attic fan electrical connection

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  #1  
Old 09-10-04, 06:41 PM
William521
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attic fan electrical connection

Hello, I have a question regarding how to properly hook up an attic fan to a thermostat and also a 24 hour programmable timer. The problem is that both of these need to be hooked up on the hot (black) wire and if I do this and the thermostat and the timer are on at the same time I will have problems or atleast only the circuit breaker will go off. I was thinking mayby they made a relay switch or something for this but I have searched all over the net for some information on how to properly do this but all to no avail . Any suggestions and/or helpful knowledge will be very much appreciated.
 
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  #2  
Old 09-10-04, 06:54 PM
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I'm not sure why you want both a timer and a thermostat.I would skip the timer and control the fan by the thermostat. Properly set, it comes on at a certain high temp in the attic - say 135 and goes off when the attic is cooler - say 90.

You could feed power through a timer to the thermostat and then to the fan if you want. It's no different than an ON/OFF switch controlling the power to the thermostat and then to the fan. But why make an easy job harder?
 
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Old 09-10-04, 06:59 PM
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There won't be any problem is both the thermostat and timer are on at the same time. It's just two switches in parallel.
 
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Old 09-10-04, 07:23 PM
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What John said, no problem, as long as you are feeding from one circuit and one circuit only. You absolutely cannot mix circuits and do a parallel feed.
 
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Old 09-10-04, 07:44 PM
William521
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Well I suppose I should clarify more deeply. I live in north dakota where as you know it goes from one extreme to the other (hot to cold). The thermostat was to control the temparature during the summer where when it got really hot it would turn on and off by itself while the timer was for the winter where I need to have it running every know and then for good ventilation and also to prevent ice damning from occuring (I have). The thermostat switch will be off all winter long though so I can't exact run it parallel with it going from the circuit breaker to the timer then to the thermostat and then to the fan. As you see even if the timer was on the fan couldn't go on because the themostat would be off all the time during the winter. So I figured I would have to have 2 separate hot lines running to the fan one on the thermostat and another on the timer switch. If I do that then I could control it independently with both but as you can see if both where on by accident during the summer by chance then there would be a popped circuit. I hope that makes sense. I did read an article that said you could solve the thermostat problem by adding a timer to control it during the winter but they never said how to do this . I suppose I could just put it on a timer and have the fan turn on and off during the summer like I have during the winter but I figured a thermostat would save me some money on electrical bills. Sorry for the length of the reply gyes. I hope this makes sense. Much thanks as always. Will
 
  #6  
Old 09-10-04, 08:04 PM
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What you just described is a serial connection. John and I suggested a parallel connection.

Run the power to the input of the programmable timer and to the input ofd the thermostat. Run each output to the fan. This would be a parallel connection, meaning there are two paths for power to follow to the fan.

If you want to select between the two, then use a three way switch. Run the power to the three way switch. Connect the power to the common side of three way. Connect one traveler to the input of the timer and the other traveller to the input of the thermostat. With this setup only one path will have power at a time. Of course the programmable timer will get messed up (wrong time) due to lack of power.
 
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Old 09-10-04, 08:09 PM
William521
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Hey that's fine . I will only have to reset it once every year anyway . Thanks abunch. Will
 

Last edited by William521; 09-10-04 at 10:24 PM.
  #8  
Old 09-11-04, 07:41 AM
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but as you can see if both where on by accident during the summer by chance then there would be a popped circuit
No I cannot see. Is this from actual experience, or is this still a theoretical problem. If you have actually tripped the breaker, you have a more fundamental mistake. Two switches (one a thermostat and one a timer switch) properly wired in parallel cannot cause this problem, even if both are on at the same time.
 
  #9  
Old 09-11-04, 10:15 AM
William521
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I'm sorry John. Please forgive me for being confuzed . So if I run 2 hot wires from the circuit breaker and connect one to the thermostat and another to the timer and then connect both of them together with it then running to the attic fan wouldn't that be like taking two hot wires and connecting them together because essentially that is what I would be doing if both the thermostat and timer where on at the same time. Or perhaps your saying there is something built into thermostats and timers to solve this problem. Please clarify if you don't mind. Thanks as always for the help . Will
 
  #10  
Old 09-11-04, 10:20 AM
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Yes, that is exactly what I am saying. There is absolutely nothing wrong with connecting two hot wires from the same 120-volt circuit together. I'm confused. What problem do you forsee?
 
  #11  
Old 09-11-04, 11:40 AM
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As long as you use the same circuit there is no problem. What would happen if both are on on at the same time is that some of the electricity would flow through each part of the circuit. This is not a problem.

There would be a problem if you mixed circuits together, especially if you had circuits from opposite sides of your incoming service.
 
  #12  
Old 09-11-04, 11:47 AM
William521
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I understand know. I quess I should take a basic course on the way how electricity flows. great help though.
 
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