally if temperatures reach 83, an exhaust system with a big-ass, room clearing fan comes on, and stays on unless temps drop to 76.

Lux makes a $10 heating thermostat and a $10 cooling thermostat. If you do this, be careful you donâ??t get a thermostat for controlling 24 volt systems. Both those, and 110 volt are common (Weâ??re talking United States here.) For this project, I only needed a heating thermostat, but one could easily employ the same techniques to control a swamp cooler or whatever. You could also have the roomâ??s exhaust controlled by one thermostat, then when the room gets cool enough to shut off the exhaust, have another one turn on CO2. Or you can just shell out the $250 for the Green Air CT-DH-3 (scroll down a bit), and be able to exhaust according to humidity as well.

Tools needed:
- Standard slotted screwdriver
- Knife or wire stripper

Mounting the unit:
I wonâ??t go into great detail here, and tools and supplies for this Iâ??ll leave up to you. I nearly put it on the wall with a couple of Velcro strips, but changed my mind and drilled a couple holes in the back of the electric box, and screwed it. I also thought about attaching a hook on the top, and making it more portable. You might want to move it up or down, depending on where your fan or the canopy is.

Photo 1 (Materials, most of em anyway):
Hereâ??s what I used. An extension cord cut in two, a thermostat, and a standard switch or outlet electrical box. I got everything except the tape (see below) at BiMart, a cheaper version of Walmart, believe it or not. Also used but not shown in photo 1 are 2 additional wire nuts (the thermostat comes with 2, youâ??ll need 4), a 5 inch length of wire, and Stretch & Seal silicon tape. IMO this is much better than standard electricians tape. The tape is optional, but the books recommend taping up your wire nut connections, just to be safe, and so do I.

Photo 2:
A slightly blurry photo of the thermostat in itâ??s package. Their website is luxproducts.com. They have timers and some other stuff too.

Photo 3 (wiring, part 1):
Here it is with the wire nuts on. Be sure to run the wires through the back of the box before attaching them to the thermostat. Keep in mind the orientation of the unit at this point. If you are screwing the thing to the wall, itâ??s easier to drill holes in the box first. There are 2 knock-out holes on top and 2 on the bottom of the back of the box. I ran the male plug-in part of the cord into the top of the box, and the female out the bottom, since the male part will go out the top of my closet when Iâ??m done remodeling, and I like my fans down low, blowing upward.

Photo 4 (wiring, part 2):
Hereâ??s the wiring more close up. A single pole thermostat should come with three connections; ground, line, and load. On the Lux, the black wire is load, and the red wire is line. Be sure to check these wires, mine were loose. For ground, you screw a wire to the metal frame. Connect the white (neutral) wires from the two ends of the cord together. Connect the green (ground) wires together as well, along with another short wire, which is connected to the ground on the thermostat. Connecting several wires together, then connecting them to the unit with one wire is called a pigtail connection, and is required according to code.

Connect the black (hot) wire from the male portion of the cord to the â??lineâ?� connection, or in the case of the Lux, the â??lineâ?� wire. Connect the black wire from the female part of the cord to the â??loadâ?� connection.

Gently tug on each wire to make sure it is secure in the wire nut. If not, keep trying until it is, or try a different size nut. You donâ??t want these coming loose as you cram them into the box. And again, you really should wrap the connections in tape.

Photo 5 (wiring, part 3):
Wiring schematic. Thank you Photoshop.

Photo 1:
Hereâ??s the 2 types of tape I was talking about. On the left, silicone Stretch & Seal, made by Nashua. On the right, your typical crappy electrical tape, that separates itself from itâ??s adhesive after a week.

Photo 2:
My heat lamp underneath my germinating seeds. The shelf is from a Raid insecticide display from the same Bimart. I snagged 2 of em for $5 each. Right place, right time.

Photo 3:
The unit installed, along side the Green Air atmospheric controller. I know, a lot of friggen cords. Did I mention I was remodeling, still?

Hereâ??s how the package works: The heat lamp is plugged into a repeating cycle timer, which is set to 3 minutes on and 12 off. I just didnâ??t want it too stay on real long and melt something. The timer is plugged into my newly assemble thermostat, which is plugged into the side of the Green Air controller that is normally on. The new thermostat is set to 81, which means the timer starts to get power at 71 or below, and continues to have power until temperatures reach 81. The Green Air controller is set to 83, which means thatâ??s what temperature will turn off the power for the timer and heat lamp, and turn on the power for the exhaust fans. The controller is designed for exhaust to stay on until there is a 7 degree drop in temperature.

The reason itâ??s so elaborate is because I wanted to make sure that both the heat and the exhaust werenâ??t on at the same time, and that the heat lamp didnâ??t burn down my house. I should mention that you canâ??t just set these things to whatâ??s marked on the dials and hope everything works out. Youâ??re going to have to do a little testing and adjusting based on where they are positioned, and where fans and lights are, and the canopy is. I highly recommend passing a laser thermometer along your canopy while you are testing, and trying to keep things at 80 degrees. You should pay close attention during at least one complete heating and cooling/exhaust cycle to make sure everything is operating according to plan.

Hope you like. Comments, questions and criticisms are all welcome. Also, Iâ??m not an electrician; use your best judgment.

PS. My seeds are sprouting after 40 hours.

Uhhh WOW! I'm way too stoned to understand this right now but will definitely give it another try when sober.

Thanks for the helpful post. Will give it a try

yeah wickid

sticky maybe?

Nice work Opie; it looks professional and SAFE from here.

If you rigged it with an outlet instead of hardwired to a heat lamp, you could also use it to trigger a seedling heat mat to come on- I'd use that in a situation where I wanted to heat JUST the seedlings and not the space.

Looks like it would work for chicks and ducklings too! ;)

hey.. this is great and i think it is exactly what i am looking for. I am trying to grow a certain kind of fungus ;) and need to rig a heat lamp to a thermostat for incubation. Will this work for having a heat lamp shut off and on at a desired temperature range? or does it have to be used with timers and stuff?