Variac thermostat setup

Looking on a single variac setup to control my exhaust tornado box fan wouldnt mind been abit more automated to go slow and faster when need to

So what would i need to buy thermostat and some sort of relay

Then the wiring what goes where?

Should i wire the intake in so slows down with outtake thanks

Why don’t you just buy an SMS FAN SPEED CONTROLLER and stop worrying about wiring?

I use a single fan speed controller 4.5A. they make various different ones.

To tell you what wiring goes where we would need to see the wiring instructions.

I think i would need the 7.5amp hybrid to stop any humming since the fan is rated at 7 amp think cost about 250 if comes to that might have to just read variac is 100% no hum

Renfro said:

To tell you what wiring goes where we would need to see the wiring instructions.

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Was thinking of using this style thermostat with it
Just got these of websites

Tornad2020 said:

Was thinking of using this style thermostat with it
Just got these of websites

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You’re from the U.K. right based on the variac you Posted about.

most users on this site are USA some electrical wiring wouldn’t be easy.

I use an SMS non variac and the hum is negligible on an RVK150A1 460m3/h.

Tornad2020 said:

Looking on a single variac setup to control my exhaust tornado box fan wouldnt mind been abit more automated to go slow and faster when need to

So what would i need to buy thermostat and some sort of relay

Then the wiring what goes where?

Should i wire the intake in so slows down with outtake thanks

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I own that, it should have a temp probe with it shouldn't it?

The smscom hybrid would have a probe but a variac wouldn't it just slows the fan down 5 step manually useless its controlled by a thermostat i think

Thats not technically a variac. It's a multi tap transformer, so it has pre set "speeds" that you can choose from, assuming thats what the switch is for on the front.

It looks like it's wired to plug into power source and the fan plugs into it. I don't see where the thermostat / temperature probe would go though. Need more information.

It might not be able to be done then i was hoping that a thermostat would be able be wired in somewhere so guessing id just be able to use it manually then

Tornad2020 said:

The smscom hybrid would have a probe but a variac wouldn't it just slows the fan down 5 step manually useless its controlled by a thermostat i think

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If its the one with the switch on the front with 3-5 speeds then you cant rig it to a thermostat. Need manual control

If its the one with buttons on the front and digi screen it should have a probe that you wire ito the third port, I cant see the insides well enough and cant find mine online to show you.

What I will say is either way the minimum speed is 50% so if you need more control than that then pick another option.

Well one could wire up a thermostat to a double throw relay, then switch the hot leg between the "variac" or low speed and straight power or full speed.

Use a relay with line voltage coil (probably 240 VAC) for you. That and a line voltage thermostat. If it's a cooling thermostat then when the room gets too warm you can have it kick the relay over to high speed. When it's not then the relay drops back to the default and uses the variac for low speed.

Also, remember the thermostat will have a dead band. Usually about 7 degrees F. That might be too much swing for you and therefore may want a thermostat that has a variable dead band.

You got something like this @coreywebster

An inkbird temperature controller would be a good option for the line voltage thermostat.

All this 240vac an relays i dont have a clue i could follow diagram but not just words maybe am best looking into something that easier

Tornad2020 said:

You got something like this @coreywebster

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Yeah, I used to have the first one you posted and upgraded to this one with the probe.

They are ok, but like I say if you need to be lower than around 50% airflow like I do in winter then they don't give enough variation for me.

I also have a proper variac with a knob, red thing. I like that much more because I can turn shit down to real low.

I understand that situation could happen very easy to where did you get the red one from?