Advice on T-Stat to Controll 3 Speed Fan

[Morton]

I have a problem controlling a fan and need some help.
I have a 3 speed ( rocker switch controlled with seperate on/off switch) 110/120v fan and wish to have it controlled with a cooling t-stat ( line voltage ) that has an adjustable variance setting up to about +30 degrees. operating range about 80F to 120F.

I want to be able to set the low temp and have the fan running on low until the t-stat reaches the upper variable setting.
Once "cooling" is called for I want the fan to switch to high speed until the lower setting is reached at which time the fan will return to the low setting.

Everything is line voltage and must be easily set up with extension cords or plugged in at remote locations.
I am more than capable of jumper wiring something into the rocker switch assembly and the like but have no idea where to start with what stuff.
Any HVAC people, control engineers, or just plain good old boys that know their stuff that can lead me in the right direction?
Looked at Granger but the gobeldy-gook doesn't mean much to me.
Thanks in advance
Morton

[AllenW]

A series paralell circuit and controlling stats of the right temp might work.
Finding the stats with the right temps might be the kicker.

Clicks-on are a name brand of what might work.

Al...I think

[jeffbilodeau]

I'm guessing that the separate fan speed inputs cannot be on at the same time. (speed 1 needs to be off when speed 2 is on) If that's the case parallel single pole line voltage stats with one set higher than the other will not work. You need to find a single unit that has separate relays for each stage and when one "makes" the other must "break". You could ask at a local HVAC place...but it wouldn't be cheap. Otherwise trying to build something out of multiple stats is going to be difficult and problematic. The only other thing I can think of is building a little control panel with digital temperature controls and a thermocouple. Again....not cheap.

[rbsangler]

It can be done.....refer to above replies.......A 3 stage low voltage t-stat, driving three coils of separate relays would work. Whatcha got, a greenhouse or something? If that's the case, cost would not be an issue.

[REW]

Morton,
Send me an e-mail and I will draw up a circuit with a parts list for your needs.

REW

hflier@comcast.net

[Morton]

Thanks everyone for your suggestions.
As you can tell it has been perplexing for me to say the least.

Morton

[REW]

Rick,
The design has been completed. The schematic and instructions have been mailed to you.

Good luck with your project.

REW

[Morton]

Thanks REW
The mail came through and I'll attempt to begin working on it monday.
Your efforts are greatly appreciated.
Will keep you posted on progress.

Morton

[NCESI]

By using a double pole relay like a RIB Relay you could accomplish this. I assume that REW has that part down for you. Simply use the normally closed relay contacts for the low speed and when you call for high the relay can puck up closing one set of contacts for high and opening the set for low. A $20.00 relay and a few minits of wiring and you are set. Good lcuk.

[REW]

NCESI,
Actually, you used the term double pole relay.

The double pole relay will not work, but a single pole double throw relay will work and that is what I put on the schematic and parts list.

---------------
The double pole simply indicates that there are two lines that may be switched with the relay.

The number of throws, in this case a double throw indicates the number of switch positions that the relay can be placed. In the case of a single pole double throw relay, the relay will be able to switch one conductor into two different position, as your post illustrated was needed for this user.

Thanks for the update.
REW