I am designing my grow box and have an electrical question i was hoping someone could help out with. I have a Soler Palau mixvent fan which has separate inputs for high and low speed. I would like to use a thermostat and a relay to switch between the low and high settings at a selected temp but I am a bit fuzzy on the wiring. I know I need a spdt relay with a 12v control but I'm not quite sure how to set up the control circuit. Do I need any other pieces to make it work? Any help is much appreciated
wiring a relay to control fan speed
- Thread starter ShyGuru
- Start date
Dr. Who
Well-Known Member
You can get premade Temp control units.....you have to manually set them by sitting there and setting it at the temps you require....
On at "x" temp and off at "y" temp - perpetual repeat till you change a setting.....Reostat control...dial it in......kid of a pain to set but they work...
all you really need is on and off!
On at "x" temp and off at "y" temp - perpetual repeat till you change a setting.....Reostat control...dial it in......kid of a pain to set but they work...
all you really need is on and off!
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I appreciate the suggestion Dr. Who and I've looked at a few of the pre made units but I haven't seen any that will do what I'm trying to do. See this particular fan has two inputs, think of it almost as two separate fans if you will, and I am trying to switch from one to the other at a programmable set temperature. If you have a link to something that will do that i would love to see it. I know it can be done by using a 12v power source to control a relay but I'm hazy on the specifics. A premade unit would be much simpler and cleaner.
jijiandfarmgang
Well-Known Member
you should be able to do this with just a 120v spdt relay, and a cheap line voltage thermostat
I'm not an electrician so there’s that, I'd check on an electrical forum or something. Should be pretty straight forward wiring.
- Jiji
I'm not an electrician so there’s that, I'd check on an electrical forum or something. Should be pretty straight forward wiring.
- Jiji
Thanks Jiji I think I have this figured out. And yes your idea would work. I'm still going to go with a 12v transformer and low voltage thermostat thru a relay simply because of price. A line voltage thermostat can be more pricey with less features and the relay would also cost a bit more. Even having to buy a small transformer to power it I should still come out a few dollars cheaper. Plus there's the additional bonus of not having to run line voltage into the grow side of the box, only into the control area. Thank you much for the suggestion maybe someone will use the idea in the future.
High Power
Active Member
Get a Ranco etc 211000, it has two stages to control to separate internal relays.
pseudobotanist
Well-Known Member
An stc 1000 would be a cheaper controller that does the same
High Power
Active Member
The etc111000 will work just use NO and NC for whichever speed required.
SPLFreak808
Well-Known Member
30 is the switching pin which rest at 87a. 30 will switch its input from 87a to 87 when you energize the (86 & 85) pin. Basically all it does is swap 87a to 87 when energized. Heres an example, i use a 12/6vdc fan setup. 30 = main output / 87a = 6v in / 87 = 12v in / 85 = negitive input from thermostat / 86 = 12vdc. if you have a positive 12v output from the thermostat then just ground 85 and use the 86 as positive input. When temps get too high, my thermostat sends a negitive trigger to the relay (pin 85), which swap pins from 6v(87a) to 12v(87) pretty much doubling voltage. Dont forget though relays have voltage drop especially in the 30amp range.
@SPLFreak808 do those number apply to a relay that uses a 12v control circuit but 110v on the switch side?
Those ranco units seem like they might work my concern would be programming them properly. They are a nice unit but maybe more than I need. The concern being if I set the parameters wrong I could power both the high and low at the same time. I have no idea would that would do but I fear it wouldn't be good for the fan.
Those ranco units seem like they might work my concern would be programming them properly. They are a nice unit but maybe more than I need. The concern being if I set the parameters wrong I could power both the high and low at the same time. I have no idea would that would do but I fear it wouldn't be good for the fan.
SPLFreak808
Well-Known Member
It is extremly important to use the proper amp rating relay for your application. A 12v 30 amp relay should handle 110 @ 2 amps maximum but it is not recommended to use high voltage through an automobile relay because high voltage could jump the post gaps in the relay itself. Its easier and safer for you to find a relay capable of passing 110vac. Is this for extra fans or something? A timer would be 100x better.
I have a soler & palau 110 v fan which has separate inputs for hi and lo speed. I want to switch from lo to hi at a preset temperature to take advantage of both setting. Current ideas so far are 12v transformer to thermostat to relay (thinking relay in a box model ribu1c) or the ranco units. The ranco units are very nice but maybe more complex than I need. Too many parameters to set are extra chances to screw something up lol. Any ideas/input/criticism?
High Power
Active Member
Rancos are easy peasy to program and the have a differential setpoint as well.
@highpower Do you have a ranco? Will it work for the way I'm trying to use it? Basically will it put power to the normally closed contact and then switch to the open contact at the setpoint during close on rise operation? My question really comes down to whether this unit can actually power both sides of the contacts. From reading the brochure it seems as if its designed to fit multiple purposes but to only control one device at a time. It does seem like a really nice unit, sturdy and definitely cleaner than using multiple devices to do the same thing. I would be well within the operating limits since the fan draws very little power but my fear is buying the unit and finding it doesn't work for my intention. Thank you for your input.