Timer suggestion anyone?

[ironhat]

I'm going to hang a box fan from the ceiling of my shop as an air purifier. I'm hanging it upside-down so that the speed control will be accessable but I'd like to wire in a timer. What should I be looking for? Since the 110vAC is on the ceiling the plug-in timers aren't going to work and I don't want the redundancy on a daily basis anyway. I'm not quite sure what I'm looking for so I thought that someone might offer a short-cut to the answer.

TIA!

[leehljp]

I'm going to hang a box fan from the ceiling of my shop as an air purifier. I'm hanging it upside-down so that the speed control will be accessable but I'd like to wire in a timer. What should I be looking for? Since the 110vAC is on the ceiling the plug-in timers aren't going to work and I don't want the redundancy on a daily basis anyway. I'm not quite sure what I'm looking for so I thought that someone might offer a short-cut to the answer.
TIA!

Since you don't want "plug in" and you don't want "redundancy on a daily basis", even a computer controlled "on and off" will require input according to your specific timing/use. This would be overkill. the fact that you want a "timer" but do not want anything with specific timing - i.e. you want it at random according to when you need it - that suggests timing only according to your own needs. In this case, it seems to me that your choices are one of six things:

A. A switch similar to the DC switches for table saws that automatically trigger DC systems to turn on;

B. A switch that turns on the fan as you turn on the lights;

C. On and off sensor that works when someone walks into the room. These are available with adjustable timing if I remember correctly. This could be wired to not function unless the lights are on. In this case the lights could stay on but the fan would only operate as long as someone was in the room.

D. Manual: If the fan switch is too high or not where you have ready access - We have a type of extension cord here with the switch on the end. Since you only want the fan on when you want it, the switch is at the end of a 6 to 8 ft cord.

E. Remote Switch

F. Mind reading switch.

[sparkeyjames]

Find a fan with a remote control. Yes they exist. I have a 2 fan window model.

[LCHIEN]

I use this electromechanical "spring-wound bypass timer". You frequently see them for bathroom ventilation fans so you can clear the humidity out after taking a shower.

http://www.intermatic.com/Default.as...6&cid=53&did=5



Mine is I think 12 hours and cost about $10. You can mount them in a wall bx for switches. You turn it to the amount of time you want it to run, I usually turn mine to several hours when I start cutting - I want it to keep clearing the suspended dust out of the air for an hour or two or three after I finish. You can override it turn it more or less or turn it off.

Mine I just mounted in a duplex box with an power cord and a duplex outlet in the second slot. Then I plug the air cleaner into it.

you can figure how long you want it to run after you leave the shop by taking your shop volume V in cubic feet (LxWxH) and the Air cleaner flow rate R in CFM and assumin you want to circulate the entire air thru it 6 times or more (assuming some air goes thru it more times and some less due to proximity and randomness) then you want to run it for at least 6 x V / R.
If your shop is 20 x 20 with 8 ft ceilings then V=3200
If your air cleaner is rated 500 CFM
then you need to run it at least 6 x 3200 / R or 38 minutes.

[master53yoda]

I use a motion sensor that way it is on if i'm in the shop

[shoottx]

I use a motion sensor that way it is on if i'm in the shop

That would mean it would have to sense motion. As cluttered as my shop is I am not sure there would be enough motion

[ironhat]

It's looking like I'm going to have to run an extension cord across the ceiling and down to a wall recepticle to simplify things. I definitely want the fan to run longer than just while I'm in there. Loring, thanks for the formula. This is an ooooold box fan and I don't see a CFM rating on it. I'll have to research online to see at what CFM they typically run. Thanks all!

[Mr__Bill]

How about an X10 appliance module and the computer interface. You can set up a very complicated schedule. As a bonus you can get more modules and control the Christmas lights and anything else.


X10 products



Bill, on the Sunny Oregon Coast

[master53yoda]

That would mean it would have to sense motion. As cluttered as my shop is I am not sure there would be enough motion

they sense a change in infrared with in there scan range my shop lights as well as the fan operate of the sensor. the range is about 25' any change in the infrared will trigger it. The sensor also has a timer built in that can be set for 5 to 30 minutes . Mine is set at 20 minutes I have never had it shut down will I'm in the shop. It might be possible if you where sitting at the lathe maybe.

[ironhat]

Hey Art, are those switches readily available at the box store or is it more of an electrical supply house type item? Now that you mention the variable 'on' period you have my attention.

[Tom Slick]

Basic adjustable motion detectors that replace wall switches are available at the box stores. more high tech, stand alone type units are sold at electrical supply houses.

they work well, the better ones don't need to "see" you to sense you.

[eezlock]

timer suggestion anyone?

I was thinking about your "timer " sugestion and came up with an idea.
Why not wire the overhead box that the fan will plug into, make it a switched outlet controlled by a timer. What I'm saying is this....wherever
you turn on the lights for the room, install another switch box beside it,
make this switch a single pole timer mounted in the box instead of a regular
switch? You can buy a single pole, rotary switch with plate, cover and knob
at an electrical supply house. You will have to tell them the lenght of time
you want the timer to stay on....longer run time may make it cost more money but that is it. Try this and see if that is what you want.....eezlock

[master53yoda]

Hey Art, are those switches readily available at the box store or is it more of an electrical supply house type item? Now that you mention the variable 'on' period you have my attention.

they are available at lowes or home depot. It is the same switch that you would replace your light switch with

[ironhat]

I was thinking about your "timer " sugestion and came up with an idea.
Why not wire the overhead box that the fan will plug into, make it a switched outlet controlled by a timer. What I'm saying is this....wherever
you turn on the lights for the room, install another switch box beside it,
make this switch a single pole timer mounted in the box instead of a regular
switch? You can buy a single pole, rotary switch with plate, cover and knob
at an electrical supply house. You will have to tell them the lenght of time
you want the timer to stay on....longer run time may make it cost more money but that is it. Try this and see if that is what you want.....eezlock

I like that idea. My downside is that I don't know how I'd get the hot wire from one of the wall outlets, behind the OSB walls and then under the foamboard ceiling which is nailed in place. Maybe a conduit up the wall and into the joist space and use a snake to pull the wire to the new hole in the foamboard for the box and timer. I'm thinking on it. Thanks for the help.