Cheap Chinese 2-stage Temp Controller

[glasseye]

remember your OHMS law: E * I = P

*Pedantic Electrical Engineer Mode*

That's not Ohm's law.

Ohm's law -> V = I*R

P = I*V is one of Joule's laws.

[nashvegas]

so i found the controller which led me to here. i plan on getting a 5 or 7 cu.ft. chest freezer for a fermentation cabinet and legerer. could one of these things handle it and a small ceramic heater? i havent gotten the chest yet so i dont know how much current they draw. anyone see any problems with this setup? also could one of you guys provide a simple wiring schematic. im confused with just this pic

[BadRock]

could one of these things handle it and a small ceramic heater?

Probably not, most heaters operate around 1000w to 1500w, these units appear to be rated at 10A. If your heater is less than 1200w I guess you would be fine but I would probably just wire in a interposing relay to so all the high current switching.

[ajdelange]

remember your OHMS law: E * I = P

*Pedantic Electrical Engineer Mode*

That's not Ohm's law.

Ohm's law -> V = I*R

P = I*V is one of Joule's laws.

If we're going to be really pedantic, Joules law is Q = I^2*R*t and Ohms law is I = V/R. Substituting R = V/I into Joules law and dividing both sides by t gives P = Q/t = I*R. See my post of 2/12 (in this thread) for the special significance of Joules Law to brewers.

[nashvegas]

could one of these things handle it and a small ceramic heater?

Probably not, most heaters operate around 1000w to 1500w, these units appear to be rated at 10A. If your heater is less than 1200w I guess you would be fine but I would probably just wire in a interposing relay to so all the high current switching.

well thinking about it i will probably just use a light box with an incandescent light bulb which is what, 100w max. but would one of these units handle the chest freezer? also how would it need to be wired?

[Elbone]

buy cheap extension cords and cut them in half.



Note: this is not the original, bonehead diagram that AJ correctly calls me on later! It has been corrected with his help. Thanks AJ.

[andersonimes]

well thinking about it i will probably just use a light box with an incandescent light bulb which is what, 100w max. but would one of these units handle the chest freezer? also how would it need to be wired?

nah. The cheapo walmart heating pads draw less than an amp.

[andersonimes]

buy cheap extension cords and cut them in half.

thanks! Wouldn't have known what to do about the grounds.